JP2004032747A - Receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a receiver for transmitting more information in the same frequency band by solving the problem that a transmission information amount cannot be increased when a frequency band is limited in a transmitter for transmitting a digital signal. <P>SOLUTION: The receiver for receiving a terrestrial digital broadcast signal and a satellite digital broadcast signal is provided with a first demodulating unit for demodulating the satellite digital broadcast signal, and a second demodulating unit for demodulating the terrestrial digital broadcast signal. The terrestrial digital broadcast signal contains a first data row and a second data row. The receiver is provided with a first error correction decoding unit for applying a first error correction decoding processing to the second data row, and a second error correction decoding unit for deinterleaving the output of the first error correction decoding unit and applying second error correction decoding processing to the deinterleaved output. <P>COPYRIGHT: (C)2004,JPO

Description

【０１６６】
第２データ列の誤り率をＰｅ２とすると
【０１６７】
【数２】

【０１６８】
となる。
次に３６ＳＲＱＡＭもしくは３２ＳＲＱＡＭのエラーレートを計算する。図１００は３６ＳＲＱＡＭの信号ベクトル図である。第１象限において３６ＱＡＭの信号点間距離は２δであると定義する。
【０１６９】
３６ＱＡＭの信号点８３ａは座標軸よりδの距離にある。この信号点８３ａは３６ＳＲＱＡＭになると信号点８３の位置にシフトし、座標軸よりｎδの距離となる。各々の信号点はシフトして信号点８３、８４、８５、８６、９７、９８、９９、１００、１０１となる。９ヶの信号点からなる信号点群９０を一つの信号点とみなして、変形４ＰＳＫ受信機で受信し、第１データ列Ｄ_１のみー再生した　場合の誤り率をＰｅ１とし、信号点群９０の中の９個の信号点を各々弁別し、第２データ列Ｄ_２を再生した場合の誤り率をＰｅ２とすると
【０１７０】
【数３】

【０１７１】
となる。
この場合、図１０１のＣ／Ｎ〜エラーレート図はエラーレートＰｅと伝送系のＣ／Ｎとの関係を計算した一例を示す。曲線９００は比較のため従来方式の３２ＱＡＭのエラーレートを示す。直線９０５はエラーレートが１０の−１．５乗の直線を示す。本発明のＳＲＱＡＭのシフト量ｎを１．５とした場合の第１階層Ｄ_１のエラーレートは曲線９０１ａとなり、エラーレートが１０^−１．５において曲線　９００の３２ＱＡＭに対してＣ／Ｎ値が５ｄＢ下がってもＤ_１は同等のエラーレ　ートで再生できるという効果がある。
【０１７２】
次にｎ＝１．５の場合の第２階層Ｄ_２のエラーレートは曲線９０２ａで示され　る。エラーレートが１０^−１．５において、曲線９００に示す３２ＱＡＭに比べてＣ／Ｎを２．５ｄＢ上げないと同等のエラーレートで再生できない。曲線９０１ｂ、曲線９０２ｂはｎ＝２．０の場合のＤ_１、Ｄ_２を示す。曲線９０２ＣはＤ_２を示　す。これをまとめると、エラーレートが１０の−１．５乗の値において２２ｎ＝　１．５、２．０、２．５の時、３２ＱＡＭに比べて各々Ｄ_１は５、８、１０ｄＢ　改善され、Ｄ_２は２．５ｄＢ劣化する。
【０１７３】
３２ＳＲＱＡＭの場合にシフト量ｎを変化させた場合に所定のエラーレートを得るのに必要な第１データ列Ｄ_１と第２データ列Ｄ_２のＣ／Ｎ値を図１０３のシフト量ｎとＣ／Ｎの関係図で示す。図１０３をみると明らかなように、ｎが０．８以上であれば、階層伝送つまり第１データ列Ｄ_１と第２データ列Ｄ_２の伝送に必要なＣ／Ｎ値の差が生まれ、本発明の効果が生じることがわかる。従って、３２ＳＲＱＡＭの場合ｎ＞０．８５の条件下で効果がある。１６ＳＲＱＡＭの場合のエラーレートは図１０２のＣ／Ｎとエラーレートの関係図のようになる。
【０１７４】
図１０２において曲線９００は１６ＱＡＭのエラーレートを示す。曲線９０１ａ、９０１ｂ、９０１ｃは各々第１データ列Ｄ_１のｎ＝１．２、１．５、１．８　の　場合のエラーレートを示す。曲線９０２ａ、９０２ｂ、９０２ｃは各々第２　データ列Ｄ_２のｎ＝１．２、１．５、１．８の場合のエラーレートを示す。
【０１７５】
図１０４のシフト量ｎとＣ／Ｎの関係図は１６ＳＲＱＡＭの場合にシフト量ｎを変化させた場合に特定のエラーレートを得るのに必要な第１データ列Ｄ_１と第　２データ列Ｄ_２のＣ／Ｎの値を示したものである。図１０４から明らかなように　１６ＳＲＱＡＭの場合ｎ＞０．９であれば本発明の階層伝送が可能となることがわかる。以上からｎ＞０．９なら階層伝送が成立する。
【０１７６】
ここで具体的にデジタルＴＶの地上放送に本発明のＳＲＱＡＭを適用した場合の一例を示す。図１０５は地上放送時の送信アンテナと受信アンテナとの距離と、信号レベルとの関係図を示す。曲線９１１は送信アンテナの高さが１２５０ｆｔの場合の受信アンテナの信号レベルを示す。まず、現在検討が進められているデジタルＴＶ放送方式において要求される伝送系の要求エラーレートを１０の−１．５乗と仮定する。領域９１２はノイズレベルを示し、点９１０はＣ／Ｎ＝１５ｄＢになる地点で従来方式の３２ＱＡＭ方式の受信限界点を示す。このＬ＝６０ｍｉｌｅの地点においてデジタルのＨＤＴＶ放送が受信できる。
【０１７７】
しかし、天候等の受信条件の悪化により時間的にＣ／Ｎは５ｄＢの巾で変動する。Ｃ／Ｎ位が閾値に近い受信状況においてＣ／Ｎが低下すると急激にＨＤＴＶの受信が不能となる問題を持っている。また地形や建築物の影響により、少なくとも１０ｄＢ程度の変動が見込まれ、６０ｍｉｌｅの半径内の全ての地点で受信できる訳でない。この場合、アナログと違いデジタルの場合完全に映像が伝送できない。従って従来のデジタルＴＶ放送方式のサービスエリアは不確実なものであった。
【０１７８】
一方、本発明の３２ＳＲＱＡＭもしくは図６８に示す８−ＶＳＢの場合、前述のように図１３３、図１３７の構成により３層の階層となる。第１ー１階層Ｄ_１−１でＭＰＥＧレベルの低解像度ＮＴＳＣ信号を送り、第１−２階層Ｄ_１−２でＮＴＳＣ等の中解像度ＴＶ成分を送り、第２階層Ｄ_２でＨＤＴＶの高域成分を送ることができ　る。例えば図１０５において第１−２階層のサービスエリアは点９１０ａのように　７０ｍｉｌｅ地点まで拡大し、第２階層は９１０ｂのように、５５ｍｉｌｅ地点まで後退する。図１０６の３２ＳＲＱＡＭのサービスエリア図はこの場合のサービスエリアの面積の違いを示す。図１０６はコンピュータシミュレーションを行い、図５３のサービスエリア図をより具体的に計算したものである。図１０６において領域７０８、７０３ｃ、７０３ａ、７０３ｂ、７１２は各々従来方式の３２ＱＡＭのサービスエリア、第１−１階層Ｄ_１−１のサービスエリア、第１−２階層Ｄ_１−２のサービスエリア、第２階層Ｄ_２のサービスエリア、隣接アナログ局のサービス　エリアを示す。このうち、従来方式の３２ＱＡＭのサービスエリアのデータは従来開示されているデータを用いている。
【０１７９】
従来方式の３２ＱＡＭの放送方式では名目上６０マイルのサービスエリアを設定できる。しかし、実際は天候や地形の条件変化により受信限界地近傍においてきわめて受信状態が不安定であった。
【０１８０】
しかし、本発明の３６ＳＲＱＡＭを用い、第１−１階層Ｄ_１−１でＭＰＥＧ１グレードの低域ＴＶ成分を第１−２階層Ｄ_１−２でＮＴＳＣグレードの　中域ＴＶ成分を送信　し、第２階層Ｄ_２でＨＤＴＶの高域ＴＶ成分を送信することにより、図１０６の　ように高解像度グレードのＨＤＴＶのサービスエリアの半径が５マイル縮小するものの、中解像度グレードのＥＤＴＶのサービスエリアの半径が１０マイル以上拡大し、低解像度のＬＤＴＶのサービスエリアは１８マイル拡大するという効果が生まれる。図１０７はシフトファクターｎもしくはｓ＝１．８の場合のサービスエリアを示し、図１３５は図１０７のサービスエリアを面積で示したものです。
【０１８１】
このことにより、一番目に従来方式では、受信条件が悪い地域において存在した受信不能地域においても本発明のＳＲＱＡＭ方式を適用することにより、少なくとも設定したサービスエリア内においては殆んどの受信機で中解像度もしくは低解像度グレードでＴＶ放送を受信できるような送信が可能となる。従って通常のＱＡＭでは発生するビルかげや低地の受信不能領域と隣接アナログ局からの妨害を受けるような地域において本発明を用いることによりこの受信不能地域が大巾に減少し、これに伴い実質的な受信者数を増大できる。
【０１８２】
二番目に従来のデジタルＴＶ放送方式では高価なＨＤＴＶ受信機と受像機をもつ受信者しか放送を受信できなかったため、サービスエリア内においても一部の受信者しか視聴できなかった。しかし本発明では従来のＮＴＳＣやＰＡＬやＳＥＣＡＭ方式の従来型のＴＶ受像機を持っている受信者もデジタル受信機のみを増設することにより、デジタルＨＤＴＶ放送の番組をＮＴＳＣグレードもしくはＬＤＴＶグレードではあるが受信可能になるという効果がある。このため受信者はより少ない経済的負担で番組が視聴できる。
【０１８３】
同時に総受信者数が増えるためＴＶ送信者側はより多くの視聴者を得られるためＴＶ事業としての経営がより安定するという社会的効果が生まれる。
【０１８４】
三番目に中低解像度グレードの受信地域の面積はｎ＝２．５の場合、３６％従来方式に比して拡大する。拡大に応じて受信者が増える。サービスエリアの拡大と受信者数の増加によりその分ＴＶ事業者の事業収入が増大する。このことによりデジタル放送の事業リスクが減りデジタルＴＶ放送の普及が早まることが期待できる。
【０１８５】
さて、図１０７の３２ＳＲＱＡＭのサービスエリア図にみるように、ｎもしくはｓ＝１．８の場合も同様の効果が得られる。シフト値ｎを変更することにより　、各々の放　送局がＨＤＴＶ受像機とＮＴＳＣＴＶ受像機の分布状況等の地域特　有の条件や事情に応じてｎを変更し、ＳＲＱＡＭのＤ_１とＤ_２のサービスエリア７０３ａと７０３ｂを最適な条件に設定することにより、受信者は最大の満足を放送局は最大の受信者数を得ることができる。
【０１８６】
この場合
ｎ＞１．０
の時、以上のような効果が得られる。
従って、３２ＳＲＱＡＭの場合ｎは
１＜ｎ＜５
となる。
同様にして１６ＳＲＱＡＭの場合ｎは
１＜ｎ＜３
となる。
【０１８７】
この場合図９９、図１００のようにシフトさせて第１と第２階層を得るＳＲＱＡＭ方式において、１６ＳＲＱＡＭ、３２ＳＲＱＡＭ、６４ＳＲＱＡＭにおいてｎが１．０以上であれば、地上放送において本発明の効果が得られる。
【０１８８】
実施例では映像信号を伝送した場合を説明したが音声信号を高域部もしくは高分解能部と低域部もしくは低分解能部にわけ、それぞれ第２データ列、第１データ列として本発明の伝送方式を用いて伝送すると、同様の効果が得られる。
【０１８９】
ＰＣＭ放送、ラジオ、携帯電話に用いるとサービスエリアが広がるという効果がある。
【０１９０】
また、実施例３では図１３３に示すように時間分割多重（ＴＤＭ）方式と組み合わせてＴＤＭによるサブチャンネルを設け、ＥＣＣ　Ｅｎｃｏｄｅｒ７４３ａ　とＥＣＣ　Ｅｎｃｏｄｅｒ７４３ｂに示すように２つのサブチャンネルのエラー訂正のコードゲインを差別化することにより、各サブチャンネルの閾値に差をつけ多値型伝送のサブチャンネルを増やすことができる。この場合、図１３７に示すように４ＶＳＢ、８ＶＳＢ、１６ＶＳＢのＶＳＢ−ＡＳＫ信号の２つのサブチャンネルのＴｒｅｌｌｉｓ　Ｅｎｃｏｄｅｒ等のＥＣＣエンコーダーのＣｏｄｅ　ｇａｉｎｓを変えてもよ　い。詳しい説明は後述する実施例６の図１３１の説明と同じであるため省略する。
【０１９１】
図１３１のブロック図は磁気記録再生装置で図１３７のブロック図は伝送装置である。伝送装置の送信機のＵｐ　ｃｏｎｖｅｒｔｅｒ；受信機のＤｏｗｎ　ｃｏｎｖｅｒｔｏｒを各々、磁気記録再生装置の磁気ヘッド記録信号増巾回路、磁気ヘッド再生信号増巾回路に置き換えることにより両者は全く、同じ構成になることがわかる。従って、変復調部の構成と動作は全く同じである。同様にして図８４の磁気記録再生システムは図１５６の伝送システムと同じ構成であることがわかる。また構成を簡単にしたい場合は、図１５７、更に簡単にしたい場合は図１５８のような構成にすることができる。
【０１９２】
図１０６のシミュレーションにおいては第１−１サブチャンネルＤ_１−１と第１−２サ　ブチャンネルＤ_１−２と間に５ｄＢのＣｏｄｉｎｇ　Ｇａｉｎの差をつけた場合を示している。ＳＲＱＡＭは“Ｃ−ＣＤＭ”とよばれる本発明の信号点符号分割多重方式（Ｃｏｎｓｔｅｌｌａｔｉｏｎ−Ｃｏｄｅ　Ｄｉｖｉｓｉｏｎ　Ｍｕｌｔｉｐｌｅｘ）をｒｅｃｔａｎｇｌｅ−ＱＡＭに応用したものである。Ｃ−ＣＤＭはＴＤＭやＦＤＭと独立した多重化方式である。コードに対応した信号点コードを分割することにより、サブチャンネルを得る方式である。この信号点の数を増やすことによりＴＤＭやＦＤＭにはない伝送容量の拡張性が得られる。このことは従来機器とほぼ完全な互換性を保ちながら実現する。このようにＣ−ＣＤＭは優れた効果をもつ。
【０１９３】
さて、Ｃ−ＣＤＭとＴＤＭを組み合わせた実施例を用いたが周波数分割多重方式（ＦＤＭ）と組み合わせても、同様の閾値の緩和効果が生まれる。例えば、ＴＶ放送に用いた場合、図１０８のＴＶ信号の周波数分布図に示すようになる。従来のアナログ放送例えばＮＴＳＣ方式の信号はスペクトラム７２５のような周波数分布をしている。一番大きな信号は映像のキャリア７２２である。カラーのキャリア７２３や音声のキャリア７２４はそれほど大きくない。お互いの干渉を避けるため、デジタル放送の信号をＦＤＭにより２つの周波数に分ける方法がある。この場合、図に示すように映像のキャリア７２２を避けるように第１キャリア７２６と第２キャリア７２７に分割し各々第１信号７２０と第２信号７２１を送ることにより干渉は軽減できる。第１信号７２０により低解像度ＴＶ信号を大きな出力で送信し、第２信号７２１により高解像度信号を小さな出力で送信することにより、妨害を避けながらＦＤＭによる階層型放送が実現する。
【０１９４】
ここで図１３４に従来の方式３２ＱＡＭを用いた場合の図を示す。サブチャンネルＡの方が出力が大きいため、閾値はＴｈｒｅｓｈｏｌｄ１はサブチャンネルＢの閾値Ｔｈｅｓｈｏｌｄ２に比べて４〜５ｄＢ小さくて良い。従って４〜５ｄＢ閾値の差をもつ２　層の階層型放送が実現する。しかし、この場合、受信信号のレベルがＴｈｅｓｈｏｌｄ２　以下になると情報量の大巾を占める第２信号７２１ａの斜線で示す信号の全部が全く受信できなくなり、情報量の少ない第１信号７２０ａしか受信できなくなり、第２階層では画質の著しく悪い画像しか受信できない。
【０１９５】
しかし、本発明を用いた場合、図１０８に示すようにまず第１信号７２０にＣ−ＣＤＭにより得られる３２ＳＲＱＡＭを用いてサブチャンネル１ｏｆＡを追加する。この閾値の低いサブチャンネル１ｏｆＡにさらに低解像度の成分をのせる。第２信号７２１を３２ＳＲＱＡＭとし、サブチャンネル１ｏｆＢの閾値を第１信号の閾値Ｔｈｅｒｓｈｏｌｄ２に合わせる。すると信号レベルがＴｈｒｅｓｈｏｌｄ−２に下がっ　ても受信できなくなる。領域は斜線で示す第２信号部７２１ａのみとなり、サブチャンネル１ｏｆＢとサブチャンネルＡが受信できるため伝送量はあまり減らない。従って第２階層においても画質の良い画像がＴｈ−２の信号レベルにおいても受信できるという効果がある。
【０１９６】
一方のサブチャンネルに普通解像度の成分を伝送することにより、さらに階層の数が増え、低解像度のサービスエリアが拡がるという効果も生まれる。この閾値の低いサブチャンネルに音声情報叉は同期情報、各データのヘッダー等の重要な情報を入れることにより、この重要な情報は確実に受信できるため安定した受信が可能となる。第２信号７２１に、同様の手法を用いると、サービスエリアの階層が増える。ＨＤＴＶの走査線が１０５０本の場合、５２５本に加えて、Ｃ−ＣＤＭにより７７５本のサービスエリアが加わる。
【０１９７】
このようにして、ＦＤＭとＣ−ＣＤＭを組み合わせるとサービスエリアが拡大するという効果が生まれる。この場合ＦＤＭにより２つのサブチャンネルを設けたが３つの周波数に分割し、３つのサブチャンネルを設けてもよい。
【０１９８】
次にＴＤＭとＣ−ＣＤＭを組み合わせて妨害を避ける方法を述べる。図１０９に示すようにアナログＴＶ信号には水平帰線部７３２と映像信号部７３１がある。水平帰線部７３２の信号レベルが低いことと、この期間中は妨害を受けても画面に出力されないことを利用する。デジタルＴＶ信号の同期をアナログＴＶ信号と合わせ、水平帰線部７３２の期間の水平帰線同期スロット７３３、７３３ａに重要なデータ、例えば同期信号等を送るか高い出力で多くのデータを送ることができる。このことにより、妨害を増やさないでデータ量を増やしたり出力を上げられるという効果がある。なお垂直帰線部７３５、７３５ａの期間に同期させて垂直帰線同期スロット７３７、７３７ａを設けても同様の効果が得られる。
【０１９９】
図１１０はＣ−ＣＤＭの原理図である。叉、図１１１は１６ＱＡＭの拡張版のＣ−ＣＤＭのコード割り当て図を示し、図１１２は３２ＱＡＭ拡張版のコード割り当て図を示す。図１１０、１１１に示すように２５６ＱＡＭは第１、２、３、４層７４０ａ、７４０ｂ、７４０ｃ、７４０ｄの４つの層に分けられ、各々４、１６、６４、２５６ケのセグメントを持つ。第４層７４０ｄの２５６ＱＡＭの信号点コードワード７４２ｄは８ｂｉｔの“１１１１１１１１”である。これを２ｂｉｔずつ４つのコードワード７４１ａ、７４１ｂ、７４１ｃ、７４１ｄに分割し、各第１、２、３、４層７４０ａ、７４０ｂ、７４０ｃ、７４０ｄの信号点領域７４２ａ、７４２ｂ、７４２ｃ、７４２ｄに各々“１１”、“１１”“１１”、“１１”を割り当てる。かくして、２ｂｉｔずつのサブチャンネルすなわち、サブチャンネル１、サブチャンネル２、サブチャンネル３、サブチャンネル４ができる。これを信号点符号分割多重方式という。図１１１は１６ＱＡＭの拡張版の具体的な符号配置を示し、図１１２は３６ＱＡＭの拡張版を示す。Ｃ−ＣＤＭ多重化方式は独立したものである。従って従来の周波数分割多重方式（ＦＤＭ）や時間分割多重方式（ＴＤＭ）と組み合わせることにより、更にサブチャンネルが増やせるという効果がある。こうしてＣ−ＣＤＭ方式により新しい多重化方式を実現できる。Ｒｅｃｔａｎｇｌｅ−ＱＡＭを用いてＣ−ＣＤＭを説明したが、信号点をもつ　他の変調方式例えば他の形のＱＡＭやＰＳＫ、ＡＳＫ、そして周波数領域を信号点とみなし、ＦＳＫも同様に多重化できる。
【０２００】
例えば前述の８ＰＳ−ＡＰＳＫのサブチャンネル１のエラーレートは
【０２０１】
【数４】

【０２０２】
サブチャンネル２のＰｅ_２−８は
【０２０３】
【数５】

【０２０４】
１６−ＰＳ−ＡＰＳＫ（ＰＳ型）のサブチャンネル１のエラーレートは
【０２０５】
【数６】

【０２０６】
サブチャンネル２のエラーレートは
【０２０７】
【数７】

【０２０８】
サブチャンネル３のエラーレートは
【０２０９】
【数８】

【０２１０】
で現せる。
（実施例４）
以下本発明の第４の一実施例について図面を参照しながら説明する。
【０２１１】
図３７は実施例４の全体のシステム図である。実施例４は実施例３で説明した伝送装置を地上放送に用いたもので、ほぼ同じ構成、動作である。実施例３で説明した図２９との違いは、送信用のアンテナ６ａが地上伝送用アンテナになっている点と各受信機の各々のアンテナ２１ａ，３１ａ，４１ａが地上伝送用アンテナになっている点のみである。その他の動作はまったく同じであるため重復する説明を省略する。衛星放送と違い、地上放送の場合は送信アンテナ６ａと受信機との距離が重要となる。遠距離にある受信機は到達電波が弱くなり、従来の送信機で単に多値ＱＡＭ変調した信号では全く復調できず番組を視聴することはできない。
【０２１２】
しかし本発明の伝送装置を用いた場合、図３７のように遠距離にアンテナ２２ａがある第１受信機２３は変形６４ＱＭＡ変調信号もしくは変形１６ＱＡＭ変調信号を受信して４ＰＳＫモードで復調し第１データ列のＤ１信号を再生するのでＮＴＳＣのＴＶ信号が得られる。従って電波が弱くても中解像度でＴＶ番組を視聴できる。
【０２１３】
次に中距離にアンテナ３２ａがある第２受信機３３では到達電波が充分強いため変形１６または６４ＱＡＭ信号から第２データ列と第１データ列を復調できＨＤＴＶ信号が得られる。従って同じＴＶ番組をＨＤＴＶで視聴できる。
【０２１４】
一方、近距離にあるか超高感度のアンテナ４２ａをもつ第３受信機４３は電波が変形６４ＱＡＭ信号の復調に充分な強度であるため第１、２、３、データ列Ｄ１，Ｄ２，Ｄ３を復調し超高解像度ＨＤＴＶ信号が得られる。同じＴＶ番組を大型映画と同じ画質のスーパーＨＤＴＶで視聴できる。
【０２１５】
この場合の周波数の配置方法は図３４、図３５、図３６の図を用いて時間多重配置を周波数配置に読み代えることにより説明できる。図３４のように１から６チャンネルまで周波数がわり割当られている場合Ｄ１信号にＮＴＳＣのＬ１を第１チャンネルに、Ｄ２信号の第１チャンネルのＭ１にＨＤＴＶの差分情報を、Ｄ３信号の第１チャンネルのＨ１に超高解像度ＨＤＴＶの差分情報を配置することによりＮＴＳＣとＨＤＴＶと超解像度ＨＤＴＶを同一のチャンネルで送信することができる。また図３５、図３６のように他のチャンネルのＤ２信号やＤ３信号を使用することが許可されれば、より高画質のＨＤＴＶや超高解像度ＨＤＴＶが放送できる。
【０２１６】
以上のように互いに両立性のある３つのデジタルＴＶ地上放送を１つのチャンネルもしくは他のチャンネルのＤ２，Ｄ３信号領域を使用して放送できるという効果がある。本発明の場合、同じチャンネルで同じ内容のＴＶ番組を中解像度であれば、より広範囲の地域で受信できるという効果がある。
【０２１７】
デジタル地上放送として１６ＱＡＭを用いた６ＭＨｚの帯域のＨＤＴＶ放送等が提案されている。しかしこれらの方式はＮＴＳＣとの両立性がないため同じ番組をＮＴＳＣの別チャンネルで送信するサイマルキャスト方式の採用が前提となっている。また１６ＱＡＭの場合、伝送できるサービスエリアが狭くなることが予想されている。本発明を地上放送に用いることにより別にチャンネルを設ける必要がなくなるだけでなく、遠距離の受信機でも中解像度で番組を視聴できるため放送サービスエリアが広いという効果がある。
【０２１８】
図５２は従来提案されている方式のＨＤＴＶのデジタル地上放送時の受信妨害領域図を示すもので、従来提案されている方式を用いたＨＤＴＶのデジタル放送局７０１からＨＤＴＶの受信できる受信可能領域７０２と隣接するアナログ放送局７１１の受信可能領域７１２を示している。両者の重複する重複部７１３においてはアナログ放送局７１１の電波妨害により、少なくともＨＤＴＶを安定して受信することができなくなる。
【０２１９】
次に図５３は本発明による階層型の放送方式を用いた場合の受信妨害領域図を示す。本発明は従来方式と同一の送信電力の場合、電力利用効率が低いため、ＨＤＴＶの高解像度受信可能領域７０３は上述の従来方式の受信可能領域７０２より若干狭くなる。しかし、従来方式の受信可能領域７０２より広い範囲のデジタルＮＴＳＣ等の低解像度受信可能領域７０４が存在する。以上の２つの領域から構成される。この場合のデジタル放送局７０１からアナログ放送局７１１への電波妨害は図５２で示した従来方式と同レベルである。
【０２２０】
この場合、本発明ではアナログ放送局７１１からのデジタル放送局７０１への妨害は３つの領域が存在する。１つはＨＤＴＶもＮＴＳＣも受信できない第１妨害領域７０５である。第２は妨害を受けるもののＮＴＳＣを妨害前と同様に受信できる第２妨害領域７０６で一重斜線で示す。ここではＮＴＳＣはＣ／Ｎが低くても受信可能な第１データ列を使用しているためアナログ局７１１の電波妨害によりＣ／Ｎが低下しても妨害の影響範囲は狭い。
【０２２１】
第３は妨害前はＨＤＴＶが受信できていたが妨害後はＮＴＳＣのみ受信できる第３妨害領域７０７で２重斜線で示す。
【０２２２】
以上のようにして従来方式より妨害前のＨＤＴＶの受信領域は若干狭くなるが、ＮＴＳＣを含めた受信範囲は広くなる。さらにアナログ放送局７１１からの妨害により従来方式ではＨＤＴＶが妨害により受信できなかった領域においてもＨＤＴＶと同一の番組をＮＴＳＣで受信可能となる。こうして番組の受信不能領域が大巾に削減するという効果がある。この場合、放送局の送信電力を若干増やすことにより、ＨＤＴＶの受信可能領域は従来方式と同等になる。さらに従来方式では全く番組を視聴できなかった遠方地域や、アナログ局との重複地域において、ＮＴＳＣＴＶの品位で番組が受信できる。
【０２２３】
また２階層の伝送方式を用いた例を示したが、図７８の時間配置図のように３階層の伝送方式を用いることもできる。ＨＤＴＶをＨＤＴＶ、ＮＴＳＣ、低解像度ＮＴＳＣの３つのレベルの画像に分離し、送信することにより、図５３の受信可能領域は２層から３層に広がり最外層は広い領域となるとともに２階層伝送では全く受信不可能であった第１妨害領域７０５では低解像度ＮＴＳＣＴＶの品位で番組が受信可能となる。以上はデジタル放送局がアナログ放送に妨害を与える例を示した。
【０２２４】
次にデジタル放送がアナログ放送に妨害を与えないという規制条件のもとにおける実施例を示す。現在米国等で検討されている空きチャンネルを利用する方式は、隣接して同じチャンネルを使用する。このため後から放送するデジタル放送は既存のアナログ放送に妨害を与えてはならない。従ってデジタル放送の送信レベルを図５３の条件で送信する場合より下げる必要がある。この場合、従来方式の１６ＱＡＭや４ＡＳＫ変調の場合、図５４の妨害状態図に示すように二重斜線で示した受信不能領域７１３が大きいためＨＤＴＶの受信可能領域７０８は大巾に小さくなってしまう。サービスエリアが狭くなり、その分受信者が減るためスポンサーが減る。従って従来方式では放送事業が経済的に成立しにくいことが予想されている。
【０２２５】
次に図５５に本発明の放送方式を用いた場合を示す。ＨＤＴＶの高解像度受信可能領域７０３は、従来方式の受信可能領域７０８より若干狭くなる。しかし、従来方式より広い範囲のＮＴＳＣ等の低解像度受信可能領域７０４が得られる。一重斜線で示す部分は、同一番組をＨＤＴＶレベルでは受信できないが、ＮＴＳＣレベルで受信できる領域を示す。このうち第１妨害領域７０５においてアナログ放送局７１１からの妨害を受け、ＨＤＴＶも、ＮＴＳＣも両方受信できない。
【０２２６】
以上のように同じ電波強度の場合、本発明の階層型放送ではＨＤＴＶ品位の受信可能地域は若干狭くなる一方で、同一番組をＮＴＳＣＴＶの品位で受信できる地域が増える。このため放送局のサービスエリアが増えるという効果がある。より多くの受信者に番組を提供できる効果がある。ＨＤＴＶ／ＮＴＳＣＴＶの放送事業を、より経済的に安定して成立させることができる。将来デジタル放送受信機の比率が増えた段階ではアナログ放送への妨害規則は緩和されるため電波強度を強くすることができる。この時点でＨＤＴＶのサービスエリアを大きくすることができる。この場合、第１データ列と第２データ列の信号点の間隔を調整することにより図５５で示したデジタルＨＤＴＶＩＮＴＳＣの受信可能地域とデジタルＮＴＳＣの受信可能地域を調整することができる。この場合、前述のように第１データ列に、この間隔の情報を送信することにより、より安定して受信ができる。
【０２２７】
図５６は、将来デジタル放送に切り替えた場合の妨害状況図を示す。この場合、図５２と違い隣接局はデジタル放送を行うデジタル放送局７０１ａとなる。送信電力を増やすことができるため、ＨＤＴＶ等の高解像度受信可能領域７０３はアナログＴＶ放送と同等の受信可能領域７０２まで拡大できる。
【０２２８】
そして両方の受信可能領域の競合領域７１４では互いに妨害を受けるため通常の指向性のアンテナでは番組をＨＤＴＶの品位では再生できないが、受信アンテナの指向性の方向にあるデジタル放送局の番組をＮＴＳＣＴＶの品位で受信できる。また非常に高い指向性のアンテナを用いた場合アンテナの指向性方向にある放送局の番組をＨＤＴＶの品位で受信できる。低解像度受信可能領域７０４は、アナログＴＶ放送の標準の受信可能領域７０２より広くなり、隣接の放送局の低解像度受信可能領域７０４ａの競合領域７１５、７１６ではアンテナの指向性の方向にある放送局の番組がＮＴＳＣＴＶの品位で再生できる。
【０２２９】
さて、かなり将来のデジタル放送の本格普及時期においては規制条件がさらに緩和され、本発明の階層型の多値放送により広いサービスエリアのＨＤＴＶ放送が可能となる。この時点においても、本発明の階層型の多値放送方式を採用するにより従来方式と同程及の広い範囲のＨＤＴＶ受信範囲を確保するとともに従来方式では受信不可能であった遠方地域や競合地域においてもＮＴＳＣＴＶの品位で番組が受信できるため、サービスエリアの欠損部が大巾に減少するという効果がある。
【０２３０】
（実施例５）
実施例５は本発明を振巾変調つまりＡＳＫ方式に用いた場合の実施例である
図５７は実施例５の４値のＶＳＢ−ＡＳＫ信号信号点配置図を示し、４つの信号点７２１、７２２、７２３、７２４をもつ。図６８（ａ）は８値のＶＳＢ信号のＣｏｎｓｔｅｌｌａｔｉｏｎを示す。４値の場合２ｂｉｔのデータ、８値の場合４ｂｉｔのデータを１周期で送ることができる。４ＶＳＢの場合、信号点７２１、７２２、７２３、７２４を例えば００、０１、１０、１１に対応させることができる。
【０２３１】
本発明による多値型伝送を行うために、図５８の４ｌｅｖｅｌＶＳＢ等の４ｌｅｖｅｌＡＳＫの信号点配置図に示すように、信号点７２１、７２２を１つのグループつまり第１の信号点群７２５として扱い、信号点７２３、７２４を別のグループ、第２の信号点群７２６と定義する。そして２つの信号点群の間の間隔を等間隔の信号点の間隔より広くする。つまり信号点７２１、７２２の間隔をＬとすると信号点７２３、７２４の間隔は同じＬで良いが、信号点７２２と信号点７２３の間隔Ｌ_ｏはＬより大きく設定する。
【０２３２】
つまり　　Ｌ_ｏ＞Ｌ
と設定する。これが本発明の階層型の多値伝送システムの特徴である。ただしシステムの設計によっては条件や設定により一時的もしくは恒久的にＬ＝Ｌ_ｏに　なって　も良い。８値のＶＳＢの場合、図６８（ａ）（ｂ）のようなＣｏｎｓｔ　ｅｌｌａｔｉｏｎとなる。
【０２３３】
そして図５９（ａ）のように２つの信号点群に第１データ列Ｄ_１の１ｂｉｔの　データを対応させることができる。例えば第１の信号点群７２５を０、第２の信号点群７２６を１と定義すれば、第１データ列の１ｂｉｔの信号が定義できる。次に第２データ列Ｄ_２の１ｂｉｔの信号を各信号群の中の２つの信号点群に対応　させる。例えば、図５９（ｂ）のように信号点７２１、７２３をＤ_２＝０とし、　信号点７２２、７２４をＤ_２＝１とすれば第２データ列Ｄ_２のデータを定義できる。この場合も２ｂｉｔ／シンボルとなる。
【０２３４】
このように信号点を配置することにより、ＡＳＫ方式で本発明の多値伝送が可能となる。階層型の多値伝送システムは信号対雑音比つまりＣ／Ｎ値が充分高い時は従来の等間隔信号点方式と変わりはない。しかし、Ｃ／Ｎ値が低い場合、従来方式では全くデーターを再生できない条件においても本発明を用いることにより第２データ列Ｄ_２は再生できなくなるが、第１データ列Ｄ_１は再生できる。これを説明するとＣ／Ｎが悪くなった状態は図６０の４ＶＳＢ−ＡＳＫの信号点配置図のように示せる。つまり受信機で再生した信号点はノイズや伝送歪等により、分散信号点領域７２１ａ７２２ａ、７２３ａ、７２４ａの広い範囲にガウス分布状に分散する。このような場合、４値のスライサーによるスライスレベル２による信号点７２１と信号点７２２の区別や、スライスレベル４による信号点７２３と信号点７２４の区別が難しくなる。つまり第２データ列Ｄ_２のエラーレートが　非常に高くなる。しかし図から明らかなよ　うに信号点７２１，７２２のグルー　プと信号点７２３，７２４のグループとの区別は容易である。つまり第１の信号点群７２５と第２の信号点群７２６との区別ができる。このため、第１データ列Ｄ_１は低いエラーレートで再生できることに　なる。
【０２３５】
こうして２つの階層のデータ列Ｄ_１とＤ_２が送受信できる。従って伝送システムのＣ／Ｎの良い状態及び地域では第１データ列Ｄ_１と第２列Ｄ_２の両方がＣ／Ｎの悪い状態及び地域では第１データ列Ｄ_１のみが再生される多値型伝送ができると　いう効果がある。
【０２３６】
図６１は送信機７４１のブロック図で入力部７４２は第１データ列入力部７４３と第２データ列入力部７４４から構成される。搬送波発生器６４からの搬送波は入力部７４２からの信号を処理部７４５でまとめた入力信号により乗算器７４６において振巾変調され、図６２（ａ）のような４値もしくは８値のＡＳＫ信号となる。４ＡＳＫもしくは８ＡＳＫ信号は、さらにバンドパスフィルタ７４７により帯域制限され、図６２（ｂ）のようにＣａｒｒｉｅｒが少し残留したＳｉｄｅ　ＢａｎｄをもつＶｅｓｔｉｇｉａｌ　Ｓｉｄｅ　ＢａｎｄつまりＶＳＢ信号のＡＳＫ信号となり　出力部７４８から出力される。
【０２３７】
ここでフィルタを通過した後の出力波形について述べる。図６２（ａ）はＡＳＫ　変調信号の周波数分布図である。図のようにキャリアの両側に側波帯がある。この信号をフィルタ７４７のバンドパスフィルタ図６２（ｂ）の送信信号７４９のよ　うにキャリア成分を少し残して片側の側波帯を取り去る。これをＶＳＢ信号というが、ｆ_０を変調周波数帯域とすると、約ｆ_０／２の周波数帯域で送信できるため、周波数利用効率が良いことが知られている。図６０のＡＳＫ信号は元来２ｂｉｔ／シンボルであるがＶＳＢ方式を用いると４ＶＳＢと８ＶＳＢは同一周波数帯域で１６ＱＡＭ、３２ＱＡＭの４ｂｉｔ／シンボルの５ｂｉｔ／シンボルに相当する情報量が伝送できる。
【０２３８】
次に図６３のブロック図で示すＶＳＢ受信機７５１では地上のアンテナ３２ａで受けた信号は入力部７５２を経て、チャンネル選択により可変する可変発振器７５４からの信号と、混合器７５３において混合され、低い中間周波数に変換される。次に検波器７５５において検波され、ＬＰＦ７５６によりベースバンド信号となり４ＶＳＢの場合は４ｌｅｖｅｌのＳｌｉｃｅｒ、８ＶＳＢの場合は８ｌｅｖｅｌのＳｌｉｃｅｒをもつ識別再生器７５７により第１データ列Ｄ_１と第２　データ列Ｄ_２が再生され第１データ列出力部７５８と第２データ列出力部７５９　から出力される。
【０２３９】
次にこの送信機と受信機を用いてＴＶ信号を送る場合を説明する。図６４は映像信号送信機７７４のブロック図である。ＨＤＴＶ信号等の高解像度ＴＶ信号は第１画像エンコーダー４０１の入力部４０３に入力し、サブバンドフィルター等　の映像の分離回路４０４により、Ｈ_ＬＶ_Ｌ，Ｈ_ＬＶ_Ｈ，Ｈ_ＨＶ_Ｌ，Ｈ_ＨＨ_Ｈ等の高域ＴＶ信号と低域ＴＶ信号に分離される。この内容は実施例３で図３０を用いて説明したので詳しい説明は省略する。分離されたＴＶ信号は圧縮部４０５において、ＭＰＥＧ等で用いられているＤＰＣＭＤＣＴ可変長符号化や等の手法を用いて符号化される。動き補償は入力部４０３において処理される。圧縮された４つの画像データは合成器７７１によって第１データ列Ｄ_１と第２データ列Ｄ_２の２つのデータ列となる。この場合Ｈ_ＬＶ_Ｌ信号つまり低域の画像信号は第１データ列に含まれる。送信機の７４１の第１データ列入力部７４３と第２データ列入力部７４４に入力され振巾変調を受け、ＶＳＢ等のＡＳＫ信号となり、地上アンテナから放送される。
【０２４０】
このデジタルＴＶ放送のＴＶ受信機全体のブロック図が図６５である。地上アンテナ３２ａで受信した放送信号はＴＶ受信機７８１の中の受信機７５１の入力部７５２に入力され、検波復調部７６０により受信者が希望する任意のチャンネルの信号が選局され復調され、第１データ列Ｄ_１と第２データ列Ｄ_２が再生され第１データ列出力部７５８と第２データ列出力部７５９から出力される。詳しい説明は重なるため省く。Ｄ_１，Ｄ_２信号は分離部７７６に入力される。Ｄ_１信号は分　離器７７７により分離されＨ_ＬＶ_Ｌ圧縮成分は第１入力部５２１に入力される。他方は合成器７７８によりＤ_２信号と合成され第２入力部５３１に入力される。第　２画像デコーダにおいて第１入力部５２１に入ったＨ_ＬＶ_Ｌ圧縮信号は、第１伸長部５２３によりＨ_ＬＶ_Ｌ信号に伸長され画像合成部５４８と画面比率変更回路７７９に送られる。元のＴＶ信号がＨＤＴＶ信号の場合、Ｈ_ＬＶ_Ｌ信号はワイドのＮＴＳＣ信号になり、元の信号がＮＴＳＣ信号の場合、ＭＰＥＧ１のようなＮＴＳＣより品位が低い低解像度ＴＶ信号になる。
【０２４１】
この説明では元の映像信号をＨＤＴＶ信号と設定しているため、Ｈ_ＬＶ_Ｌ信号はワイドＮＴＳＣのＴＶ信号となる。ＴＶの画面アスペクト比が１６：９であれば１６：９の画面比率のまま出力部７８０を介して映像出力４２６として出力する。もし、ＴＶの画面アスペクト比が４：３であれば、画面比率変更回路７７９により１６：９から４：３の画面アスペクト比のレターボックス形式かサイドパネル形式に変更して出力部７８０を介して映像出力４２５として出力する。
【０２４２】
一方、第２データ列出力部７５９からの第２データ列Ｄ_２は、分離部７７６の　合成器７７８において分離器７７７の信号と合成され、第２画像デコーダの第２入力部５３１に入力され、分離回路５３１によりＨ_ＬＶ_Ｈ、Ｈ_ＨＶ_Ｌ、Ｈ_ＨＶ_Ｈの圧縮信号に分離されて各々第２伸張部５３５、第３伸長部５３６、第４伸長部に送られ、伸長されて元のＨ_ＬＶ_Ｈ、Ｈ_ＨＶ_Ｌ、Ｈ_ＨＶ_Ｈ信号となる。これらの信号にＨ_ＬＶ_Ｌ信号を加え、画像合成部５４８に入力され、合成されて１つのＨＤＴＶ信号となり出力部５４６より出力され、出力部７８０を介してＨＤＴＶの映像信号４２７として出力される。
【０２４３】
この出力部７８０は第２データ列出力部７５９の第２データ列の誤まり率を誤まり率検知部７８２で検知し、エラーレートが高い状態が一定時間続いた場合は一定時間自動的にＨ_ＬＶ_Ｌ信号の低解像度の映像信号を出力させたり、映像出力を停止させたり、フィルタを作動させたり、同期を回復させたり等のシステムのコントロール命令を出す。
【０２４４】
以上のようにして、階層型放送の送信、受信が可能となる。伝送条件が良い場合、例えばＴＶ送信アンテナが近い放送に対しては、第１データ列と第２データ列の両方が再生できるので、ＨＤＴＶの品位で番組を受信できる。また送信アンテナとの距離が遠い放送に対しては、第１データ列を再生し、このＶ_ＬＨ_Ｌ信号か　ら低解像度のＴＶ信号を出力する。このことにより、ＨＤＴＶの品位もしくはＮＴＳＣＴＶの品位で同一番組をより広い地域で受信できるという効果がある。
【０２４５】
また図６６のＴＶ受信機のブロック図のように第１データ列出力部７６８だけに受信機７５１の機能を縮小すると受信機は第２データ列およびＨＤＴＶ信号を扱わなくてもよくなるため、構成が大巾には簡略化できる。画像デコーダーは　図３１で説明した第１画像デコーダ４２１を用いればよい。この場合ＮＴＳＣＴＶの品位の画像が得られる。ＨＤＴＶの品位では番組を受信できないが受信機のコストは大巾に安くなる。従って広く普及する可能性がある。このシステムでは従来のＴＶディスプレイをもつ多くの受信システムを変更しないでアダプターとして追加することにより、デジタルＴＶ放送が受信できるという効果がある。
【０２４６】
なお、図６６に示すようにスクランブルをかけた４ＶＳＢ，８ＶＳＢ信号を受信する場合、４ＶＳＢ，８ＶＳＢ信号で送信されるスクランブル解除信号とデスクランブラー５０２の中のＤｅｓｃｒａｍｂｌｅ番号メモリー５０２ｃの番号をＤｅｓｃｒａｍｂｌｅ番号照合器５０２ｂにより照合し、一致している場合のみＤｅｓｃｒａｍｂｌｅを解除することにより特定のスクランブル番組のスクランブルを正当に解除することができる。
【０２４７】
図６７のような構成にするとＰＳＫ信号を復調する衛星放送受信機とＶＳＢ信号を復調する地上放送受信機の機能をもつ受信機を簡単に構成できる。この場合、衛星アンテナ３２から受信したＰＳＫ信号は発振器７８７からの信号と混合器７８６において混合され、低い周波数に変換されＴＶ受信機７８１の入力部３４に入力され、図６３で説明した混合器７５３に入力される。衛星ＴＶ放送の特定のチャンネルの低い周波数に変換されたＰＳＫ、もしくはＱＡＭ信号は復調部３５によりデータ列Ｄ_１、Ｄ_２が復調され、分離部７８８を介して第２画像エンコーダ４２２により、画像信号として再生され、出力部７８０より出力される。一方、地上用のアンテナ３２ａにより受信されたデジタル地上放送とアナログ放送は、入力部７５２に入力され図６３で説明したのと同じプロセスで混合器７５３により特定のチャンネルが選択され、検波され、低域のみのベースバンド信号となる。アナログ衛星ＴＶ放送に混合器７５３に入り復調される。デジタル放送の場合は、識別再生器７５７によりデータ列Ｄ_１とＤ_２が再生され第２画像デコーダ４２２により映像信号が再生され、出力される。また地上と衛星のアナログＴＶ放送を受信する場合は映像復調部７８８によりＡＭ復調されたアナログＴＶ信号が出力部７８０より出力される。図６７の構成をとると混合器７５３が衛星放送と地上放送で共用できる。また第２画像デコーダ４２２も共用できる。又、デジタル地上放送でＡＳＫ信号を用いた場合、ＡＭ復調のため従来のアナログ放送と同様の検波器７５５とＬＰＦ７５６等の受信回路を兼用できる。以上のように図６７の構成にすると大巾に受信回路を共用化し、回路を削減するという効果がある。
【０２４８】
また、実施例では４値のＡＳＫ信号を２つのグループに分け、Ｄ_１、Ｄ_２の２層の各１ｂｉｔの多値伝送を行った。しかし、図６８（ａ）（ｂ）の８ＶＳＢ信号のＣｏｎｓｔｅｌｌａｔｉｏｎ図に示す、８値のＡＳＫ信号つまり８ｌｅｖｅｌ−ＶＳＢを用いるとＤ_１、Ｄ_２、Ｄ_３の３層の各１ｂｉｔの合計３ｂｉｔ／ｓｙｍ　ｂｏｌの多値伝送を行うことができる　。図６８（ａ）に示すように、まず１ｂ　ｉｔ目の符号のつけ方を説明すると、Ｄ_３信号の信号点は信号点７２１ａと７２　１ｂ、７２２ａと７２２　ｂ、７２３ａと７２３ｂ、７２４ａと７２４ｂの２値つまり１ｂｉｔである。次に次の１ｂｉｔの符号化を説明すると、Ｄ_２の信号点は　信号点群７２１と７２２、信号点群７２３と７２４の２値の１　ｂｉｔである。　Ｄ_３のデータは大信号点群７２５と７２６の２値の１ｂｉｔとな　る。この場合、図５７の４つの信号点７２１、７２２、７２３、７２４を各２ヶの信号点７２１ａと７２１ｂ、７２２ａと７２２ｂ、７２３ａと７２３ｂ、７２４ａと７２４ｂに分離し、各グループの間の距離を離すことにより最大３層の階層型の多値伝送が可能となる。前述のようにＬ＝Ｌ_０にすることもできる。
【０２４９】
この３層の多値伝送システムを用いて３層等のデジタルＨＤＴＶの映像伝送を行うことは実施例３と実施例４で説明したもので動作の詳しい説明は省略する。
【０２５０】
ここで、図６８の８値のＶＳＢによるＴＶ放送を行うことによる効果について述べる。８ＶＳＢは伝送情報量が多い反面、同じＣ／Ｎ値に対するエラーレートは４ＶＳＢより高い。しかし高画質のＨＤＴＶ放送を行う場合、伝送容量に余裕があるためエラー訂正符号が多く入るため、エラーレートを下げたり、また将来階層型のＴＶ放送が可能となるという効果がある。
【０２５１】
ここで４ＶＳＢと８ＶＳＢと１６ＶＳＢの効果について比較しながら述べる。
ＮＴＳＣやＰＡＬの周波数帯を用いて地上放送を行う場合、図１３６に示したようにＮＴＳＣの場合６ＭＨｚの帯域制限があり約５ＭＨｚの実質的な伝送帯域が許される。４ＶＳＢの場合、周波数利用効率は４ｂｉｔ／Ｈｚであるため、実質的に５ＭＨｚ×４＝２０Ｍｂｐｓのデータ伝送容量がある。一方、デジタルＨＤＴＶ信号の伝送には少なくとも１５Ｍｂｐｓ〜１８Ｍｂｐｓ必要である。このため、４−ＶＳＢではデータ容量に余裕がないため、図１６９の比較図に示すように誤り訂正符号のための冗長度をＨＤＴＶの実質伝送量の１０〜２０％しかとれない。
【０２５２】
次に８−ＶＳＢの場合、周波数利用効率は６ｂｉｔ／ＨＺであるため５ＭＨｚ×６＝３０Ｍｂｐｓのデータ伝送容量が得られる。上述のようにＨＤＴＶ信号の伝送には１５〜１８ＭＨｚ必要であるが、８ＶＳＢ変調方式の場合、図１６９に示すようにＨＤＴＶ信号の実質伝送量の５０％以上の情報量を誤り訂正の符号に用いることができる。従って、同じデータレートのＨＤＴＶデジタル信号を６ＭＨｚの帯域で地上放送するという条件のもとでは、８ＶＳＢの方がより大容量の誤り訂正符号を付加できるため、図１６１のエラーレートカーブ８０５と８０６に示すように、伝送系の同じＣ／Ｎ値に対して、エラー訂正のＣｏｄｅ　Ｇａｉｎを高くしたＴＣＭ−８ＶＳＢの方がエラー訂正後のエラーレートがエラー訂正のＣｏｄｅ　Ｇａｉｎの低い４ＶＳＢより低くなる。従って、Ｈｉｇｈ　ｃｏｄａ　ｇａｉｎでエラー符号化された８ＶＳＢの方が４ＶＳＢより、ＴＶ地上放送におけるサービスエリアが拡がるという効果がある。確かに８ＶＳＢの方が誤り訂正回路の増大により、受信機の回路がより複雑になる欠点がある。しかしＶＳＢ・ＡＳＫ方式は、振巾変調方式のため、位相成分を含むＱＡＭ変調方式に比べて、元々受信機のＥｑｕａｌｉｚｅｒの回路規模が大巾に小さい。このため誤り訂正回路を追加しても、全体の回路規模は８ＶＳＢ方式の方が３２ＱＡＭ方式に比べて大きくならない。従って、８ＶＳＢ方式により、サービスエリアが広く、全体の回路規模の適切なデジタルＨＤＴＶ受信機が実現する。
【０２５３】
なお、具体的な誤り訂正方式の例としては、後の実施例５等で説明するが、図８４や実施例６の図１３１、図１３７、図１５６、図１５７の送受信機のブロック図のＥＣＣ７４４ａとＴｒｅｌｌｉｓ　Ｅｎｃｏｄｅｒ７４４ｂを用い、図６１で説明した４ＶＳＢ、８ＶＳＢ、１６ＶＳＢのＶＳＢの変調部７４９を用いて送信する。受信機側としては、図６３を用いて説明したＶＳＢの復調部７６０を用いて４ＶＳＢもしくは８ＶＳＢもしくは１６ＶＳＢ信号から４、８、１６値のｌｅｖｅｌ　ｓｌｉｃｅｒ７５７によりデジタルデータを再生し、同じく後の実施例５等で説明する図８４、実施例６の図１３１、図１３７、図１５６、図１５７のＴｒｅｌｌｉｓ　Ｄｅｃｏｄｅｒ７５９ｂとＥＣＣ　Ｄｅｃｏｄｅｒ７５９ａにより、誤り訂正をした後、画像デコータ４０２の画像伸長器により、デジタルＨＤＴＶ信号を再生し、出力する。
【０２５４】
ＥＣＣ　Ｅｎｃｏｄｅｒ７４４ａは実施例６で説明する図１６０（ａ）、（ｂ）に示すように、Ｒｅｅｄ　ｓｏｌｏｍｏｎ　Ｅｎｃｏｄｅｒ７４４ｊとＩｎｔｅｒｌｅａｖｅｒ７４４ｋを用い、ＥＣＣ　Ｄｅｃｏｄｅｒ７５９ａにはＤｅＩｎｔｅｒｌｅａｖｅｒ７５９ｋとＲｅｅｄ　ｓｏｌｏｍｏｎ　Ｄｅｃｏｄｅｒ７５９ｊを用いる。前の実施例で述べたようにＩｎｔｅｒｌｅａｖｅをかけることにより、バーストエラーに強くなる。
【０２５５】
図１２８（ａ）（ｂ）（ｃ）（ｄ）（ｅ）（ｆ）に示すＴｒｅｌｌｉｓ　ｅｎｃｏｄｅｒを採用することによりさらにＣｏｄｅ　Ｇａｉｎを上げることができ、エラーレートが下がる。８ＶＳＢの場合図１７２に示すようにＲａｔｉｏ２／３のＴｒｅｌｌｉｓ　ｅｎｃｏｄｅｒ７４４ｂ，ｄｅｃｏｄｅｒ７５９ｂが適用できる。
【０２５６】
実施例では、主に階層型のデジタルＴＶ信号を伝送する例を用いて説明した。階層型の場合、理想的な放送ができるが、画像圧縮回路や変復調器の回路が複雑になるため、放送開始時にはコストの点で好ましくない。実施例５の冒頭に述べたように４ＶＳＢや８ＶＳＢの信号点間隔Ｌ＝Ｌ_０つまり等間隔にして、非階層　型のＴＶ伝送を行い、図１３７を図１５７に示すような、簡単な構成にすることにより、回路の簡単なＴＶの放送システムが実現する。そして、普及した段階で８ＶＳＢの階層型伝送に切り換えればよい。
【０２５７】
さて、以上４ＶＳＢと８ＶＳＢについて説明したが、図１５９（ａ）〜（ｄ）では１６ＶＳＢと３２ＶＳＢについて説明する。図１５９（ａ）は１６ＶＳＢのＣｏｎｓｔｅｌｌａｔｉｏｎを示す。図１５９（ｂ）は２つの信号点のグループ７２２ａ〜７２２ｈにグループ化し、８つの信号点とみなすことにより、８ＶＳＢとして扱えるため２層の階層型の多値伝送が実現する。この場合Ｔｉｍｅ　Ｄｉｖｉｓｉｏｎ　Ｍａｌｔｉｐｌｅｘで、間欠的に８ＶＳＢ信号を送っても階層型伝送が実現する。但し、この方式では最大データレートが２／３になる。図１５７（ｃ）はさらに４つのグループ７２３ａ〜７２３ｄとし、４ＶＳＢとして扱うためさらに１層階層が増える。この場合も、Ｔｉｍｅ　Ｄｉｖｉｓｉｏｎ　Ｍａｌｔｉｐｌｅｘで間欠的に４ＶＳＢ信号を送っても、最大データレートが下がるが階層型伝送が実現する。以上により、３層の階層型ＶＳＢが実現する。
【０２５８】
この方式により、１６ＶＳＢのＣ／Ｎが悪くなった時８ＶＳＢ、もしくは４ＶＳＢのデータが再生できるという階層型伝送が実現する。また図１５９（ｄ）のように１６ＶＳＢの信号点を２倍にすることにより、３２ＶＳＢが伝送できる。将来１６ＶＳＢの容量を拡大したい場合、この方式により、互換性を保ちながら５ｂｉｔ／ｓｙｍｂｏｌのデータ容量が得られるという効果がある。
【０２５９】
これまで述べたことをまとめると、図１６１のＶＳＢ受信機のブロック図に示す受信機と図１６２のＶＳＢ送信機のブロック図に示す送信機の構成となる。
【０２６０】
主に４−ＶＳＢと８−ＶＳＢを用いて説明したが、図１５９（ａ）（ｂ）（ｃ）のような１６ＶＳＢを用いて伝送することもできる。１６ＶＳＢの場合は地上放送を行う場合６ＭＨｚの帯域で、４０Ｍｂｐｓの伝送容量がとれる。しかしＨＤＴＶデジタル圧縮信号のデータレートは、ＭＰＥＧ規格を用いた場合１５〜１８Ｍｂｐｓとなるため、伝送容量の余裕が大きくなりすぎる。図１６９に示すようにＲｅｄｕｎｄａｎｃｙ：Ｒ_１６＝１００％以上となり、１チャンネルのデジタルＨＤＴＶを伝送するには冗長度が大きくなりすぎて回路が複雑になるだけで、８ＶＳＢに対して効果が少ない。そして２チャンネルのＨＤＴＶの地上放送をするには１６ＶＳＢであると冗長度は４ＶＳＢと同じで１０ｂ程度しかとれないため充分な誤り訂正符号をいれることができないため、サービスエリアが狭くなる。前述のように４−ＶＳＢではＲｅｄｕｎｄａｎｃｙ：Ｒ_４＝１０〜２０％で充　分なエラー訂正ができないためサービスエリアを広くとれない。図１６９から明らかなように、８−ＶＳＢのＲｅｄｕｎｄａｎｃｙ：Ｒ_８＝５０％で充分なエラ　ー訂正符号化ができる。エラー訂正の回路規模もさほど大きくならずにサービスエリアがとれる。従ってデジタルＨＤＴＶ地上放送を６〜８ＭＨｚの帯域制限で行う条件のもとでは、図１６９から明らかなように、８Ｌｅｖｅｌ−ＶＳＢが最も効果があり最適なＶＳＢ変調方式であることがわかる。
【０２６１】
さて実施例３では図３０のような画像エンコーダ４０１を説明したが、図３０のブロック図は、図６９のように書き換えることができる。内容は全く同じであるため説明は省略する。このように、画像エンコーダ４０１はサブバンドフィルタ等の映像の分離回路４０４、４０４ａを２つもつ。これらを分離部７９４とすると、図７０の分離部のブロック図に示す。ように１つの分離回路に信号を時分割で２回通すことにより回路を削減できる。これを説明すると、第１サイクルでは入力部４０３からのＨＤＴＶやスーパーＨＤＴＶの映像信号は時間軸圧縮回路７９５により、時間軸を圧縮されて分離回路４０４により、Ｈ_ＨＶ_Ｈ−Ｈ、Ｈ_ＨＶ_Ｌ−Ｈ、Ｈ_ＬＶ_Ｈ−Ｈ、Ｈ_ＬＶ_Ｌ＋１の４つの成分に分けられる。この場合、スイッチ７６５、７６５ａ、７６５ｂ、７６５ｃは１の位置にあり、圧縮部４０５に、Ｈ_ＨＶ_Ｈ−Ｈ、Ｈ_ＨＶ_Ｌ−Ｈ、Ｈ_ＬＶ_Ｈ−Ｈの３つの信号を出力する。しかし、Ｈ_ＬＶ_Ｌ−Ｈの信号はスイッチ７６５ｃの出力１から時間軸調整回路７９５の入力２へ入力し、第２サイクルつまり時分割処理の空き時間に分離回路４０４に送られ分離処理されＨ_ＨＶ_Ｈ、Ｈ_ＨＶ_Ｌ、Ｈ_ＬＶ_Ｈ、Ｈ_ＬＶ_Ｌの４つの成分に分けられ出力される。第２サイクルではスイッチ７６５、７６５ａ、７６５ｂ、７６５ｃは出力２の位置に変わるため、４つの成分は圧縮部４０５へ送られる。このようにして図７０の構成をとり時分割処理することにより分離回路が削減できるという効果がある。
【０２６２】
次にこのような３層の階層型の画像伝送を行うと受信機側には実施例３の図３３のブロック図で説明したような、画像デコーダが必要となる。これを、書き換えると図７１のようなブロック図となる。処理能力は違うものの同じ構成の合成器５６６が２つ存在することになる。
【０２６３】
これは図７２のような構成をとると図７０の分離回路の場合と同様にして１つの合成器で実現できる。図７２を説明すると、５つのスイッチ、７６５ａ，７６５ｂ，７６５ｃ，７６５ｄにより、まず、タイミング１において、スイッチ７６５、７６５ａ，７６５ｂ，７６５ｃの入力が１に切り替わる。すると、第１伸長部５２２、第２伸長部５２２ａ，第３伸長部５２２ｂ，第４伸長部５２２ｃから各々Ｈ_ＬＶ_Ｌ，Ｈ_ＬＶ_Ｈ，Ｈ_ＨＶ_Ｌ，Ｈ_ＨＶ_Ｈの信号が、スイッチを介して合成器５５６の対応する入力部に入力され、合成処理されて１つの映像信号となる。この映像信号はスイッチ７６５ｄに送られ出力１より出力し再びスイッチ７６５ｃの入力２に送られる。この映像信号はもともと、高解像度映像信号を分割したＨ_ＬＶ_Ｌ−Ｈ成分の信号である。次のタイミング２において、スイッチ７６５、７６５ａ，７６５ｂ，７６５ｃは入力２に切替わる。こうして、今度はＨ_ＨＶ_Ｈ−Ｈ，Ｈ_ＨＶ_Ｌ−Ｈ，Ｈ_ＬＶ_Ｈ−ＨそしてＨ_ＬＶ_Ｌ−Ｈ信号が合成器５５６に送られ、合成処理されて１つの映像信号が得られる。この映像信号はスイッチ７６５ｄの出力２より出力部５５４から出力される。
【０２６４】
このようにして、３層の階層型放送を受信する場合時分割処理により２ケの合成器を１ケに削減するという効果がある。
【０２６５】
さて、この方式は、まずタイミング１においてＨ_ＨＶ_Ｈ，Ｈ_ＨＶ_Ｌ，Ｈ_ＬＶ_Ｈ，Ｈ_ＬＶ_Ｌ信号を入力させ、Ｈ_ＬＶ_Ｌ−Ｈ信号を合成させる。その後、タイミング１と別の期間タイミング２において、Ｈ_ＨＶ_Ｈ−Ｈ，Ｈ_ＨＶ_Ｌ−Ｈ，Ｈ_ＬＶ_Ｈ−Ｈと上記のＨ_ＬＶ_Ｌ−Ｈ信号を入力させ、最終の映像信号を得るという手順をとっている。従って、２つのグループの信号のタイミングをずらす必要がある。
【０２６６】
もし、もともと、入力した信号の上記成分のタイミングの順序が違っていたり重複している場合は時間的に分離するためスイッチ７６５、７６５ａ，７６５ｂ，７６５ｃにメモリを設け蓄積し、時間軸を調整することが必要となる。しかし送信機の送信信号を図７３のようにタイミング１とタイミング２に時間的に分離して送信することにより、受信機側に時間軸調整回路が不要となる。従って、受信機の構成が簡単になるという効果がある。
【０２６７】
図７３の時間配置図のＤ１は送信信号の第１データ列Ｄ１を示し、タイミング１の期間中にＤチャンネルでＨ_ＬＶ_Ｌ，Ｈ_ＬＶ_Ｈ，Ｈ_ＨＶ_Ｌ，Ｈ_ＨＶ_Ｈ信号を送り、タイミング２の期間にＤ２チャンネルでＨ_ＬＶ_Ｈ−Ｈ，Ｈ_ＨＶ_Ｌ−Ｈ，Ｈ_ＨＶ_Ｈ−Ｈを送る場合の信号の時間配置を示している。このようにして時間的に分離して送信信号を送ることにより、受信機のエコンコーダの回路構成を削除するという効果がある。
【０２６８】
次に受信機の伸長部の数が多い。これらの数を削減する方法について述べる。図７４（ｂ）は送信信号のデータ８１０、８１０ａ，８１０ｂ，８１０ｃの時間配置図を示す。この図において、データの間に別データ８１１，８１０ａ，８１１ｂ，８１１ｃを送信する。すると、目的とする送信データは間欠的に送られてくることになる。すると、図７４（ａ）のブロック図に示す第２画像エンコーダ４２２はデータ列Ｄ１を第１入力部５２１とスイッチ８１２を介して次々と伸長部５０３に入力する。例えば、データ８１０の入力完了後は別データ８１１の時間中に伸長処理を行い、データ８１０の処理修了後、次のデータ８１０ａが入力することになる。こうすることにより、合成器の場合と同様の手法で時分割で１つの伸長部５０３を共用することができる。こうして、伸長部の総数を減らすことができる。
【０２６９】
図７５はＨＤＴＶを送信する場合の時間配置図である。例えば放送番組の第１チャンネルのＮＴＳＣ成分に相当するＨ_ＬＶ_Ｌ信号をＨ_ＬＶ_Ｌ（１）とすると、これをＤ１信号の太線で示すデータ８２１の位置に時間配置する。第１チャンネルのＨＤＴＶ付加成分に相当するＨ_ＬＶ_Ｈ，Ｈ_ＨＶ_Ｌ，Ｈ_ＨＶ_Ｈ信号はＤ２信号のデータ８２１ａ，８２１ｂ，８２１ｃの位置に配置する。すると第１チャンネルの全てのデータの間には別のＴＶ番組の情報である別データ８２２，８２２ａ，８２２ｂ，８２２ｃが存在するため、この期間中に伸長部の伸長処理が可能となる。こうして１つの伸長部で全ての成分を処理できる。この方式は伸長器の処理が速い場合に適用できる。
【０２７０】
また、図７６のようにＤ１信号に、データ８２１，８２１ａ，８２１ｂ，８２１ｃを配置しても同様の効果が得られる。通常の４ＰＳＫや４ＡＳＫのように階層がない伝送を用いて送受信する場合に有効である。
【０２７１】
図７７は、例えばＮＴＳＣとＨＤＴＶと高解像度ＨＤＴＶもしくは、低解像度ＮＴＳＣとＮＴＳＣとＨＤＴＶのような３層の映像を物理的に２層の階層伝送方式を用いて階層型の多値放送を行う場合の時間配置図を示す。例えば、低解像度ＮＴＳＣとＮＴＳＣとＨＤＴＶの３層の映像を放送する場合Ｄ１信号には低解像ＮＴＳＣ信号に相当するＨ_ＬＶ_Ｌ信号がデータ８２１に配置されている。又、ＮＴＳＣの分離信号であるＨ_ＬＶ_Ｈ，Ｈ_ＨＶ_Ｌ，Ｈ_ＨＶ_Ｈの各成分の信号はデータ８２１ａ，８２１ｂ，８２１ｃの位置に配置されている。ＨＤＴＶの分離信号であるＨ_Ｌ　Ｖ_Ｈ−Ｈ，Ｈ_ＨＶ_Ｌ−Ｈ，Ｈ_ＨＶ_Ｈ−Ｈ信号はデータ８２３，８２３ａ，８２３ｂに　配置されている。
【０２７２】
ここでは、図１５６や図１７０のブロック図に示すように、実施例２で説明したエラー訂正能力の差別化による論理的な階層伝送を４ＶＳＢや８ＶＳＢや１６ＶＳＢに追加している。具体的にはＨ_ＬＤ_ＬはＤ_１信号の中のＤ_１−１チャンネルを用いている。Ｄ_１−１チャンネルは実施例２で述べたようにＤ_１−２チャンネルより大巾に訂正能力の高い誤り訂正方式を採用している。Ｄ_１−１チャンネルはＤ_１−２チャンネルに比べて冗長度は高いが再生後のエラーレートは低いため、他のデータ８２１ａ，８２１ｂ，８２１ｃよりＣ／Ｎ値の低い条件においても再生できる。このためアンテナから遠い地域や自動車の車内等の受信条件の悪い場合においても低解像度のＮＴＳＣＴＶの品位で番組を再生することができる。実施例２で述べたようにエラーレートの観点でみた場合、Ｄ_１信号の中のＤ_１−１チャンネルにあるデ　ータ　８２１はＤ_１−２チャンネルにある他のデータ８２１ａ，８２１ｂ，８２１ｃより　受信妨害に強く、差別化されており論理的な階層が異なる。実施例２で述　べたようにＤ_１，Ｄ_２の階層は物理的階層といえ、このエラー訂正符号間距離の差別化による階層構造は論理的な階層構造といえる。
【０２７３】
さて、Ｄ_２信号の復調には物理的にＤ_１信号より高いＣ／Ｎ値を必要とする。従って、遠隔地等のＣ／Ｎ値の一番低い受信条件では，Ｈ_ＬＶ_Ｌ信号つまり、低解像度ＮＴＳＣ信号が再生される。そして、Ｃ／Ｎ値が次に低い受信条件では加えてＨ_ＬＶ_Ｈ，Ｈ_ＨＶ_Ｌ，Ｈ_ＨＶ_Ｈが再生され、ＮＴＳＣ信号が再生できる。さらにＣ／Ｎ値の高い受信条件ではＨ_ＬＶ_Ｌに加えてＨ_ＬＶ_Ｈ−Ｈ，Ｈ_ＨＶ_Ｌ−Ｈ，Ｈ_ＨＶ_Ｈ−Ｈも再生されるためＨＤＴＶ信号が再生される。こうして３つの階層の放送ができる。この方式を用いることにより図５３で説明した受信可能領域は図９０の受信妨害領域図に示すように２層から３層に拡大し、より番組受信可能領域が拡がる。
【０２７４】
ここで図７８は図７７の時間配置の場合の第３画像デコーダのブロック図を示す。基本的には図７２のブロック図からＤ３信号の第３入力部５５１を省いた構成に図７４（ａ）のブロック図の構成を加えた構成になっている。
【０２７５】
動作を説明するとタイミング１において入力部５２１よりＤ１信号が、入力部　５３０よりＤ２信号が入力される。Ｈ_ＬＶ_Ｈ等の各成分は時間的に分離されているためこれらはスイッチ８１２により伸長部５０３に順次、独立して送られる。こ　の順序を図７７の時間配置図を用いて説明する。まず、第１チャンネルのＨ_ＬＶ_Ｌ　の圧縮信号が伸長部５０３に入り、伸長処理される。次に第１チャンネルのＨ_Ｌ　Ｖ_Ｈ，Ｈ_ＨＶ_Ｌ，Ｈ_ＨＶ_Ｈが伸長処理され、スイッチ８１２ａを介して、合成器５５　６の所定の入力部に入力され、合成処理され、まずＨ_ＬＶ_Ｌ−Ｈ信号が合成される。この信号はスイッチ７６５ａの出力１からスイッチ７６５の入力２に入力され、合成器５５６のＨ_ＬＶ_Ｌ入力部に入力される。
【０２７６】
次にタイミング２において、図７７の時間配置図に示すようにＤ２信号のＨ_Ｌ　Ｖ_Ｈ−Ｈ，Ｈ_ＨＶ_Ｌ−Ｈ，Ｈ_ＨＶ_Ｈ−Ｈ信号が入力され伸長部５０３により伸長され　、スイッチ８１２ａを介して各信号が合成器５５６の所定の入力に入力され、合成処理されＨＤＴＶ信号が出力される。このＨＤＴＶ信号はスイッチ７６５ａの出力２より出力部５２１を介してＨＤＴＶ信号が出力される。上述のように図７７の時間配置により送信することにより受信機の伸長部と合成器の数を大巾に削減するという効果がある。なお、図７７は時間配置図ではＤ１，Ｄ２信号の２つの段階を用いたが、前述のＤ３信号を用いると、高解像度ＨＤＴＶを加え４つの階層のＴＶ放送ができる。
【０２７７】
図７９はＤ１，Ｄ２，Ｄ３の３層の物理階層を用いた３つの階層の映像を放送する階層型放送の時間配置図である。図から明かなように同一ＴＶチャンネルの各成分は時間的に重複しないように配置してある。又、図８０は図７８のブロック図で説明した受信機に第３入力部５２１ａを加えた受信機である。図７９の時間配置により放送することにより、図８０のブロック図で示すような簡単な構成で受信機が構成できるという効果がある。
【０２７８】
動作は、図７７の時間配置図、図７８のブロック図とほぼ同じである。このため説明は省略する。又、図８１の時間配置図のようにＤ１信号に全ての信号を時間多重することもできる。この場合、データ８２１と別データ８２２の２つのデータはデータ８２１ａ，８１２ｂ，８２１ｃに比べてエラー訂正能力を高めてある。このため、他のデータに比べて階層が高くなっている。前述のように物理的には一層であるが論理的には２層の階層伝送となっている。又、番組チャンネル１のデータの間に別の番組チャンネル２の別データが括入されている。このため、受信機側でシリアル処理が可能となり、図７９の時間配置図と同じ効果が得られる。
【０２７９】
図８１の時間配置図の場合、論理的な階層となっているが、データ８２１，別データ８２２の伝送ビットレートを１／２や１／３に落とすことにより、このデータの伝送時のエラーレートが下がるため、物理的な階層伝送をすることもできる。この場合、物理階層は３層となる。
【０２８０】
図８２は、図８１の時間配置図のような、データ列Ｄ１信号のみを伝送する場合の画像デコーダ４２３のブロック図で、図８０のブロック図に示す画像デコーダに比べて、より簡単な構成となる。動作は図８０で説明した画像デコーダと同じため説明を省略する。
【０２８１】
以上のように、図８１の時間配置図のような送信信号を送信すると図８２のブロック図のように伸長部５０３合成器５５６の数を大巾に削減できるという効果がある。又、４つの成分が時間的に分離されて入力されるため、合成器５５６つまり図３２の画像合成部５４８の内部の回路ブロックを入力する画像成分に応じて接続変更により、いくつかのブロックを時分割で共用し回路を省略することもできる。
【０２８２】
以上のようにして簡単な構成で受信機が構成できるという効果がある。
なお、実施例５では、ＡＳＫ変調を用いて動作を説明したが、実施例５で説明した多くの手法は実施例１，２，３で説明したＰＳＫやＱＡＭ変調にも使える。
【０２８３】
又、これまでの実施例はＦＳＫ変調にも使える。
例えば、図８３のようにｆ１，ｆ２，ｆ３，ｆ４の多値のＦＳＫ変調を行う場合、実施例５の図５８の信号点配置図のようにグループ化を行い、各グループの信号点位置を離すことにより、階層型伝送ができる。
【０２８４】
図８３において周波数ｆ１，ｆ２の周波数群８４１をＤ１＝０と定義し、周波　数ｆ３，ｆ４の周波数群８４２をＤ１＝１と定義する。そして、ｆ１，ｆ３をＤ２＝０，ｆ２，ｆ４をＤ２＝１と定義すると、図に示すように、Ｄ１，Ｄ２の各１ｂ　ｉｔ、計２ｂｉｔの階層型伝送が可能となる。例えば、Ｃ／Ｎの高い場合はｔ＝ｔ３において、Ｄ１＝０，Ｄ２＝１が再生でき、ｔ＝ｔ４においてＤ１＝１，Ｄ２＝０が再生できる。次にＣ／Ｎが低い場合はｔ＝ｔ３においてＤ１＝０のみが，ｔ　＝ｔ４においてＤ＝１のみが再生できる。こうしてＦＳＫの階層型伝送ができる。実施例３，４，５で説明した映像信号の階層型の放送にこのＦＳＫの階層型の多値伝送方式を用いることもできる。
【０２８５】
又、図８４のような、ブロック図に示す磁気記録再生装置に本発明の実施例５を用いることもできる。実施例５はＡＳＫのため磁気記録再生ができる。
【０２８６】
図８４は記録装置（Ｒｅｃｏｄｅｒ）／送信機（Ｔｒａｎｓｍｉｔｔｅｒ）と再生装置（Ｐｌａｙｅｒ）／受信機（Ｒｅｃｅｉｖｅｒ）のブロック図を示す。
【０２８７】
図８４のブロック図において、送信機１、受信機４３の実施例５のＶＳＢ−ＡＳＫ変調方式が送信機１の送信回路５ａを記録装置磁気記録信号アンプ８５７ａにおきかえ、受信機４３の受信回路２４ａを磁気再生信号アンプ８５７ｂに置きかえることにより、全く同じ構成になる。本文では伝送装置においてはＡＳＫ信号は全てＶＳＢ−ＡＳＫであるため、ＶＳＢ−ＡＳＫ信号をＡＳＫ信号と省略して説明する。
【０２８８】
図８４の動作を説明すると、ＨＤＴＶ信号はＶｉｄｅｏ　ｅｎｃｏｄｅｒ４０１で圧縮された後２つのデータに分けられ、第１データ列はＥＣＣエンコーダ７４３ａで誤り符号化され、第２データ列はＥＣＣ７４４ａで誤り符号化された後、Ｔｒｅｌｌｉｓ　Ｅｎｃｏｄｅｒ７４４ｂにより、トレリス符号化されて、ＶＳＢ−ＡＳＫのＭｏｄｕｌａｔｏｒ７４９に入る。Ｒｅｃｏｄｅｒの場合はＯｆｆｓｅｔ　Ｇｅｎｅｒａｔｏｒ８５６により、Ｏｆｆｓｅｔ信号を加えた上で記録回路８５３により、磁気テープ８５５上に記録される。伝送装置のＴｒａｎｓｍｉｔｔｅｒ１の場合はＯｆｆｓｅｔ　Ｇｅｎｅｒａｔｏｒ８５６によりＤＣオフセット電圧をＡＳＫ信号に重畳させてＵｐ　ｃｏｎｖｅｒｔｅｒ５ａにより送信される。ＤＣオフセットさせることにより受信機４３にキャリア再生が容易になる。送信された前述の４ＶＳＢ，８ＶＳＢ，１６ＶＳＢのＶＳＢ−ＡＳＫ信号はアンテナ３２ｂにより受信され受信回路２４ａを経て、復調器８５２ａに入力される。
【０２８９】
一方、記録装置で記録された記録信号は再生ヘッド８５４ａで再生されて再生回路８５８を経て同じく復調器８５２ｂへ送られる。
【０２９０】
復調器８５２ｂへ入力された信号は復調器８５２ｂのフィルタ８５８ａを経て、前述のＶＳＢ等のＡＳＫ復調機８５２ｂにより、復調される。復調信号の第１データ列はＥＣＣデコーダ７５８ａにより、エラー訂正され、第２データ列はＴｒｅｌｌｉｓデコーダ７５９ｂとＥＣＣデコーダ７５９ａによりエラー訂正される。そしてビデオデコーダ４０２により、映像信号に伸長されＨＤＴＶ、ＴＶ信号もしくはＳＤＴＶの信号が出力される。
【０２９１】
Ｔｒｅｌｌｉｓ符号化器の追加により回路は複雑になるが、エラーレートが下がり、伝送装置の伝送距離が拡大し、記録再生装置の画質が改善される。この場合、受信機４３のＦｉｌｔｅｒ８５８ａは、図１３４に示すようなアナログＴＶ信号のメインキャリアや映像キャリアや音声キャリアを排除するようなフィルタ特性をもった、くし型のＦｉｌｔｅｒ７６０ａを用いることにより、アナログＴＶ信号の妨害を排除でき、エラーレートが下がる。この場合、妨害がない時も常にフィルタを入れておくと受信信号が劣化する。これを避けるため図６５に示すように、エラーレート検知部７８２により、アナログＴＶの妨害により、信号が劣化した場合のみ、アナログＴＶフィルタ７６０ａをＯＮし、妨害がない時、ＯＦＦすることにより、Ｆｉｌｔｅｒによる信号劣化を防ぐことができる。
【０２９２】
また、図８４の場合第１データ列と第２データ列のち、第２データ列の方がエラーレートが少ない。従って、第２データ列に図６６のデ・スクランブル情報や各画像ブロックのイメージデータのヘッダ情報のような重要なＨｉｇｈ　ｐｒｉｏｒｉｔｙ（ＨＰ）情報を伝送／記録することにより、デ・スクランブルや、各画像ブロックの画像信号再生を安定させることができる。
【０２９３】
また図１３７、図１７２に示すように８ＶＳＢや１６ＶＳＢの伝送装置において、時間分割された各サブチャンネルのデータ列を、トレリスデコーダーやＥＣＣデコーダーの誤り訂正のコードゲインを各サブチャンネルで変え、ＨｉｇｈＰｒｉｏｒｉｔｙ（ＨＰ）情報をこのコードゲインの高い方のサブチャンネルで送る。ＨＰ情報のエラーレートは低くなるため伝送路においてある程度ノイズが発生し信号が劣化しＬｏｗＰｒｉｏｒｉｔｙ情報（ＬＰ）情報が破壊されても、ＨＰ情報のデータは破壊されないという効果が得られる。ＨＰ情報として前述のデ・スクランブル情報や画像ブロック単位のデータパケットのアドレス等のヘッダー情報を伝送することによりスクランブルの解除が長時間安定し視聴者は安定してスクランブル解除された番組を視聴できる。また各画像ブロックの壊滅的な破壊が防止されるため受信信号が劣化しても全体の画質が劣化するだけで視聴者は、ＴＶ番組をある程度の画質で視聴することができるという効果がある。
【０２９４】
（実施例６）
第６の実施例により本発明の伝送記録方式を磁気記録再生装置に応用した例を説明する。実施例５では多値伝送のＡＳＫ伝送方式に本発明を適用した場合を示したが、同じ原理で図１７３のブロック図に示すような多値のＡＳＫ記録方式の磁気記録再生装置にも本発明を応用することができる。ＡＳＫの他，ＰＳＫ，ＦＣＫ，ＱＡＭに本発明のＣ−ＣＤＭ方式を適用することにより階層型および非階層型の多値の磁気記録が可能となる。前述のように本発明は記録装置、伝送装置の双方に適用できるが、記録装置の例を用いて説明する。
【０２９５】
まず、１６ＱＡＭや３２ＱＡＭの磁気記録再生装置に本発明のＣ−ＣＤＭ方式を適用した例を用いて階層化および多値化する方法を説明する。図８４は実施例５で多値のＶＳＢ等９ＡＳＫを用いた伝送・記録装置について説明したが、この図８４のＡＳＫをＱＡＭに変えても同じ効果が得られる。図８４、図１７３ではＱＡＭにＣ−ＣＤＭを適用した場合を説明する。以下ＱＡＭをＣ−ＣＤＭ多重化したものをＳＲＱＡＭと呼ぶ。なお図１３７と図１５４では、本発明を伝送システムに応用した場合を説明する。
【０２９６】
図８４、図１７３を説明すると、磁気記録再生装置８５１は、入力したＨＤＴＶ等の映像信号を画像エンコーダ４０１の第１画像エンコーダ４０１ａと第２画像エンコーダ４０１ｂにより高域信号と低域信号に分離し圧縮し、入力部７４２の中の第１データ列入力部７４３にＨ_ＬＶ_Ｌ成分等の低域映像信号を、第２データ　列入力部７４４にＨ_ＨＶ_Ｈ　成分等を含む高域映像信号を入力し、変復調器８５２　の中の変調部７４９に入力する。第１データ列入力部７４３では、エラー訂正コードがＥＣＣ部７３ａにおいて低域信号に付加される。一方、第２データ列入力部７４４に入力された第２データ列は１６ＳＲＱＡＭ、３６ＳＲＱＡＭ、６４ＳＲＱＡＭの場合、２ｂｉｔ、３ｂｉｔ、４ｂｉｔ、になる。この信号はＥＣＣ７４４ａにより誤り符号化された後Ｔｒｅｌｌｉｓエンコーダ部７４４ｂにより１６ＳＲ　ＱＡＭ、３２ＳＲＱＡＭ、６４ＳＲＱＡＭの場合、図１２８（ａ）（ｂ）（ｃ）に示すＴｒｅｌｌｉｓ　Ｅｎｃｏｄｅｒ７４４ｂにより、各々１／２，２／３，３／４の比率のＴｒｅｌｌｉｓ符号化される。例えば６４ＳＲＱＡＭの場合、第１データ列は２ｂｉｔで第２データ列は４ｂｉｔとなる。このため図１２８（ｃ）に示すようなＴｒｅｌｌｉｓ　Ｅｎｃｏｄｅｒ７４４ｂを用い、３ｂｉｔデータを４ｂｉｔとしたＲａｔｉｏ３／４のＴｒｅｌｌｉｓ　Ｅｎｃｏｄｅを行う。４ＡＳＫ、８ＡＳＫ、１６ＡＳＫの場合、単独で１／２、２／３、３／４のトレリスエンコードする。こうして冗長度は上がり、データレートは下がる一方でエラー訂正能力が上がるため同一のデーターレートのエラーレートを下げることができる。このため実質的な記録再生系もしくは伝送系の情報伝送量は増える。実施例５で説明した８ＶＳＢの伝送システムの場合、３ｂｉｔ／ｓｙｍｂｏｌであるため、図１２８（ｂ）（ｅ）に示すＲａｔｉｏ２／３のＴｒｅｌｌｉｓ　Ｅｎｃｏｄｅｒ７４４ｇ、Ｔｒｅｌｌｉｓ　Ｄｅｃｏｄｅｒ７４４ｑを使用でき、全体のブロック図は図１７１のようになる。但し、Ｔｒｅｌｌｉｓ　Ｅｎｃｏｄｅは回路が複雑になるため、実施例６の図８４のブロック図ではエラーレートの元々低い第１データ列には使用していない。第１データ列より第２データ列の方が符号間距離が小さく、エラーレートが悪いが、第２データ列をＴｒｅｌｌｉｓ符号化することにより、エラーレート　が改善される。第１データ列のＴｒｅｌｌｉｓ符号化回路を省略する構成により、全体の回路がよりシンプルになるという効果がある。変調の動作は実施例５の図６４の送信機とほぼ同じであるため詳しい説明は省略する。変調部７４９で変調された信号は記録再生回路８５３において、バイアス発生器８５６によりＡＣバイアスされ増巾器８５７ａにより増巾され磁気へッド８５４により磁気テープ８５５上に記録される。
【０２９７】
記録信号のフォーマットは図１１３の記録信号周波数配置図に示すように周波数ｆｃなる搬送波をもつ例えば１６ＳＲＱＡＭの主信号８５９に情報が記録されるとともに、ｆ_ｃの２倍の２ｆ_ｃの周波数をもつパイロットｆ_ｐ信号８５９ａが同　時に記録される。周波数ｆ_ＢＩＡＳなるバイアス信号８５９ｂにより、ＡＣバイアスを加えて磁気記録されるため記録時の歪が少なくなる。図１１３に示す３層のうち２層の階層型の多値記録がされているため、記録再生できる閾値はＴｈ−１−２　，Ｔｈ−２の２つが存在する。記録再生のＣ／Ｎレベルにより信号８５９なら２層全てが信号８５９ＣならＤ_１のみが記録再生される。
【０２９８】
主信号に１６ＳＲＱＡＭを用いた場合、信号点配置は図１０のようになる。又３６ＳＲＱＡＭを用いた場合、図１００のようになる。４ＡＳＫ、８ＡＳＫを用いた場合、図５８、図６８（ａ）（ｂ）のような配置となる。この信号を再生する場合、磁気ヘッド８５４からは、主信号８５９とパイロット信号８５９ａが再生され、増巾器８５７ｂにより増巾される。この信号より搬送波再生回路８５８のフィルタ８５８ａにより２ｆ_ｏなるパイロット信号ｆ_ｐが周波数分離され、１／２分周器８５８ｂによりｆ_ｏの搬送波が再生され復調部７６０に送られる。この再生された搬送波を用いて復調部７６０において主信号は復調される。この時、ＨＤＴＶ用等の高Ｃ／Ｎ値の高い磁気記録テープ８５５を用いた場合、１６点の各信号点の弁別しやすくなるため復調部７６０においてＤ１とＤ２の双方が復調される。そして画像デコーダ４２２により全信号が再生される。ＨＤＴＶＶＴＲの場合例えば１５ＭｂｐｓのＨＤＴＶの高ビットレートのＴＶ信号が再生される。Ｃ／Ｎ値が低いビデオテープ程、コストは安い。現時点で市販のＶＨＳテープと放送用の高Ｃ／Ｎ型テープとは１０ｄＢ以上Ｃ／Ｎの差がある。安価なＣ／Ｎ値の低いビデオテープ８５５を用いた場合はＣ／Ｎ値が低いため１６値や３６値の信号点を全て弁別することは難しくなる。このため第１データ列Ｄ１は再生できるが第２データ列Ｄ２の２ｂｉｔもしくは３ｂｉｔもしくは４ｂｉｔのデータ列は再生できず、第１データ列の２ｂｉｔのデータ列のみが再生される。２層の階層型のＨＤＴＶ画像信号を記録再生した場合、低Ｃ／Ｎテープでは高域画像信号は再生されないため第１データ列の低レートの低域画像信号、具体的には例えば７ＭｂｐｓのワイドＮＴＳＣのＴＶ信号が出力される。
【０２９９】
また図１１４のブロック図に示すように第２データ列出力部７５９と第２データ列入力部７４４と第２画像デコーダ４２２ａを省略し、第１データ列Ｄ_１のみ　を変復調する変形ＱＰＳＫ等の変調器をもつ低ビットレート専用の記録再生装置８５１も一つの製品形態として設定できる。この装置は第１データ列のみの記録再生が行える。つまりワイドＮＴＳＣグレードの画像信号を記録再生できる。上述のＨＤＴＶ信号等の高ビットレートの信号が記録された高いＣ／Ｎ値を出力するビデオテープ８５５をこの低ビットレート専用の磁気記録再生装置で再生した場合、第１データ列のＤ１信号のみが再生され、ワイドＮＴＳＣ信号が出力され、第２データ列は再生されない。つまり同じ階層型のＨＤＴＶ信号が記録されたビデオテープ８５５を再生した場合、一方の複雑な構成の記録再生装置ではＨＤＴＶ信号、一方の簡単な構成の記録再生装置ではワイドＮＴＳＣＴＶ信号が再生できる。つまり２層の階層の場合異なるＣ／Ｎ値をもつテープと異なる記録再生データレートをもつ機種の間で４つの組み合わせの完全互換性が実現するという大きな効果がある。この場合、ＨＤＴＶ専用機に比べてＮＴＳＣ専用機は著しく簡単な構成になる。具体的には例えばＥＤＴＶのデコーダの回路規模はＨＤＴＶのデコーダ比べて１／６になる。従って低機能機は大巾に低いコストで実現できる。このようにＨＤＴＶとＥＤＴＶの画質の記録再生能力が異なる２つのタイプの記録再生装置を実現できるため巾広い価格帯の機種が設定できるという効果がある。また使用者も高価格のＣ／Ｎの高いテープから低価格の低Ｃ／Ｎのテープまで、要求画質に応じてその都度自由にテープを選択できる。このように互換性を完全に保ちながら拡張性が得られるとともに将来との互換性も確保できる。従って将来も陳腐化しない記録再生装置の規格が実現することも可能となる。この他の記録方法としては実施例１、３で説明した位相変調による階層記録もできる。
【０３００】
実施例５で説明したＡＳＫによる記録もできる。現在２値の記録を多値にして図５９（ｃ）（ｄ）や図６８（ａ）（ｂ）に示すように４値のＡＳＫや８値のＡＳＫの信号点を２つのグループに分け、２層と３層の階層化できる。
【０３０１】
ＡＳＫの場合のブロック図は図８４と同じである。図１７３のようになる。ＴｒｅｌｌｉｓとＡＳＫの組み合わせによりエラーレートが下がる。実施例で説明した以外に磁気テープ上の多トラックによる階層型等の多値記録もできる。又、エラー訂正能力を変えて、データを差別化することによる論理的な階層記録もできる。
【０３０２】
ここで将来規格との互換性について述べる。通常、ＶＴＲ等の記録再生装置の規格を設定する場合、現実に入手できる最も高いＣ／Ｎのテープを用いて規格が定められる。テープの記録特性は日進月歩で向上する。例えば１０年前のテープに比べて、現在Ｃ／Ｎ値は１０ｄＢ以上向上している。この場合、現在から１０年〜２０年後の将来においてテープ性能が向上した時点で新しい規格を設定する場合、従来方式では旧い規格との互換性をとることは非常に難しい。このため新旧規格は片互換もしくは非互換である場合が多かった。
【０３０３】
しかし、本発明の場合、まず、現行テープで第１データ列もしくは第２データ列を記録再生する規格をつくる。次に将来テープのＣ／Ｎが大巾に向上した時点で本発明を予め採用しておけば上位のデータ階層のデータ例えば第３データ列のデータを追加し、例えば３階層の６４ＳＲＱＡＭや８ＡＳＫを記録再生するスーパーＨＤＴＶＶＴＲが従来規格と完全互換を保ちながら実現する。この将来規格が実現した理時点で本発明、新規格で第３データ列まで３層記録された磁気テープを、第１データ列、第２データ列しか記録再生できない旧規格の２層の磁気記録再生装置で再生した場合、第３データ列は再生できないが第１、第２データ列は完全に再生できる。このためＨＤＴＶ信号は再生される。このため新旧規格間の互換性を保ちながら将来、記録データ量を拡張できるという効果がある。
【０３０４】
ここで図８４の再生動作の説明に戻る。再生する時は磁気テープ８５５を磁気ヘッド８５４と磁気再生回路８５３により再生信号を再生し変復調器８５２に送る。復調部は実施例１，３，４とほぼ同様な動作をするため説明を省略する。復調部７６０により第１データ列Ｄ１と第２データ列Ｄ２を再生し、第２データ列はＶｉｔａｂｉデコーダ等のＴｒｅｌｌｉｓ−Ｄｅｃｏｄｅｒ７５９ｂにより、ｃｏｄｅ　ｇａｉｎの高いエラー訂正をされ、エラーレートは低くなる。Ｄ１、Ｄ２信号は画像デコーダー４２２により復調されＨＤＴＶの映像信号が出力される。
【０３０５】
以上は２つの階層をもつ磁気記録再生装置の実施例であるが、次に２層の物理階層に１層の論理階層を加えた３層の階層の磁気記録再生装置の実施例を図１３１のブロック図を用いて説明する。基本的には、図８４と同じ構成であるが第１データ列をＴＤＭにより、さらに２つのサブチャンネルに分割し３層構造にしている。図１３１に示すように、まずＨＤＴＶ信号は第１画像エンコーダ４０１ａの中の第１―１画像エンコーダ４０１ｃと第１―２画像エンコーダ４０１ｄにより、中域と低域の映像信号の２つのデータ、Ｄ_１−１とＤ１₋２に分離され入力部７４２の第１データ列入力部に入力される。ＭＰＥＧグレードの画質のデータ列Ｄ_１−１はＥＣＣ　ｃｏｄｅｒ７４３ａにおいてＣｏｄｅ　ｇａｉｎの高い誤り訂正符号化をされ、Ｄ１₋２はＥＣＣ　Ｃｏｄｅｒ７４３ｂにおいて通常のＣｏｄｅ　ｇａｉｎをもつ誤り訂正符号化をされる。Ｄ_１−１とＤ１₋２はＴＤＭ部７４３ｃにより時間多重化され、一つのデータ列Ｄ_１とな　る。Ｄ_１とＤ２はＣ−ＣＤＭ変調部７４９で変調され磁気ヘッド８５４により磁気テープ８５５上に、２層で階層記録される。
【０３０６】
再生時には、磁気ヘッド８５４により再生された記録信号は、図８４で説明したのと同様の動作により、Ｃ−ＣＤＭ復調部７６０によりＤ_１とＤ２に復調される。第１データ列Ｄ_１は第１データ出力部７５８の中のＴＤＭ部７５８ｃにおいて　、２つのサブチャンネルＤ_１−１とＤ１₋２に復調される。Ｄ_１−１はＣｏｄｅ　ｇａｉｎの高いＥＣＣ　Ｄｅｃｏｄｅｒ７５８ａにおいて、誤り訂正されるため、Ｄ１₋２に比べてＤ_１−１は低い　Ｃ／Ｎ値においても復調され第１−１画像デコーダ４０２ａによりＬＤＴＶがＤｅｃｏｄｅされ出力される。一方Ｄ１₋２はＣｏｄｅ　ｇａｉｎの通常のＥＣＣ　Ｄｅｃｏｄｅｒ７５８ｂにおいて誤り訂正されるため、Ｄ１₋１に比べると高いＣ／Ｎのスレシホルド値をもつため　信号レベルが大きくないと再生できない。そして、第１―２画像エンコーダ４０２ｄにおいて復調され、Ｄ_１−１と合成されて、ワイドＮＴＳＣグレードのＥＤＴＶが出力される。
【０３０７】
第２データ列Ｄ２はＴｒｅｌｌｉｓ　Ｄｅｃｏｄｅｒ７５９ｂによりＶｉｔａｂｉ復号され、ＥＣＣ７５９ａによりエラー訂正され、第２画像エンコーダ４０２ｂにより高域画像信号となり、Ｄ_１−１、Ｄ１₋２と合成されてＨＤＴＶが出力される。この場合のＤ_２のＣ　／Ｎの閾値はＤ１₋２より大きく設定する。従ってテープ８５５のＣ／Ｎ値が小さ　い場合、Ｄ_１−１つまりＬＤＴＶが再生され、通常のＣ／Ｎ値のテープ８５５の場　合Ｄ_１−１、Ｄ１₋２つまりＥＤＴＶが再生され、Ｃ／Ｎ値の高いテープ８５５を用いるとＤ_１−１、Ｄ１₋２、Ｄ２つまりＨＤＴＶ信号が再生される。
【０３０８】
こうして３層の階層の磁気記録再生装置が実現する。前述のようにテープ８５５のＣ／Ｎ値とコストとは相関関係にある。本発明の場合使用者は３つのタイプのテープコストに応じた３つのグレードの画質の画像信号を記録再生できるため、使用者が記録したいＴＶ番組の内容に応じてテープのグレードを選択する巾が拡がるという効果がある。
【０３０９】
次に早送り再生時の階層記録の効果を述べる図１３２の記録トラック図に示すように磁気テープ８５５上にはアジマス角Ａの記録トラック８５５ａと逆のアジマス角のＢの記録トラック８５５ｂが記録されている。図示するように記録トラック８５５ａの中央部にこのまま記録領域８５５ｃを設け、他の領域をＤ_１−２記　録領域８５５ｄとする。これを各々の記録トラック数ヶにつき少なくとも１ヶ所設ける。この中にはＬＤＴＶ１フレーム分が記録されている。高域信号のＤ２信　号は記録トラック８５５ａの全領域のＤ２記録領域８５５ｅに記録する。通常速　度の記録再生時には、この記録フォーマットは新たな効果は生まない。さて順方向と逆方向のテープ早送り再生時にはアジマス角Ａの磁気ヘッドトレース８５５ｆは図に示すように磁気トラックと一致しなくなる。図１３２に示す本発明においてはテープ中央部の狭い領域に設定されたＤ_１−１記録領域８５５ｃを設けてあ　る。このためある一定の確率ではあるが、この領域は確実に再生される。再生されたＤ_１−１信号からはＭＰＥＧ１並みのＬＤＴＶの画質ではあるが同一時間の画　面全体の画像を復調できる。こうして早送り再生時には１秒間に数枚から数十枚のＬＤＴＶの完全な画像が再生されると使用者は早送り中の画画面を確認できるいう大きな効果がある。
【０３１０】
また逆送り再生時にはヘッドトレース８５ｇ示すように磁気トラックの一部の領域しかトレースしない。しかし、この場合においても図１３２で示す記録再生フォーマットを用いた場合、Ｄ１−１記録領域が再生できるためＬＤＴＶグレード　の画質の動画が間欠的に出力される。
【０３１１】
こうして、本発明では記録トラックの一部の狭い領域にＬＤＴＶグレードの画像を記録するため使用者は正逆両方向の早送り時にＬＤＴＶグレードの画質で早送りの間欠的にほぼ完全な静止画を再生できるため、高速検索時に画面の確認が容易になるという効果がある。
【０３１２】
次に、さらに高速の早送り再生に対応する方法を述べる。図１３２の右下に示すようにＤ_１−１記録領域８５５Ｃを設け、ＬＤＴＶの１フレームを記録するとと　もにＤ_１−１記録領域８５５Ｃの一部にさらに狭い領域のＤ_１−１・Ｄ_２記録領域８５　５ｈを設ける。この領域におけるサブチャンネルＤ_１−１にはＬＤＴＶの１フレー　ムの一部の情報が記録されている。ＬＤＴＶの残りの情報をＤ_１−１・Ｄ_２記録領域８５５ｈのＤ_２記録領域８５５ｊに重複して記録する。サブチャンネルＤ_２はサブチャンネルＤ_１−１の３〜５倍のデータ記録量をもつ。従ってＤ_１−１とＤ_２で１／３　〜１／５の面積のテープ上のＬＤＴＶの１フレームの情報を記録できる。ヘッドレースがさらに狭い領域である領域８５５ｈ，８５５ｊに記録できるため、ヘッドのトレース時間Ｔ_ｓ１に比べて時間も面積も１／３〜１／５になる。従って早送り速度を早めてヘッドのトレースがさらに傾いても、この領域全体をトレースする確率が高くなる。このためＤ_１−１のみの場合に比べてさらに３〜５倍速い早送　り時にも完全なＬＤＴＶの画像を間欠的に再生する。
【０３１３】
この方式は２階層のＶＴＲの場合、Ｄ_２記録領域８５５ｊを再生する機能がな　いため、高速の早送り時には再生できない。一方３階層の高機能型ＶＴＲにおいては２階層に比べて３〜５倍速い早送り時にも画像が確認できる。つまり、階層の数つまりコストに応じた画質だけでなく、コストに応じて再生可能な最大早送り速度が異なるＶＴＲが実現する。
【０３１４】
なお実施例では階層型変調方式を用いたが１６ＱＡＭ等の通常の変調方式でも、階層型の画像符号化を行えば本発明による早送り再生が実現する。ことはいうまでもない。
【０３１５】
従来の高度に画像を圧縮する方式の非階層型のデジタルＶＴＲの記録方式では画像データが均一に分散しているため、早送り再生時に各フレームの同一時間の画面の画像の全部を再生することはできない。このため画面の各ブロックの時間軸のずれた画像しか再生できない。しかし、本発明の階層型のＨＤＴＶＶＴＲではＬＤＴＶグレードではあるが、画面の各ブロックの時間軸のずれていない画像を早送り再生時に再生できるという効果がある。
【０３１６】
本発明のＨＤＴＶの３層の階層記録を行った場合記録再生系のＣ／Ｎが高いときはＨＤＴＶ等の高解像度ＴＶ信号を再生できる。そして記録再生系のＣ／Ｎが低い場合や機能の低い磁気再生装置で再生した場合、ワイドＮＴＳＣ等のＥＤＴＶグレードのＴＶ信号もしくは低解像度ＮＴＳＣ等のＬＤＴＶグレードのＴＶ信号が出力される。
【０３１７】
以上のように本発明を用いた磁気再生装置においては、Ｃ／Ｎが低くなった場合や、エラーレートが高くなった場合においても同一内容の映像を低い解像度、もしくは低い画質で再生できるという効果が得られる。
【０３１８】
（実施例７）
実施例７は本発明を４階層の映像階層伝送に用いたものである。実施例２で説明した４階層の伝送方式と４階層の映像データ構造を組み合わせることにより図９１の受信妨害領域図に示すように４層の受信領域ができる。図に示すように最内側に第１受信領域８９０ａ、その外側に第２受信領域８９０ｂ、第３受信領域８９０ｃ、第４受信領域８９０ｄができる。この４階層を実現する方式について述べる。
【０３１９】
４階層を実現するには変調による４層の物理階層やエラー訂正能力の差別化による４層の論理階層があるが、前者は階層間のＣ／Ｎ差が大きいため４層では大きなＣ／Ｎが必要となる。後者は、復調可能なことが前提であるため、階層間のＣ／Ｎ差を大きくとれない。現実的であるのは、２層の物理階層と２層の論理階層を用いて、４層の階層伝送を行うことである。では、まず映像信号を４層に分離する方法を述べる。
【０３２０】
図９３は分離回路３のブロック図である分離回路３は映像分離回路８９５と４つの圧縮回路から構成される。分離回路４０４ａ、４０４ｂ、４０４ｃの内部の基本的な構成は、図３０の第１画像エンコーダ４０１の中の分離回路４０４のブロック図と同じなので説明は省略する。分離回路４０４ａ等は映像信号を低域成分Ｈ_ＬＶ_Ｌと高域成分Ｈ_ＨＶ_Ｈと中間成分Ｈ_ＨＶ_Ｌ、Ｈ_ＬＶ_Ｈの４つの信号に分離する。この場合、Ｈ_ＬＶ_Ｌは解像度が元の映像信号の半分になる。
【０３２１】
さて入力した映像信号は映像分離回路４０４ａにより高域成分と低域成分に２分割される。水平と垂直方向に分割されるため４つの成分が出力される。高域と低域の分割点はこの実施例では中間点にある。従って、入力信号が垂直１０００本のＨＤＴＶ信号の場合Ｈ_ＬＶ_Ｌ信号は垂直５００本の、水平解像度も半分のＴＶ信号となる。
【０３２２】
低域成分のＨ_ＬＶ_Ｌ信号は分離回路４０４ｃにより、さらに水平、垂直方向の周波数成分が各々２分割される。従ってＨ_ＬＶ_Ｌ出力は例えば垂直２５０本、水平解像度は１／４となる。これをＬＬ信号と定義するとＬＬ成分は圧縮部４０５ａにより圧縮され、Ｄ_１−１信号として出力される。
【０３２３】
一方、Ｈ_ＬＶ_Ｌの高域成分の３成分は合成器７７２ｃにより１つのＬＨ信号に合成され、圧縮部４０５ｂにより圧縮されＤ_１−２信号として出力される。この場合　、分離回路４０４ｃと合成器７７２ｃの間に圧縮部を３つ設けてもよい。
【０３２４】
高域成分のＨ_ＨＶ_Ｈ、Ｈ_ＬＶ_Ｈ、Ｈ_ＨＶ_Ｌの３成分は合成器７７２ａにより一つのＨ_ＨＶ_Ｈ−Ｈ信号となる。圧縮信号が垂直水平とも１０００本の場合、この信号は水平、垂直方向に５００本〜１０００本の成分をもつ。そして分離回路４０４ｂにより４つの成分に分離される。
【０３２５】
従ってＨ_ＬＶ_Ｌ出力として水平、垂直方向の５００本〜７５０本の成分が分離される。これをＨＨ信号とよぶ。そしてＨ_ＨＶ_Ｈ、Ｈ_ＬＶ_Ｈ、Ｈ_ＨＶ_Ｌの３成分は７５０本〜１０００本の成分をもち、合成器７７２ｂで合成され、ＨＨ信号となり圧縮部４０５ｄで圧縮され、Ｄ_２−２信号として出力される。一方ＨＬ信号はＤ_２−１信号として出力される。従ってＬＬ、つまりＤ_１−１信号は例えば０本〜２５０本以下　の成分、ＬＨつまりＤ_１−２信号は２５０本以上５００本以下の周波数成分ＨＬつ　まりＤ_２−１信号は５００本以上７５０本以下の成分、ＨＨつまりＤ_２−２信号は７５０本以上１０００本以下の周波数成分をもつ。この分離回路３により階層型のデータ構造ができるという効果がある。この図９３の分離回路３を用いて実施例２で説明した図８７の送信機１の中の分離回路３の部分を置きかえることにより、４層の階層型伝送ができる。
【０３２６】
こうして階層型データ構造と階層型伝送を組み合わせることにより、Ｃ／Ｎの劣下に伴い段階的に画質が劣下する画像伝送が実現できる。これは放送においてはサービスエリアの拡大という大きな効果がある。次にこの信号を復調再生する受信機は実施例２で説明した図８８の第２受信機と同じ構成と動作である。従って全体の動作は省略する。ただ映像信号を扱うため合成部３７の構成がデータ送信と異なる。ここでは合成部３７を詳しく説明する。
【０３２７】
実施例２において図８８の受信機のブロック図を用いて説明したように、受信した信号は復調され、エラー訂正され、Ｄ_１−１、Ｄ_１−２、Ｄ_２−１、Ｄ_２−２の４つの信号となり、合成部３７に入力される。
【０３２８】
ここで図９４は合成部３３のブロック図である。入力されたＤ_１−１、Ｄ_１−２、Ｄ_２−１、Ｄ_２−２信号は伸長部５２３ａ、５２３ｂ、５２３ｃ、５２３ｄにおいて伸長され、図９３の分離回路において説明したＬＬ、ＬＨ、ＨＬ、ＨＨ信号となる。この信号は、元の映像信号の水平、垂直方向の帯域を１とするとＬＬは１／４、ＬＬ＋ＬＨは１／２、ＬＬ＋ＬＨ＋ＨＬは３／４、ＬＬ＋ＬＨ＋ＨＬ＋ＨＨは１の帯域となる。ＬＨ信号は分離器５３１ａにより分離され画像合成部５４８ａにおいてＬＬ信号と合成されて画像合成部５４８ｃのＨ_ＬＶ_Ｌ端子に入力される。画像合成部５３１ａの例の説明に関しては図３２の画像デコーダ５２７で説明したので省略する。一方、ＨＨ信号は分離器５３１ｂにより分離され、画像合成部５４８ｂに入力される。ＨＬ信号は画像合成部５４８ｂにおいてＨＨ信号と合成され、Ｈ_ＨＶ_Ｈ−Ｈ信号となり分離器５３１ｃにより分離され、画像合成部５４８ｃにおいてＬＨとＬＬの合成信号と合成され、映像信号となり合成部３３から出力される。そして図８８の第２受信機の出力部３６でＴＶ信号となり出力される。この場合、原信号が垂直１０５０本、約１０００本のＨＤＴＶ信号ならば図９１の受信妨害図に示した４つの受信条件により４つの画質のＴＶ信号が受信される。
【０３２９】
ＴＶ信号の画質を詳しく説明する。図９１と図８６を一つにまとめたのが図９２の伝送階層構造図である。このようにＣ／Ｎの向上とともに受信領域８６２ｄ、８６２ｃ、８６２ｂ、８６２ａにおいてＤ_１−１、Ｄ_１−２、Ｄ_２−１、Ｄ_２−２と次々と再生できる階層チャンネルが追加されデータ量が増える。
【０３３０】
映像信号の階層伝送の場合図９５伝送階層構造図のようにＣ／Ｎの向上とともにＬＬ、ＬＨ、ＨＬ、ＨＨ信号の階層チャンネルが再生されるようになる。従って送信アンテナからの距離が近づくにつれ、画質が向上する。Ｌ＝Ｌｄの時ＬＬ信号、Ｌ＝Ｌｃの時ＬＬ＋ＬＨ信号、Ｌ＝Ｌｂの時ＬＬ＋ＬＨ＋ＨＬ信号、Ｌ＝Ｌａの時ＬＬ＋ＬＨ＋ＨＬ＋ＨＨ信号が再生される。従って、原信号の帯域を１とすると１／４、１／２、３／４、１の帯域の画質が各々の受信地域で得られる。原信号が垂直走査線１０００本のＨＤＴＶの場合、２５０本、５００本、７５０本、１０００本のＴＶ信号が得られる。このようにして段階的に画質が劣化する階層型映像伝送が可能となる。図９６は従来のデジタルＨＤＴＶ放送の場合の受信妨害図である。図から明らかなように従来方式ではＣＮがＶ_Ｏ以下でＴＶ信　号の再生は全く不可能となる。従ってサービスエリア距離Ｒの内側においても他局との競合地域、ビルかげ等では×印で示すように受信できない。図９７は本発明を用いたＨＤＴＶの階層放送の受信状態図を示す。図９７に示すように、距離ＬａでＣ／Ｎ＝ａ、ＬｂでＣ／Ｎ＝ｂ、ＬｃでＣ／Ｎ＝ｃ、ＬｄでＣ／Ｎ＝ｄとなり各々の受信地域で２５０本、５００本、７５０本、１０００本の画質が得られる。距離Ｌａ以内でもＣ／Ｎが劣下し、ＨＤＴＶの画質そのものでは再生できない地域が存在する。しかし、その場合でも画質が落ちるものの再生はできる。例えばビルかげのＢ地点では７５０本、電車内のＤ地点では２５０本、ゴーストを受けるＦ地点では７５０本、自動車内のＧ地点では２５０本、他局との競合地域であるＬ地点でも２５０本の画質で再生できる。以上のようにして本発明の階層伝送を用いることにより従来提案されている方式では受信再生できなかった地域でも受信できるようになり、ＴＶ局のサービスエリアが大巾に拡大するという著しい効果がある。また、図９８の階層伝送図に示すようにＤ_１−１チャンネルで　その地域のアナログ放送と同じ番組の番組Ｄを放送し、Ｄ_１−２、Ｄ_２−１、Ｄ_２−２チ　ャンネルで他の番組Ｃ、Ｂ、Ａを放送することにより、番組Ｄのサイマルキャストを全地域で確実に放送し、サイマルキャストの役割を果たしながら他の３つの番組をサービスするという多番組化の効果も得られる。
【０３３１】
（実施例８）
以下、第７の実施例を図面に基づき説明する。実施例８は本発明の階層型伝送方式をセルラー電話システムの送受信機に応用したものである。図１１５の携帯電話機の送受信機のブロック図においてマイク７６２から入力された通話者の音声は圧縮部４０５により前述した階層構造のデータＤ_１，Ｄ_２，Ｄ_３に圧縮符号化　され、時分割部７６５においてタイミングに基づき所定のタイムスロットに時間分割され、変調器４において前述のＳＲＱＡＭ等の階層型の変調を受け１つの搬送波にのり、アンテナ共用器７６４を経てアンテナ２２より送信され、後述する基地局で受信され、他の基地局もしくは電話局に送信され、他の電話と交信できる。
【０３３２】
一方、他の電話からの交信信号は基地局からの送信電波としてアンテナ２２により受信される。この受信信号はＳＲＱＡＭ等の階層型の復調器４５において、Ｄ_１，Ｄ_２，Ｄ_３のデータとして復調される。復調信号からはタイミング回路７６　７においてタイミング信号が検出され、このタイミング信号は時分割部７６５に送られる。復調信号Ｄ_１，Ｄ_２，Ｄ_３は伸長部５０３において伸長され音声信号に　なり、スピーカ６５に送られ、音声となる。
【０３３３】
次に図１１６の基地局のブロック図にあるように６角形もしくは円形の３つの受信セル７６８，７６９，７７０，の各中心部にある基地局７７１，７７２，７７３は図１１５と同様の送受信機７６１ａ〜７６１ｊを複数個もち、送受信機の数と同じチャンネル数のデータを送受信する。各基地局に接続された基地局制御部７７４は各基地局の通信のトラフィック量を常に監視し、これに応じて各基地局へのチャンネル周波数の割り当てや各基地局の受信セルの大きさの制御等の全体システムのコントロールを行う。
【０３３４】
図１１７の従来方式の通信容量トラフィック分布図に示すようにＱＰＳＫ等の従来方式のデジタル通信方式では受信セル７６８，７７０のＡｃｈの伝送容量はｄ＝Ａの図に示すように同波数利用効率２ｂｉｔ／Ｈｚのデータ７７４ｄ、７７４ｂとｄ＝Ｂの図のデータ７７４ｃを合わせたデータ７７４ｄなり、どの地点においても２ｂｉｔ／Ｈｚの一様な周波数利用効率である。一方、実際の都市部は密集地７７５ａ，７７５ｂ，７７５ｃのようにビルの集中したところは人口密度が高く、交信トラフィック量もデータ７７４ｅに示すようにピークを示す。周辺のそれ以外の地域では交信量は少ない。実際のトラフィック量ＴＦのデータ７７４ｅに対して従来のセルラー電話の容量はデータ７７４ｄに示すように全地域、同じ２ｂｉｔ／Ｈｚの周波数効率であった。つまりトラフィック量の少ないところにも多いところと同じ周波数効率を適用しているという効率の悪さがあった。従来方式ではトラフィック量の多い地域には周波数割り当てを多くしチャンネル数を増やしたり、受信セルの大きさを小さくして対応していた。しかし、チャンネル数を増やすには周波数スペクトルの制約があった。また従来方式の１６ＱＡＭ，６４ＱＡＭ等の多値化は送信電力を増加させた。受信セルの大きさを小さくし、セル数を増やすことは基地局の数の増加を招き、設置コストを増大させる。以上の問題点がある。
【０３３５】
理想的にはトラフィック量の多い地域には周波数効率を高くし、トラフィック量の少ない地域には周波数効率を高くし、トラフィック量の少ない地域には低くすることがシステム全体の効率を高められる。本発明の階層型伝送方式の採用により以上のことを実現できる。このことを図１１８の本発明の実施例８における通信容量・トラフィック分布図を用いて説明する。図１１８の分布図は上から順に受信セル７７０Ｂ，７６８，７６９，７７０，７７０ａのＡ−Ａ’線上の通信容量を示す。受信セル７６８，７７０はチャンネル群Ａ受信セル７７０ｂ，７６９，７７０ａはチャンネル群Ａと重複しないチャンネル群Ｂの周波数を利用している。これらのチャンネルは各受信セルのトラフィック量に応じて図１１６の基地局制御器７７４により、チャンネル数が増減させられる。さて図１１８においてｄ＝ＡはＡチャンネルの通信容量の分布を示す。ｄ＝ＢはＢチャンネルの通信容量、ｄ＝Ａ＋Ｂは全チャンネルを加算した通信容量、ＴＦは通信トラフィック量、Ｐは建物と人口の分布を示す。受信セル７６８，７６９，７７０では前の実施例で説明したＳＲＱＡＭ等の多層の階層型伝送方式を用いているためデータ７７６ａ，７７６ｂ，７７６ｃに示すように、ＱＰＳＫの周波数利用効率２ｂｉｔ／Ｈｚの３倍の６ｂｉｔ／Ｈｚを基地局周辺部では得られる。周辺部にいくに従い４ｂｉｔ／Ｈｚ，２ｂｉｔ／Ｈｚと減少する。送信パワーを増やさないと点線７７７ａ，ｂ，ｃに示すＱＰＳＫの受信セルの大きさに比べて２ｂｉｔ／Ｈｚの領域が狭くなるが、基地局の送信パワーを若干上げることにより同等の受信セルの大きさが得られる。６４ＳＲＱＡＭ対応の子局は基地局から遠いところではＳＲＱＡＭのシフト量をＳ＝１にした変形ＱＰＳＫで送受信し、近いところでは１６ＳＲＱＡＭ、さらに近傍では６４ＳＲＱＡＭで送受信する。従ってＱＰＳＫに比べて最大送信パワーが増加することはない。また、回路を簡単にした図１２１のブロック図に示すような４ＳＲＱＡＭの送受信機も互換性を保ちながら他の電話と交信できる。図１２２のブロック図に示す１６ＳＲＱＡＭの場合も同様である。従って３つの変調方式の子機が存在する。携帯電話の場合小型計量性が重要である。４ＳＲＱＡＭの場合周波数利用効率が下がるため通話料金は高くなるが、回路が簡単になるため小型軽量化が要求されるユーザーには適している。こうして本方式は巾広い用途に対応できる。
【０３３６】
以上のようにして図１１８のｄ＝Ａ＋Ｂのような容量の異なる分布をもつ伝送システムができる。ＴＦのトラフィック量に合わせて基地局を設置することにより、総合的な周波数利用効率が向上するという大きな効果がある。特にセルの小さいマイクロセル方式は多くのサブ基地局を設置できるためサブ基地局をトラフィックの多い個所に設置しやすいため本発明の効果が高い。
【０３３７】
次に図１１９のデータの時間配置図を用いて各タイムスロットのデータ配置を説明する。図１１９（ａ）は従来方式のタイムスロット、図１１９（ｂ）は実施例８のタイムスロットを示す。図１１９（ａ）に示すように従来方式の送受信別周波数方式はＤｏｗｎつまり基地局から子局への送信の時に周波数Ａで時間のスロット７８０ａで同期信号Ｓを送り、スロット７８０ｂ，７８０ｃ，７８０ｄで各々Ａ，Ｂ，Ｃチャンネルの子機への送信信号を送る。次にＵｐ側つまり子機から基地局へ送る場合、周波数Ｂで時間スロット７８１ａ，７８１ｂ，７８１ｃ，７８１ｄに各々同期信号、ａ，ｂ，ｃチャンネルを送信信号する。
【０３３８】
本発明の場合、図１１９（ｂ）に示すように前述の６４ＳＲＱＡＭ等の階層型伝送方式を用いているためＤ_１，Ｄ_２，Ｄ_３の各々の２ｂｉｔ／Ｈｚの３つの階層　データをもつ。Ａ_１，Ａ_２データは１６ＳＲＱＡＭで送るためスロット７８２ｂ，７８２ｃとスロット７８３ｂ，７８３ｃに示すように約２倍のデータレートとなる。同一音質で送る場合半分の時間で送れる。従ってタイムスロット７８２ｂ，７８２ｃは半分の時間になる。こうして２倍の伝送容量が図１１８の７７６ｃの第２階層の地域つまり基地局の近傍で得られる。同様にして、タイムスロット７８２ｇ，７８３ｇではＥ_１データの送受信が６４ＳＲＱＡＭで行われる。約３倍　の伝送容量をもつため、同一タイムスロットで３倍のＥ_１，Ｅ_２，Ｅ_３の３チャン　ネルが確保できる。この場合基地局のさらに近傍地域で送受信することが要求される。このようにして最大約３倍の通話が同一周波数帯で得られるという効果がある。但し、この場合は基地局の近傍でこのままの通話が行われた場合で、実際はこの数字より低い。また実際の伝送効率は９０％程度に落ちる。本発明の効果を上げるためには、トラフィック量の地域分布と本発明による伝送容量分布が一致することが望ましい。しかし、図１１８のＴＦの図に示すように実際の都市においてはビル街を中心として緑地帯が周辺に配置されている。郊外においても住宅地の周辺に田畑や森が配置されている。従ってＴＦの図に近い分布をしている。従って本発明を適用する効果が高い。
【０３３９】
図１２０のＴＤＭＡ方式タイムスロット図で（ａ）は従来方式（ｂ）は本発明の方式を示す。図１２０（ａ）に示すように、同一周波数帯でタイムスロット７８６ａ，７８６ｂで各々Ａ，Ｂチャンネルの子機への送信を行い、タイムスロット７８７ａ，７８７ｂで各々Ａ，Ｂチャンネルの子機からの送信を行う。図１２０（ｂ）に示すように、本発明の場合１６ＳＲＱＡＭの場合スロット７８８ａでＡ_１チャンネルの受信を行い、スロット７８８ｃでＡ_１チャンネルの送信を行う。タイムスロット巾は約１／２になる。６４ＳＲＱＡＭの場合スロット７８８ｉでＤ_１チャンネルの受信を行い、スロット７８８ｌでＤ_１チャンネルの送信を行う。タイムスロット巾は約１／３になる。
【０３４０】
特に消費電力を下げるためにスロット７８８ｐにおいて１／２のタイムスロットで１６ＳＲＱＡＭのＥ_１の受信を行うが、送信はスロット７８８ｒで通常のタ　イムスロット４ＳＲＱＡＭで行う。１６ＳＲＱＡＭより４ＳＲＱＡＭの方が消費電力が少ないため、送信時の電力消費が少なくなるという効果がある。ただし、占有時間が長い分だけ通信料金は高くなる。バッテリの小さい小型軽量型の携帯電話やバッテリ残量が少ない時に効果が高い。
【０３４１】
以上のようにして実際のトラフィック分布に合わせて伝送容量分布を設定できるため実質的な伝送容量が高めることができるという効果がある。また３つのもしくは２つの伝送容量の伝送容量を基地局、子局が選択できるため周波数効率を下げて消費電力を下げたり逆に効率を上げて通話料金を下げたり自由度が高く、様々な効果が得られる。また、伝送容量の低い４ＳＲＱＡＭ等の方式により、回路を簡単にして小型化、低コスト化をした子機も設定できる。この場合、前の実施例で説明したように全ての機種間の伝送互換性がとれる点が本発明の特徴の一つである。こうして伝送容量の増大とともに超小型機から高機能機までの巾広い機種展開が計れる。
【０３４２】
（実施例９）
以下第９の実施例を図面に基づき説明する。実施例９は本発明をＯＦＤＭ伝送方式に適用したものである。図１２３のＯＦＤＭ送受信機のブロック図と図１２４のＯＦＤＭの動作原理図を示す。ＦＤＭの一種であるＯＦＤＭは隣接するキャリアを直交させることにより、一般のＦＤＭより周波数帯の利用効率が良い。またゴースト等のマルチパス妨害に強いためデジタル音楽放送用やデジタルＴＶ放送用に検討されている。図１２４のＯＦＤＭの原理図に示すようにＯＦＤＭの場合入力信号を直列並列変換部７９１で周波数軸７９３上にデータを１／ｔｓの間隔で配置し、サブチャンネル７９４ａ〜ｅを作成する。この信号を逆ＦＦＴ器４０をもつ変調器４で時間軸７９９へ逆ＦＦＴ変換し、送信信号７９５を作る。ｔｓの有効シンボル期間７９６の期間の間、この逆ＦＦＴされた信号は送信され、各シンボルの間にはｔｇのガード期間７９７が設けられる。
【０３４３】
図１２３のＯＦＤＭ−ＣＣＤＭハイブリッド方式のブロック図を用いてＨＤＴＶ信号を送受信する場合の実施例９の動作を説明する。入力されたＨＤＴＶ信号は画像エンコーダ４０１により低域Ｄ_１−１と（中域−低域）Ｄ_１−２と（高域−中域−低域）Ｄ_２の３層の階層構造の画像信号に分離され、入力部７４２に入力され　る。第１データ列入力部７４３において、Ｄ_１−１信号はＣｏｄｅ　ｇａｉｎの高いＥＣＣ符号化をされ、Ｄ_１−２信号は通常のコードゲインのＥＣＣの符号化をされる。Ｄ_１−１とＤ_２−２はＴＤＭ部７４３により、時間分割多重化され、Ｄ_１信号になり、変調器８５２ａのＤ_１直列並列変換器７９１ａに入力される。Ｄ_１信号はｎ個の並列データとなり、ｎヶのＣ−ＣＤＭ変調器４ａ，４ｂ・・・の第１入力部に入力される。
【０３４４】
一方、高域成分信号のＤ_２は入力部７４２の第２データ列入力部７４４におい　てＥＣＣ部７４４ａにおいてＥＣＣ（Ｅｒｒｏｒ　Ｃｏｒｒｅｃｔｉｏｎ　Ｃｏｄｅ）符号化されトレ　リスエンコーダ７４４ｂにおいてトレリス符号化され、変調器８５２ａのＤ_２直　列並列器７９１ｂに入力され、ｎヶの並列データとなり、Ｃ−ＣＤＭ変調器４ａ，４ｂ・・・の第２入力部に入力される。第１入力部のＤ_１データと第２入力部のＤ_２データにより各々のＣ−ＣＤＭ変調器４ａ，４ｂ，４ｃ・・・において１６ＳＲＱＡＭ等にＣ−ＣＤＭ変調される。このｎヶのＣ−ＣＤＭ変調器は各々の異なる周波数のキャリアをもつとともに隣接するキャリアは図１２４の７９４ａ，７９４ｂ，７９４ｃ・・・に示すように直交しながら周波数軸上７９３上にある。こうし　て、Ｃ−ＣＤＭ変調されたｎヶの変調信号は、逆ＦＦＴ回路４０により、周波数軸ディメンジョン７９３から時間軸のディメンジョン７９０に写像され、ｔｓの実効シンボル長の時間信号７９６ａ，７９６ｂ等になる。実効シンボル時間帯７９６ａと７９６ｂの間にはマルチパス妨害を減らすためＴｇ秒のガード時間帯７９７ａが設けられている。これを時間軸と信号レベルで表現したものが、図１２９の時間軸ー信号レベル図であり、ガード時間帯７９７ａのＴｇはマルチパスの影響時間から用途に応じて決定される。ＴＶゴースト等のマルチパスの影響時間より長くＴｇを設定することにより受信時に逆ＦＦＴ回路４０からの変調信号は並列直列コンバータ４０ｂにより、一つの信号となり送信部５により、ＲＦ信号となり送信される。
【０３４５】
次に、受信機４３の動作を述べる。図１２４の時間軸シンボル信号７９６ｅに示す。受信信号は図１２３の入力部２４に入力され、変調部８５２ｂに入力され、デジタル化され、ＦＦＴ部４０ａにより、フーリェ係数に展開され、図１２４に示すように時間軸７９９から周波数軸７９３ａに写像される。図１２４の時間軸シンボル信号から、周波数軸の信号のキャリア７９４ａ，７９４ｂ等に変換される。これらのキャリアは互いに直交しているため、各々の変調信号が分離できる。図１２５（ｂ）に示す１６ＳＲＱＡＭ等が復調され、各々のＣ−ＣＤＭ復調器４５ａ、４５ｂ等に送られる。そして、Ｃ−ＣＤＭ復調器４５の各々のＣ−ＣＤＭ復調部４５ａ、ｂ等において、階層型に復調されＤ_１、Ｄ_２のサブ信号が復調され、Ｄ_１並列直列コンバーター８５２ａとＤ_２並列直列コンバーター８５２ｂにより、直列信号となり元のＤ_１、Ｄ_２信号が復調される。この場合、図１２５（ｂ）に示すようなＣ−ＣＤＭを用いた階層伝送方式を用いているため、Ｃ／Ｎ値の悪い受信条件では、Ｄ_１信号のみが復調され、よい受信条件では、Ｄ_１とＤ２信号　の両方が復調される。復調されたＤ_１信号は出力部７５７において復調される。　Ｄ_１−２信号に比べてＤ_１−１信号エラー訂正のコードケインが高いため、Ｄ_１−１信号　のエラー信号がより受信条件の悪い条件でも再生される。Ｄ_１−１信号は第１ー１　画像デコーダ４０２ｃによりＬＤＴＶの低域信号となり、Ｄ_１−２信号は第１ー２　画像デコーダ４０２ｄによりＥＤＴＶの中域成分の信号となり、出力される。
【０３４６】
Ｄ_２信号はトレリス復号され、第２画像デコーダ４０２ｂにより、ＨＤＴＶの　高域成分となり出力される。上記の低域信号のみではＬＤＴＶが出力され、上記中域成分を加えることにより、ワイドＮＴＳＣグレードのＥＤＴＶ信号が出力され、さらに上記高域成分を加えることによりＨＤＴＶ信号が合成される。前の実施例と同様、受信Ｃ／Ｎに応じた画質のＴＶ信号が受信できる。実施例９の場合はＯＦＤＭとＣ−ＣＤＭを組み合わせて用いることにより、ＯＦＤＭそのものでは、実現できない階層型伝送を実現できる。図１３０のエラーレートＣ／Ｎに示すように従来のＯＦＤＭ−ＴＣＭ変調信号の曲線８０５に対して、本発明のＣ−ＣＤＭ−ＯＦＤＭ方式はサブチャンネル１　８０７ａはエラーレートが下がりサブチャンネル２　８０７ｂはエラーレートが上がる。こうして階層型が実現する。
【０３４７】
ＯＦＤＭは確かにガード期間Ｔｇ中にマルチパスの干渉信号を収めているためＴＶゴースト等のマルチパスに強い。従って、自動車のＴＶ受信機用のデジタルＴＶ放送用に用いることができる。しかし、階層型伝送ではないため、ある一定のＣ／Ｎのスレシホルド以下では受信できない。本発明のＣ−ＣＤＭと組み合わせることにより、マルチパスに強くかつＣ／Ｎの劣化に応じた画像受信（Ｇｒａｄｉｔｉｏｎａｌ　Ｄｅｇｒａｄａｔｉｏｎ）の２つが実現できる。自動車内でＴＶ受信をする時、単に　マルチパスだけでなくＣ／Ｎ値も劣化する。従ってマルチパス対策だけではＴＶ放送局のサービスエリアはさほど広がらない。しかし、階層型伝送のＣ−ＣＤＭと組み合わせることにより、Ｃ／Ｎがかなり劣化してもＬＤＴＶグレードで受信できる。一方、自動車用ＴＶの場合、画面サイズは通常１００寸以下であるため、ＬＤＴＶグレードで充分な画質が得られる。自動車ＴＶのＬＤＴＶグレードのサービスエリアが大巾に拡大するという効果がある。ＯＦＤＭをＨＤＴＶの全帯域に使うと現時点の半導体技術ではＤＳＰの回路規模が大きくなる。そこで低域ＴＶ信号のＤ_１−１のみをＯＦＤＭで送る方法を示す。図１３８のブロック図に示　すように、ＨＤＴＶの中域成分と高域成分のＤ_１−２とＤ_２信号の２つを本発明のＣ−ＣＤＭ多重化し、ＦＤＭ４０Ｄにより周波数帯Ａで送信する。一方受信機側で受信した信号はＦＤＭ４ｏｅにより周波数分離され、本発明のＣ−ＣＤＭ復調器４ｂで復調され、図１２３と同様にしてＨＤＴＶの中域成分と高域成分が再生される。この場合の画像デコーダーの動作は実施例１，２，３と同じであるため省略する。
【０３４８】
次にＨＤＴＶのＭＰＥＧ１グレードの低域信号であるＤ_１−１信号は直列並列コ　ンバーター７９１により並列信号となりＯＦＤＭ変換器８５２Ｃの中でＱＰＳＫや１６ＱＡＭの変調を受け、逆ＦＦＴ器４０により時間軸の信号に変換されＦＤＭ４０ｄにより周波数帯Ｂで送信される。
【０３４９】
一方、受信機４３で受信された信号はＦＤＭ部４０ｅにおいて周波数分離され、ＯＦＤＭ復調部８５２ｄにおいてＦＦＴ４０ａにより多くの周波数軸の信号となり、各々の復調器４５ａ，４５ｂ等により復調され、並列直列コンバータ８５２ａによりＤ_１−１信号が復調され、図１２３と同様にして、ＬＤＴＶグレードの　Ｄ_１−１信号が受信機４３から出力される。
【０３５０】
こうして、ＬＤＴＶ信号のみがＯＦＤＭされた階層伝送が実現する。図１３８の方法を用いることにより、ＯＦＤＭの複雑な回路はＬＤＴＶ信号のみでよい。ＨＤＴＶ信号に比べてＬＤＴＶ信号は１／２０のビットレートである。従ってＯＦＤＭの回路規模は１／２０になり、全体の回路規模は大巾に小さくなる。
【０３５１】
ＯＦＤＭはマルチパスに強い伝送方式で携帯ＴＶや自動車ＴＶの受信時や自動車のデジタル音楽放送受信時のような移動局でマルチパス妨害が大きく、かつ変動する用途を主目的として応用されようとしている。このような用途においては４インチから８インチの１０インチ以下の小さい画面サイズが主流である。従ってＨＤＴＶやＥＤＴＶのような高解像度ＴＶ信号全てをＯＦＤＭ変調する方式はかける費用の割には効果が低く、自動車ＴＶ用にはＬＤＴＶグレート゛のＴＶ信号の受信で充分である。一方、家庭用ＴＶのような固定局においてはマルチパスが常に一定であるため、マルチパス対策がとりやすい。このため強ゴースト地域以外はＯＦＤＭの効果は高くない。ＨＤＴＶの中高域成分にＯＦＤＭを用いることはＯＦＤＭの回路規模が大きい現状では得策でない。従って本発明の図１３８に示すＯＦＤＭを低域ＴＶ信号のみに使用する方法は、自動車等の移動局において受信されるＬＤＴＶのマルチパス妨害を大巾に軽減するというＯＦＤＭの効果を失なわないで、ＯＦＤＭの回路規模を１／１０以下に大巾に削減できるという大きな効果がある。
【０３５２】
なお、図１３８ではＤ_１−１のみをＯＦＤＭ変調しているがＤ_１−１とＤ_１−２をＯＦ　ＤＭ変調することもできる。この場合、Ｄ_１−１とＤ_１−２はＣ−ＣＤＭの２階層伝送ができるため、自動車等の移動体においてもマルチパルスに強い階層型放送が実現し、移動体において、ＬＤＴＶとＳＤＴＶが受信レベルやアンテナ感度に応じた画質の画像が受信できるというＧｒａｄｉｔｉｏｎａｌ　Ｄｅｇｒａｄａｔｉｏｎの効果が生まれる。
【０３５３】
こうして本発明の階層伝送が可能となり、前述した様々な効果が得られる。ＯＦＤＭの場合特にマルチパスに強いため本発明の階層伝送と組み合わせることによりマルチパスに強くかつ受信レベルの劣化に応じたデータ伝送グレードの劣化が得られるという効果が得られる。
【０３５４】
階層構造型伝送方式を実現する方法として、図１２６（ａ）に示すように、おＦＤＭの各サブチャンネル７９４ａ〜ｃを第１層８０１ａとしサブチャンネル７９４ｄ〜ｆを第２層８０１ｂとし中間にｆｇなる周波数ガード帯８０２ａを設け、図１２６（ｂ）に示すようにＰｇなる電力差８０２ｂを設けることにより、第１層８０１ａと第２層８０１ｂの送信電力を差別化できる。
【０３５５】
これを利用すると、前に説明した図１０８（ｄ）に示すようにアナログＴＶ放送に妨害を与えない範囲で第１層８０１ａの電力を増やすことができる。この場合図１０８（ｅ）に示すように第１層８０１ａの受信可能なＣ／Ｎ値のスレシホルド値は第２層８０１ｂに比べて低くなる。従って信号レベルの低い地域やノイズの多い地域においても第１層８０１ａの受信が可能となるという効果が得られる。図１４７に示すように二層の階層伝送が実現する。これをＰｏｗｅｒ−Ｗｅｉｇｈｔｅｄ−ＯＦＤＭ方式（ＰＷ−ＯＦＤＭ）と本文では呼ぶ。この本実施例のＰＷ−ＯＦＤＭに前述の本発明のＣ−ＣＤＭ方式を組み合わせることにより、図１０８（ｅ）に示すように階層は増え３層になり、より受信可能地域が拡がるという効果がある。
【０３５６】
具体的な回路は、図１４４に示すように第１層データは第１データ列回路７９１ａを介して振幅の大きい変調器４ａ〜４ｃでキャリアｆ_１〜ｆ_３で逆ＦＦＴ４０によりＯＦＤＭ変調し、第２層データは第２データ列回路７９１ｂを介して通常の振幅の変調器４ｄ〜４ｆでキャリアｆ_６〜ｆ_８で逆ＦＦＴ４０によりＯＦＤＭ変調し送信する。
【０３５７】
受信信号は受信機４３のＦＦＴ４０ａによりｆ_１〜ｆ_ｎのキャリアをもつ信号に分離され、キャリアｆ_１〜ｆ_３は復調器４５ａ〜４５ｃにより第１データ列Ｄ_１つ　まり第１層８０１ａが復調され、キャリアｆ_６〜ｆ_８からは第２データ列Ｄ_２つま　り第２層８０１ｂが復調される。
【０３５８】
第１層８０１ａの電力は大きいため信号の弱い地域においても受信できる。こうしてＰＷ−ＯＦＤＭにより、２層の階層型伝送が実現する。ＰＷ−ＯＦＤＭをＣ−ＣＤＭと組み合わせると３〜４層の階層が実現する。なお図１４４の他の動作は図１２３のブロック図の場合と動作が同じであるため説明を省略する。
【０３５９】
さて、次に本発明のＴｉｍｅ−Ｗｅｉｇｈｔｅｄ−ＯＦＤＭ（ＴＷ−ＯＦＤＭ）方式の階層化方式について述べる。ＯＦＤＭ方式は前に述べたように、ガード時間帯ｔｇがあるため、ゴーストつまりマルチパス信号の遅延時間ｔ_Ｍがｔ_Ｍ＜ｔｇの条件式を満たせばゴーストの影響をなくすことができる。一般家庭のＴＶ受信機のような固定局ではｔ_Ｍ　は数μｓと小さく、また、一定であるためキャンセルし易い。しかし、車載ＴＶ受信機のように移動局の場合は反射波が多いため、ｔ_Ｍは大きく数十μｓ近くに　なるだけなく、移動に伴い変化するためキャンセルが難しい。従ってマルチパスに対する階層化が必要になることが予想される。
【０３６０】
本実施例の階層化の方法を述べると、図１４６に示すように第Ａ層のガード時間ｔｇａを第Ｂ層のガード時間ｔｇｂに比べて大きくとることによりＡ層のサブチャンネルのシンボルはゴーストに対して強くなる。こうしてガード時間のＷｅｉｇｈｔｉｎｇによりマルチパスに対する階層型伝送が実現する。この方式をＧｕａｒｄ−Ｔｉｍｅ−Ｗｅｉｇｈｔｅｄ−ＯＦＤＭ（ＧＴＷ−ＯＦＤＭ）と呼ぶ。
【０３６１】
さらに第Ａ層と第Ｂ層のシンボル時間Ｔｓのシンボル数を同じ数に設定した場合、Ａのシンボル時間ｔｓａをＢのシンボル時間ｔｓｂより大きくとる。するとこれにより周波数軸上においてＡ，Ｂのキャリヤの間隔をそれぞれ△ｆａ、△ｆｂとすると△ｆａ＞△ｆｂである。このためＢのシンボルに比べて、Ａののシンボルを復調した場合のエラーレートは低くなる。こうしてシンボル時間ＴｓのＷｅｉｇｈｔｉｎｇの差別化により第Ａ層と第Ｂ層のマルチパスに対する２層の階層化が実　現する。この方式をＣａｒｒｉｅｒ−Ｓｐａｃｉｎｇ−Ｗｅｉｇｈｔｅｄ−ＯＦＤＭ（ＣＳＷ−ＯＦＤＭ）と呼ぶ。ＧＴＷ−０ＦＤＭを用いて２層の階層伝送を実現し、第Ａ層にて低解像度のＴＶ信号を、第Ｂ層で高域成分を送信することにより、車載ＴＶ受信機のようにゴーストの多い条件の受信でも低解像度ＴＶの安定した受信が可能となる。またＣＳＷ−ＯＦＤＭを用いたシンボル時間ｔｓの差別化により第Ａ層と第Ｂ層のＣ／Ｎに対する階層化をＧＴＷ−ＯＦＤＭとを組み合わせることにより受信信号レベルの低い車載ＴＶにおいてさらに安定した受信ができるという大きな効果が実現する。車載用途や携帯用途のＴＶにおいては高い解像度は要求されない。低解像度ＴＶ信号を含むシンボル時間の時間比率は小さいため、このガード時間のみを長くすことは全体の伝送効率をあまり下げない。従って本実施例のＧＴＷ−ＯＦＤＭを用いて低解像度ＴＶ信号に重点を置いてマルチパス対策をすることにより伝送効率に殆ど影響を与えないで携帯ＴＶや車載ＴＶのような移動局と、家庭のＴＶのような固定局とを両立させた階層型ＴＶ放送を実現するという大きな効果がある。この場合前述のようにＣＳＷ−ＯＦＤＭやＣ−ＣＤＭと組み合わせることによりＣ／Ｎにたいする階層化が加わりさらに安定　した移動局の受信が可能となる。
【０３６２】
具体的にマルチパスの影響を説明すると、図１４５（ａ）に示すように遅延時間が短いマルチパス８１０ａ〜ｄの場合は第１送と第２層の信号が受信でき、ＨＤＴＶの信号が復調できる。しかし、図１４５（ｂ）に示すように長いマルチパス８１１ａ〜ｄの場合は、第２層のＢ信号のガード時間、Ｔｇｂが短いため復調できなくなる。この場合、第１層のＡ信号はガード時間Ｔｇａが長いため、遅延時間の長いマルチパスの影響を受けない。前述のようにＢ信号にはＴＶの高域成分が含まれており、Ａ信号にはＴＶの低域成分が含まれているため、例えば車載用ＴＶではＬＤＴＶが再生できる。さらに第１層のシンボル時間ＴｓａをＴｓｂより大きくとっているためＣ／Ｎの劣化にも第１層は強い。
【０３６３】
こうしてガード時間とシンボル時間の差別化をすることにより、ＯＦＤＭの二次元の階層化が簡単な構成で可能となる。図１２３のような構成でガード時間差別化とＣ−ＣＤＭと組み合わせることにより、マルチパスとＣ／Ｎ値劣化の双方の階層化が計れる。
【０３６４】
ここで具体的な例を用いて詳しく述べる。
マルチパス遅延時間Ｔ_Ｍは、Ｄ／Ｕ比が小さい程、直接波より反射波が多くな　り、大きくなる。例えば図１４８に示すようにＤ／Ｕ＜３０ｄＢでは反射波の影響が大きくなり３０μｓ以上になる。図１４８に示すように５０μｓ以上のＴｇをとることにより、一番悪い条件でも受信できる。従って図１４９（ａ）に具体的に示すようにＴＶ信号１ｓｅｃに対して図１４９（ｂ）に示す２ｍｓの周期の　うち、各シンボルを第１層８０１ａ，第２層８０１ｂ，第３層８０１ｃの３つの階層のグループに分け、図１４９（ｃ）に示す。各々のグループのガード時間７９７ａ，７９７ｂ，７９７ｃつまりＴｇａ，Ｔｇｂ，Ｔｇｃを例えば５０μｓ，５μｓ，１μｓと重みづけをして設定することにより図１５０に示すような階層８０１ａ，８０１ｂ，８０１ｃの３つの階層のマルチパスに関する階層型放送が実現する。全ての画質に対してＧＴＷ−ＯＦＤＭを適用すると当然伝送効率は落ちてしまう。しかし、情報量の少ないＬＤＴＶの画質信号のみにＧＴＷ−ＯＦＤＭのマルチパス対策をすることにより全体の伝送効率があまり落ちないいう効果がある。特に第１層８０１ａではガード時間Ｔｇを３０μｓ以上の５０μｓにとっているため、車載用ＴＶ受信機でも受信できる。回路は図１２７のブロック図に示したものを用いる。特に車載用ＴＶはＬＤＴＶグレードの画質で良いためＭＰＥＧ１クラスの１Ｍｂｐｓ程度の伝送容量でよい。従って図１４９に示したようにシンボル時間７９６ａＴｓａを２ｍｓの周期に対して２００μｓとれば２Ｍｂｐｓとれるため良く、さらにシンボルレートを半分に下げても１Ｍｂｐｓ近くになり、ＬＤＴＶグレードの画質が得られるため本発明のＣＳＷ−ＯＦＤＭ　に　より伝送効率は若干落ちるがエラーレートが低くなる。特に本発明のＣ−ＣＤＭをＧＴＷ−ＯＦＤＭと組み合わせた場合、伝送効率が低下しないため効果がさらに高い。図１４９では同じシンボル数に対してシンボル時間７９６ａ，７９６ｂ，７９６ｃを２００μｓ，１５０μｓ，１００μｓに差別化している。従って第１層，第２層，第３層の順にエラーレートが高くなってゆく階層型伝送となっている。
【０３６５】
同時にＣ／Ｎに対しても階層型伝送が実現する。図１５１に示すようにＣＳＷ−ＯＦＤＭとＣＳＷ−ＯＦＤＭの組み合わせにより、マルチパスとＣ／Ｎの２次元の階層型伝送が実現する。前述のようにＣＳＷ−ＯＦＤＭと本発明のＣ−ＣＤＭを組み合わせても実現でき、この場合全体の伝送効率の低下が少ないという効果がある。第１層８０１ａおよび第１−２層８５１ａ，第１−３層８５１ａではマルチパスＴ_Ｍが大きくかつＣ／Ｎが低い用途例えば車載用ＴＶＲｅｃｅｉｖｅｒ　においてもＬＤＴＶグレードの安定した受信ができる。第２層８０１ｂと第２−３層８５１ｂではサービスエリアのフリンジエリアのようにＣ／Ｎが低く、ゴーストの多い受信地域の固定局において標準解像度のＳＤＴＶグレードの受信ができる。サービスエリアの半分以上を占める第３層８０１ｃではＣ／Ｎが高く、直接波が大きくゴーストが少ないためＨＤＴＶグレードの画質で受信できる。こうしてＣ／Ｎとマルチパスの２次元の階層型放送が実現する。このように大きな効果が本発明のＧＴＷ−ＯＦＤＭとＣ−ＣＤＭの組み合わせまたは、ＧＴＷ−ＯＦＤＭとＣＳＷ−Ｃ−ＣＤＭの組み合わせにより得られる。従来はＣ／Ｎに対する階層型放送方式が提案されているが、本発明により、Ｃ／Ｎとマルチパスの２次元のマトリクス型の階層型放送が実現する。
【０３６６】
Ｃ／Ｎの３層とマルチパスの３層の２次元の階層型放送の具体的なＨＤＴＶ、ＳＤＴＶ、ＬＤＴＶの３階層のＴＶ信号の時間配置図を図１５２に示す。図に示すように１番マルチパスに強いＡ層の第１階層のスロット７９６ａ１にはＬＤＴＶを配置し、次にマルチパスに強いスロット７９６ａ２やＣ／Ｎ劣化に強いスロット７９６ｂ１にはＳＤＴＶの同期信号やアドレス信号等の重要なＨＰ信号を配置する。Ｂ層の第２層、３層にはＳＤＴＶの一般信号つまりＬＰ信号や、ＨＤＴＶのＨＰ信号を配置する。Ｃ層には１、２、３層にＳＤＴＶ，ＥＤＴＶ，ＨＤＴＶ等の高域成分ＴＶ信号を配置する。
【０３６７】
この場合ＣＮ劣化やマルチパスに強くすればするほど伝送レートが落ちるためＴＶ信号の解像度が減少し、図１５３に示すように３次元のＧｒａｃｅｆｕｌ　Ｄｅｇｒａｄａｔｉｏｎが実現するという従来にない効果が本発明により得られる。図１５３はＣＮＲ、マルチパス遅延時間、伝送レートの３つのパラメーターにより本発明の３次元構造の階層型放送を表現したものである。
【０３６８】
本発明のＧＴＷ−ＯＦＤＭと前述の本発明のＣ−ＣＤＭの組み合わせまたは、ＧＴＷ−ＯＦＤＭとＣＳＷ−Ｃ−ＣＤＭの組み合わせにより２次元の階層構造が得られる例を用いて実施例を説明したがＧＴＷ−ＯＦＤＭとＰｏｗｅｒ−Ｗｅｉｇｈｔｅｄ−ＯＦＤＭの組み合わせや、ＧＴＷ−ＯＦＤＭと他のＣＮＲの階層伝送方式と組み合わせても２次元の階層型放送は実現する。
【０３６９】
図１５４はキャリア７９４ａ、７９４ｃ，７９４ｅの電力をキャリア７９４ｂ，７９４ｄ，７９４ｆに比べて小さく重みずけして送信したもので、２階層のＰｏｗｅｒ−Ｗｅｉｇｈｔｅｄ−ＯＦＤＭが実現する。キャリア７９４ａに直交するキャリア７９５ａ，７９５ｃの電力も同様にしてキャリア７９５ｂ，７９５ｄに対して電力重みずけすることにより２階層がえられる。あわせると４層の階層が得られるが、図１５４では２層の場合の実施例をしめしている。図に示すようにキャリアの周波数分布が分散するため同一周波数帯にある他のアナログ放送等への妨害が分散されるため影響が小さくなるという効果がある。
【０３７０】
また、図１５５のように１つのシンボル７９６ａ，７９６ｂ，７９６ｃ毎にガード時間７９７ａ，７９７ｂ，７９７ｃの時間幅を変化させた時間配置をとることにより３層のマルチパスに対する階層型の多値伝送が実現する。図１５５の時間配置にするとＡ層、Ｂ層、Ｃ層のデータが時間軸上に分散する。このため特定時間に発生するバーストノイズが発生しても各層のデータにインターリーブをかけることによりデータの破壊が防止されＴＶ信号が安定して復調できるという効果がある。特にＡ層のデータを分散させインターリーブをかけることにより車載ＴＶ受信時に発生する他の自動車の点火装置から発生するバーストノイズの妨害を大幅に低減できる。
【０３７１】
この場合の具体的なＥＣＣエンコーダー７４４ｊとＥＣＣデコーダー７４９ｊのブロック図を図１６０（ａ）（ｂ）にそれぞれ示す。また図１６７にデ・インターリーブ部９３６ｂのブロック図を示す。デ・インターリーブ部９３６ｂのデ・インターリーブＲＡＭ９３６ａの中で処理されるインターリーブテーブル９５４を図１６８（ａ）で示し、インターリーブ距離Ｌ１を図１６８（ｂ）に示す。
【０３７２】
こうしてデータをインターリーブすることによりバーストノイズの妨害を軽減することができる。図１６１のＶＳＢ受信機のブロック図と図１６２のＶＳＢ送信機のブロック図に示すように実施例４、５、６等で説明した４ＶＳＢや８ＶＳＢや１６ＶＳＢの伝送装置や実施例１、２等で説明したＱＡＭやＰＳＫ伝送装置に用いることにより、バーストノイズの妨害を軽減できるため、地上放送においてノイズの少ないＴＶ受信ができるという効果がある。
【０３７３】
図１５５の方式により３階層の階層放送を行うことによりＡ層は前述のマルチパス、Ｃ／Ｎ劣化に加えてバーストノイズの妨害を低減できるため車載ＴＶ受信機やポケットＴＶ等の移動局によるＬＤＴＶグレードのＴＶ受信を安定させるという効果がある。
【０３７４】
本発明はＡＳＫ，ＱＡＭ，ＰＳＫ、ＯＦＤＭの変調方式を用いて実施例を説明したが他の変調方式でも同様の効果がえられる。またパーシャルレスポンスを用いることにより記録系のみならず伝送系でもエラーレートを下げることができる。
【０３７５】
本発明の多値伝送方式の一つの特徴は周波数利用効率を向上させるものであるが一部の受信機にとっては電力利用効率がかなり低下する。従って全ての伝送システムに適用できるものではない。例えば特定受信者間の衛星通信システムならその時期に得られる最高の周波数利用効率と最高の電力利用効率の機器にとりかえるのが最も経済性が高い方法である。このような場合必ずしも本発明を使う必要はない。
【０３７６】
しかし、衛星放送方式や地上放送方式の場合は本発明のような階層型伝送方式が必要である。なぜなら衛星放送の規格の場合５０年以上の永続性が求められる。この期間、放送規格は変更されないが技術革新に伴い衛星の送信電力は飛躍的に向上する。放送局は数十年後の将来において現時点においても製造された受信機がＴＶ番組を受信視聴できるように互換性のある放送を行わなければならない。本発明を用いると既存のＮＴＳＣ放送とＨＤＴＶ放送との互換性と将来の情報伝送量の拡張性という効果が得られる。
【０３７７】
本発明は電力効率よりも周波数効率を重視したものであるが、受信機側に各伝送段階に応じて設計受信感度を設けた各々、何種類かの受信機を設定することにより送信機の電力をさほど増やす必要はなくなる。このため現在の電力の小さい衛星でも充分送信可能である。また将来、送信電力が増大した場合でも同一の規格で伝送できるため将来の拡張性と、新旧の受信機との間の互換性が得られる。以上述べたように本発明は衛星放送規格に用いた場合、顕著な効果がえられる。
【０３７８】
また本発明の多値伝送方式を地上放送に用いた場合、電力利用効率を全く考慮する必要がないため衛星放送より本発明は実施しやすい。前述のように従来のデジタルＨＤＴＶ放送方式では存在したサービスエリア内の受信不能地域を大巾に減少させるという顕著な効果と前述のＮＴＳＣとＨＤＴＶ受信機もしくは受像機の両立性の効果がある。またＴＶ番組のスポンサーからみた場合のサービスエリアが実質的に拡大するという効果もある。なお、実施例ではＱＰＳＫ、１６ＱＡＭ、３２ＱＡＭと４ＶＳＢ、８ＶＳＢ、１６ＶＳＢの変調方式を用いた例を用いて説明したが、６４ＱＡＭ、１２８ＱＡＭ、２５６ＱＡＭや３２ＶＳＢ、６４ＶＳＢ等に適用できることはいうまでもない。また、図を用いて説明したように多値のＰＳＫやＡＳＫやＦＳＫに適用できることもいうまでもない。本発明とＴＤＭを組み合わせて伝送する実施例を説明したが、ＦＤＭ，ＣＤＭＡや拡散通信方式を組み合わせて伝送することもできる。
【０３７９】
本発明の多値伝送方式の一つの特徴は周波数利用効率を向上させるものであるが一部の受信機にとっては電力利用効率がかなり低下する。従って全ての伝送システムに適用できるものではない。例えば特定受信者間の衛星通信システムならその時期に得られる最高の周波数利用効率と最高の電力利用効率の機器にとりかえるのが最も経済性が高い方法である。このような場合必ずしも本発明を使う必要はない。
【０３８０】
しかし、衛星放送方式や地上放送方式の場合は本発明のような多値伝送方式が必要である。なぜなら衛星放送の規格の場合５０年以上の永続性が求められる。この期間、放送規格は変更されないが技術革新に伴い衛星の送信電力は飛躍的に向上する。放送局は数十年後の将来において現時点においても製造された受信機がＴＶ番組を受信視聴できるように互換性のある放送を行わなければならない。本発明を用いると既存のＮＴＳＣ放送とＨＤＴＶ放送との互換性と将来の情報伝送量の拡張性という効果が得られる。
【０３８１】
本発明は電力効率よりも周波数効率を重視したものであるが、受信機側に各伝送段階に応じて設計受信感度を設けた各々、何種類かの受信機を設定することにより送信機の電力をさほど増やす必要はなくなる。このため現在の電力の小さい衛星でも充分送信可能である。また将来、送信電力が増大した場合でも同一の規格で伝送できるため将来の拡張性と、新旧の受信機との間の互換性が得られる。以上述べたように本発明は衛星放送規格に用いた場合、顕著な効果がえられる。
【０３８２】
また本発明の多値伝送方式を地上放送に用いた場合、電力利用効率を全く考慮する必要がないため衛星放送より本発明は実施しやすい。前述のように従来のデジタルＨＤＴＶ放送方式では存在したサービスエリア内の受信不能地域を大巾に減少させるという顕著な効果と前述のＮＴＳＣとＨＤＴＶ受信機もしくは受像機の両立性の効果がある。またＴＶ番組のスポンサーからみた場合のサービスエリアが実質的に拡大するという効果もある。なお、実施例では１６ＱＡＭと３２ＱＡＭの変調方式を用いた例を用いて説明したが、６４ＱＡＭや１２８ＱＡＭや２５６ＱＡＭ等に適用できることはいうまでもない。また、図を用いて説明したように多値のＰＳＫやＡＳＫやＦＳＫに適用できることもいうまでもない。
【０３８３】
【発明の効果】
以上のように本発明は、信号入力部と、位相の異なる複数の搬送波を上記入力部からの入力信号により変調し信号ベクトル図上になるｍ値の信号点を発生させる変調部と、変調信号を送信する送信部からなりデータ伝送を行う伝送装置においてｎ値の第１データ列と第２データ列を入力し、上記信号をｎ個の信号点群に分割し、該信号点群の各々第１データ列のデータに割りあて上記信号点群の中の各信号点に第２データ群の各データを割りあて、送信する送信機により信号を送信し、該送信信号の入力部と、信号スペースダイヤグラム上でｐ値の信号点のＱＡＭ変調波を復調する復調器と出力部を有する受信装置において上記信号点をｎ値の信号点群に分割し、各信号点群ｎ値の第１データ列を対応させて復調し、信号点群の中の略々ｐ／ｎ値の信号点にｐ／ｎ値の第２データ列のデータを復調再生し、受信装置を用いてデータを伝送することにより、例えば送信機１の変調器４により、ｎ値の第１データ列と第２データ列と第３データ列を信号点群にデータを割りあてて変形ｍ値のＱＡＭ変調信号を送信し、第１受信機２３では、復調器２５によりｎ値の第１データ列を、第２受信機３３では第１データ列と第２データ列を、第３受信機４３では第１データ列、第２データ列、第３データ列を復調することにより、効果として最大ｍ値のデータを変調した多値変調波をｎ＜ｍなるｎ値の復調能力しかない受信機でもｎ値のデータを復調可能とした両立性と発展性のある伝送装置が得られる。さらに、ＱＡＭ方式の信号点のうち最も原点に近い信号点とＩ軸もしくはＱ軸との距離をｆとした場合、この距離がｎ＞１なるｎｆとなるように上記信号点をシフトさせることにより、階層型の伝送が可能となる。
【０３８４】
この伝送系にＮＴＳＣ信号を第１データ列、ＨＤＴＶとＮＴＳＣとの差信号を第２データ列として送信することにより、衛星放送においてはＮＴＳＣ放送とＨＤＴＶ放送との両立性があり、情報量の拡張性の高いデジタル放送が可能となり、地上放送においてはサービスエリアの拡大と受信不能地域の解消という顕著な効果がある。
【図面の簡単な説明】
【図１】本発明の第１の実施例における伝送装置のシステム全体を示す構成図
【図２】本発明の実施例１の送信機１のブロック図
【図３】本発明の実施例１の送信信号のベクトル図
【図４】本発明の実施例１の送信信号のベクトル図
【図５】本発明の実施例１の信号点へのコードの割り当て図
【図６】本発明の実施例１の信号点群へのコーディング図
【図７】本発明の実施例１の信号点群の中の信号点へのコーディング図
【図８】本発明の実施例１の信号点群と信号点へのコーディング図
【図９】本発明の実施例１の送信信号の信号点群の閾値状態図
【図１０】本発明の実施例１の変形１６値ＱＡＭのベクトル図
【図１１】本発明の実施例１のアンテナ半径ｒ_２と送信電力比ｎとの関係図
【図１２】本発明の実施例１の変形６４値ＱＡＭの信号点の図
【図１３】本発明の実施例１のアンテナ半径ｒ_３と送信電力比ｎとの関係図
【図１４】本発明の実施例１の変形６４値ＱＡＭの信号群と副信号点群のベクトル図
【図１５】本発明の実施例１の変形６４値ＱＡＭの比率Ａ_１，Ａ_２の説明図
【図１６】本発明の実施例１のアンテナ半径ｒ_２，ｒ_３と送信電力比ｎ_１６，ｎ_６４の関係図
【図１７】本発明の実施例１のデジタル送信機のブロック図
【図１８】本発明の実施例１の４ＰＳＫ変調の信号スペースダイアグラム図
【図１９】本発明の実施例１の第１受信機のブロック図
【図２０】本発明の実施例１の４ＰＳＫ変調信の信号スペースダイアグラム図
【図２１】本発明の実施例１の第２受信機のブロック図
【図２２】本発明の実施例１の変形１６値ＱＡＭの信号ベクトル図
【図２３】本発明の実施例１の変形６４値ＱＡＭの信号ベクトル図
【図２４】本発明の実施例１のフローチャート
【図２５】（ａ）は本発明の実施例１の８値ＱＡＭの信号ベクトル図、
（ｂ）は本発明の実施例１の１６値ＱＡＭの信号ベクトル図
【図２６】本発明の実施例１の第３受信機のブロック図
【図２７】本発明の実施例１の変形６４値ＱＡＭの信号点の図
【図２８】本発明の実施例１のフローチャート
【図２９】本発明の実施例３における伝送システムの全体の構成図
【図３０】本発明の実施例３の第１画像エンコーダーのブロック図
【図３１】本発明の実施例３の第１画像デコーダのブロック図
【図３２】本発明の実施例３の第２画像デコーダのブロック図
【図３３】本発明の実施例３の第３画像デコーダのブロック図
【図３４】本発明の実施例３のＤ_１，Ｄ_２，Ｄ_３信号の時間多重化の説明図
【図３５】本発明の実施例３のＤ_１，Ｄ_２，Ｄ_３信号の時間多重化の説明図
【図３６】本発明の実施例３のＤ_１，Ｄ_２，Ｄ_３信号の時間多重化の説明図
【図３７】本発明の実施例４における伝送装置のシステム全体の構成図
【図３８】本発明の実施例３における変形１６ＱＡＭの信号点のベクトル図
【図３９】本発明の実施例３における変形１６ＱＡＭの信号点のベクトル図
【図４０】本発明の実施例３における変形６４ＱＡＭの信号点のベクトル図
【図４１】本発明の実施例３の時間軸上の信号配置図
【図４２】本発明の実施例３のＴＤＭＡ方式の時間軸上の信号配置図
【図４３】本発明の実施例３の搬送波再生回路のブロック図
【図４４】本発明の実施例３の搬送波再生の原理図
【図４５】本発明の実施例３の逆変調方式の搬送波再生回路のブロック図
【図４６】本発明の実施例３の１６ＱＡＭ信号の信号点配置図
【図４７】本発明の実施例３の６４ＱＡＭ信号の信号点配置図
【図４８】本発明の実施例３の１６逓倍方式の搬送波再生回路のブロック図
【図４９】本発明の実施例３のＤ_Ｖ１，Ｄ_Ｈ１，Ｄ_Ｖ２、Ｄ_Ｈ２，Ｄ_Ｖ３，Ｄ_Ｈ３信号の時間多重化の説明図
【図５０】本発明の実施例３のＤ_Ｖ１，Ｄ_Ｈ１，Ｄ_Ｖ２、Ｄ_Ｈ２，Ｄ_Ｖ３，Ｄ_Ｈ３信号のＴＤＭＡ方式の時間多重化の説明図
【図５１】本発明の実施例３のＤ_Ｖ１，Ｄ_Ｈ１，Ｄ_Ｖ２、Ｄ_Ｈ２，Ｄ_Ｖ３，Ｄ_Ｈ３信号のＴＤＭＡ方式の時間多重化の説明図
【図５２】本発明の実施例４における従来方式の受信妨害領域図
【図５３】本発明の実施例４における階層型放送方式の場合の受信妨害領域図
【図５４】本発明の実施例４における従来方式の受信妨害領域図
【図５５】本発明の実施例４における階層型放送方式の場合の受信妨害領域図
【図５６】本発明の実施例４におけるデジタル放送局２局の受信妨害領域図
【図５７】本発明の実施例５における変形４ＡＳＫ信号の信号点配置図
【図５８】本発明の実施例５における変形４ＡＳＫの信号点配置図
【図５９】（ａ）は本発明の実施例５における変形４ＡＳＫの信号点配置図、（ｂ）は本発明の実施例５における変形４ＡＳＫの信号点配置図
【図６０】本発明の実施例５における低いＣ／Ｎ値の場合の変形４ＡＳＫ信号の信号点配置図
【図６１】実施例５における４ＶＳＢ、８ＶＳＢの送信機
【図６２】（ａ）は本発明の実施例５におけるＡＳＫ信号つまりフィルタリングの多値ＶＳＢ信号のスペクトル図、（ｂ）は本発明の実施例５におけるＶＳＢ信号の周波数分布図
【図６３】実施例５における４ＶＳＢ、８ＶＳＢ、１６ＶＳＢのＲｅｃｅｉｖｅｒのブロック図
【図６４】本発明の実施例５における映像信号送信機のブロック図
【図６５】本発明の実施例５におけるＴＶ受信機全体のブロック図
【図６６】本発明の実施例５における別のＴＶ受信機のブロック図
【図６７】本発明の実施例５における衛星・地上ＴＶ受信機のブロック図
【図６８】（ａ）は実施例５、６における８ＶＳＢのＣｏｎｓｔｅｌｌａｔｉｏｎ図、（ｂ）は実施例５、６における８ＶＳＢのＣｏｎｓｔｅｌｌａｔｉｏｎ図、（ｃ）は実施例５、６における８ＶＳＢの信号−時間波形図
【図６９】本発明の実施例５における画像エンコーダの別のブロック図
【図７０】本発明の実施例５における分離回路１つの画像エンコーダのブロック図
【図７１】本発明の実施例５における画像デコーダのブロック図
【図７２】本発明の実施例５における合成器１つの画像デコーダのブロック図
【図７３】本発明による実施例５の送信信号の時間配置図
【図７４】（ａ）は本発明による実施例５の画像デコーダのブロック図、
（ｂ）は本発明による実施例５の送信信号の時間配置図
【図７５】本発明による実施例５の送信信号の時間配置図
【図７６】本発明による実施例５の送信信号の時間配置図
【図７７】本発明による実施例５の送信信号の時間配置図
【図７８】本発明による実施例５の画像デコーダのブロック図
【図７９】本発明による実施例５の３階層の送信信号の時間配置図
【図８０】本発明による実施例５の画像デコーダーのブロック図
【図８１】本発明による実施例５の送信信号の時間配置図
【図８２】本発明による実施例５のＤ１の画像デコーダーのブロック図
【図８３】本発明による実施例５の周波数変調信号の周波数−時間図
【図８４】本発明による実施例５の磁気記録再生装置のブロック図
【図８５】本発明による実施例２のＣ／Ｎと階層番号の関係図
【図８６】本発明による実施例２の伝送距離とＣ／Ｎの関係図
【図８７】本発明による実施例２の送信機のブロック図
【図８８】本発明による実施例２の受信機のブロック図
【図８９】本発明によ実施例２のＣ／Ｎ−エラーレートの関係図
【図９０】本発明による実施例５の３階層の受信妨害領域図
【図９１】本発明による実施例６の４階層の受信妨害領域図
【図９２】本発明による実施例６の階層伝送図
【図９３】本発明による実施例６の分離回路のブロック図
【図９４】本発明による実施例６の合成部のブロック図
【図９５】本発明による実施例６の伝送階層構造図
【図９６】従来方式のデジタルＴＶ放送の受信状態図
【図９７】本発明による実施例６のデジタルＴＶ階層放送の受信状態図
【図９８】本発明による実施例６の伝送階層構造図
【図９９】本発明による実施例３の１６ＳＲＱＡＭのベクトル図
【図１００】本発明による実施例３の３２ＳＲＱＡＭのベクトル図
【図１０１】本発明による実施例３のＣ／Ｎ−エラーレートの関係図
【図１０２】本発明による実施例３のＣ／Ｎ−エラーレートの関係図
【図１０３】本発明による実施例３のシフト量ｎと伝送に必要なＣ／Ｎの関係図
【図１０４】本発明による実施例３のシフト量ｎと伝送に必要なＣ／Ｎの関係図
【図１０５】本発明による実施例３の地上放送時の送信アンテナからの距離と信号レベルと
【図１０６】本発明による実施例３の３２ＳＲＱＡＭのサービスエリア図
【図１０７】本発明による実施例３の３２ＳＲＱＡＭのサービスエリア図
【図１０８】（ａ）は従来のＴＶ信号の周波数分布図、（ｂ）は従来の二階層のＴＶ信号の周波数分布図、（ｃ）は本発明の実施例３のスレシホルド値を現す図、（ｄ）は実施例９の２階層のＯＦＤＭのキャリヤ群の周波数分布図、（ｅ）は実施例９の３改装のＯＦＤＭの３つのスレシホルド値を示す図
【図１０９】本発明による実施例３のＴＶ信号時間配置図
【図１１０】本発明による実施例３のＣ−ＣＤＭの原理図
【図１１１】本発明による実施例３の符号割り当て図
【図１１２】本発明による実施例３の３６ＱＡＭを拡張した場合の符号割り当て図
【図１１３】本発明による実施例５の変調信号周波数配置図
【図１１４】本発明による実施例５の磁気記録再生装置のブロック図
【図１１５】本発明による実施例７の携帯電話の送受信機のブロック図
【図１１６】本発明による実施例７の基地局のブロック図
【図１１７】従来方式の通信容量とトラフィックの分布図
【図１１８】本発明による実施例７の通信容量とトラフィックの分布図
【図１１９】（ａ）は従来方式のタイムスロット配置図、（ｂ）は本発明による実施例７のタイムスロット配置図
【図１２０】（ａ）は従来方式のＴＤＭＡ方式タイムスロット配置図、（ｂ）は本発明による実施例７のＴＤＭＡ方式タイムスロット配置図
【図１２１】本発明による実施例７の１階層の送受信機のブロック図
【図１２２】本発明による実施例７の２階層の送受信機のブロック図
【図１２３】本発明による実施例８のＯＦＤＭ方式送受信機のブロック図
【図１２４】本発明による実施例８のＯＦＤＭ方式の動作原理図
【図１２５】（ａ）は従来方式の変調信号の周波数配置図、（ｂ）は本発明による実施例８の変調信号の周波数配置図
【図１２６】（ａ）は実施例９におけるＯＦＤＭのＷｅｉｇｈｔｉｎｇしない状態を示す図、（ｂ）は実施例９における送信電力によりＷｅｉｇｈｔｉｎｇした２階層のＯＦＤＭの２つ　のサブチャンネルを示す図、（ｃ）は実施例９におけるキャリヤ間隔を二倍にＷｅｉｇｈｔｉｎｇしたＯＦＤＭの周波数分布図、（ｅ）は実施例９におけるＷｅｉｇｈｔｉｎｇしないキャリヤ間隔のＯＦＤＭの周波数分布図
【図１２７】本発明による実施例９の送受信機のブロック図
【図１２８】（ａ）は実施例２、４、５におけるＴｒｅｌｌｉｓ　Ｅｎｃｏｄｅｒ（Ｒａｔｉｏ１／２）のブロック図、（ｂ）は実施例２、４、５におけるＴｒｅｌｌｉｓ　Ｅｎｃｏｄｅｒ（Ｒａｔｉｏ２／３）のブロック図、（ｃ）は実施例２、４、５におけるＴｒｅｌｌｉｓ　Ｅｎｃｏｄｅｒ（Ｒａｔｉｏ３／４）のブロック図、（ｄ）は実施例２、４、５におけるＴｒｅｌｌｉｓ　Ｄｅｃｏｄｅｒ（Ｒａｔｉｏ１／２）のブロック図、（ｅ）は実施例２、４、５におけるＴｒｅｌｌｉｓ　Ｄｅｃｏｄｅｒ（Ｒａｔｉｏ２／３）のブロック図、（ｆ）は実施例２、４、５におけるＴｒｅｌｌｉｓ　Ｄｅｃｏｄｅｒ（Ｒａｔｉｏ３／４）のブロック図
【図１２９】実施例９の実効シンボル期間とガード期間の時間配置図
【図１３０】従来例と実施例９のＣ／Ｎ対エラーレートの関係図
【図１３１】実施例５の磁気記録再生装置のブロック図
【図１３２】実施例５の磁気テープ上のトラックの記録フォーマットとヘッドの走行図
【図１３３】実施例３の送受信機のブロック図
【図１３４】従来例の放送方式の周波数配置図
【図１３５】実施例３の３層の階層型伝送方式を用いた場合のサービスエリアと画質の関係図
【図１３６】実施例３の階層型伝送方式とＦＤＭを組み合わせた場合の周波数配置図
【図１３７】実施例３におけるトレリス符号化を用いた場合の送受信機のブロック図
【図１３８】実施例９における１部の低域信号をＯＦＤＭで伝送する場合の送受信機のブロック図
【図１３９】実施例１における８−ＰＳ−ＡＰＳＫの信号点配置図
【図１４０】実施例１における１６−ＰＳ−ＡＰＳＫの信号点配置図
【図１４１】実施例１における８−ＰＳ−ＰＳＫの信号点配置図
【図１４２】実施例１における１６−ＰＳ−ＰＳＫ（ＰＳ型）の信号点配置図
【図１４３】実施例１における衛星アンテナの半径と伝送容量との関係図
【図１４４】実施例９におけるＷｅｉｇｈｔｅｄ　ＯＦＤＭ送受信機のブロック図
【図１４５】（ａ）は実施例９におけるマルチパスの短い場合のガード時間、シンボル時間階層型ＯＦＤＭの波形図、（ｂ）は実施例９におけるマルチパスの長い場合のガード時間、シンボル時間階層型ＯＦＤＭの波形図
【図１４６】（ａ）は実施例９におけるガード時間、シンボル時間階層型ＯＦＤＭの原理図
【図１４７】実施例９のおける電力重み付けによる２階層伝送方式のサブチャンネル配置図
【図１４８】実施例９におけるＤ／Ｖ化とマルチパス遅延時間とガード時間の関係図
【図１４９】（ａ）は実施例９における、各階層のタイムスロット図、
（ｂ）は実施例９における、各階層のガード時間の時間分布図、（ｃ）は実施例９における、各階層のガード時間の時間分布図図
【図１５０】実施例９のマルチパス遅延時間と伝送レート図の関係図におけるマルチパスに対する３階層の階層型放送方式の説明図
【図１５１】実施例９のＧＴＷ−ＯＦＤＭとＣ−ＣＤＭ（又はＣＳＷ−ＯＦＤＭ）を組み合わせた場合の、遅延時間とＣＮ値の関係図における２次元マトリクス構造の階層型放送方式の説明図
【図１５２】実施例９のＧＴＷ−ＯＦＤＭとＣ−ＣＤＭ（又はＣＳＷ−ＯＦＤＭ）を組み合わせた場合の、各タイムスロットにおける３階層のＴＶ信号の時間配置図
【図１５３】実施例９のＧＴＷ−ＯＦＤＭとＣ−ＣＤＭ（又はＣＳＷ−ＯＦＤＭ）を組み合わせた場合の、マルチパス信号遅延時間とＣＮ値と伝送レートの関係図における３次元マトリクス構造の階層型放送方式の説明図
【図１５４】実施例９のＰｏｗｅｒ−Ｗｅｉｇｈｔｅｄ−ＯＦＤＭの周波数分布図
【図１５５】実施例９のＧｕａｒｄ−Ｔｉｍｅ−ＯＦＤＭとＣ−ＣＤＭを組み合わせた場合の各タイムスロットにおける３階層のＴＶ信号の時間軸上の配置図
【図１５６】実施例４、５における送信機と受信機のブロック図
【図１５７】実施例４、５における送信機と受信機のブロック図
【図１５８】実施例４、５における送信機と受信機のブロック図
【図１５９】（ａ）は実施例５における１６ＶＳＢの信号点配置図、（ｂ）は実施例５における１６ＶＳＢの信号点配置図（８ＶＳＢ）、（ｃ）は実施例５における１６ＶＳＢの信号点配置図（４ＶＳＢ）、（ｄ）は実施例５における１６ＶＳＢの信号点配置図（１６ＶＳＢ）
【図１６０】（ａ）は実施例５、６におけるＥＣＣ　Ｅｎｃｏｄｅｒのブロック図、（ｂ）は実施例５、６におけるＥＣＣ　Ｅｎｃｏｄｅｒのブロック図
【図１６１】実施例５におけるＶＳＢ受信機の全体ブロック図
【図１６２】実施例５における送信機を示す図
【図１６３】実施例４ＶＳＢとＴＣ−８ＶＳＢのエラーレート／Ｃ／Ｎ値曲線
【図１６４】実施例４ＶＳＢとＴＣ−８ＶＳＢのサブチャンネル１とサブチャンネル２のエラーレートカーブ
【図１６５】（ａ）は実施例２、４、５におけるＲｅｅｄ　Ｓｏｌｏｍｏｎ　Ｅｎｃｏｄｅｒのブロック図、（ｂ）は実施例２、５、６におけるＲｅｅｄ
Ｓｏｌｏｍｏｎ　Ｄｅｃｏｄｅｒのブロック図
【図１６６】実施例２、４、５のＲｅｅｄ　Ｓｏｌｏｍｏｎ誤り訂正、演算のフローチャート図
【図１６７】実施例２、３、４、５、６におけるデインターリーブ部のブロック図
【図１６８】（ａ）は実施例２、３、４、５におけるインターリーブ、デインターリーブテーブルの図、（ｂ）は実施例２、３、４、５におけるインターリーブ距離を示す図
【図１６９】実施例５における４−ＶＳＢ，８−ＶＳＢ，１６−ＶＳＢのＲｅｄｕｎｄａｎｃｙの比較図
【図１７０】実施例２、３、４、５におけるＨｉｇｈ　Ｐｒｉｏｒｉｔｙ信号を受信するＴＶ　Ｒｅｃｅｉｖｅｒのブロック図
【図１７１】実施例２、３、４、５における送信機と受信機のブロック図
【図１７２】実施例２、３、４、５における送信機と受信機のブロック図
【図１７３】実施例６のＡＳＫ方式の磁気記録再生装置のブロック図
【符号の説明】
１　送信機
４　変調器
６　アンテナ
６ａ　地上アンテナ
１０　衛星
１２　中継器
２３　第１受信機
２５　復調器
３３　第２受信機
３５　復調器
４３　第３受信機
５１　デジタル送信機
８５　信号点
９１　第１分割信号点群
４０１　第１画像エンコーダー
７０３　ＳＲＱＡＭの受信可能地域[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a transmission device for transmitting a digital signal by modulating a carrier wave.
[0002]
[Prior art]
In recent years, digital transmission devices have been increasingly used in various fields. In particular, the development of digital video transmission technology is remarkable.
[0003]
In particular, digital TV transmission systems have recently been receiving attention. At present, digital TV transmission devices are only partially used for relaying between broadcasting stations. However, development to terrestrial broadcasting and satellite broadcasting is scheduled in the near future, and studies are being conducted in various countries.
[0004]
It is necessary to improve the quality and quantity of contents of broadcasting services such as HDTV broadcasting, PCM music broadcasting, information providing broadcasting, and FAX broadcasting in order to meet the demands of consumers who are becoming more sophisticated. In this case, it is necessary to increase the amount of information in a limited frequency band of TV broadcasting. The amount of information that can be transmitted in this band increases according to the technological limitations of the era. Therefore, ideally, it is desirable that the receiving system can be changed according to the times and the information transmission amount can be expanded.
[0005]
However, from the broadcasting point of view, publicity is important, and it is important to secure the vested rights of all viewers over a long period of time. When starting a new broadcast service, it is a necessary condition that the existing receiver or receiver can enjoy the service. The compatibility of receivers or receivers between the past and present, and the present and future new and old broadcast services, and the compatibility of broadcasting can be said to be the most important.
[0006]
New transmission standards that will appear in the future, for example, digital TV broadcasting standards, require expandability of the amount of information to meet future social requirements and technological advances, and compatibility and compatibility with existing receiving devices. .
[0007]
Here, transmission systems of TV broadcasting that have been proposed so far will be described from the viewpoint of expandability and compatibility.
[0008]
First, as a digital TV satellite broadcast system, NTSC-TV signals are compressed to about 6 Mbps and multiplexed by TDM using 4-level PSK modulation, and one transponder broadcasts 4 to 20 channels NTSC TV programs or 1 channel HDTV. A method has been proposed. As a terrestrial broadcasting method of HDTV, a method of compressing an HDTV video signal of one channel into data of about 15 Mbps and performing terrestrial broadcasting using a 16 or 32 QAM modulation method is being studied.
[0009]
First, in the satellite broadcasting system, the currently proposed broadcasting system uses an NTSC frequency band for several channels for one-channel HDTV program broadcasting in order to simply broadcast by a conventional transmission system. For this reason, there has been a problem that an NTSC program of several channels cannot be received and broadcast in a broadcast time zone of an HDTV program. It can be said that there was no compatibility or compatibility between the receiver and the receiver between NTSC and HDTV broadcasting. It can also be said that the scalability of the amount of information transmission required with future technological progress was not considered at all.
[0010]
Next, the conventional HDTV terrestrial broadcasting system under consideration at present is merely broadcasting an HDTV signal as it is using a conventional modulation system such as 16QAM or 32QAM. In the case of the existing analog broadcasting, there is always an area having a bad reception condition such as a building shadow, a lowland, or interference from an adjacent TV station even in the broadcasting service area. In such an area, although the image quality deteriorates in the case of the existing analog broadcasting, the video can be reproduced and the TV program can be viewed. However, the conventional digital TV broadcasting system has a serious problem that no video can be reproduced at all in such an area and that no TV program can be viewed. This involves an essential problem of digital TV broadcasting, and was a problem that could be fatal to the spread of digital TV broadcasting. This is due to the fact that signal points of a conventional modulation method such as QAM are arranged at equal positions or at equal intervals. There has not been a method of changing or modulating the arrangement of signal points.
[0011]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems, and in particular, to provide a transmission apparatus that greatly reduces the unreceivable area in a service area of terrestrial broadcasting, and the compatibility of NTSC broadcasting and HDTV broadcasting in satellite broadcasting. With the goal.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, a transmission device according to the present invention comprises a signal input unit, a modulation unit that modulates a carrier with an input signal from the input unit, and generates an m-value signal point on a signal vector diagram. And a transmission unit for transmitting data, an input unit for the transmission signal, and a modified PSK or modified APSK modulated wave of a P-value signal point on a vector diagram that can be expressed in a polar coordinate system (r, θ). It has two configurations: a demodulator for demodulation and a receiving device having an output unit.
[0013]
[Action]
With this configuration, a first data sequence and a second data sequence having n-valued data are input as input signals, and a modulator of the transmitting apparatus modulates a modified m-valued QAM system having m-valued signal points on a vector diagram. Make waves. The m signal points are divided into n sets of signal points, and the signal points are assigned to n data in the first data sequence, and m / n signal points or Each data of the second data sequence is allocated to the sub-signal point group, trellis-encoded and modulated, and the transmission device transmits a transmission signal. In some cases, the third data can also be transmitted.
[0014]
Next, in a receiving apparatus having a demodulator having a p-value of p> m, the transmitting signal is received, and p signal points are first set to n sets of signal points with respect to p signal points on the signal space diagram. The signal is divided into groups, and the signal of the first data string is demodulated and reproduced. Next, the p / n value second data string is made to correspond to the p / n signal points in the corresponding signal point group and demodulated to demodulate and reproduce the first data and the second data. At this time, the first data string and / or the second data string are trellis-encoded. In the receiver with p = n, n groups of signal points are reproduced, and only the first data string is demodulated and reproduced with the n values corresponding to each group.
[0015]
When the same signal is received from the transmitting device by the above operation, the first data sequence and the second data sequence can be demodulated by the large antenna and the receiver having the multi-level demodulation capability. At the same time, a small antenna and a receiver having a small demodulation capability can receive the first data string. Thus, a compatible transmission system can be constructed. In this case, the first data stream is allocated to a low-frequency TV signal such as a low frequency component of NTSC or HDTV, and the second data stream is allocated to a high-frequency TV signal such as a high frequency component of HDTV. A receiver having a value demodulation capability can receive an NTSC signal, and a receiver having a multi-value demodulation capability can receive an HDTV signal. This enables digital broadcasting compatible with NTSC and HDTV.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
(Example 1)
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[0017]
In an embodiment of the present invention, a digital signal such as a digital HDTV signal is transmitted, and a digital signal such as an HDTV signal is recorded and reproduced on a recording medium such as a magnetic tape or the like, and a transmission device including a combination of a transmitter and a receiver for receiving. Both recording and reproducing devices will be described.
[0018]
However, the operation principle of the digital modulation / demodulation unit, the encoder for error correction, the encoder for decoding an image such as an HDTV signal, and the decoder of the present invention is the same for the transmission apparatus and the recording / reproducing apparatus and basically the same technology. It is. Accordingly, in each embodiment, the present invention will be described with reference to a block diagram of one of the transmission device and the recording / reproducing device for efficient description. Further, the configuration of each embodiment of the present invention can be applied to any multi-level digital modulation system such as QAM, ASK, PSK, which arranges signal points on a constellation, but one modulation system is used. Will be explained.
[0019]
FIG. 1 shows an overall system diagram of a transmission device according to the present invention. A transmitter 1 having an input unit 2, a separation circuit unit 3, a modulator 4 and a transmission unit 5 separates a plurality of multiplexed input signals into a first data stream D₁, And the second data string, D₂, And the third data string, D₃The modulated signal is output from the transmitting section 5 by the modulator 4, and the modulated signal is transmitted to the artificial satellite 10 through the transmission path 7 by the antenna 6. This signal is received by the antenna 11 in the artificial satellite 10, amplified by the repeater 12, and transmitted to the earth again by the antenna 13.
[0020]
The transmission radio wave is transmitted to the first receiver 23, the second receiver 33, and the third receiver 43 via the transmission paths 21, 31, and 41. First, in the first receiver 23, input is made from the input unit 24 via the antenna 22, only the first data sequence is demodulated by the demodulator 25, and output from the output unit 26. In this case, the second data string and the third data string have no demodulation ability.
[0021]
In the second receiver 33, the signal output from the input unit 34 via the antenna 32 is obtained by demodulating the first data sequence and the second data sequence by the demodulator 35, combining them into one data sequence by the combiner 37, and outputting It is output from the unit 36.
[0022]
In the third receiver 43, the input from the antenna 42 enters the input unit 44, and the demodulator 45 demodulates the first data sequence, the second data sequence, and the third data sequence into one data sequence. They are output as a group from the output unit 46.
[0023]
As described above, even when radio waves of the same frequency band are received from the same transmitter 1, the amount of receivable information is different due to the difference in the performance of the demodulators of the above three receivers. With this feature, it is possible to simultaneously transmit compatible three pieces of information according to the performance to receivers having different performances in one radio band. For example, when transmitting three digital TV signals of NTSC, HDTV, and super-resolution HDTV of the same program, the super HDTV signal is separated into a low-frequency component, a high-frequency difference component, and a super-high-frequency difference component, and each is separated into first data. Corresponding to the sequence, the second data sequence, and the third data group, it is possible to simultaneously broadcast three types of compatible digital TV signals of medium resolution, high resolution, and ultra-high resolution in the frequency band of one channel.
[0024]
In this case, a receiver capable of demodulation using an NTSC-TV signal with a small antenna using a small antenna, and a receiver capable of multi-level demodulation using a large antenna with an HDTV signal using a medium antenna and a receiver capable of medium value demodulation. Can receive an ultra-high resolution HDTV. Referring to FIG. 1 further, a digital transmitter 51 for performing NTSC digital TV broadcasting receives only the same data as the first data group from an input unit 52, modulates the data with a modulator 54, and transmits the same with a transmitter 55 and an antenna 56. The signal is transmitted to the satellite 10 via the path 57 and transmitted again to the earth via the transmission path 58.
[0025]
In the first receiver 23, the demodulator 24 demodulates a signal corresponding to the first data sequence from the received signal from the digital transmitter 1. Similarly, the second receiver 33 and the third receiver 43 demodulate a data group having the same content as the first data string. That is, the three receivers can also receive digital broadcasting such as digital general TV broadcasting.
[0026]
Now, each part will be described.
FIG. 2 is a block diagram of the transmitter 1.
[0027]
The input signal enters the input unit 2 and is separated by the separation circuit 3 into three digital signals of a first data string signal, a second data string signal, and a third data string signal.
[0028]
For example, when a video signal is input, a low-frequency component of the video signal is allocated to a first data sequence signal, a high-frequency component of the video signal is allocated to a second data sequence signal, and an ultra-high frequency component of the video signal is allocated to a third data sequence signal. It is possible. The three separated signals are input to a modulation input unit 61 inside the modulator 4. Here, there is a signal point position modulation / change circuit 67 for modulating or changing the position of the signal point based on the external signal, and modulates or changes the position of the signal point according to the external signal. In the modulator 4, amplitude modulation is performed on each of two orthogonal carrier waves to obtain a multilevel QAM signal. The signal from the modulation input unit 61 is sent to the first AM modulator 62 and the second AM modulator 63. cos (2πf_ct) One of the carrier waves from the carrier generator 64 is AM-modulated by the first AM modulator 62 and sent to the combiner 65, and the other carrier is sent to the π / 2 phase shifter 66 and shifted by 90 °. And sin (2πf_cAfter being sent to the second AM modulator 63 in the state of t) and subjected to multi-level amplitude modulation, it is combined with the second AM modulated wave by the combiner 65 and output as a transmission signal by the transmitter 5. Since this method has been generally implemented conventionally, a detailed description of the operation will be omitted.
[0029]
The operation will be described using the first quadrant of the signal space diagram of the 16-valued general QAM of FIG. All the signals generated by the modulator 4 are two orthogonal carrier waves Acos2πf_cvector 81 of t and B sin2πf_cIt can be represented by a composite vector of two vectors of the vector 82 of t. If the tip of the combined vector from the zero point is defined as a signal point, a₁, A₂, A₃, A₄Quaternary amplitude value and b₁, B₂, B₃, B₄A total of 16 signal points can be set by a combination of the four values of the amplitude value. In the first quadrant of FIG.₁₁, C at signal point 84₁₂, Signal point 85 C₂₂, C at signal point 86₂₁There are four signals:
[0030]
C₁₁Is the vector 0-a₁And the vector 0-b₁Is a composite vector of₁₁= A₁cos2πf_ctb₁sin2πf_ct = Acos (2πf_ct + dπ / 2).
[0031]
Here, 0-a on the rectangular coordinates in FIG.₁A is the distance between₁, A₁-A₂A between₂, $ 0-b₁B between₁, B₁-B₂B between₂And shown on the figure.
[0032]
As shown in the overall vector diagram of FIG. 4, there are a total of 16 signal points. Therefore, by associating each point with 4-bit information, 4-bit information can be transmitted in one cycle, that is, in one time slot.
[0033]
FIG. 5 shows an example of general assignment when each point is expressed in a binary system.
Of course, the greater the distance between the signal points, the easier it is for the receiver to distinguish. Therefore, in general, the arrangement is such that the distance between each signal point is as far as possible. If the distance between specific signal points is reduced, it becomes difficult for the receiver to discriminate between the two points, and the error rate deteriorates. Therefore, it is generally said that it is desirable to arrange them at equal intervals as shown in FIG. Therefore, in the case of 16QAM, a signal point arrangement of A1 = A2 / 2 is generally implemented.
[0034]
Now, in the case of the transmitter 1 of the present invention, first, data is divided into a first data string and a second data string, and possibly into a third data string. Then, as shown in FIG. 6, the 16 signal points or signal point groups are divided into four signal point groups, and the four data of the first data string are first allocated to each signal point group. That is, when the first data string is 11, one of the four signal points of the first signal point group 91 in the first data quadrant is transmitted, and when the first data string is 01, the second signal point group 92 in the second quadrant is transmitted. , 00, one signal point among the four signal points in the fourth signal point group 94 in the fourth quadrant in the third signal point group 93 in the third quadrant is used as the second data string. Select and transmit according to the value of. Next, in the case of 16 QAM, 2 bits of the second data sequence, 4-value data, and in the case of 64-value QAM, 4 bits and 16 values of data are divided into four signal points in each of the 91, 92, 93, 94 divided signal point groups or Assignment is made to the sub-signal point group as shown in FIG. All quadrants are targeted. Assignment of signal points to 91, 92, 93, and 94 is preferentially determined by 2-bit data of the first data group. Thus, 2 bits of the first data string and 2 bits of the second data string can be transmitted completely independently. The first data string can be demodulated by a 4PSK receiver if the antenna sensitivity of the receiver is equal to or more than a certain value. If the antenna has higher sensitivity, both the first data group and the second data group can be demodulated by the modified 16QAM receiver of the present invention.
[0035]
Here, FIG. 8 shows an example of allocation of 2 bits of the first data string and 2 bits of the second data string.
[0036]
In this case, the HDTV signal is divided into a low-frequency component and a high-frequency component, a low-frequency video signal is allocated to the first data sequence, and a high-frequency video signal is allocated to the second data sequence. In the 16 QAM or 64 QAM receiving system, both the first data string and the second data string can be reproduced, and an HDTV image can be obtained by adding these.
[0037]
However, when the distance between signal points is made equal as shown in FIG. 9, there is a threshold distance between the hatched portion in the first quadrant as viewed from the 4PSK receiver. Threshold distance A_TOThen if you only send 4PSK, A_TOMay be used. But A_TOTrying to send 16QAM while maintaining 3A_TOThat is, three times the amplitude is required. In other words, it requires nine times as much energy as transmitting 4PSK. Sending 4PSK signal points in 16QAM mode without any consideration is inefficient in power use. Regeneration of the carrier wave also becomes difficult. The power available for satellite transmission is limited. Such a system with poor power use efficiency is not practical until the transmission power of the satellite increases. It is expected that a large number of 4PSK receivers will be available when digital TV broadcasting is started in the future. It is impossible to increase the receiving sensitivity once it has been widely used because of the compatibility problem of the receiver. Therefore, the transmission power in the 4PSK mode cannot be reduced. For this reason, when transmitting a pseudo 4PSK signal point in the 16QAM mode, it is expected that a method of lowering the transmission power than the conventional 16QAM is required. Otherwise, transmission will not be possible with limited satellite power.
[0038]
The feature of the present invention is that the transmission power of the pseudo 4PSK 16QAM modulation can be reduced by increasing the distance between the four divided signal point groups of FIGS. 91 to 94 as shown in FIG.
[0039]
Here, in order to clarify the relationship between the receiving sensitivity and the transmission output, returning to FIG. 1, the receiving method of the digital transmitter 51 and the first receiver 23 will be described.
[0040]
First, the digital transmitter 51 and the first receiver 23 are general transmission devices, and perform data transmission or video transmission including broadcasting. As shown in FIG. 7, the digital transmitter 51 is a 4PSK transmitter, which is obtained by removing the AM modulation function from the multi-level QAM transmitter 1 described in FIG. The input signal is input to the modulator 54 via the input unit 52. In the modulator 54, the modulation input unit 121 divides the input signal into two signals and modulates the phase of the reference carrier with a 1-2 phase modulation circuit 122. The signals are sent to the two-phase modulation circuit 123, and these phase modulation waves are combined by the combiner 65 and transmitted by the transmission unit 55.
[0041]
FIG. 18 shows a modulated signal space diagram at this time.
In general, it is common practice to set four signal points and make the distances between signal points equally spaced in order to increase power use efficiency. As an example, a case where the signal point 125 is defined as (11), the signal point 126 is defined as (01), the signal point 127 is defined as (00), and the signal point 128 is defined as (10). In this case, in order for the first receiver 23 of 4PSK to receive satisfactory data, the output of the digital transmitter 51 is required to have a certain amplitude value or more. Referring to FIG. 18, the first receiver 23 needs the minimum amplitude value of the transmission signal, that is, 0-a, which is the minimum necessary for receiving the signal of the digital transmitter 51 at 4PSK.₁A is the distance between_TODefined as the minimum amplitude A of the transmission limit_TOWith the above transmission, the first receiver 23 can receive.
[0042]
Next, the first receiver 23 will be described. The first receiver 23 receives a transmission signal from the transmitter 1 or a 4PSK transmission signal from the digital transmitter 51 via the repeater 12 of the satellite 10 with the small antenna 22, and converts the reception signal with the demodulator 24. Demodulation is performed assuming that the signal is a 4PSK signal. The first receiver 23 is originally designed to receive a signal of 4PSK or 2PSK of the digital transmitter 51, and to receive signals of digital TV broadcast, data transmission, and the like.
[0043]
FIG. 19 is a block diagram showing the configuration of the first receiver. The radio wave from the satellite 12 is received by the antenna 22. After this signal is input from the input unit 24, the carrier is reproduced by the carrier recovery circuit 131 and the π / 2 phase shifter 132. The orthogonal carrier is reproduced, and the orthogonal components are detected independently by the first phase detection circuit 133 and the second phase detection circuit 134, respectively, and are identified independently by the time slot by the timing wave extraction circuit 135. The two independent demodulated signals are demodulated into a first data stream by a first data stream playback section 232 by a first identification playback circuit 136 and a second identification playback circuit 137, and output by an output section 26.
[0044]
Here, the received signal will be described with reference to the vector diagram of FIG. The signal received by the first receiver 23 based on the 4PSK transmission radio wave of the digital transmitter 51 can be represented by four signal points 151 to 154 in FIG. 20 under ideal conditions where there is no transmission distortion or noise.
[0045]
However, actually, the received signal points are distributed in a certain range around the signal point under the influence of noise in the transmission path and amplitude distortion and phase distortion of the transmission system. The error rate gradually increases because the signal point cannot be distinguished from the adjacent signal point when the signal point is apart from the signal point. When the signal point exceeds a certain set range, data cannot be restored. In order to perform demodulation within the set error rate even in the worst condition, the distance between adjacent signal points may be set. This distance is 2A_ROIs defined. At the time of 4PSK limit reception input, the signal point 151 is | 0-a in FIG._R1| ≧ A_R0, | 0-b_R1| ≧ A_R0If the transmission system is set so as to enter the first discrimination area 155 indicated by the slanted line, demodulation can be performed after the carrier wave can be reproduced. The minimum radius value set by the antenna 22 is r₀Then, if the transmission output is set to a certain level or more, all systems can receive the signal. The amplitude of the transmission signal in FIG. 18 is the 4PSK minimum reception amplitude value of the first receiver 23, A_R0Set to be. The minimum transmission amplitude value is A_T0Is defined. This allows the radius of the antenna 22 to be r₀In this case, the first receiver 23 can demodulate the signal of the digital transmitter 51 even if the reception condition is the worst. When receiving the modified 16QAM and 64QAM of the present invention, it becomes difficult for the first receiver 23 to recover the carrier. Therefore, if the transmitter 1 arranges and transmits eight signal points at positions on the angle of (π / 4 + nπ / 2) as shown in FIG. 25 (a), the carrier can be reproduced by the quadrupling method. If 16 signal points are arranged on an extension of the angle of nπ / 8 as shown in FIG. 25 (b), the signal points are degenerated by adopting a 16-times carrier wave reproducing method in the carrier wave reproducing circuit 131. The carrier of the pseudo 4PSK type 16QAM modulated signal can be easily reproduced. In this case A₁/ (A₁+ A₂) = Tan (π / 8), the signal point of the transmitter 1 may be set and transmitted. Here, consider the case where a QPSK signal is received. As in the signal point position modulation / change circuit 67 of the transmitter in FIG. 2, the signal point position (FIG. 18) can be superimposed with the modulation such as AM on the signal point position of the QPSK signal. In this case, the signal point position demodulation unit 138 of the first receiver 23 demodulates the position modulation signal or the position change signal of the signal point to PM, AM, or the like. Then, a first data string and a demodulated signal are output from the transmission signal.
[0046]
Next, returning to the transmitter 1, the transmission signal of 16PSK of the transmitter 1 will be described with reference to the vector diagram of FIG. 9, as shown in FIG.₁= 4PSK minimum transmission output A of digital transmitter 51 in FIG._TOMake it bigger. Then, the signals at the signal points 83, 84, 85, and 86 in the first quadrant of FIG. 9 enter the fourteenth PSK receivable area 87 shown by oblique lines. When these signals are received by the first receiver 23, these four signal points fall into the first discrimination area of the reception vector diagram of FIG. Therefore, the first receiver 23 determines that the signal point is the signal point 151 in FIG. 20 regardless of the signal points 83, 84, 85, and 86 in FIG. 9 and demodulates the data (11) into this time slot. As shown in FIG. 8, this data is (11) of the first divided signal point group 91 of the transmitter 1, that is, (11) of the first data string. The first data string is similarly demodulated in the second, third, and fourth quadrants. That is, the first receiver 23 demodulates only the 2-bit data of the first data string among the plurality of data strings of the modulated signal from the 16 QAM, 32 QAM, or 64 QAM transmitter 1. In this case, since the signals of the second data string and the third data string are all included in the first to fourth divided signal point groups 91, the signal of the first data string is not affected. However, it has an effect on the reproduction of the carrier wave, so that the following measures are required.
[0047]
If the output of the satellite transponder has no limit, it can be realized by a conventional signal point equidistant 16-64 QAM as shown in FIG. However, as described above, unlike terrestrial transmission, satellite transmission significantly increases the launch cost as the weight of the satellite increases. Therefore, the transmission output is restricted by the output limit of the repeater of the main body and the power limit of the solar cell. This situation will continue for some time unless the launch cost of the rocket is reduced by technological innovation. The transmission output is about 20 W for communication satellites and about 100 W to 200 W for broadcast satellites. Therefore, when trying to transmit 4PSK by 16QAM of the signal point equidistant system as shown in FIG. 9, the amplitude of 16QAM is 2A.₁= A₂Because it is 3A_TOIt is needed and expressed in terms of electric power, it is required 9 times. Nine times as much power as 4PSK is required for compatibility. In addition, if the first receiver of 4PSK is to be receivable with a small antenna, it is difficult to obtain such an output with a satellite currently being planned. For example, a system of 40 W requires 360 W and cannot be realized economically.
[0048]
Here, when it is considered, in the case where all the receivers have the same size of antenna, the same number of antennas of the same distance signal point method with the same transmission power provides good external lot number efficiency. However, considering a system in which receiver groups of antennas having different sizes are combined, a new transmission system can be configured.
[0049]
More specifically, 4PSK increases the number of recipients by allowing reception with a simple and low-cost receiving system using a small antenna. Next, 16QAM is a high-performance but high-cost multi-level demodulation receiving system that uses a medium-sized antenna, receives high-value-added services such as HDTV that matches the investment, and limits the target to specific recipients. To establish. In this way, 4PSK and 16QAM, and in some cases, 64DMA can be transmitted hierarchically by slightly increasing the transmission output.
[0050]
For example, by taking the signal point intervals so that A1 = A2 as shown in FIG. 10, the total transmission output can be reduced. In this case, the amplitude A (4) for transmitting 4PSK can be represented by a vector 95, and 2A₁ ²Is the square root of The overall amplitude A (16) can be represented by a vector 96 (A₁+ A₂)²+ (B₁+ B₂)²Is the square root of
[0051]
| A (4) |²= A₁ ²+ B₁ ²= A_TO ²+ A_TO ²= 2A_TO ²
| A (16) |²= (A₁+ A₂)²+ (B₁+ B₂)²= 4A_TO ²+ 4A_TO ²= 28A_TO ²
| A (16) | / | A (4) | = 2
That is, transmission can be performed with twice the amplitude and four times the transmission energy of transmitting 4PSK. A general receiver transmitting at equidistant signal points cannot demodulate the modified 16-value QAM,₁And A₂By setting the two thresholds in advance, the second receiver 33 can receive. In the case of FIG. 10, the shortest distance of the signal point in the first divided signal point group 91 is A₁あ り, distance between 4PSK signal points 2A₁A compared to₂/ 2A₁Become. A₁= A₂Therefore, the distance between signal points becomes 1/2, and if the same error rate is to be obtained, the receiving sensitivity of twice the amplitude and the receiving sensitivity of four times in the energy are required. To obtain four times the receiving sensitivity, the radius r of the antenna 32 of the second receiver 33₂Is the radius r of the antenna # 22 of the first receiver 23.₁Twice, ie, r₂= 2r₁What should I do? For example, if the antenna of the first receiver 23 has a diameter of 30 cm, this can be realized by setting the antenna diameter of the second receiver 33 to 60 cm. As a result, by demodulating the second data sequence and allocating it to the high frequency component of HDTV, a new service such as HDTV becomes possible on the same channel. Since the service content is doubled, the receiver can receive the service corresponding to the investment of the antenna and the receiver. Therefore, the second receiver 33 may be more expensive. Here, since the minimum transmission power is determined for 4PSK mode reception, A in FIG.₁And A₂The transmission power ratio n of the modified 16APSK to the transmission power of 4PSK by the ratio of₁₆And the antenna radius r of the second receiver 33₂Is determined.
[0052]
When calculating to measure this optimization, the minimum required transmission energy of 4PSK is ｛(A₁+ A₂) / A₁｝²Times this n₁₆, The distance between signal points when receiving in modified 16-value QAM is A₂The distance between signal points when receiving at 4PSK is 2A₁, The ratio of the distance between signal points is A₂/ 2A, the radius of the receiving antenna is r₂Then, the relationship is as shown in FIG. Curve 101 is the transmission energy magnification n₁₆And the radius r of the antenna 22 of the second receiver 23₂Represents the relationship
[0053]
Point 102 is a case where 16QAM is transmitted in the case of equidistant signal points, which requires 9 times the transmission energy as described above and is not practical. From FIG. 11 to n₁₆Is increased 5 times or more, the antenna radius r of the second receiver 23₂The graph shows that the size is not so small.
[0054]
In the case of a satellite, the transmission power is limited and cannot exceed a certain value. From this, it becomes clear that n16 is desirably 5 times or less. This area is indicated by the hatched area 103 in FIG. For example, in this area, for example, the point 104 has a transmission energy four times and the antenna radius r of the second receiver 23.₂Is doubled. The point 105 indicates that the transmission energy is twice and r₂Becomes about 5 times. These are in a range that can be put to practical use.
[0055]
n₁₆A is less than 5.₁And A₂Expressed as
n₁₆= ((A₁+ A₂) / A₁)²≦ 5
A₂≤1.23A₁
Assuming that the distance between the divided signal point groups is 2A (4) and the maximum amplitude is 2A (16) from FIG. 10, ΔA (4) and A (16) −A (4) are A₁And A₂Proportional to
Therefore
｛A (16)｝²≦ 5 ｛A (14)｝²And it is sufficient
Next, an example using a modified 64APSK modulation will be described. The third receiver 43 can perform 64-level QAM demodulation.
[0056]
The vector diagram of FIG. 12 shows a case where the divided signal point group of the vector diagram of FIG. 10 is increased from four values to 16 values. In the first divided signal point group 91 of FIG. 12, signal points of 4 × 4 = 16 values including signal point 170 are arranged at equal intervals. In this case, the transmission amplitude A₁≧ A_TOMust be set to. Let the radius of the antenna of the third receiver 43 be r₃Where r is defined as the transmission and output signal n64₃Is calculated in the same way.
r₃ ²= $ 6²/ (N-1)｝ r₁ ²
Figure 13 Radius r of 64-value QAM₃A graph such as the output multiple n.
[0057]
However, in the arrangement as shown in FIG. 12, since only 2 bits of 4PSK can be demodulated when received by the second receiver 33, the second receiver 33 needs to have the first, second, and third compatibility. It is desirable to have a function of demodulating the modified 16-level QAM from the modified 64-level QAM modulated wave.
[0058]
By performing grouping of signal points of three layers as shown in FIG. 14, compatibility of three receivers is established. Explaining only in the first quadrant, it has been described that the first divided signal point group 91 is assigned 2-bit (11) of the first data string.
[0059]
Next, 2-bit (11) of the second data string is allocated to the first sub-divided signal point group 181. (01) is assigned to the second sub-divided signal point group 182, (00) is assigned to the third sub-divided signal point group 183, and (10) is assigned to the fourth sub-divided signal point group 184. This is equivalent to FIG.
[0060]
The signal point arrangement of the third data string will be described in detail with reference to the vector diagram of the first quadrant in FIG. 15. For example, signal points 201, 205, 209 and 213 are (11), and signal points 202, 206, 210 and 214 are ( 01), signal points 203, 207, 211, and 215 are (00), and signal points 204, 208, 212, and 216 are (10), the 2-bit data of the third data string is the first data and the second data. Independently, three-layer 2-bit data can be transmitted independently.
[0061]
In addition to the transmission of 6-bit data, a feature of the present invention is that a receiver having three levels of different performances can transmit data of different transmission amounts of 2 bits, 4 bits, and 6 bits, and the compatibility between the transmissions of the three layers is improved. Can be given.
[0062]
Here, a method of arranging signal points necessary for achieving compatibility during three-layer transmission will be described.
[0063]
As shown in FIG. 15, first, in order for the first receiver 23 to receive the data of the first data string, A₁≧ A_TOThat has already been mentioned.
[0064]
Next, it is necessary to secure a distance between signal points so that the signal points in the second data string, for example, the signal points 91 in FIG. 10 and the signal points 182, 183, and 184 in the sub-divided signal point group in FIG. .
[0065]
In FIG. 15, 2 / 3A₂Only when they are separated. In this case, the distance between signal points 201 and 202 in first sub-divided signal point group 1 # 81 is A₂/ 6. The receiving energy required for receiving by the third receiver 43 is calculated. In this case, let the radius of the antenna 32 be r₃Assuming that the required transmission energy is 4PSK transmission energy n_{6 4}If we define it as double,
r₃ ²= (12r₁)²/ (N-1)
This graph can be represented by a curve 221 in FIG. For example, in the case of the points 222 and 223, the first, second, and third data are obtained by using the antenna having the radius of 8 times if the transmission energy of 6 times the 4PSK transmission energy is obtained, or by using the antenna of 6 times if the transmission energy is 9 times. It can be seen that the columns can be demodulated. In this case, the distance between signal points of the second data string is 2 / 3A₂To get closer
r₂ ²= (3r₁)²/ (N-1)
It is necessary to slightly increase the antenna 32 of the second receiver 33 as shown by the curve 223.
[0066]
This method transmits the first data string and the second data string while the transmission energy of the satellite is small as of the present time, and in the future where the transmission energy of the satellite is greatly increased, the first receiver 23 or the second receiver is used. As a result, the third data stream can be sent without damaging the 33 received data and without any modification.
[0067]
First, the second receiver 33 will be described in order to explain the reception state. The above-mentioned first receiver 23 originally has a radius r₁The 4PSK modulation signal of the digital transmitter 51 and the first data string of the transmitter 1 are set to be demodulated with an antenna having a smaller size, whereas the second receiver 33 is shown in FIG. It is possible to completely demodulate the 16-value signal point, that is, the 2-bit signal of 16QAM of the second data string. A 4-bit signal can be demodulated together with the first data string. In this case, the ratio of A1 and A2 differs depending on the transmitter. This data is set by the demodulation control unit 231 in FIG. 21 and a threshold is sent to the demodulation circuit. This enables AM demodulation.
[0068]
The block diagram of the second receiver 33 in FIG. 21 and the block diagram of the first receiver 23 in FIG. 19 have substantially the same configuration. The difference is that first the antenna 32 has a radius r₂It has a point. Therefore, a signal having a shorter distance between signal points can be discriminated. Next, the demodulator 35 includes a demodulation control unit 231, a first data string reproducing unit 232, and a second data string reproducing unit 233. The first identification reproducing circuit 136 has an AM demodulation function for demodulating the modified 16QAM. In this case, each carrier has a quaternary value, and has a zero level and ± 2 threshold values. In the case of the present invention, the threshold differs depending on the transmission output of the transmitter as shown in the signal vector diagram of FIG. 22 because of the modified 16QAM signal. Therefore, TH₁₆Assuming that the threshold value is standardized as shown in FIG.
TH₁₆= (A₁+ A₂/ 2) / (A₁+ A₂)
It becomes.
[0069]
This A1, A2 or TH₁₆The demodulation information of the value m of the multi-level modulation is transmitted from the transmitter 1 while being included in the first data string. In addition, there is a method in which the demodulation control unit 231 statistically processes the received signal to obtain demodulation information.
[0070]
Shift factor A using FIG.₁/ A₂A method for determining the ratio of the numbers will be described. A₁/ A₂The threshold value changes when is changed. A set on the receiver side₁/ A₂A set on the transmitter side₁/ A₂The error increases as the distance from the value increases. The demodulated signal from the second data stream reproducing unit 233 of FIG. 26 is field-backed to the demodulation control circuit 231 to shift the error factor A in the direction of decreasing the error rate.₁/ A₂, The third receiver 43 sets the shift factor to A₁/ A₂The circuit is simplified because it is not necessary to demodulate the signal. The transmitter is A₁/ A₂This eliminates the need to send data and increases the transmission capacity. This can be used for the second receiver 33.
The demodulation control circuit 231 has a memory 231a. When a threshold value different for each TV broadcast channel, that is, a shift ratio, the number of signal points, and a synchronization rule is stored and the channel is received again, recalling this value has the effect of promptly stabilizing reception.
[0071]
If the demodulation information is unknown, demodulation of the second data string becomes difficult. This will be described below with reference to the flowchart of FIG.
[0072]
Even when demodulation information cannot be obtained, demodulation of 4PSK in step 313 and demodulation of the first data string in step 301 can be performed. Therefore, the demodulation information obtained by the first data string reproducing unit 232 is sent to the demodulation control unit 231 in step 302. If m is 4 or 2 in step 303, the demodulation control unit 231 performs demodulation of 4PSK or 2PSK in step 313. If NO, the process proceeds to step 304, and if m is 8 or 16, the process proceeds to step 305. If NO, the process proceeds to step 310. In step 305, calculations of TH8 and TH16 are performed. In step 306, the demodulation control unit 231 sends the threshold value TH16 for AM demodulation to the first identification reproduction circuit 136 and the second identification reproduction circuit 137. In steps 307 and 315, demodulation of the modified 16QAM and reproduction of the second data string are performed. In step 308, the error rate is checked. If the error rate is bad, the flow returns to step 313 to perform 4PSK demodulation.
[0073]
In this case, the signal point 85.83 in FIG. 22 is on the angle of cos (ωt + nπ / 2), but the signal point 84.86 is not on this angle. Therefore, the carrier wave transmission information of the second data string is sent from the second data string reproducing unit 233 to the carrier wave reproducing circuit 131 in FIG. 21 so that the carrier wave is not extracted from the signal at the timing of the signal point 84.86.
[0074]
Assuming a case where the second data sequence cannot be demodulated, the transmitter 1 intermittently transmits the carrier timing signal using the first data sequence. Even if the second data string cannot be demodulated by this signal, the signal point 83.85 can be recognized only from the first data string. Therefore, the carrier wave can be reproduced by sending the carrier wave transmission information to the carrier wave reproducing circuit 131.
[0075]
Next, when a signal of the modified 64QAM as shown in FIG. 23 is transmitted from the transmitter 1, returning to the flowchart of FIG. 24, it is determined in step 304 whether m is not 16 and in step 310, it is determined whether m is 64 or less. If it is checked and the signal is not the equidistant signal point method in step 311, the process proceeds to step 312. Here, signal point distance TH at the time of modified 64QAM₆₄And ask for
TH₆₄= (A₁+ A₂/ 2) / (A₁+ A₂)
And TH₁₆Is the same as However, the distance between signal points becomes smaller.
[0076]
The distance between signal points in the first sub-divided signal point group 181 is represented by A₃Then, the distance between the first sub-divided signal point group 181 and the second sub-divided signal point group 182 is (A₂-2A₃), Standardized (A₂-2A₃) / (A₁+ A₂). This is d₆₄Is defined as₆₄Is the discrimination capability T of the second receiver 33₂The following cannot be distinguished. In this case, it is determined in step 313 that d₆₄Is outside the allowable range, the process enters the 4PSK mode in step 313. If it is in the discrimination range, the process proceeds to step 305, and 16QAM demodulation in step 307 is performed. If the error rate is high in step 308, the process enters the 4PSK mode in step 313.
[0077]
In this case, if the transmitter 1 transmits the modified 8QAM signal of the signal point as shown in FIG. 25A, all the signal points are on the angle of cos (2πf + n · π / 4), so that the quadrupling circuit is used. As a result, all carriers are degenerated to the same phase, so that there is an effect that the reproduction of the carrier is simplified. In this case, 2 bits of the first data string can be demodulated even by the 4PSK receiver, which is not considered, and the second receiver 33 outputs 1b of the second data string {signal point arrangement diagrams of FIGS. 25 (a) and 25 (b). Indicates a signal point of C-CDM when a signal point shifted in the polar coordinate direction (r, θ) is added. The C-CDM in which the signal points are shifted in the orthogonal coordinates, that is, in the XY directions, is referred to as the orthogonal coordinate system C-CDM, and the C-CDM in which the signal points are shifted in the r, θ directions is the polar coordinate system. C-CDM is called a polar coordinate system C-CDM.
[0078]
First, the signal point arrangement diagram of 8PS-APSK in FIG. 25A is obtained by adding another signal point shifted in the radius r direction in polar coordinates to each of the four signal points of QPSK. Thus, as shown in FIG. 25A, the APSK of the polar coordinate C-CDM having eight signal points is realized from the QPSK. Since this is an APSK to which a signal point whose pole (Pole) has been shifted on polar coordinates has been added, it is referred to as SP-APSK for abbreviation Shifted @ Pole-APSK. In this case, as shown in FIG.₁Can be used to define the coordinates of the signal point 85 added to the QPSK. The signal point of 8PS-APSK is represented by polar coordinates (r₀, Θ₀) Signal point 83 in the radius r direction₁r₀Signal point ((S₁+1) r₀, Θ₀). Thus, 1-bit sub-channel 2 is added to 2-bit sub-channel 1 which is the same as QPSK.
[0079]
As shown in the constellation diagram of FIG. 140, the coordinates (r₀, Θ₀), (R₀+ S₁r₀, Θ₀) Are newly added by adding signal points shifted by S2ro in the radius r direction to the eight signal points (r).₀+ S₂r₀, Θ₀) And (r₀+ S₁r₀+ S₂r₀, Θ₀) Is added. Since there are two types of arrangement, a 1-bit subchannel is obtained. This is called 16PS-APSK and has a 2-bit sub-channel 1, a 1-bit sub-channel 2 and a 1-bit sub-channel 3. Since 16-PS-APSK also has signal points on θ = 1/4 (2n + 1) π, the carrier can be reproduced by the ordinary QPSK receiver described with reference to FIG. The subchannel can be demodulated. Thus, the C-CDM system that shifts in the polar coordinate direction has an effect that the amount of transmission information can be expanded while maintaining compatibility with PSK, particularly a QPSK receiver that is mainstream in current satellite broadcasting. For this reason, it is possible to extend to a satellite broadcast with a large amount of information of multi-level modulation using a second-generation APSK without losing viewers of the first-generation satellite broadcast using PSK while maintaining compatibility.
[0080]
The signal point in the case of FIG. 25B is on the angle = π / 8 in polar coordinates. This is limited to four signal points in each quadrant of the 16PSK signal points, that is, three signal points in each quadrant out of a total of 16 signal points, that is, 12 signal points. By limiting, when viewed roughly, these three signal points can be regarded as one signal point and can be regarded as four QPSK signal points in total. Thus, the first sub-channel can be reproduced using the QPSK receiver in the same manner as described above.
[0081]
These signal points are arranged at angles of θ = π / 4, θ = π / 4 + π / 8, and θ = π / 4−π / 8. That is, a signal point obtained by shifting a QPSK signal point on the angle π / 4 by ± π / 8 in the polar coordinate angle direction is added. Since it is in the range of θ = π / 4 ± π / 8, it can be regarded as substantially one signal point on θ = π / 4 of θPSK. In this case, the error rate is slightly deteriorated, but the QPSK receiver 23 shown in FIG. 19 can discriminate it from signal points on four angles, so that demodulation can be performed and 2-bit data is reproduced.
[0082]
In the case of the angle shift C-CDM, when the angle is on π / n, the carrier recovery circuit can recover the carrier by the n-multiplier circuit as in the other embodiments. If it is not above π / n, the carrier can be reproduced by sending several pieces of carrier information in a fixed period as in the other embodiments.
[0083]
As shown in FIG. 141, the angle in polar coordinates between the signal points of QPSK or 8-SP-APSK is 2θ.₀, The primary angle shift factor is P₁Then, the signal point is divided into two and ± P in the angle θ direction.₁θ₀, The case of QPSK (r₀, Θ₀+ P₁θ₀) And (r₀, Θ₀-P₁θ₀) And the number of signal points is doubled. Thus, 1-bit sub-channel-3 is added. This is P = P₁Is called 8-SP-PSK. As shown in FIG. 142, the signal point of 8-SP-P SK is shifted S in the radius r direction.₁r₀16-SP-APSK (P, S₁Type). Subchannel 1.2 can be reproduced by 8PS-PSK having the same phase. Now, return to FIG. 25B. Since the C-CDM using the angle shift of the polar coordinate system can be applied to PSK as shown in FIG. 141, it can also be used for first generation satellite broadcasting. However, when used for the second generation APSK satellite broadcasting, the polar coordinate system C-CDM cannot make the intervals between signal points in a group uniform as shown in FIG. Therefore, power use efficiency is poor. On the other hand, C-CDM at the time of rectangular coordinates is not compatible with PSK.
[0084]
The method shown in FIG. 25B is compatible with both the rectangular coordinate system and the polar coordinate system. Since the signal points are arranged at an angle of 16 PSK, demodulation can be performed by 16 PSK. In addition, since the signal points are grouped, demodulation can be performed by a QPSK receiver. In addition, since they are also arranged on orthogonal coordinates, demodulation can be performed even with 16-SRQAM. This is a method having a great effect that it can be extended while realizing compatibility between the polar coordinate system among the three of QPSK, 16PSK and 16-SRQAM and the rectangular coordinate system C-CDM.
It is possible to play back a total of 3 bits.
[0085]
Next, the third receiver 43 will be described. FIG. 26 is a block diagram of the third receiver 43, which has almost the same configuration as the second receiver 33 of FIG. The difference is that the third data string reproducing unit 234 is added, and that the identification reproducing circuit has an eight-level identification capability. Radius r of antenna 42₃Is r₂Since the signal size becomes even larger, a signal with a shorter distance between signal points, for example, a 32-level QAM or a 64-level QAM can be demodulated. For this reason, in order to demodulate 64-value QAM, the first discriminating / reproducing circuit 136 needs to discriminate an 8-level level from the detection signal wave. In this case, there are seven threshold levels. One of these is 0, so there are three thresholds in one quadrant.
[0086]
As shown in the signal space diagram of FIG. 27, there are three thresholds in the first quadrant.
[0087]
As shown in FIG. 27, three normalized thresholds, TH1₆₄And TH2₆₄And TH3₆₄Exists.
[0088]
TH1₆₄= (A₁+ A₃/ 2) / (A₁+ A₂)
TH2₆₄= (A₁+ A₂/ 2) / (A₁+ A₂)
TH3₆₄= (A₁+ A₂-A₃/ 2) / (A₁+ A₂)
Can be represented by
[0089]
By performing AM demodulation of the phase-detected received signal using the threshold value, data of the third data sequence is demodulated in the same manner as the first data sequence and the second data sequence described with reference to FIG. As shown in FIG. 23, the third data string is quaternary, that is, 2 bits, by discriminating the four signal points 201, 202, 203, and 204 in the first sub-divided signal group 181, for example. In this way, demodulation of 6 bits, that is, modified 64-level QAM becomes possible.
[0090]
At this time, the demodulation control unit 231 uses the demodulation information included in the first data sequence of the first data sequence reproduction unit 232 to calculate m, A₁, A₂, A₃Of the threshold value TH1₆₄And TH2₆₄And TH3₆₄Is calculated and sent to the first discriminating / reproducing circuit 136 and the second discriminating / reproducing circuit 137, so that the modified 64QAM demodulation can be reliably performed. In this case, since the demodulation information is scrambled, only the authorized receiver can demodulate 64QAM. FIG. 28 shows a flowchart of the demodulation control section 231 of the modified 64QAM. Only differences from the 16-value QAM flowchart of FIG. 24 will be described. From step 304 in FIG. 28, step 320 is reached. If m = 32, the 32-value QAM in step 322 is demodulated. If NO, it is determined in step 321 whether m = 64, and in step 323, A is determined.₃Cannot be reproduced from the set value or less, the process proceeds to step 30 # 5, and the same flowchart as that in FIG. 24 is performed, and demodulation of the modified 16QAM is performed. Here, returning to step 323, A₃Is greater than or equal to the set value, the threshold value 計算 is calculated in step 324, the three threshold values are sent to the first and second discriminating / reproducing circuits in step 325, and the modified 64QAM is reproduced in step 326, and the first, second, and The reproduction of the third data is performed. If the error rate is high in step 328, the process proceeds to step 305 to perform 16QAM demodulation. If the error rate is low, the 64QAM demodulation is continued.
[0091]
Here, a carrier recovery method important for demodulation will be described. One of the features of the present invention is that the first data string of modified 16QAM or modified 64QAM is reproduced by a 4PSK receiver. In this case, when a normal 4PSK receiver is used, it is difficult to reproduce a carrier wave, and normal demodulation cannot be performed. To prevent this, some measures are required on the transmitter side and the receiver side.
[0092]
There are two types of methods according to the present invention. The first method is a method of intermittently sending signal points on an angle of (2n-1) π / 4 with a fixed regular basis. The second method is a method in which substantially all signal points are arranged and transmitted on an angle of nπ / 8.
[0093]
The first method is to send a signal point at four angles, π / 4, 3π / 4, 5π / 4, 7π / 4, as shown in FIG. 38, synchronous time slots 452, 453, 454, and 455, which are intermittently transmitted and are indicated by oblique lines, in the time slot group 451 in the time chart of the transmission signal in FIG. 38 are set based on a certain rule. Then, during this period, one of the eight signal points on the angle is always transmitted. In other time slots, an arbitrary signal point is transmitted. Then, the transmitter 1 arranges the above rule for transmitting this time slot in the data synchronization timing information section 499 shown in FIG. 41 and transmits it.
[0094]
The contents of the transmission signal in this case will be described in more detail with reference to FIG. 41. A time slot group 451 including synchronization time slots 452, 453, 454, and 455 forms one unit data string 491, Dn.
[0095]
Since the synchronization time slots are intermittently arranged in this signal based on the rules of the synchronization timing information, if this arrangement rule is understood, the carrier wave can be easily reproduced by extracting the information in the synchronization time slots.
[0096]
On the other hand, at the beginning of the frame of the data string 492, there is a synchronization area 493 indicated by S, which is composed of only synchronization time slots indicated by oblique lines. With this configuration, the amount of extracted information for carrier wave reproduction described above is increased, so that there is an effect that carrier wave reproduction of the 4PSK receiver can be performed reliably and quickly.
[0097]
The synchronization area 493 includes synchronization sections 496, 497, and 498 indicated by S1, S2, and S3, and contains a unique word for synchronization and the above-described demodulation information. Further I_TThere is also a phase synchronization signal arrangement information section 499 indicated by, in which contains information such as information on the arrangement interval of the phase synchronization time slot and information on the arrangement rule.
[0098]
Since the signal point in the region of the phase synchronization time slot has only a specific phase, the carrier can be reproduced by a 4PSK receiver._TCan be reliably reproduced, and after obtaining this information, the carrier can be reliably reproduced.
[0099]
A demodulation information section 501 is provided next to the synchronization area 493 in FIG. 41, and contains demodulation information relating to a threshold voltage required when demodulating a modified multi-level QAM signal. Since this information is important for demodulation of multi-level QAM, if demodulation information 502 is put in the synchronization area as in the synchronization area 502 in FIG. 41, the demodulation information can be obtained more reliably.
[0100]
FIG. 42 is a signal arrangement diagram in the case of transmitting a burst signal by the TDMA method. The difference from FIG. 41 is that a guard time 521 is provided between the data strings 492 and Dn and other data strings, and no transmission signal is transmitted during this period. A synchronization section 522 for synchronizing is provided at the head of the data sequence 492. During this period, only the signal point having the phase of (2n-1) π / 4 is transmitted. Therefore, a carrier wave can be reproduced even by a 4PSK demodulator. Thus, synchronization and carrier wave reproduction can be performed even in the TDMA system.
[0101]
Next, the carrier recovery method of the first receiver 23 in FIG. 19 will be described in detail with reference to FIGS. 43 and 44. In FIG. 43, the received signal input enters the input circuit 24, and one of the demodulated signals synchronously detected by the synchronous detection circuit 541 is sent to the output circuit 542 and output, and the first data string is reproduced. The phase synchronization section arrangement information section 499 of FIG. 41 is reproduced by the extraction timing control circuit 543, and at which timing the signal of the phase synchronization section of (2n-1) π / 4 enters, the intermittent state as shown in FIG. Phase synchronization control signal 561 is sent. The demodulated signal is sent to the multiplying circuit 545, multiplied by 4 and sent to the carrier recovery control circuit 54. A signal of true phase information 563 and other signals are included like a signal 562 in FIG. As shown by hatching in the timing chart 564, a phase synchronization time slot 452 including signal points having a phase of (2n-1) π / 4 is intermittently included. This is sampled by the carrier reproduction control circuit 544 using the phase synchronization control signal 564 to obtain a phase sample signal 565. By sampling and holding this, a predetermined phase signal 566 is obtained. This signal passes through the loop filter 546, is sent to the VCO 547, the carrier is reproduced, and sent to the synchronous detection circuit 541. In this manner, signal points having a phase of (2n-1) π / 4 as shown by oblique lines in FIG. 39 are extracted. Based on this signal, an accurate carrier wave can be reproduced by the quadrupling method. At this time, a plurality of phases are reproduced, but by inserting a unique word into the synchronization section 496 in FIG. 41, the absolute phase of the carrier can be specified.
[0102]
When a modified 64QAM signal is transmitted as shown in FIG. 40, phase synchronization time slots 452, 452b, etc. are set only for signal points in the phase synchronization area 471 indicated by hatching with a phase of approximately (2n-1) π / 4. Transmitter sends. For this reason, a carrier wave cannot be reproduced by a normal 4PSK receiver, but the first receiver 23 of 4PSK has an effect that the carrier wave can be reproduced by providing the carrier wave recovery circuit of the present invention.
[0103]
The above is the case where the carrier recovery circuit of the Costas system is used. Next, the case where the present invention is applied to an inverse modulation type carrier recovery circuit will be described.
[0104]
FIG. 45 shows an inverse modulation type carrier recovery circuit of the present invention. The demodulated signal is reproduced by the synchronous detection circuit 541 from the received signal from the input circuit 24. On the other hand, the input signal delayed by the first delay circuit 591 is inversely demodulated by the demodulated signal in the four-phase modulator 592 to become a carrier signal. The carrier signal that has passed through the carrier reproduction control circuit 544 is sent to the phase comparator 593. On the other hand, the reproduced carrier wave from the VCO 547 is delayed by the second delay circuit 594, and the phase is compared with the above-mentioned inversely modulated carrier signal by the phase comparator 593. The phase carrier is recovered. In this case, in the same manner as the Costas-type carrier recovery circuit in FIG. 43, the extraction timing control circuit 543 causes only the phase information of the signal points in the hatched area in FIG. 39 to be sampled. A carrier wave can be reproduced by 23 4PSK modulators.
[0105]
Next, a method of reproducing a carrier by a 16-times multiplication method will be described. Transmitter 1 shown in FIG. 2 performs modulation and transmission by arranging signal points of modified 16QAM at a phase of nπ / 8 as shown in FIG. The first receiver 23 in FIG. 19 can reproduce a carrier by using a Costas-type carrier recovery circuit having a 16-multiplier circuit 661 as shown in FIG. The signal point having the phase of nπ / 8 as shown in FIG. 46 is degenerated into the first quadrant by the 16-multiplier circuit 661, so that the carrier can be reproduced by the loop filter 546 and the VCO 541. By arranging the unique word in the synchronization area, the absolute phase can be extracted from the 16 phases.
[0106]
Next, the configuration of the 16-multiplier circuit will be described. A sum signal and a difference signal are generated from the demodulated signal by a sum circuit 662 and a difference circuit 663, and multiplied by a multiplier 664 to form cos2θ. The multiplier 665 produces sin2θ. These are multiplied by a multiplier 666 to generate sin4θ.
[0107]
Similarly, sin8θ is formed from sin2θ and cos2θ by a sum circuit 667, a difference circuit 668, and a multiplier 670. Con8θ is created by the sum circuit 671, the difference circuit 672, and the multiplier. Then, by making sin16θ by the multiplier 674, 16 multiplication can be performed.
[0108]
With the 16-times multiplication method described above, there is a great effect that the carrier waves of all the signal points of the modified 16QAM signal having the signal point arrangement as shown in FIG. 46 can be reproduced without extracting a specific signal point.
[0109]
Also, the carrier wave of the modified 64QAM signal arranged as shown in FIG. 47 can be reproduced, but since some signal points are slightly shifted from the synchronization area 471, the demodulation error rate increases.
[0110]
There are two ways to deal with this. One is not to transmit a signal at a signal point outside the synchronization area. The amount of information is reduced, but the structure is simplified. Another is to provide a synchronous time slot as described with reference to FIG. By transmitting signal points such as the synchronous phase regions 471 and 471a having a phase of nπ / 8 indicated by oblique lines during a synchronous time slot in the time slot group 451, accurate synchronization can be achieved during this period. Therefore, the phase error is reduced.
[0111]
As described above, the 16-multiplying method has a great effect that the carrier of the modified 16QAM or modified 64QAM signal can be reproduced by the 4PSK receiver with a simple receiver configuration. Further, when a synchronization time slot is further set, an effect of increasing the phase accuracy at the time of carrier reproduction of the modified 64QAM can be obtained.
[0112]
As described above in detail, by using the transmission device of the present invention, a plurality of data can be simultaneously transmitted in a single radio band in a hierarchical structure.
[0113]
In this case, by setting three levels of receivers having different reception sensitivities and demodulation capabilities for one transmitter, there is an advantage that the data amount commensurate with the investment of the receiver can be demodulated. First, a human receiver who purchases a small antenna and a low-resolution but low-cost first receiver can demodulate and reproduce the first data string. Next, a receiver who has purchased a medium-sized antenna and a medium-resolution high-cost second receiver can reproduce the first and second data strings. Also, a person who has purchased a large antenna and a high-resolution, high-cost third receiver can demodulate and reproduce all of the first, second, and third data strings.
[0114]
If the first receiver is a home digital satellite broadcast receiver, the receiver can be realized at a low price that can be accepted by many general consumers. Although the second receiver initially requires a large antenna and is expensive, it is unacceptable to consumers in general, but it is worthwhile for those who want to watch HDTV a little higher. The third receiver requires a rather large industrial antenna until the satellite power increases, and is not practical for home use and is initially suitable for industrial use. For example, if an ultra-high resolution HDTV signal is transmitted and transmitted to various movie theaters by satellite, the movie theater can be digitized by video. In this case, there is also an effect that operating costs of movie theaters and video theaters are reduced.
[0115]
As described above, when the present invention is applied to TV transmission, there is a great effect that video services of three image quality can be provided in one radio frequency band, and that they are compatible with each other. In the embodiment, examples of 4PSK, modified 8QAM, modified 16QAM, and modified 64QAM have been described, but 32QAM and 256QAM can also be realized. Also, the present invention can be applied to quaternary or octal ASK signals as shown in FIGS. 58 and 68 (a) and (b). In addition, the present invention can be implemented with 8PSK, 16PSK, and 32PSK. Further, in the embodiment, the example of the satellite transmission is shown, but it goes without saying that the same can be realized by the terrestrial transmission or the wired transmission.
[0116]
(Example 2)
The second embodiment is obtained by logically further dividing the physical hierarchical structure described in the first embodiment by differentiating the error correction capability and adding a logical hierarchical structure. In the case of the first embodiment, the respective hierarchical channels have different electric signal levels, that is, different physical demodulation capabilities. On the other hand, in the second embodiment, the logical reproduction capability such as the error correction capability is different. Specifically, for example, D₁The data in the hierarchical channel of_1-1And D_1-2, And one of the divided data, for example, D_1-1Error correction capability of data_1-2Data and demodulation and reproduction,_1-1And D_1-2Since the data has different error post-tuning capabilities, if the C / N value of the transmission signal is reduced, D_1-2At a signal level that cannot be reproduced_1-1Is within the set error rate and can reproduce the original signal. This can be called a logical hierarchical structure.
[0117]
In other words, by dividing the data of the modulation hierarchical channel, and by differentiating the magnitude of the inter-code distance of error correction such as the use of an error correction code and a product code, a logical hierarchical structure based on error correction capability is added, Finer hierarchical transmission is possible.
[0118]
Using this, D₁Channel is D_1-1, D_1-2Two subchannels, D₂Channel is D_2-1, D_2-2To two sub-channels.
[0119]
This will be described with reference to FIG. 87 showing the C / N value of the input signal and the hierarchical channel number._1-1Can be reproduced with the lowest input signal. Assuming that this CN value is d, when CN = d, D_1-1Is played but D_1-2, D_2-1, D_2-2Does not play. Next, when CN = C or more, D_1-2Is further reproduced, and when CN = b, D_2-1Is added, and when CN = a, D_2-2Joins. Thus, as the CN increases, the total number of reproducible layers increases. Conversely, as the CN decreases, the total number of reproducible hierarchies decreases. This will be described with reference to the transmission distance and reproducible CN values shown in FIG. Generally, as the transmission distance becomes longer as shown by a solid line 861 in FIG. 86, the C / N value of the received signal decreases. It is assumed that the distance from the transmitting antenna at the point where CN = a described in FIG. 85 is La, Lb when CN = b, Lc when CN = C, Ld when CN = d, and Le when CN = e. As described with reference to FIG._1-1Only channels can be played. This D_1-1Is indicated by a shaded area 862. As is clear from the figure, D_1-1Channels can be played in the widest area. Similarly, D_1-2The channel can be reproduced in an area 863 within a distance ΔLc from the transmitting antenna. Since the area 862 is included in the range within the distance Lc, the D1-1 channel can also be reproduced. Similarly, in area 864, D_2-1The channel can be played, and the D_2-2The channel can be played. In this way, hierarchical transmission in which the number of transmission channels that do not accompany the deterioration of the CN value decreases stepwise can be performed. By separating the data structure into a hierarchical structure and using the multi-level transmission of the present invention, it is possible to achieve a hierarchical transmission in which the data amount gradually decreases as the C / N deteriorates, as in analog transmission. is there.
[0120]
Next, a specific configuration will be described. Here, an embodiment of two physical layers and two logical layers will be described. FIG. 87 is a block diagram of the transmitter 1. Since it is basically the same as the block diagram of the transmitter of FIG. 2 described in the first embodiment, detailed description is omitted, but the difference is that an error correction code encoder is added. This is abbreviated as ECC encoder. The separation circuit 3 has four outputs 1-1, 1-2, 2-1 and 2-2, and outputs an input signal D._1-1, D_1-2, D_2-1, D_2-2And outputs the four signals. Of these, D_1-1, D_1-2The signal is input to the first ECC encoder 871a, and is sent to the main ECC encoder 872a and the sub ECC encoder 873a, respectively, where the error correction is encoded.
[0121]
Here, the main ECC encoder 872a has a stronger error correction capability than the sub ECC encoder 873a. Therefore, as described with reference to the graph of the CN-hierarchical channel in FIG._1-1Channel is D_1-2D even at C / N values lower than channel_1-1Can be reproduced below the reference error rate. D_1-1Is D_1-2It has a logical hierarchical structure that is more resistant to a decrease in C / N. Error corrected D_1-1, D_1-2The signal is D₁The signal is combined with the signal and input to the modulator 4. On the other hand, D_2-1, D_2-2The signal is error-correction-encoded by the main encoder 872b and the sub-ECC encoder 873b in the second ECC encoder 871b, and D-coded by the synthesizer 874b.₂The signal is combined with the signal and input by the modulator 4. The main ECC encoder # 87b has a higher error correction capability than the sub ECC encoder 873b. In this case, modulator 4₁Signal, D₂A hierarchical modulation signal is generated from the signal and transmitted from the transmission unit 5. As described above, the transmitter 1 of FIG.₁, D₂Has a two-layer physical hierarchy structure. This description has already been given. Next, by differentiating the error correction capability, D_1-1And D_1-2Or D_2-1, D_2-2Has a logical hierarchical structure of two layers.
[0122]
Next, the state of receiving this signal will be described. FIG. 88 is a block diagram of the receiver. The basic configuration of the second receiver 33 that has received the transmission signal of the transmitter in FIG. 87 is substantially the same as that of the second receiver 33 described in FIG. 21 of the first embodiment. The difference is that ECC decoders 876a and 876b are added. In this case, an example of QAM modulation / demodulation is shown. However, the present invention can be applied to an ASK signal such as a quaternary or octal VSB as shown in FIGS. 58 and 68 (a) and (b). Alternatively, PSK or FSK modulation / demodulation may be used.
[0123]
Now, in FIG. 88, the received signal is demodulated by the demodulator 35 to D₁, D₂And reproduced by the separators 3a and 3b._1-1And D_1-2, D_2-1, D_2-2Are generated and input to the first ECC decoder 876a and the second ECC decoder 876b. In the first ECC decoder 876a, D_1-1The signal is error-corrected by main ECC decoder # 877a and sent to combining section 37. On the other hand, D_1-2The signal is error-corrected by the sub E @ CC decoder 878a and sent to the combining unit 37. Similarly, in the second ECC decoder 876b, D_2-1The signal goes to the main ECC decoder 877b and_2-2The signal is error-corrected in the sub ECC decoder 878b, and is input to the combining unit 37. Error corrected D_1-1, D_1-2, D_2-1, D_2-2The signal becomes one signal in the synthesizing unit 37 and is output from the output unit 36.
[0124]
In this case, D_1-1Is D_1-2More and D_2-1Is D_2-2Since the error correction capability is higher, as described with reference to FIG. 85, even when the C / N value of the input signal is lower, a predetermined error rate can be obtained, and the original signal can be reproduced.
[0125]
Specifically, a method for differentiating the error correction capability between the main ECC decoders 877a and 877b of High Code Gain and the sub ECC decoders 878a and 878b of Low Code Gain will be described. When a coding method of a standard inter-code distance such as a Reed-Solomon code or a BCH code as shown in the ECC @ Decoder diagram of FIG. Use a product code or a long coding method of both Reed-Solomon codes and a coding method with a large inter-code distance for error correction using Trellis @ Decoder 744p, 744q, and 744r shown in FIGS. 128 (d) (e) (f). Thus, the error correction capability, that is, Code @ Gain, can be differentiated. Thus, a logical hierarchical structure can be realized. Various methods are known for increasing the inter-symbol distance, and other methods are omitted. The present invention can basically apply any method.
[0126]
As shown in the block diagrams of FIGS. 160 and 167, an interleaver 744K is provided in the transmission unit, and deinterleavers 759K and 936b are provided in the reception unit. The interleaver is interleaved by the interleave table 954 in FIG. By decoding with the deinterleave RAM 936x of 936b, strong transmission against burst errors of the transmission system becomes possible, and the image is stabilized.
[0127]
Here, the logical hierarchical structure will be described with reference to the relationship diagram between C / N and the error rate after error correction in FIG. In FIG. 89, a straight line 881 corresponds to D_1-1The relationship between the C / N of the channel and the error rate is shown._1-2The relationship between the C / N of the channel and the error rate after the correction is shown.
[0128]
The error rate of the corrected data increases as the C / N value of the input signal decreases. Below a certain C / N value, the error rate after error correction does not fall below the reference error rate Eth at the time of system design, and the original data is not reproduced normally. By the way, in FIG. 89, when C / N is gradually increased, D_1-1When the C / N is equal to or less than e as indicated by indicated by the signal straight line 881, D₁The channel cannot be demodulated. D if e ≦ C / N <d₁The channel can be demodulated, but D_1-1The error rate of the channel exceeds Eth, and the original data cannot be reproduced normally.
[0129]
When C / N = d, D_1-1Has an error correction capability of D_1-2Since the error rate is higher, the error rate after error correction becomes equal to or lower than Eth as shown by a point 885d, and data can be reproduced. On the other hand, D_1-2Error correction capability is D_1-1The error rate after correction is D_1-1Error rate after correction is not so low₂Cannot be reproduced because it exceeds Eth. So in this case D_1-1Only can play.
[0130]
When C / N is improved and C / N = C, D_1-2Since the error rate 誤 り after error correction reaches Eth as shown by a point 885C, the data can be reproduced. At this point D_2-1, D_2-2That is, D₂Channel demodulation is in an uncertain situation. With the improvement of C / N, D at C / N = b '₂The channel can be reliably demodulated.
[0131]
When C / N is further improved and C / N = b, D_2-1Is reduced to Eth as shown at point # 885b, and D_2-1Can be played. At this time, D_2-2Cannot be reproduced because the error rate is higher than Eth. When C / N = a, D becomes as shown at point 885a._2-2Error rate decreases to Eth and D_2-2The channel can be played.
[0132]
In this way, by using the error correction capability differentiation, the physical layer D₁, D₂The channel can be further divided into two logical hierarchies, and an effect of transmitting a total of four hierarchies can be obtained.
[0133]
In this case, the data structure is set to a hierarchical structure such that a part of the original signal can be reproduced even if data of a higher hierarchy is lost, and by combining with the multi-level transmission of the present invention, the degradation of C / N like the analog transmission is performed. Accordingly, there is an effect that hierarchical transmission in which the data amount gradually decreases becomes possible. In particular, image compression technology in recent years has progressed rapidly, and when image compression data is structured in a hierarchical structure and combined with hierarchical transmission, video with much higher image quality than the analog transmission is transmitted between the same points, As in transmission, it is possible to receive in a wide area while lowering the image quality according to the received signal level in a stepwise manner. As described above, the effect of hierarchical transmission, which has not been provided by conventional digital video transmission, can be obtained while maintaining high digital image quality.
[0134]
Further, the most important data for image expansion of the HDTV signal such as the address data of the image segment data, the reference image data at the time of image compression, the descrambling data shown in the rascramble section of FIG. 66, and the frame synchronization signal are described as High Priority Data. D_1-188, 133, 170, and 172, the ECC Encoder 743a of H code Gain and the ECC４３Decoder 758 of High の code gain of the receiver 43 receive. In this method, even if the C / N is degraded and the error rate of the signal is increased, High Priority Data D_1-1Since the error rate does not increase so much, the fatal destruction of image quality peculiar to digital video can be prevented, and the effect of Graceful Degradation, which often deteriorates image quality, can be obtained. The modulation unit 749 and the demodulation unit 760 in FIGS. 133 and 170 can obtain the effect of GracefulｇDegradation by the above 16QAM and 32QAM, 4VSB in FIG. 57 described later in the fourth embodiment, 8VSB and 8PSK in FIG.
[0135]
As shown in FIG. 133 and FIG. 156, High Priority Data is converted to ECC Encoder 744a and Trellis Encoder 744b in 2nd data stream input 744, and High-code is performed in the low-level, low-order, low-level, low-order, and low-level, low-, low-, high-, low, , It is possible to make a large difference between the error rates of High Priority data and Low Priority data at the time of reception. For this reason, High Priority Data can be received even with a large C / N deterioration of the transmission system, so that the C / N is severely deteriorated like a receiver having poor reception conditions such as an automobile TV receiver. Also, the image quality is deteriorated with the deterioration of Low Priority Data. However, since High Priority Data is reproduced, the arrangement information of the pixel blocks is reproduced, so that an image with reduced resolution and noise is obtained without destruction of the image, and the viewer can watch the TV program. Remarkable effect is obtained.
[0136]
(Example 3)
Hereinafter, a third embodiment of the present invention will be described with reference to the drawings.
[0137]
FIG. 29 is an overall view of the third embodiment. Embodiment 3 shows an example in which the transmission device of the present invention is used in a digital TV broadcasting system. An input video 402 having an ultra-high resolution is input to an input unit 403 of a first image encoder 401, The data stream is separated into a data stream, a second data stream, and a third data stream, and compressed and output by the compression circuit 405.
[0138]
The other input images 406, 407, and 408 are compressed and output by the second image encoders 409, 410, and 411 having the same configuration as the first image encoder 401, respectively.
[0139]
Of these four sets of data, the four sets of signals in the first data sequence are time-multiplexed by the first multiplexer 413 of the multiplexer 412 using the TDM method or the like, and are transmitted as a first data sequence to the transmitter. Sent to 1.
[0140]
All or a part of the signal group of the second data string is multiplexed by the multiplexer 414 and sent to the transmitter 1 as a second data string. All or a part of the signal group of the third data string is multiplexed by the multiplexer 415 and sent to the transmitter 1 as a third data string.
[0141]
In response to this, the transmitter 1 modulates the three data strings by the modulator 4 as described in the first embodiment, sends the data stream to the satellite 10 by the antenna 6 and the transmission path 7 by the transmitter 5, and sends the first data by the repeater 12 by the repeater 12. It is sent to three types of receivers such as the receiver 23.
[0142]
In the first receiver 23, the radius r₁Received by the small-diameter antenna 22, and only the first data sequence in the received signal is reproduced by the first data sequence reproducing unit 232, and the first image decoder 421 outputs a low-resolution video signal such as an NTSC signal or a wide NTSC signal. 425 and 426 are reproduced and output.
[0143]
In the second receiver 33, the radius r₂Received by the medium-diameter antenna 32, the first data stream and the second data stream are reproduced by the first data stream reproduction section 232 and the second data stream reproduction section 233, and the HDTV signal and the like are reproduced by the second image decoder 422. The high-resolution video output 427 or the video outputs 425 and 426 are reproduced and output.
[0144]
In the third receiver 43, the radius r₃Received by the large-diameter antenna 33, the first data sequence, the second data sequence, and the third data sequence are reproduced by the first data sequence reproduction unit 232, the second data sequence reproduction unit 233, and the third data sequence reproduction unit 234. It reproduces and outputs an ultra-high resolution video output 428 such as an ultra-high resolution HDTV for video theaters and movie theaters. Video outputs 425, 4266, and 427 can also be output. A general digital TV broadcast is broadcast from the digital transmitter 51 and, when received by the first receiver 23, is output as a low-resolution video output 426 such as NTSC.
[0145]
Next, the configuration will be described in detail based on the block diagram of the first image encoder 401 in FIG. The ultra high resolution video signal is input to the input unit 403 and sent to the separation circuit 404. The separation circuit 404 separates the signals into four signals by a sub-band coding method. The horizontal low-pass component 451 and the horizontal high-pass filter 452 such as QMF separate the horizontal low-pass component and the horizontal high-pass component, and the sub-sampling units 453 and 454 halve the sampling rate, then halve the sampling rate. The components are output by a vertical low-pass filter 455 and a vertical high-pass filter 456, respectively._LV_LSignal and horizontal low frequency vertical high frequency signal, abbreviated as H_LV_HThe signal is separated into signals, and sent to the compression unit 405 at a reduced sampling rate by the sub-sampling units 457 and 458.
[0146]
The horizontal high-pass component is converted into a horizontal high-pass vertical low-pass signal, abbreviated as H, by a vertical low-pass filter 459 and a vertical high-pass filter 460._HV_LSignal, horizontal high band vertical low band signal,_HL_HThe signal is separated into signals, and is sent to the compression unit 405 at a reduced sampling rate by the sub-sampling units 461 and 462.
[0147]
In the compression unit 405, H_LV_LThe signal is subjected to optimal compression such as DCT by the first compression section 471 and output from the first output section 472 as a first data string.
[0148]
H_LV_HThe signal is compressed by the second compression section 473 and sent to the second output section 464. H_HV_LThe signal is compressed by the third compression section 463 and sent to the second output section 464. H_HV_HThe signal is separated into high-resolution video symbols (H_HV_H1) and super high resolution video signal (H_HV_H2) divided into H_HV_H1 is output to the second output unit 464 as H_HV_H2 is sent to the third output unit 468.
[0149]
Next, the first image decoder 421 will be described with reference to FIG. The first image decoder 421 outputs an output from the first receiver 23, a first data stream, that is, D₁Is input to the input unit 501 #, descrambled by the descramble unit 502, and then decompressed by the decompression unit 503._LV_LAfter the signal is expanded, the screen ratio is changed by the screen ratio changing circuit 504 and the output unit 505, and the image 506 of the NTSC signal, the image 507 of the stripe screen with the NTSC signal, the image 508 of the full screen of the wide TV, or the side of the wide TV are displayed. An image 509 of the panel screen is output. In this case, two types of scanning lines, non-interlaced or interlaced, can be selected. In the case of NTSC, 525 scanning lines and 1,050 scanning lines by double writing are obtained. When a 4PSK general digital TV broadcast is received from the digital transmitter 51, the TV image can be demodulated and reproduced by the first receiver 23 and the first image decoder 421. Next, the second image decoder will be described with reference to the block diagram of the second image decoder in FIG. First, D from the second receiver 33₁The signal is input from a first input unit 521, expanded by a first expansion unit 522, is doubled in sampling rate by an oversampling unit 523, and is converted to H by a vertical low-pass filter 524._LV_LThe signal is reproduced. D₂The signal is input from the second input unit # 530, separated into three signals by the separation circuit 531, expanded and descrambled by the second expansion unit 532, the third expansion unit 533, and the third expansion unit 534, respectively. The sampling rate is doubled by the sampling units 535, 536, and 537, and sent by the vertical high-pass filter 538, the vertical low-pass filter 539, and the vertical high-pass filter 540. H_LV_LSignal and H_LV_HThe signals are added by an adder 525, become a horizontal low-frequency video signal by an oversampling unit 541 and a horizontal low-pass filter 542, and sent to an adder 543. H_HV_LSignal and H_HV_HThe one signal is added by an adder 526, becomes a horizontal high-frequency video signal by an oversampling unit 544 and a horizontal high-pass filter 545, becomes a high-resolution video signal HD signal such as an HDTV by an adder 543, and is output from an output unit 546 to an image output of an HDTV or the like. 547 is output. In some cases, an NTSC signal is also output.
[0150]
FIG. 33 is a block diagram of the third image decoder.₁The signal is input from the first input unit 521 to D₂The signal is input from the second input unit 530, and the HD signal is reproduced by the high-frequency image decoder 527 in the above-mentioned procedure (2). D₃The signal is input from the third input unit 551, decompressed, descrambled, and synthesized by the super-high-frequency image decoder 552, and_HV_HTwo signals are reproduced. This signal is combined with the HD signal by the combiner 553 to become an ultra-high resolution TV signal and S-HD signal, and an ultra-high resolution video signal 555 is output from the output unit 554.
[0151]
Next, a specific multiplexing method of the multiplexer 401 mentioned in the description of FIG. 29 will be described.
[0152]
FIG. 34 is a data array diagram showing a first data string, D₁And the second data string, D₂And the third data string D₃How the six NTSC channels L1, L2, L3, L4, L5, L6}, the six HDTV channels M1 to M6, and the six S-HDTV channels H1 to H6 are arranged on the time axis during the period of T. It is what I drew. FIG. 34 shows that D₁L1 to L6 are arranged in a signal by time multiplexing using the TDM method or the like. D₁H of the first channel in the domain 601_LV_LSend a signal. Next D₂In the signal domain 602, difference information M1 between the HDTV of the first channel and the NTSC in the time domain corresponding to the first channel, that is, the above-described H_LV_HSignal and H_HV_LSignal and H_HV_HSend one signal. Also D₃In the signal domain 603, the super HDTV difference information H1 of the first channel, that is, H described in FIG._HV_H-Send 2H1.
[0153]
Here, the case where the TV station of the first channel is selected will be described. First, a general receiver having a small antenna, the first receiver 23 and the first image decoder 421 system can obtain the NTSC or wide NTSC TV signal shown in FIG. Next, a specific receiver having a medium-sized antenna, a second reception transceiver 33, and a second image encoder 422 selects the first data stream, D₁Domain 601 and the second data string, D₂To synthesize an HDTV signal having the same program content as the NTSC program of channel 1.
[0154]
Some receivers such as movie theaters having a large antenna, a third receiver 43 capable of multi-level demodulation, and a third image decoder 423 have D₁Domain 601 and D₂Domain 602 and D₃To obtain a super-resolution HDTV signal having the same program contents as the NTSC of channel 1 and the image quality for a movie theater. The other channels 2 to 3 are reproduced in the same manner.
[0155]
FIG. 35 shows the configuration of another domain. First, the first channel of NTSC is arranged in L1. This L1 is D₁The signal is located at the position of the domain 601 of the first time domain, and information S11 including the descrambling information between NTSCs and the demodulation information described in the first embodiment is contained at the head. Next, the first channel of the HDTV is divided into L1 and M1. M1 is difference information between HDTV and NTSC.₂In both domain 602 and domain 611. In this case, when the NTSC compressed signal of 6 Mbps s is adopted and accommodated in L1, the bandwidth of M1 is doubled to 12 Mbps. When L1 and M1 are combined, a band of 18 Mbps can be demodulated and reproduced from the second receiver 33 and the second image decoder 423. On the other hand, an HDTV compressed signal can be realized in a band of about 15 Mbps by using a currently proposed compression method. Therefore, HDTV and NTSC can be simultaneously broadcast on channel 1 in the arrangement shown in FIG. In this case, HDTV cannot be reproduced on channel 2. S21 is HDTV descrambling information. The super HDTV signal is broadcast by being divided into L1, M1, and H1. Super HDTV difference information is D₃When the NTSC is set to 6 Mbps using the domains 603, 61 2, and 613, a total of 36 Mbps can be transmitted, and if the compression is increased, a super HDTV signal of about 2,000 scanning lines of movie theater quality can be transmitted.
[0156]
36 is D₃Shows a case where six time domains are occupied to transmit a super HDTV signal. When the NTSC compressed signal is set to 6 Mbps, the transmission rate of 54 Mbps can be increased nine times. Therefore, super HDTV with higher image quality can be transmitted.
[0157]
The above is the case where one of the horizontal and vertical polarization planes of the radio wave of the transmission signal is used. Here, by using two horizontal and vertical polarization planes, the frequency utilization efficiency is doubled. This will be described below.
[0158]
FIG. 49 shows the horizontal polarization signal D of the first data string._V1And vertical polarization signal D_H1And D of the second data string_V2And D_H2, D of the third data string_V3And D_H3FIG. In this case, the vertical polarization signal D of the first data sequence_V1Contains a low-frequency TV signal such as NTSC and the horizontal polarization signal D of the first data string._H1Contains a high-frequency TV signal. Therefore, the first receiver 23 having only a vertically polarized antenna can reproduce a low band signal such as NTSC. On the other hand, the first receiver 23 having both vertical and horizontal polarization antennas is, for example, L₁And M₁HDTV signals can be obtained by synthesizing the signals. In other words, when the first receiver 23 is used, NTSC can be reproduced on the one hand, and NTSC and HDTV can be reproduced on the other hand, so that there is a great effect that the two systems are compatible.
[0159]
FIG. 50 shows a case where the TDMA system is used. A synchronization section 731 and a card section 741 are provided at the head of each data burst 721. A synchronization information section 720 is provided at the head of the frame. In this case, each time slot group is assigned one channel. For example, in the first time slot 750, NTSC, HDTV, and super HDTV of the same program on the first channel can be transmitted. Each time slot 750-750e is completely independent. Therefore, when a specific broadcasting station broadcasts in a TDMA system using a specific time slot, there is an effect that NTSC, HDTV, and super HDTV can be broadcast independently of other stations. In the case where the receiving side is also a horizontally polarized antenna and has the first receiver 23, if the NTSCTV signal is a dual polarized antenna, HDTV can be reproduced. With the second receiver 33, a low-resolution super HDTV can be reproduced. By using the third receiver 43, a super HDTV signal can be completely reproduced. As described above, a compatible broadcasting system can be constructed. In this case, with the arrangement as shown in FIG. 50, it is possible to perform time multiplexing of continuous signals as shown in FIG. 49 instead of the burst-like TDMA method. With the signal arrangement shown in FIG. 51, a higher resolution HDTV signal can be reproduced.
[0160]
As described above, according to the third embodiment, there is a remarkable effect that a digital TV broadcast compatible with three signals of an ultra-high resolution type HDTV, HDTV and NTSC-TV becomes possible. In particular, when transmitted to a movie theater or the like, there is a new effect that images can be digitized.
[0161]
Here, the modified QAM according to the present invention is called SRQAM, and a specific error rate will be described.
[0162]
First, an error rate of 16 SRQAM is calculated. FIG. 99 is a vector diagram of signal points of 16 SRQAM. In the first quadrant, in the case of 16QAM, the intervals between the 16 signal points such as the signal points 83a, 83b, 84a, 85, 83a are equally spaced, and are all 2δ.
[0163]
The signal point 83a of 16QAM is located at a distance of δ from the I axis and the Q axis of the coordinate axes. Here, in the case of 16 SRQAM, if n is defined as a shift value, the signal point 83a shifts and moves the distance from the coordinate axis to the signal point 83 at the position of nδ. In this case, n is
0 <n <3
It is. The other signal points 84a and 86a also shift and move to the positions of the signal points 84 and 86.
[0164]
If the error rate of the first data string is Pe1,
[0165]
(Equation 1)

[0166]
If the error rate of the second data string is Pe2
[0167]
(Equation 2)

[0168]
It becomes.
Next, the error rate of 36 SRQAM or 32 SRQAM is calculated. FIG. 100 is a signal vector diagram of 36 SRQAM. In the first quadrant, the distance between signal points of 36QAM is defined as 2δ.
[0169]
The signal point 83a of 36QAM is located at a distance of δ from the coordinate axis. The signal point 83a shifts to the position of the signal point 83 when it reaches 36 SRQAM, and has a distance of nδ from the coordinate axis. Each signal point is shifted to signal points 83, 84, 85, 86, 97, 98, 99, 100, 101. A signal point group 90 consisting of nine signal points is regarded as one signal point, and is received by the modified 4PSK receiver.₁The error rate in the case of “only reproduction” is Pe1, the nine signal points in the signal point group 90 are discriminated, and the second data string D₂If the error rate when reproducing is Pe2,
[0170]
(Equation 3)

[0171]
It becomes.
In this case, the C / N to error rate diagram in FIG. 101 shows an example of calculating the relationship between the error rate Pe and the C / N of the transmission system. Curve 900 shows the conventional 32QAM error rate for comparison. A straight line 905 indicates a straight line having an error rate of 10 to the power of -1.5. First layer D when shift amount n of SRQAM of the present invention is 1.5₁Is the curve 901a, and the error rate is 10^−1.5, Even if the C / N value drops by 5 dB with respect to 32QAM of curve₁Has the effect that it can be reproduced with the same error rate.
[0172]
Next, the second hierarchy D when n = 1.5₂Is shown by curve 902a. Error rate is 10^−1.5In this case, reproduction cannot be performed at the same error rate unless the C / N is increased by 2.5 dB as compared with 32QAM indicated by the curve 900. Curves 901b and 902b represent D for n = 2.0.₁, D₂Is shown. Curve 902C is D₂Is shown. To sum up, when the error rate is 10 −1.5 to 22n = 1.5, 2.0, 2.5, D is smaller than 32QAM.₁Is improved by 5, 8, 10 dB and D₂Degrades by 2.5 dB.
[0173]
In the case of 32 SRQAM, the first data string D required to obtain a predetermined error rate when the shift amount n is changed₁And the second data string D₂Are shown in the relationship diagram between the shift amount n and the C / N in FIG. As is apparent from FIG. 103, if n is 0.8 or more, hierarchical transmission, that is, the first data stream D₁And the second data string D₂It can be seen that a difference in C / N value required for transmission of the data is generated, and the effect of the present invention is generated. Therefore, in the case of 32 SRQAM, it is effective under the condition of n> 0.85. The error rate in the case of 16 SRQAM is as shown in the relationship between C / N and error rate in FIG.
[0174]
In FIG. 102, a curve 900 indicates an error rate of 16QAM. Curves 901a, 901b, and 901c are each a first data string D₁Shows the error rate when n = 1.2, 1.5, 1.8}. Curves 902a, 902b, and 902c are each a second data string D₂Are the error rates when n = 1.2, 1.5, 1.8.
[0175]
The relationship between shift amount n and C / N in FIG. 104 is the first data string D necessary to obtain a specific error rate when shift amount n is changed in the case of 16 SRQAM.₁And the second data string D₂3 shows the C / N values of the above. As is clear from FIG. 104, in the case of $ 16 SRQAM, if n> 0.9, the hierarchical transmission of the present invention can be performed. From the above, if n> 0.9, hierarchical transmission is established.
[0176]
Here, an example in which the SRQAM of the present invention is specifically applied to digital TV terrestrial broadcasting will be described. FIG. 105 is a diagram showing the relationship between the distance between the transmitting antenna and the receiving antenna during terrestrial broadcasting and the signal level. Curve 911 shows the signal level of the receiving antenna when the height of the transmitting antenna is 1250 ft. First, it is assumed that the required error rate of the transmission system required in the digital TV broadcasting system under study is 10 −1.5. An area 912 indicates a noise level, and a point 910 indicates a reception limit point of the conventional 32QAM system at a point where C / N = 15 dB. At this point of L = 60 miles, digital HDTV broadcast can be received.
[0177]
However, the C / N fluctuates temporally with a width of 5 dB due to deterioration of reception conditions such as weather. There is a problem that if the C / N drops in a reception situation where the C / N rank is close to the threshold value, HDTV reception becomes abruptly impossible. In addition, a fluctuation of at least about 10 dB is expected due to the influence of the terrain and the building, and the signal cannot be received at all points within a radius of 60 miles. In this case, unlike analog, video cannot be transmitted completely in digital. Therefore, the service area of the conventional digital TV broadcasting system is uncertain.
[0178]
On the other hand, in the case of the 32 SRQAM of the present invention or the 8-VSB shown in FIG. 68, as described above, a three-layer hierarchy is formed by the configurations of FIGS. 133 and 137. 1st-1st level D_1-1Sends a low-resolution NTSC signal at the MPEG level, and₁-2 to send a medium resolution TV component such as NTSC,₂Can send high frequency components of HDTV. For example, in FIG. 105, the service area of the 1-2nd layer expands to a $ 70 point as shown at a point 910a, and the second layer retreats to a 55mile point as shown at 910b. The service area diagram of 32 SRQAM in FIG. 106 shows the difference in the service area area in this case. FIG. 106 shows the service area diagram of FIG. 53 calculated more specifically by performing computer simulation. In FIG. 106, areas 708, 703c, 703a, 703b, and 712 are respectively the service area of the conventional 32QAM, and the 1-1st layer D_1-1Service area, Level 1-2 D₁-2 service area, second layer D₂And the service area of the adjacent analog station. Among them, the data of the service area of the conventional 32QAM uses the conventionally disclosed data.
[0179]
With the conventional 32QAM broadcast system, a nominal 60 mile service area can be set. However, in practice, reception conditions were extremely unstable near the reception limit area due to changes in weather and topographic conditions.
[0180]
However, using 36 SRQAM of the present invention,_1-1To transfer the MPEG1 grade low-frequency TV component to the 1-2nd layer D_1-2At NTSC grade {transmit mid-range TV component}₂106, the radius of the service area of the high-resolution grade HDTV is reduced by 5 miles, but the radius of the service area of the medium-resolution grade EDTV is increased by 10 miles or more, as shown in Fig. 106. However, the service area of the low-resolution LDTV can be expanded by 18 miles. FIG. 107 shows the service area when the shift factor is n or s = 1.8, and FIG. 135 shows the service area in FIG. 107 in terms of area.
[0181]
As a result, by applying the SRQAM method of the present invention even in an unreceivable area which existed in an area where reception conditions are poor in the conventional method, at least in most of the receivers at least within the set service area. Transmission that enables TV broadcasts to be received at a resolution or a low resolution grade becomes possible. Therefore, the use of the present invention greatly reduces the unreceivable area in the area where the ordinary QAM occurs, such as a building shadow or an unreceivable area in a lowland and an area where interference from an adjacent analog station occurs, thereby substantially reducing the unreceivable area. The number of recipients can be increased.
[0182]
Secondly, in the conventional digital TV broadcasting system, only a receiver having an expensive HDTV receiver and a receiver can receive a broadcast, so that only a part of the receivers can view in the service area. However, in the present invention, a receiver having a conventional TV receiver of the conventional NTSC, PAL or SECAM system can also increase the digital HDTV broadcast program by NTSC or LDTV grade by adding only a digital receiver. This has the effect of enabling reception. Therefore, the receiver can view the program with less economic burden.
[0183]
At the same time, the total number of receivers increases, so that the TV sender can obtain more viewers, so that a social effect that management as a TV business is more stable is produced.
[0184]
Third, the area of the receiving area of the middle and low resolution grade is 36% larger than that of the conventional system when n = 2.5. The number of recipients increases with the expansion. Due to the expansion of the service area and the increase in the number of receivers, the business revenue of the TV operator increases accordingly. This is expected to reduce the business risk of digital broadcasting and accelerate the spread of digital TV broadcasting.
[0185]
Now, as shown in the service area diagram of 32 SRQAM in FIG. 107, the same effect can be obtained when n or s = 1.8. By changing the shift value n, each broadcasting station changes n in accordance with local conditions and circumstances such as the distribution status of the HDTV receiver and the NTSCTV receiver, and the D of SRQAM is changed.₁And D₂By setting the service areas 703a and 703b to optimal conditions, the receiver can obtain the maximum satisfaction and the broadcasting station can obtain the maximum number of receivers.
[0186]
in this case
n> 1.0
In such a case, the above effects can be obtained.
Therefore, in the case of 32 SRQAM, n is
1 <n <5
It becomes.
Similarly, for 16 SRQAM, n is
1 <n <3
It becomes.
[0187]
In this case, in the SRQAM system in which the first and second layers are shifted as shown in FIGS. 99 and 100, if n is 1.0 or more in 16 SRQAM, 32 SRQAM, and 64 SRQAM, the effect of the present invention can be obtained in terrestrial broadcasting. Can be
[0188]
In the embodiment, the case where the video signal is transmitted has been described. However, the audio signal is divided into a high-frequency part or a high-resolution part and a low-frequency part or a low-resolution part, and the transmission method of the present invention is used as a second data string and a first data string, respectively. The same effect can be obtained by transmitting using.
[0189]
When used for PCM broadcasting, radio, and mobile phones, there is an effect that the service area is expanded.
[0190]
In the third embodiment, as shown in FIG. 133, a sub-channel based on TDM is provided in combination with a time division multiplexing (TDM) system, and the code gains for error correction of two sub-channels are discriminated as shown in ECC {Encoder 743a} and ECC @ Encoder 743b. This makes it possible to increase the number of sub-channels for multilevel transmission by making a difference between the thresholds of the respective sub-channels. In this case, as shown in FIG. 137, Code @ gains of an ECC encoder such as Trellis @ Encoder of two sub-channels of the VSB-ASK signal of 4VSB, 8VSB, and 16VSB may be changed. The detailed description is the same as the description of FIG.
[0191]
The block diagram in FIG. 131 is a magnetic recording / reproducing device, and the block diagram in FIG. 137 is a transmission device. Up @ converter of the transmitter of the transmission device; Down @ converter of the receiver are replaced with the magnetic head recording signal amplification circuit and the magnetic head reproduction signal amplification circuit of the magnetic recording / reproducing device, so that both have exactly the same configuration. I understand. Therefore, the configuration and operation of the modem are exactly the same. Similarly, it can be seen that the magnetic recording / reproducing system of FIG. 84 has the same configuration as the transmission system of FIG. 156. In addition, the configuration shown in FIG. 157 can be used to simplify the configuration, and the configuration shown in FIG. 158 can be used to further simplify the configuration.
[0192]
In the simulation of FIG. 106, the 1-1 subchannel D_1-1And the 1-2 subchannel D_1-25 shows a case where a difference of 5 dB of Coding @ Gain is provided. The SRQAM is an application of the signal point code division multiplexing (Constellation-Code / Division / Multiplex) of the present invention called "C-CDM" to the rectangle-QAM. C-CDM is a multiplexing method independent of TDM and FDM. This is a method of obtaining a sub-channel by dividing a signal point code corresponding to a code. By increasing the number of signal points, expandability of transmission capacity not available in TDM or FDM can be obtained. This is achieved while maintaining almost complete compatibility with conventional equipment. Thus, C-CDM has an excellent effect.
[0193]
Although the embodiment in which the C-CDM and the TDM are combined is used, the same effect of reducing the threshold can be obtained by combining the embodiment with the frequency division multiplexing (FDM). For example, when used for TV broadcasting, the frequency distribution of a TV signal shown in FIG. 108 is obtained. Conventional analog broadcasting, for example, an NTSC signal has a frequency distribution like a spectrum 725. The largest signal is the image carrier 722. The color carrier 723 and the audio carrier 724 are not so large. In order to avoid mutual interference, there is a method of dividing a digital broadcast signal into two frequencies by FDM. In this case, as shown in the figure, the interference can be reduced by dividing into a first carrier 726 and a second carrier 727 so as to avoid the image carrier 722 and sending the first signal 720 and the second signal 721, respectively. By transmitting a low-resolution TV signal with a large output using the first signal 720 and transmitting a high-resolution signal with a small output using the second signal 721, hierarchical broadcasting by FDM is realized while avoiding interference.
[0194]
Here, FIG. 134 shows a diagram in the case where the conventional system 32QAM is used. Since the output of the sub-channel A is larger, the threshold value Threshold1 may be smaller by 4 to 5 dB than the threshold value Threshold2 of the sub-channel B. Therefore, hierarchical broadcasting of 2 layers having a difference of 4 to 5 dB threshold is realized. However, in this case, when the level of the received signal becomes equal to or lower than Thehold2, all of the signals indicated by oblique lines of the second signal 721a occupying a large amount of information cannot be received at all, and only the first signal 720a having a small amount of information can be received. In the second layer, only images having extremely poor image quality can be received.
[0195]
However, when the present invention is used, as shown in FIG. 108, first, a subchannel 1ofA is added to the first signal 720 using 32 SRQAM obtained by C-CDM. A lower resolution component is added to the sub-channel 1ofA having a lower threshold. The second signal 721 is set to 32 SRQAM, and the threshold value of the sub-channel 1ofB is adjusted to the threshold value Threshold2 of the first signal. Then, even if the signal level drops to Threshold-2, reception becomes impossible. The area is only the second signal portion 721a indicated by oblique lines, and since the sub-channel 1ofB and the sub-channel A can be received, the transmission amount does not decrease much. Therefore, there is an effect that an image with good image quality can be received even at the signal level of Th-2 in the second layer.
[0196]
By transmitting the normal resolution component to one of the sub-channels, the number of hierarchies is further increased, and the effect of expanding the low-resolution service area is produced. By putting important information such as audio information, synchronization information, and header of each data into the sub-channel having a low threshold value, the important information can be reliably received and stable reception is possible. If a similar technique is used for the second signal 721, the number of service area layers increases. When the HDTV has 1050 scanning lines, 775 service areas are added by C-CDM in addition to 525 scanning lines.
[0197]
In this way, when FDM and C-CDM are combined, there is an effect that the service area is expanded. In this case, two sub-channels are provided by FDM, but the frequency may be divided into three and three sub-channels may be provided.
[0198]
Next, a method of avoiding interference by combining TDM and C-CDM will be described. As shown in FIG. 109, the analog TV signal includes a horizontal retrace unit 732 and a video signal unit 731. The fact that the signal level of the horizontal retrace unit 732 is low, and that the signal is not output to the screen during the period during the interruption is used. By synchronizing the digital TV signal with the analog TV signal, it is possible to send important data, for example, a synchronization signal or the like, or send a lot of data at a high output to the horizontal retrace synchronization slots 733 and 733a during the horizontal retrace unit 732. it can. This has the effect of increasing the amount of data and increasing the output without increasing interference. Similar effects can be obtained by providing the vertical retrace synchronization slots 737 and 737a in synchronization with the periods of the vertical retrace units 735 and 735a.
[0199]
FIG. 110 is a diagram showing the principle of C-CDM. FIG. 111 shows a code allocation diagram of the 16-QAM extended version C-CDM, and FIG. 112 shows a code allocation diagram of the 32-QAM extended version. As shown in FIGS. 110 and 111, 256QAM is divided into first, second, third, and fourth layers 740a, 740b, 740c, and 740d, and has 4, 16, 64, and 256 segments, respectively. The signal point codeword 742d of 256QAM of the fourth layer 740d is "11111111" of 8 bits. This is divided into four codewords 741a, 741b, 741c and 741d by 2 bits, and the signal point areas 742a, 742b, 742c and 742d of the first, second, third and fourth layers 740a, 740b, 740c and 740d are respectively " 11 "," 11 "," 11 ", and" 11 "are assigned. Thus, sub-channels of 2 bits each, that is, sub-channel 1, sub-channel 2, sub-channel 3, and sub-channel 4 are formed. This is called signal point code division multiplexing. FIG. 111 shows a specific code arrangement of an extended version of 16QAM, and FIG. 112 shows an extended version of 36QAM. The C-CDM multiplexing scheme is independent. Therefore, by combining with the conventional frequency division multiplexing (FDM) or time division multiplexing (TDM), there is an effect that the number of sub-channels can be further increased. Thus, a new multiplexing system can be realized by the C-CDM system. Although C-CDM has been described using Rectangle-QAM, it has signal points. Other modulation schemes, such as other forms of QAM, PSK, ASK, and the frequency domain can be regarded as signal points, and FSK can be multiplexed similarly.
[0200]
For example, the error rate of sub-channel 1 of 8PS-APSK is
[0201]
(Equation 4)

[0202]
Sub channel 2 Pe_2-8Is
[0203]
(Equation 5)

[0204]
The error rate of sub-channel 1 of 16-PS-APSK (PS type) is
[0205]
(Equation 6)

[0206]
The error rate of subchannel 2 is
[0207]
(Equation 7)

[0208]
The error rate of subchannel 3 is
[0209]
(Equation 8)

[0210]
Indicate by.
(Example 4)
Hereinafter, a fourth embodiment of the present invention will be described with reference to the drawings.
[0211]
FIG. 37 is an overall system diagram of the fourth embodiment. The fourth embodiment uses the transmission apparatus described in the third embodiment for terrestrial broadcasting, and has almost the same configuration and operation. The difference from FIG. 29 described in the third embodiment is that the transmitting antenna 6a is a terrestrial transmission antenna and each of the antennas 21a, 31a, and 41a of each receiver is a terrestrial transmission antenna. Only points. The other operations are exactly the same, and a repeated explanation will be omitted. Unlike satellite broadcasting, in the case of terrestrial broadcasting, the distance between the transmitting antenna 6a and the receiver is important. A distant receiver has a weaker arrival radio wave, and cannot demodulate at all with a signal simply multi-valued QAM-modulated by a conventional transmitter and cannot watch a program.
[0212]
However, when the transmission apparatus of the present invention is used, the first receiver 23 having the antenna 22a at a long distance as shown in FIG. 37 receives the modified 64QMA modulated signal or the modified 16QAM modulated signal, demodulates it in the 4PSK mode, and Since the D1 signal in the column is reproduced, an NTSC TV signal is obtained. Therefore, even if the radio wave is weak, a TV program can be viewed at a medium resolution.
[0213]
Next, in the second receiver 33 having the antenna 32a at the middle distance, since the arriving radio wave is sufficiently strong, the second data string and the first data string can be demodulated from the modified 16 or 64 QAM signal, and the HDTV signal can be obtained. Therefore, the same TV program can be viewed on HDTV.
[0214]
On the other hand, the third receiver 43, which is located at a short distance or has an antenna 42a of ultra-high sensitivity, transmits the first, second, and third data strings D1, D2, and D3 because the radio waves are strong enough to demodulate the modified 64QAM signal. Demodulation results in an ultra-high resolution HDTV signal. You can watch the same TV program on a super HDTV with the same image quality as a large movie.
[0215]
The method of allocating frequencies in this case can be explained by replacing the time multiplexing arrangement with the frequency arrangement with reference to FIGS. 34, 35 and 36. As shown in FIG. 34, when the frequency is assigned from channel 1 to channel 6, NTSC L1 is assigned to the D1 signal as the first channel, HDTV difference information is assigned to the M1 of the first channel of the D2 signal, and D1 signal is assigned to the first channel. By arranging the difference information of the ultra-high resolution HDTV in H1, the NTSC, HDTV and super-resolution HDTV can be transmitted on the same channel. If the use of the D2 signal or D3 signal of another channel is permitted as shown in FIGS. 35 and 36, higher-quality HDTV and super-high-resolution HDTV can be broadcast.
[0216]
As described above, there is an effect that three digital TV terrestrial broadcasts compatible with each other can be broadcast using the D2 and D3 signal areas of one channel or another channel. In the case of the present invention, there is an effect that a TV program of the same content on the same channel can be received in a wider area if the resolution is medium.
[0219]
As a digital terrestrial broadcast, an HDTV broadcast in a 6 MHz band using 16QAM has been proposed. However, since these systems are not compatible with NTSC, it is premised that a simulcast system in which the same program is transmitted by another channel of NTSC is used. In the case of 16QAM, it is expected that a service area that can be transmitted becomes narrow. The use of the present invention for terrestrial broadcasting not only eliminates the need to provide a separate channel, but also has the effect that a broadcast service area is wide because a remote receiver can view a program with a medium resolution.
[0218]
FIG. 52 is a diagram showing a reception interference area diagram of a conventionally proposed HDTV in digital terrestrial broadcasting, and a receivable area 702 capable of receiving an HDTV from an HDTV digital broadcasting station 701 using a conventionally proposed method. And a receivable area 712 of an analog broadcasting station 711 adjacent to the area 712. In the overlapping portion 713 where the two overlap, it is impossible to stably receive at least HDTV due to radio wave interference of the analog broadcasting station 711.
[0219]
Next, FIG. 53 is a diagram showing a reception interference area when the hierarchical broadcasting system according to the present invention is used. In the present invention, when the transmission power is the same as that of the conventional method, the high-resolution receivable area 703 of the HDTV is slightly narrower than the receivable area 702 of the above-described conventional method because the power use efficiency is low. However, there is a low-resolution receivable area 704 such as digital NTSC which is wider than the receivable area 702 of the conventional method. It is composed of the above two areas. In this case, the radio wave interference from the digital broadcasting station 701 to the analog broadcasting station 711 is at the same level as in the conventional system shown in FIG.
[0220]
In this case, in the present invention, there are three areas in which the analog broadcast station 711 interferes with the digital broadcast station 701. One is a first interference area 705 that cannot receive HDTV or NTSC. The second is a second obstruction area 706 that can receive NTSC in the same manner as before interference but is indicated by a single oblique line. Here, the NTSC uses the first data string that can be received even if the C / N is low, so that the influence range of the interference is narrow even if the C / N decreases due to the radio wave interference of the analog station 711.
[0221]
The third is a third obstruction area 707 in which HDTV can be received before the interference, but only NTSC can be received after the interference.
[0222]
As described above, the reception area of the HDTV before the interference is slightly narrower than the conventional method, but the reception range including the NTSC is widened. Furthermore, even in an area where HDTV could not be received by the conventional system due to interference from the analog broadcasting station 711, the same program as HDTV can be received by NTSC. Thus, there is an effect that the unreceivable area of the program is greatly reduced. In this case, by slightly increasing the transmission power of the broadcasting station, the receivable area of the HDTV becomes equivalent to the conventional system. Further, in a distant area where the program could not be viewed at all in the conventional method, or in an overlapping area with an analog station, the program can be received with NTSCTV quality.
[0223]
Although an example using a two-layer transmission system has been described, a three-layer transmission system may be used as shown in the time allocation diagram of FIG. By separating and transmitting the HDTV into three levels of images of HDTV, NTSC and low-resolution NTSC, the receivable area shown in FIG. 53 is expanded from two layers to three layers, and the outermost layer becomes a wide area. In the first obstruction area 705, which cannot be received at all, a program can be received with the quality of low-resolution NTSCTV. The above is an example in which a digital broadcasting station interferes with analog broadcasting.
[0224]
Next, an embodiment under the restriction condition that digital broadcasting does not interfere with analog broadcasting will be described. In the system using an empty channel which is currently being studied in the United States and the like, the same channel is used adjacently. For this reason, digital broadcasts to be broadcast later must not interfere with existing analog broadcasts. Therefore, it is necessary to lower the transmission level of the digital broadcast as compared with the case of transmitting under the conditions of FIG. In this case, in the case of the conventional 16QAM or 4ASK modulation, as shown in the interference state diagram of FIG. 54, the non-receivable area 713 indicated by double oblique lines is large, so that the receivable area 708 of the HDTV becomes very small. . The service area is narrowed, and the number of recipients is reduced, which reduces the number of sponsors. Therefore, it is expected that the broadcasting business is hardly economically established in the conventional system.
[0225]
Next, FIG. 55 shows a case where the broadcast system of the present invention is used. The HDTV high-resolution receivable area 703 is slightly smaller than the conventional receivable area 708. However, a lower resolution receivable area 704 such as NTSC is obtained in a wider range than the conventional method. A portion indicated by a single oblique line indicates an area where the same program cannot be received at the HDTV level but can be received at the NTSC level. Of these, in the first interference area 705, interference from the analog broadcasting station 711 causes reception of neither HDTV nor NTSC.
[0226]
As described above, in the case of the same radio wave intensity, in the hierarchical broadcasting according to the present invention, the receivable area of the HDTV quality is slightly narrowed, but the area where the same program can be received in the NTSCTV quality increases. This has the effect of increasing the service area of the broadcasting station. The effect is that the program can be provided to more recipients. The broadcasting business of HDTV / NTSCTV can be established more economically and stably. When the ratio of digital broadcast receivers increases in the future, the interference rules for analog broadcasting will be relaxed, so that the radio wave intensity can be increased. At this point, the service area of the HDTV can be enlarged. In this case, by adjusting the interval between the signal points of the first data string and the second data string, the receivable area of digital HDTVINTSC and the receivable area of digital NTSC shown in FIG. 55 can be adjusted. In this case, by transmitting information of this interval to the first data string as described above, reception can be performed more stably.
[0227]
FIG. 56 shows a disturbance situation diagram when switching to digital broadcasting in the future. In this case, unlike FIG. 52, the adjacent station is a digital broadcasting station 701a that performs digital broadcasting. Since the transmission power can be increased, the high-resolution receivable area 703 such as HDTV can be expanded to the receivable area 702 equivalent to analog TV broadcasting.
[0228]
In the competing area 714 of the both receivable areas, the program cannot be reproduced in the HDTV quality with a normal directional antenna because they are obstructed from each other, but the program of the digital broadcasting station in the direction of the directivity of the receiving antenna is reproduced in the NTSCTV. We can receive with quality. When an antenna having a very high directivity is used, a program of a broadcasting station in the directivity direction of the antenna can be received with HDTV quality. The low-resolution receivable area 704 is wider than the standard receivable area 702 of analog TV broadcasting, and the competing areas 715 and 716 of the low-resolution receivable area 704a of an adjacent broadcast station are broadcasting stations in the direction of the antenna directivity. Can be reproduced with the quality of NTSCTV.
[0229]
By the way, the regulation conditions will be further relaxed in the future of full-scale digital broadcasting, and the hierarchical multi-level broadcasting of the present invention will enable HDTV broadcasting over a wide service area. Even at this time, by adopting the hierarchical multi-valued broadcasting system of the present invention, a HDTV reception range as wide as that of the conventional system can be ensured, and distant regions and competitive regions that cannot be received by the conventional system. In this case, since the program can be received with NTSCTV quality, there is an effect that the defective portion of the service area is greatly reduced.
[0230]
(Example 5)
Embodiment 5 is an embodiment in which the present invention is applied to amplitude modulation, that is, ASK method.
FIG. 57 shows a quaternary VSB-ASK signal signal point arrangement diagram according to the fifth embodiment, which has four signal points 721, 722, 723, and 724. FIG. 68A shows the constellation of an 8-level VSB signal. It is possible to transmit 2-bit data in the case of 4-level data and 4-bit data in the case of 8-level data in one cycle. In the case of 4VSB, the signal points 721, 722, 723, and 724 can correspond to, for example, 00, 01, 10, and 11.
[0231]
In order to perform the multilevel transmission according to the present invention, as shown in the signal point arrangement diagram of 4-level ASK such as 4-level VSB in FIG. 58, signal points 721 and 722 are treated as one group, that is, a first signal point group 725, Points 723 and 724 are defined as another group, a second signal point group 726. Then, the interval between the two signal point groups is made wider than the interval between the equally spaced signal points. That is, if the interval between the signal points 721 and 722 is L, the interval between the signal points 723 and 724 may be the same L, but the interval L between the signal points 722 and 723 is L._oIs set to be larger than L.
[0232]
That is, L_o> L
Set. This is a feature of the hierarchical multilevel transmission system of the present invention. However, depending on the system design, L = L may be temporarily or permanently set depending on conditions and settings._oIt is also good In the case of an 8-level VSB, the Constellation is as shown in FIGS.
[0233]
Then, as shown in FIG. 59 (a), the first data string D is added to the two signal point groups.₁1-bit $ data can be made to correspond. For example, if the first signal point group 725 is defined as 0 and the second signal point group 726 is defined as 1, a 1-bit signal of the first data string can be defined. Next, the second data string D₂Are made to correspond to two signal point groups in each signal group. For example, as shown in FIG. 59B, signal points 721 and 723 are₂= 0 and signal points 722 and 724₂= 1, the second data string D₂Data can be defined. Also in this case, it is 2 bits / symbol.
[0234]
By arranging the signal points in this way, the multi-level transmission of the present invention can be performed by the ASK method. When the signal-to-noise ratio, that is, the C / N value, is sufficiently high, the hierarchical multilevel transmission system is no different from the conventional equally spaced signal point system. However, when the C / N value is low, the second data string D can be obtained by using the present invention even under the condition that no data can be reproduced by the conventional method.₂Cannot be reproduced, but the first data string D₁Can be played. Explaining this, the state in which the C / N is deteriorated can be shown as a signal point arrangement diagram of 4VSB-ASK in FIG. That is, the signal points reproduced by the receiver are dispersed in a Gaussian distribution over a wide range of the dispersed signal point regions 721a 722a, 723a, and 724a due to noise, transmission distortion, and the like. In such a case, it is difficult to distinguish between the signal points 721 and 722 based on the slice level 2 and the signal points 723 and 724 based on the slice level 4 using a quaternary slicer. That is, the second data string D₂Error rate becomes very high. However, as is apparent from the figure, it is easy to distinguish between the group of signal points 721 and 722 and the group of signal points 723 and 724. That is, the first signal point group 725 and the second signal point group 726 can be distinguished. Therefore, the first data string D₁Can be reproduced at a low error rate.
[0235]
Thus, a data string D of two layers₁And D₂Can be sent and received. Therefore, in a good C / N condition and area of the transmission system, the first data stream D₁And the second column D₂Are in the poor C / N condition and in the area, the first data string D₁There is an effect that multi-level transmission in which only the data is reproduced can be performed.
[0236]
FIG. 61 is a block diagram of the transmitter 741. The input section 742 is composed of a first data string input section 743 and a second data string input section 744. The carrier wave from the carrier generator 64 is amplitude-modulated in a multiplier 746 by an input signal obtained by combining a signal from an input unit 742 in a processing unit 745, and is converted into a quaternary or octal ASK signal as shown in FIG. Become. The 4ASK or 8ASK signal is further band-limited by a band-pass filter 747, and becomes a VEST signal Side Band having Side Band with a little Carrier as shown in FIG. 62 (b), that is, becomes an ASK signal of the VSB signal, and is output from the output unit 748. .
[0237]
Here, the output waveform after passing through the filter will be described. FIG. 62A is a frequency distribution diagram of the ASK modulation signal. As shown, there are sidebands on both sides of the carrier. This signal is removed from one sideband, leaving a small carrier component like the transmission signal 749 in the band pass filter 747 of FIG. 62B. This is called a VSB signal.₀Is the modulation frequency band, then about f₀It is known that transmission can be performed in a frequency band of / 2, so that the frequency utilization efficiency is good. The ASK signal shown in FIG. 60 is originally 2 bits / symbol, but if the VSB method is used, 4VSB and 8VSB can transmit an information amount corresponding to 5 bits / symbol of 4 bits / symbol of 16QAM and 32QAM in the same frequency band.
[0238]
Next, in the VSB receiver 751 shown in the block diagram of FIG. 63, a signal received by the terrestrial antenna 32a is mixed with a signal from a variable oscillator 754 that is variable by channel selection via an input unit 752 in a mixer 753, Converted to intermediate frequency. Next, the signal is detected by the detector 755 and becomes a baseband signal by the LPF 756. In the case of 4VSB, the first data string D is output by the discriminator / reproducer 757 having a 4-level slicer, and in the case of 8VSB, an 8-level slicer.₁And the second data string D₂Is reproduced from the first data string output unit 758 and the second data string output unit 759 #.
[0239]
Next, a case where a TV signal is transmitted using the transmitter and the receiver will be described. FIG. 64 is a block diagram of the video signal transmitter 774. A high-resolution TV signal such as an HDTV signal is input to an input unit 403 of a first image encoder 401, and the image is separated by a video separation circuit 404 such as a sub-band filter._LV_L, H_LV_H, H_HV_L, H_HH_HEtc., are separated into a high-frequency TV signal and a low-frequency TV signal. Since this content has been described in the third embodiment with reference to FIG. 30, detailed description will be omitted. The separated TV signal is encoded in the compression unit 405 using a technique such as DPCMDCT variable length encoding used in MPEG or the like. The motion compensation is processed in the input unit 403. The four compressed image data are combined by the synthesizer 771 into a first data string D.₁And the second data string D₂Are obtained. In this case H_LV_LThe signal, that is, the low-frequency image signal is included in the first data string. The signal is input to the first data string input section 743 and the second data string input section 744 of the transmitter 741 and subjected to amplitude modulation to become an ASK signal such as VSB, which is broadcast from a terrestrial antenna.
[0240]
FIG. 65 is a block diagram of the entire TV receiver for digital TV broadcasting. The broadcast signal received by the terrestrial antenna 32a is input to the input unit 752 of the receiver 751 in the TV receiver 781, and a signal of an arbitrary channel desired by the receiver is selected and demodulated by the detection and demodulation unit 760. One data string D₁And the second data string D₂Is reproduced and output from the first data string output unit 758 and the second data string output unit 759. Detailed explanations are omitted because they overlap. D₁, D₂The signal is input to separation section 776. D₁The signal is separated by a separator 777 and H_LV_LThe compression component is input to the first input unit 521. The other is D₂The signal is combined with the signal and input to the second input unit 531. H input to the first input unit 521 in the # 2nd image decoder_LV_LThe compressed signal is converted by the first decompression unit 523 to H_LV_LThe signal is expanded to a signal and sent to the image synthesizing unit 548 and the screen ratio changing circuit 779. If the original TV signal is an HDTV signal, H_LV_LThe signal becomes a wide NTSC signal, and when the original signal is an NTSC signal, it becomes a low-resolution TV signal such as MPEG1 which is lower in quality than NTSC.
[0241]
In this description, since the original video signal is set as the HDTV signal,_LV_LThe signal is a wide NTSC TV signal. If the screen aspect ratio of the TV is 16: 9, it is output as the video output 426 via the output unit 780 with the screen ratio of 16: 9. If the screen aspect ratio of the TV is 4: 3, the screen aspect ratio change circuit 779 changes the screen aspect ratio from 16: 9 to 4: 3 in the letterbox format or the side panel format, and outputs it via the output unit 780. Output as video output 425.
[0242]
On the other hand, the second data string D from the second data string output unit 759₂Is combined with the signal of the separator 777 in the combiner 778 of the separation unit 776, input to the second input unit 531 of the second image decoder, and_LV_H, H_HV_L, H_HV_H, And sent to the second decompression unit 535, the third decompression unit 536, and the fourth decompression unit, and decompressed to obtain the original H signal._LV_H, H_HV_L, H_HV_HSignal. H_LV_LThe signal is added, input to the image synthesizing unit 548, synthesized into one HDTV signal, output from the output unit 546, and output as an HDTV video signal 427 via the output unit 780.
[0243]
This output unit 780 detects the error rate of the second data string of the second data string output unit 759 by the error rate detection unit 782, and automatically sets H to a predetermined time when a high error rate continues for a certain time._LV_LIt issues a system control command such as outputting a low-resolution video signal, stopping video output, activating a filter, or restoring synchronization.
[0244]
As described above, transmission and reception of the hierarchical broadcast can be performed. If the transmission conditions are good, for example, for a broadcast with a TV transmission antenna close to it, both the first data string and the second data string can be reproduced, so that the program can be received with HDTV quality. For a broadcast that is far from the transmitting antenna, the first data stream is reproduced and the V_LH_LA low-resolution TV signal is output from the signal. This has the effect that the same program can be received in a wider area with HDTV quality or NTSCTV quality.
[0245]
When the function of the receiver 751 is reduced only to the first data string output unit 768 as shown in the block diagram of the TV receiver in FIG. 66, the receiver does not need to handle the second data string and the HDTV signal. It can be greatly simplified. As the image decoder, the first image decoder 421 described in FIG. 31 may be used. In this case, an image of NTSCTV quality is obtained. Although the program cannot be received at the HDTV quality, the cost of the receiver is greatly reduced. Therefore, it may be widely spread. In this system, digital TV broadcasts can be received by adding many receiving systems having conventional TV displays as adapters without changing them.
[0246]
When a scrambled 4VSB or 8VSB signal is received as shown in FIG. 66, the descrambling signal transmitted by the 4VSB or 8VSB signal and the number of the descrambling number memory 502c in the descrambler 502 are used as the descrambling number collator. By performing collation by 502b and releasing the descrambling only when they match, the scramble of the specific scrambled program can be properly released.
[0247]
With the configuration as shown in FIG. 67, a receiver having the functions of a satellite broadcast receiver for demodulating a PSK signal and a terrestrial broadcast receiver for demodulating a VSB signal can be easily configured. In this case, the PSK signal received from the satellite antenna 32 is mixed with the signal from the oscillator 787 in the mixer 786, converted to a low frequency and input to the input unit 34 of the TV receiver 781, and the mixer 753 described in FIG. Is input to The PSK or QAM signal converted to a lower frequency of a specific channel of the satellite TV broadcast is demodulated by the demodulator 35 into a data stream D.₁, D₂Is demodulated, reproduced as an image signal by the second image encoder 422 via the separation unit 788, and output from the output unit 780. On the other hand, digital terrestrial broadcasting and analog broadcasting received by the terrestrial antenna 32a are input to the input unit 752, and a specific channel is selected by the mixer 753 in the same process as described with reference to FIG. It becomes a baseband signal of only the band. The signal enters a mixer 753 for analog satellite TV broadcasting and is demodulated. In the case of digital broadcasting, the data stream D₁And D₂Are reproduced, and the video signal is reproduced and output by the second image decoder 422. When receiving terrestrial and satellite analog TV broadcasts, an analog TV signal AM-demodulated by the video demodulation unit 788 is output from the output unit 780. With the configuration shown in FIG. 67, the mixer 753 can be shared by satellite broadcasting and terrestrial broadcasting. Also, the second image decoder 422 can be shared. Further, when an ASK signal is used in digital terrestrial broadcasting, a receiving circuit such as a detector 755 and an LPF 756 can be used for demodulation for AM, similar to conventional analog broadcasting. As described above, the configuration shown in FIG. 67 has an effect that the receiving circuit is largely shared and the number of circuits is reduced.
[0248]
In the embodiment, the quaternary ASK signal is divided into two groups,₁, D₂The multi-level transmission of 1 bit for each of the two layers was performed. However, when an 8-level ASK signal, that is, 8-level-VSB is used as shown in the Constellation diagram of the 8VSB signal in FIGS.₁, D₂, D₃The multi-level transmission of a total of 3 bits / sym {bol of 1 bit of each of the three layers} can be performed. First, as shown in FIG. 68 (a), how to attach the 1st bit code will be described.₃The signal points of the signal are binary points of signal points 721a and 72 と 1b, 722a and 722 b, 723a and 723b, 724a and 724b, that is, 1 bit. Next, the encoding of the next 1 bit will be described.₂Are signal points 721 and 722, and signal points 723 and 724 are binary 1 bits. D₃Is one bit of binary of large signal point groups 725 and 726. In this case, the four signal points 721, 722, 723, and 724 in FIG. 57 are separated into two signal points 721a and 721b, 722a and 722b, 723a and 723b, 724a and 724b, and the distance between the groups is reduced. By separating the layers, hierarchical multi-level transmission of up to three layers can be performed. L = L as described above₀You can also
[0249]
The transmission of digital HDTV video of three layers or the like using this three-layer multi-level transmission system has been described in the third and fourth embodiments, and a detailed description of the operation will be omitted.
[0250]
Here, the effect of performing TV broadcasting using the 8-level VSB in FIG. 68 will be described. While 8VSB has a large amount of transmission information, the error rate for the same C / N value is higher than 4VSB. However, when performing high-quality HDTV broadcasting, there is an effect that the error rate is reduced because a transmission capacity has a margin and a large number of error correction codes are included, and a hierarchical TV broadcasting will be possible in the future.
[0251]
Here, the effects of 4VSB, 8VSB and 16VSB will be described in comparison.
When performing terrestrial broadcasting using the frequency band of NTSC or PAL, as shown in FIG. 136, in the case of NTSC, the band is limited to 6 MHz, and a substantial transmission band of about 5 MHz is allowed. In the case of 4VSB, since the frequency utilization efficiency is 4 bit / Hz, there is a data transmission capacity of substantially 5 MHz × 4 = 20 Mbps. On the other hand, transmission of a digital HDTV signal requires at least 15 Mbps to 18 Mbps. For this reason, since there is no margin in the data capacity in 4-VSB, as shown in the comparison diagram of FIG. 169, the redundancy for the error correction code can be only 10 to 20% of the actual transmission amount of HDTV.
[0252]
Next, in the case of 8-VSB, since the frequency utilization efficiency is 6 bits / HZ, a data transmission capacity of 5 MHz × 6 = 30 Mbps can be obtained. As described above, transmission of an HDTV signal requires 15 to 18 MHz, but in the case of the 8VSB modulation method, an information amount of 50% or more of the substantial transmission amount of the HDTV signal is used as an error correction code as shown in FIG. be able to. Therefore, under the condition that an HDTV digital signal of the same data rate is terrestrial broadcast in a 6 MHz band, 8VSB can add a larger capacity error correction code, so that the error rate curves 805 and 806 in FIG. As shown, for the same C / N value of the transmission system, the error rate after error correction is lower in TCM-8VSB in which Code @ Gain for error correction is higher than in 4VSB in which Code @ Gain for error correction is lower. Therefore, there is an effect that the service area in TV terrestrial broadcasting is wider in 8VSB error-encoded by High @ codeagain than in 4VSB. Certainly, the 8VSB has a disadvantage that the circuit of the receiver becomes more complicated due to the increase of the error correction circuit. However, since the VSB / ASK system is the amplitude modulation system, the circuit scale of the equalizer of the receiver is significantly smaller than the QAM modulation system including a phase component. Therefore, even if an error correction circuit is added, the overall circuit scale does not become larger in the 8VSB system than in the 32QAM system. Therefore, the 8VSB system realizes an appropriate digital HDTV receiver having a wide service area and an overall circuit scale.
[0253]
Although a specific example of the error correction method will be described later in Example 5 and the like, the ECC 744a in the block diagram of the transceiver shown in FIGS. 84, 137, 156, and 157 in FIG. The transmission is performed using the 4 VSB, 8 VSB, and 16 VSB VSB modulation units 749 described with reference to FIG. The receiver uses the VSB demodulator 760 described with reference to FIG. 63 to reproduce digital data from the 4VSB, 8VSB, or 16VSB signals using a 4, 8, or 16-level level @ slicer 757. FIG. 84 described in Example 6, FIG. 131, FIG. 137, FIG. 156, and FIG. 157 of FIG. And output.
[0254]
The ECC Encoder 744a uses Reed solomon Encoder 744j and Interleaver 744k, and the ECC Decoder 759a uses DeInterleaver 759k and Reed @ solarmon9J as shown in FIGS. By applying the interleave as described in the previous embodiment, it becomes more resistant to burst errors.
[0255]
By employing the Trellis encoder shown in FIGS. 128 (a), (b), (c), (d), (e), and (f), the Code @ Gain can be further increased, and the error rate decreases. In the case of 8VSB, Trellis @ encoder 744b and decoder 759b of Ratio 2/3 can be applied as shown in FIG.
[0256]
In the embodiment, an example in which a hierarchical digital TV signal is transmitted has been mainly described. In the case of the hierarchical type, ideal broadcasting can be performed. However, since the circuits of the image compression circuit and the modulator / demodulator become complicated, it is not preferable in terms of cost at the start of broadcasting. As described at the beginning of the fifth embodiment, the signal point interval L = L of 4VSB or 8VSB₀That is, non-hierarchical -type TV transmission is performed at equal intervals, and by adopting a simple configuration as shown in FIG. 137 as shown in FIG. 157, a TV broadcasting system with a simple circuit is realized. Then, it may be switched to the 8VSB hierarchical transmission at the stage of widespread use.
[0257]
By the way, 4VSB and 8VSB have been described above, but 16VSB and 32VSB will be described in FIGS. 159 (a) to 159 (d). FIG. 159 (a) shows a 16VSB Constellation. In FIG. 159 (b), two signal point groups 722a to 722h are grouped and regarded as eight signal points, so that it can be handled as 8VSB, thereby realizing a two-layer hierarchical multi-level transmission. In this case, hierarchical transmission is realized even if the 8VSB signal is intermittently transmitted with Time \ Division \ Multiplex. However, in this method, the maximum data rate is 2/3. In FIG. 157 (c), there are four groups 723a to 723d, and the number of layers is further increased by one layer to handle 4VSB. Even in this case, even if the 4VSB signal is intermittently transmitted at Time \ Division \ Multiplex, the maximum data rate is reduced but hierarchical transmission is realized. As described above, a three-layer hierarchical VSB is realized.
[0258]
By this method, a hierarchical transmission is realized in which 8 VSB or 4 VSB data can be reproduced when the C / N of 16 VSB deteriorates. As shown in FIG. 159 (d), by doubling the signal point of 16VSB, 32VSB can be transmitted. If it is desired to increase the capacity of 16 VSB in the future, this method has an effect that a data capacity of 5 bits / symbol can be obtained while maintaining compatibility.
[0259]
To summarize the above, the configuration of the receiver shown in the block diagram of the VSB receiver of FIG. 161 and the configuration of the transmitter shown in the block diagram of the VSB transmitter of FIG. 162 are obtained.
[0260]
Although mainly described using 4-VSB and 8-VSB, it is also possible to transmit using 16VSB as shown in FIGS. 159 (a), (b) and (c). In the case of terrestrial broadcasting in the case of 16 VSB, a transmission capacity of 40 Mbps can be obtained in a 6 MHz band. However, the data rate of the HDTV digital compressed signal is 15 to 18 Mbps when the MPEG standard is used, so that the margin of the transmission capacity becomes too large. As shown in FIG. 169, Redundancy: R₁₆= 100% or more, so that the redundancy becomes too large to transmit one channel of digital HDTV, and the circuit becomes complicated, but the effect on 8VSB is small. If 16 VSB is used for terrestrial broadcasting of two channels of HDTV, the redundancy is the same as 4 VSB and only about 10 b, so that a sufficient error correction code cannot be inserted, so that the service area is narrowed. As described above, in 4-VSB, Redundancy: R₄= 10% to 20%, it is not possible to make a sufficient error correction, so the service area cannot be widened. As is clear from FIG. 169, Redundancy: R of 8-VSB₈= 50%, sufficient error correction coding can be performed. A service area can be obtained without increasing the circuit scale of error correction. Accordingly, under the condition that digital HDTV terrestrial broadcasting is performed with a band limitation of 6 to 8 MHz, as is clear from FIG. 169, it is understood that 8Level-VSB is the most effective and optimal VSB modulation method.
[0261]
In the third embodiment, the image encoder 401 as shown in FIG. 30 has been described. However, the block diagram of FIG. 30 can be rewritten as shown in FIG. The description is omitted because the contents are completely the same. As described above, the image encoder 401 has two video separation circuits 404 and 404a such as subband filters. Assuming that these are the separating unit 794, it is shown in the block diagram of the separating unit in FIG. As described above, the number of circuits can be reduced by passing a signal twice through one separation circuit in a time-division manner. To explain this, in the first cycle, the HDTV or super HDTV video signal from the input unit 403 is compressed on the time axis by the time axis compression circuit 795,_HV_H-H, H_HV_L-H, H_LV_H-H, H_LV_L+1 is divided into four components. In this case, the switches 765, 765a, 765b, and 765c are at the position 1 and the compression unit 405_HV_H-H, H_HV_L-H, H_LV_H-H three signals are output. But H_LV_LThe -H signal is input from the output 1 of the switch 765c to the input 2 of the time base adjustment circuit 795, and is sent to the separation circuit 404 in the second cycle, that is, the idle time of the time division processing, and is subjected to the separation processing._HV_H, H_HV_L, H_LV_H, H_LV_LAnd output. In the second cycle, the switches 765, 765a, 765b, and 765c change to the position of the output 2, so that the four components are sent to the compression unit 405. By performing the time-division processing with the configuration shown in FIG. 70 in this manner, there is an effect that the number of separation circuits can be reduced.
[0262]
Next, when such a three-layer hierarchical image transmission is performed, an image decoder as described in the block diagram of FIG. 33 of the third embodiment is required on the receiver side. When this is rewritten, a block diagram as shown in FIG. 71 is obtained. Although there are different processing capacities, there are two combiners 566 having the same configuration.
[0263]
This can be realized by one synthesizer in the same manner as in the case of the separation circuit of FIG. Referring to FIG. 72, first, at timing 1, the input of the switches 765, 765a, 765b, and 765c is switched to 1 by five switches, 765a, 765b, 765c, and 765d. Then, each of the first extending portion 522, the second extending portion 522a, the third extending portion 522b, and the fourth extending portion 522c receives H_LV_L, H_LV_H, H_HV_L, H_HV_HAre input to the corresponding input unit of the combiner 556 via the switch, and are combined to form one video signal. This video signal is sent to the switch 765d, output from the output 1 and sent again to the input 2 of the switch 765c. This video signal is originally H_LV_L-H component signal. At the next timing 2, the switches 765, 765a, 765b, and 765c are switched to input 2. Thus, this time H_HV_H-H, H_HV_L-H, H_LV_H-H and H_LV_LThe −H signal is sent to the combiner 556, and is subjected to a combining process to obtain one video signal. This video signal is output from the output unit 554 from the output 2 of the switch 765d.
[0264]
In this way, when three-layer hierarchical broadcasting is received, there is an effect that two synthesizers are reduced to one by time division processing.
[0265]
Now, in this method, first, at timing 1, H_HV_H, H_HV_L, H_LV_H, H_LV_LInput a signal_LV_L-Synthesize the H signal. Thereafter, at timing 2 different from timing 1, H_HV_H-H, H_HV_L-H, H_LV_H-H and the above H_LV_LThe procedure of inputting the -H signal and obtaining the final video signal is adopted. Therefore, it is necessary to shift the timing of the signals of the two groups.
[0266]
If the timings of the components of the input signal are originally different or overlapping, a memory is provided in the switches 765, 765a, 765b, and 765c to separate them in time, and the time is adjusted by accumulating the memories. It is necessary. However, by transmitting the transmission signal of the transmitter in a time-separated manner at timing 1 and timing 2 as shown in FIG. 73, a time axis adjusting circuit on the receiver side becomes unnecessary. Therefore, there is an effect that the configuration of the receiver is simplified.
[0267]
D1 in the time allocation diagram of FIG. 73 indicates the first data string D1 of the transmission signal, and during the period of the timing 1, the H level is set on the D channel._LV_L, H_LV_H, H_HV_L, H_HV_HA signal is sent, and during the period of timing 2, H_LV_H-H, H_HV_L-H, H_HV_HThe time allocation of the signal when sending -H is shown. By transmitting the transmission signals in a temporally separated manner as described above, there is an effect that the circuit configuration of the econcoder of the receiver is eliminated.
[0268]
Next, the number of expansion units of the receiver is large. A method for reducing these numbers will be described. FIG. 74 (b) shows a time allocation diagram of transmission signal data 810, 810a, 810b, 810c. In this figure, separate data 811, 810a, 811b, 811c are transmitted between data. Then, the target transmission data is intermittently transmitted. Then, the second image encoder 422 shown in the block diagram of FIG. 74A sequentially inputs the data sequence D1 to the decompression unit 503 via the first input unit 521 and the switch 812. For example, after the input of the data 810 is completed, the decompression process is performed during the time of the separate data 811. After the processing of the data 810 is completed, the next data 810a is input. By doing so, one decompressor 503 can be shared in a time sharing manner in the same manner as in the case of the synthesizer. Thus, the total number of extension portions can be reduced.
[0269]
FIG. 75 is a time allocation diagram when transmitting HDTV. For example, H corresponding to the NTSC component of the first channel of the broadcast program_LV_LH signal_LV_LAssuming (1), this is time-arranged at the position of the data 821 indicated by the bold line of the D1 signal. H corresponding to the HDTV additional component of the first channel_LV_H, H_HV_L, H_HV_HThe signal is arranged at the position of the data 821a, 821b, 821c of the D2 signal. Then, since other data 822, 822a, 822b, and 822c, which are information of another TV program, exist between all the data of the first channel, the expansion processing of the expansion unit can be performed during this period. In this way, all the components can be processed in one extension unit. This method can be applied when the processing of the decompressor is fast.
[0270]
A similar effect can be obtained by arranging data 821, 821a, 821b, and 821c in the D1 signal as shown in FIG. This is effective when transmission / reception is performed using transmission without a layer such as normal 4PSK or 4ASK.
[0271]
FIG. 77 shows a case where hierarchical multi-level broadcasting is performed using a physically two-layer hierarchical transmission method for three-layer video such as NTSC, HDTV, and high-resolution HDTV, or low-resolution NTSC, NTSC, and HDTV. FIG. For example, in the case of broadcasting low-resolution NTSC, NTSC, and HDTV three-layer video, the D1 signal has H corresponding to the low-resolution NTSC signal._LV_LThe signal is arranged in the data 821. The NTSC separation signal H_LV_H, H_HV_L, H_HV_HAre arranged at the positions of the data 821a, 821b and 821c. H which is an HDTV separation signal_LV_H-H, H_HV_L-H, H_HV_HThe -H signal is placed in the data 823, 823a, and 823b.
[0272]
Here, as shown in the block diagrams of FIG. 156 and FIG. 170, the logical hierarchical transmission by differentiating the error correction capability described in the second embodiment is added to 4VSB, 8VSB, and 16VSB. Specifically, H_LD_LIs D₁D in the signal_1-1Channels are used. D_1-1The channel is D as described in the second embodiment._1-2It employs an error correction method that has a higher correction capability than the channel. D_1-1Channel is D_1-2Since the redundancy is higher than that of the channel but the error rate after reproduction is lower, the reproduction can be performed even under the condition that the C / N value is lower than that of the other data 821a, 821b, 821c. For this reason, even in a case where reception conditions are poor, such as in an area far from the antenna or in a car, a program can be reproduced with low-resolution NTSCTV quality. As described in the second embodiment, when viewed from the viewpoint of the error rate, D₁D in the signal_1-1Data 821 in the channel is D_1-2It is more resistant to reception interference than other data 821a, 821b, 821c in the channel, is differentiated, and has a different logical hierarchy. As described in the second embodiment, D₁, D₂Can be said to be a physical layer, and the layer structure obtained by differentiating the distance between the error correction codes is a logical layer structure.
[0273]
Well, D₂Physically demodulates the signal₁Requires a higher C / N value than the signal. Therefore, under the reception condition with the lowest C / N value such as a remote place, H_LV_LA signal, that is, a low-resolution NTSC signal is reproduced. Then, in the reception condition where the C / N value is the next lowest, H is additionally added._LV_H, H_HV_L, H_HV_HIs reproduced, and the NTSC signal can be reproduced. Further, in a reception condition having a high C / N value, H_LV_LPlus H_LV_H-H, H_HV_L-H, H_HV_HSince −H is also reproduced, the HDTV signal is reproduced. Thus, broadcasting of three layers can be performed. By using this method, the receivable area described with reference to FIG. 53 is expanded from two layers to three layers as shown in the reception interference area diagram of FIG. 90, and the program receivable area is further expanded.
[0274]
Here, FIG. 78 is a block diagram of the third image decoder in the case of the time arrangement of FIG. 77. Basically, it has a configuration in which the third input unit 551 of the D3 signal is omitted from the block diagram of FIG. 72 and the configuration of the block diagram of FIG. 74A is added.
[0275]
In operation, at timing 1, the D1 signal is input from the input unit 521, and the D2 signal is input from the input unit # 530. H_LV_HSince the components such as are separated in time, they are sequentially and independently sent to the expansion unit 503 by the switch 812. This sequence will be described with reference to the time allocation diagram of FIG. First, the first channel H_LV_LThe compressed signal enters the decompression unit 503 and is decompressed. Next, H of the first channel_LV_H, H_HV_L, H_HV_HIs decompressed, input to a predetermined input unit of the synthesizer 55 # 6 via the switch 812a, synthesized, and_LV_LThe -H signal is synthesized. This signal is input from the output 1 of the switch 765a to the input 2 of the switch 765._LV_LInput to the input unit.
[0276]
Next, at timing 2, as shown in the time allocation diagram of FIG._LV_H-H, H_HV_L-H, H_HV_HThe -H signal is input, expanded by the expansion unit 503, and the respective signals are input to a predetermined input of the synthesizer 556 via the switch 812a, subjected to synthesis processing, and output an HDTV signal. The HDTV signal is output from the output 2 of the switch 765a via the output unit 521. As described above, transmission by the time arrangement shown in FIG. 77 has the effect of greatly reducing the number of decompression units and combiners in the receiver. In FIG. 77, two stages of D1 and D2 signals are used in the time allocation diagram. However, if the above-mentioned D3 signal is used, high-resolution HDTV can be added and TV broadcasting of four layers can be performed.
[0277]
FIG. 79 is a time allocation diagram of a hierarchical broadcast that broadcasts images of three layers using three physical layers D1, D2, and D3. As is clear from the figure, the components of the same TV channel are arranged so as not to overlap in time. FIG. 80 shows a receiver obtained by adding the third input unit 521a to the receiver described in the block diagram of FIG. Broadcasting by the time arrangement shown in FIG. 79 has an effect that the receiver can be configured with a simple configuration as shown in the block diagram of FIG.
[0278]
The operation is almost the same as the time allocation diagram of FIG. 77 and the block diagram of FIG. Therefore, the description is omitted. Also, as shown in the time allocation diagram of FIG. 81, all signals can be time-multiplexed to the D1 signal. In this case, the two data, the data 821 and the separate data 822, have higher error correction capabilities than the data 821a, 812b, and 821c. For this reason, the hierarchy is higher than other data. As described above, it is a hierarchical transmission of two layers although it is physically a single layer. Further, another data of another program channel 2 is included between the data of the program channel 1. Therefore, serial processing can be performed on the receiver side, and the same effect as that in the time allocation diagram of FIG. 79 can be obtained.
[0279]
In the case of the time allocation diagram shown in FIG. 81, the data has a logical hierarchy. By reducing the transmission bit rate of the data 821 and the separate data 822 to 1/2 or 1/3, the error rate at the time of transmitting this data is reduced. Therefore, physical hierarchical transmission can be performed. In this case, there are three physical layers.
[0280]
FIG. 82 is a block diagram of the image decoder 423 when only the data string D1 signal is transmitted as in the time allocation diagram of FIG. 81, and has a simpler configuration and a simpler configuration than the image decoder shown in the block diagram of FIG. Become. The operation is the same as that of the image decoder described with reference to FIG.
[0281]
As described above, when a transmission signal as shown in the time allocation diagram of FIG. 81 is transmitted, there is an effect that the number of decompressor 503 synthesizers 556 can be significantly reduced as shown in the block diagram of FIG. In addition, since the four components are temporally separated and input, some blocks are changed by changing the connection according to the input image components to the synthesizer 556, that is, the circuit block inside the image synthesis unit 548 in FIG. The circuit can be shared by time sharing and the circuit can be omitted.
[0282]
As described above, there is an effect that the receiver can be configured with a simple configuration.
In the fifth embodiment, the operation is described using the ASK modulation. However, many of the methods described in the fifth embodiment can be used for the PSK and QAM modulation described in the first, second, and third embodiments.
[0283]
Further, the above embodiments can be used for FSK modulation.
For example, when multi-level FSK modulation of f1, f2, f3, and f4 is performed as shown in FIG. 83, grouping is performed as in the signal point arrangement diagram of FIG. 58 of the fifth embodiment, and the signal point positions of each group are determined. Separation allows hierarchical transmission.
[0284]
In FIG. 83, a frequency group 841 of frequencies f1 and f2 is defined as D1 = 0, and a frequency group 842 of frequencies f3 and f4 is defined as D1 = 1. If f1 and f3 are defined as D2 = 0 and f2 and f4 are defined as D2 = 1, hierarchical transmission of a total of 2 bits, that is, 1 bit each of D1 and D2, is possible as shown in the figure. For example, when C / N is high, D1 = 0 and D2 = 1 can be reproduced at t = t3, and D1 = 1 and D2 = 0 can be reproduced at t = t4. Next, when C / N is low, only D1 = 0 can be reproduced at t = t3, and only D = 1 can be reproduced at t = t4. Thus, hierarchical transmission of FSK can be performed. The hierarchical multilevel transmission method of FSK can be used for the hierarchical broadcasting of the video signal described in the third, fourth, and fifth embodiments.
[0285]
Also, the fifth embodiment of the present invention can be used in a magnetic recording / reproducing apparatus shown in a block diagram as in FIG. In the fifth embodiment, magnetic recording and reproduction can be performed because of ASK.
[0286]
FIG. 84 shows a block diagram of a recording device (Recorder) / transmitter (Transmitter) and a reproducing device (Player) / receiver (Receiver).
[0287]
In the block diagram of FIG. 84, the VSB-ASK modulation method of the transmitter 1 and the receiver 43 according to the fifth embodiment replaces the transmission circuit 5a of the transmitter 1 with a recording device magnetic recording signal amplifier 857a, and the reception circuit 24a of the receiver 43. Is replaced by the magnetic reproduction signal amplifier 857b, thereby obtaining the same configuration. In the text, all the ASK signals are VSB-ASK in the transmission device, and therefore, the description will be made by omitting the VSB-ASK signal as the ASK signal.
[0288]
84, the HDTV signal is compressed by the Video @ encoder 401 and then divided into two pieces of data. The first data string is error-coded by the ECC encoder 743a, and the second data string is error-coded by the ECC 744a. After that, the data is trellis-encoded by Trellis @ Encoder 744b and enters the Modulator 749 of VSB-ASK. In the case of a Recorder, an Offset @ Generator 856 adds an Offset signal, and then the recording circuit 853 records the signal on the magnetic tape 855. In the case of the transmitter 1 of the transmission device, the DC offset voltage is superimposed on the ASK signal by the Offset Generator 856 and transmitted by the Up converter 5a. Carrier reproduction by the receiver 43 is facilitated by the DC offset. The transmitted VSB-ASK signal of 4VSB, 8VSB, and 16VSB is received by the antenna 32b and input to the demodulator 852a via the receiving circuit 24a.
[0289]
On the other hand, the recording signal recorded by the recording device is reproduced by the reproducing head 854a and sent to the demodulator 852b via the reproducing circuit 858.
[0290]
The signal input to the demodulator 852b passes through the filter 858a of the demodulator 852b and is demodulated by the above-described ASK demodulator 852b such as VSB. The first data string of the demodulated signal is error-corrected by the ECC decoder 758a, and the second data string is error-corrected by the Trellis decoder 759b and the ECC decoder 759a. The video decoder 402 expands the video signal and outputs an HDTV, TV signal or SDTV signal.
[0291]
Although the circuit is complicated by the addition of the Trellis encoder, the error rate is reduced, the transmission distance of the transmission device is increased, and the image quality of the recording / reproducing device is improved. In this case, the filter 858a of the receiver 43 uses a comb-type filter 760a having a filter characteristic for eliminating a main carrier, a video carrier, and an audio carrier of the analog TV signal as shown in FIG. Signal interference can be eliminated, and the error rate decreases. In this case, if a filter is always inserted even when there is no interference, the received signal deteriorates. In order to avoid this, as shown in FIG. 65, the error rate detection unit 782 turns on the analog TV filter 760a only when the signal is deteriorated due to the interference of the analog TV, and turns off the filter when there is no interference. Can prevent signal degradation.
[0292]
In the case of FIG. 84, the second data string has a lower error rate after the first data string and the second data string. Therefore, by transmitting / recording important High Priority (HP) information such as the descrambling information of FIG. 66 and the header information of the image data of each image block in the second data string, the descrambling and each image can be performed. The image signal reproduction of the block can be stabilized.
[0293]
As shown in FIGS. 137 and 172, in the 8VSB or 16VSB transmission device, the data sequence of each time-divided sub-channel is changed for each sub-channel by the error correction code gain of the trellis decoder or the ECC decoder, and HighPriority ( HP) information is sent on the subchannel with the higher code gain. Since the error rate of the HP information becomes lower, even if noise is generated to some extent in the transmission path and the signal is degraded and the Low Priority information (LP) information is destroyed, the effect that the HP information data is not destroyed is obtained. By transmitting the aforementioned descramble information or header information such as the address of a data packet in image block units as the HP information, the descrambling is stabilized for a long time, and the viewer can stably view the descrambled program. Further, since catastrophic destruction of each image block is prevented, even if the received signal is degraded, the entire picture quality is only degraded, so that the viewer can view the TV program with a certain picture quality.
[0294]
(Example 6)
An example in which the transmission recording method of the present invention is applied to a magnetic recording / reproducing apparatus according to a sixth embodiment will be described. In the fifth embodiment, the case where the present invention is applied to the ASK transmission system of multi-level transmission is shown. However, the present invention is applied to a magnetic recording / reproducing apparatus of the multi-level ASK recording system as shown in the block diagram of FIG. Can be applied. By applying the C-CDM method of the present invention to PSK, FCK, and QAM in addition to ASK, hierarchical and non-hierarchical multivalued magnetic recording can be performed. As described above, the present invention can be applied to both the recording device and the transmission device, but the description will be made using an example of the recording device.
[0295]
First, a method of hierarchization and multi-leveling will be described using an example in which the C-CDM system of the present invention is applied to a 16QAM or 32QAM magnetic recording / reproducing apparatus. FIG. 84 illustrates the transmission / recording apparatus using the 9-ASK such as the multi-level VSB in the fifth embodiment. However, the same effect can be obtained by changing the ASK of FIG. 84 to QAM. 84 and 173, the case where C-CDM is applied to QAM will be described. Hereinafter, the QAM obtained by C-CDM multiplexing is referred to as SRQAM. 137 and 154 illustrate a case where the present invention is applied to a transmission system.
[0296]
Referring to FIG. 84 and FIG. 173, the magnetic recording / reproducing device 851 separates an input video signal such as HDTV into a high-frequency signal and a low-frequency signal by the first image encoder 401a and the second image encoder 401b of the image encoder 401. After compression, the first data string input unit 743 in the input unit 742 is_LV_LThe low-frequency video signal such as the component is input to the second data_HV_HA high-frequency video signal including a {component and the like is input, and is input to a modulation unit 749 in the modem 852 #. In the first data string input unit 743, the error correction code is added to the low band signal in the ECC unit 73a. On the other hand, the second data string input to the second data string input unit 744 is 2 bits, 3 bits, and 4 bits in the case of 16 SRQAM, 36 SRQAM, and 64 SRQAM. This signal is error-encoded by the ECC 744a, and in the case of 16SR @ QAM, 32SRQAM, and 64SRQAM by the Trellis encoder unit 744b, the signals are 1/2, 2/3 by Trellis @ Encoder 744b shown in FIGS. 128 (a), (b) and (c), respectively. , 3/4 are Trellis encoded. For example, in the case of 64 SRQAM, the first data string is 2 bits and the second data string is 4 bits. For this reason, using Trellis @ Encoder 744b as shown in FIG. 128 (c), Trellis @ Encode of Ratio3 / 4 in which 3-bit data is set to 4 bits is performed. In the case of 4ASK, 8ASK, and 16ASK, trellis encoding of 1/2, 2/3, and 3/4 is performed alone. In this way, the redundancy is increased, and the data rate is reduced, while the error correction capability is increased, so that the error rate of the same data rate can be reduced. For this reason, a substantial information transmission amount of the recording / reproducing system or the transmission system increases. In the case of the 8VSB transmission system described in the fifth embodiment, since the transmission rate is 3 bits / symbol, the Trellis @ Encoder 744g and Trellis @ Decoder 744q of Ratio2 / 3 shown in FIGS. 128 (b) and (e) can be used, and the entire block diagram is FIG. 171. become that way. However, since Trellis @ Encode has a complicated circuit, it is not used for the first data string originally having a low error rate in the block diagram of FIG. 84 of the sixth embodiment. The second data sequence has a smaller inter-code distance and a lower error rate than the first data sequence, but the error rate is improved by Trellis-encoding the second data sequence. The configuration in which the Trellis encoding circuit for the first data string is omitted has the effect of simplifying the entire circuit. The modulation operation is almost the same as that of the transmitter of the fifth embodiment shown in FIG. The signal modulated by the modulator 749 is AC-biased by the bias generator 856 in the recording / reproducing circuit 853, amplified by the amplifier 857a, and recorded on the magnetic tape 855 by the magnetic head 854.
[0297]
The format of the recording signal is such that, as shown in the recording signal frequency arrangement diagram of FIG. 113, information is recorded in a main signal 859 of, for example, 16 SRQAM having a carrier having a frequency fc, and_c2f of twice_cPilot f with frequency_pSignal 859a is recorded at the same time. Frequency f_BIASDue to the bias signal 859b, magnetic recording is performed by applying an AC bias, thereby reducing distortion during recording. Since multi-level recording of two layers out of the three layers shown in FIG. 113 is performed, there are two thresholds Th-1-2 and Th-2 for recording and reproduction. Depending on the recording / reproducing C / N level, if the signal is 859, all the two layers are D if the signal is 859C.₁Only recording and playback are performed.
[0298]
When 16 SRQAM is used for the main signal, the signal point arrangement is as shown in FIG. FIG. 100 shows a case where 36 SRQAM is used. When 4ASK and 8ASK are used, the arrangement is as shown in FIGS. 58 and 68 (a) and (b). When reproducing this signal, the main signal 859 and the pilot signal 859a are reproduced from the magnetic head 854, and are amplified by the amplifier 857b. From this signal, the filter 858a of the carrier wave recovery circuit 858 causes 2f_oThe pilot signal f_pIs frequency-separated, and the frequency is divided by 1/2 frequency divider 858b._oIs reproduced and sent to the demodulation unit 760. The main signal is demodulated in the demodulator 760 using the reproduced carrier. At this time, when a magnetic recording tape 855 having a high C / N value for HDTV or the like is used, it is easy to discriminate each of the 16 signal points, so that both D1 and D2 are demodulated in the demodulation unit 760. Then, all signals are reproduced by the image decoder 422. In the case of an HDTV VTR, for example, a TV signal of a high bit rate of 15 Mbps HDTV is reproduced. Video tapes with lower C / N values have lower costs. At present, there is a difference of 10 dB or more between the commercially available VHS tape and the high C / N type tape for broadcasting. When an inexpensive video tape 855 having a low C / N value is used, it is difficult to discriminate all 16-value and 36-value signal points because the C / N value is low. Therefore, the first data string D1 can be reproduced, but the 2-bit, 3-bit or 4-bit data string of the second data string D2 cannot be reproduced, and only the 2-bit data string of the first data string is reproduced. When a two-layered HDTV image signal is recorded and reproduced, a high-frequency image signal is not reproduced on a low C / N tape, so a low-rate low-frequency image signal of the first data stream, specifically, for example, a 7 Mbps wide signal An NTSC TV signal is output.
[0299]
Further, as shown in the block diagram of FIG. 114, the second data string output unit 759, the second data string input unit 744, and the second image decoder 422a are omitted, and the first data string D₁A low bit rate dedicated recording / reproducing device 851 having a modulator such as a modified QPSK that modulates and demodulates only can be set as one product form. This device can record and reproduce only the first data string. That is, image signals of wide NTSC grade can be recorded and reproduced. When a video tape 855 that outputs a high C / N value on which a high bit rate signal such as the HDTV signal is recorded is reproduced by the low bit rate dedicated magnetic recording / reproducing apparatus, only the D1 signal of the first data string is output. Is reproduced, a wide NTSC signal is output, and the second data string is not reproduced. That is, when the video tape 855 on which the HDTV signal of the same hierarchical type is recorded is reproduced, the HDTV signal can be reproduced by the recording / reproducing apparatus having one complicated configuration, and the wide NTSCTV signal can be reproduced by the recording / reproducing apparatus having the simple configuration. In other words, in the case of two layers, there is a great effect that complete compatibility of the four combinations is realized between tapes having different C / N values and models having different recording / reproducing data rates. In this case, the dedicated NTSC device has a significantly simpler configuration than the dedicated HDTV device. Specifically, for example, the circuit size of the EDTV decoder is 1/6 of that of the HDTV decoder. Therefore, a low-function machine can be realized at a very low cost. As described above, two types of recording / reproducing apparatuses having different recording / reproducing abilities of HDTV and EDTV image quality can be realized, so that there is an effect that a model in a wide price range can be set. In addition, the user can freely select a tape from a high-price high-C / N tape to a low-price low-C / N tape in accordance with the required image quality. Thus, extensibility can be obtained while completely maintaining compatibility, and compatibility in the future can be secured. Therefore, it is possible to realize a standard of a recording / reproducing apparatus which will not become obsolete in the future. As another recording method, hierarchical recording by phase modulation described in the first and third embodiments can also be performed.
[0300]
Recording by ASK described in the fifth embodiment can also be performed. As shown in FIGS. 59 (c) and (d) and FIGS. 68 (a) and (b), signal points of quaternary ASK and octal ASK are divided into two groups by making the current binary recording a multi-level. Two or three layers can be hierarchized.
[0301]
The block diagram in the case of ASK is the same as FIG. As shown in FIG. The error rate is reduced by the combination of Trellis and ASK. In addition to the description in the embodiment, multi-level recording such as a hierarchical type using multiple tracks on a magnetic tape can also be performed. Further, it is also possible to perform logical hierarchical recording by differentiating data by changing the error correction capability.
[0302]
Here, compatibility with future standards will be described. Normally, when a standard for a recording / reproducing apparatus such as a VTR is set, the standard is determined using the highest C / N tape that can be actually obtained. The recording characteristics of the tape improve with the progress of the day. For example, the C / N value is currently improved by 10 dB or more compared to a tape 10 years ago. In this case, if a new standard is set when the tape performance is improved in the future 10 to 20 years from now, it is very difficult to achieve compatibility with the old standard in the conventional method. For this reason, the old and new standards were often incompatible or incompatible.
[0303]
However, in the case of the present invention, first, a standard for recording and reproducing the first data string or the second data string on the current tape is created. If the present invention is adopted in advance when the C / N of the tape is greatly improved in the future, data of a higher data layer, for example, data of a third data string is added, and for example, 64 SRQAM or 8ASK of three layers is added. A super HDTV VTR for recording and reproducing is realized while maintaining complete compatibility with the conventional standard. At the time when this future standard is realized, the present invention provides a two-layer magnetic recording of the old standard which can record and reproduce only the first data line and the second data line on the magnetic tape on which the third data line is recorded in the three layers by the new standard. When reproduced by the reproducing apparatus, the third data string cannot be reproduced, but the first and second data strings can be completely reproduced. Therefore, the HDTV signal is reproduced. Therefore, there is an effect that the amount of recording data can be expanded in the future while maintaining compatibility between the old and new standards.
[0304]
Here, the description returns to the reproduction operation in FIG. At the time of reproduction, a reproduction signal is reproduced from the magnetic tape 855 by the magnetic head 854 and the magnetic reproduction circuit 853 and sent to the modem 852. The operation of the demodulation unit is substantially the same as that of the first, third, and fourth embodiments, and a description thereof will be omitted. The first data sequence D1 and the second data sequence D2 are reproduced by the demodulation unit 760, and the Trellis-Decoder 759b such as a Vitabi decoder performs error correction of high codeｃｏgain on the second data sequence, thereby lowering the error rate. The D1 and D2 signals are demodulated by the image decoder 422 and an HDTV video signal is output.
[0305]
The above is an embodiment of a magnetic recording / reproducing apparatus having two layers. Next, an embodiment of a magnetic recording / reproducing apparatus of three layers obtained by adding one logical layer to two physical layers is shown in FIG. This will be described with reference to a block diagram. Basically, the configuration is the same as that of FIG. 84, but the first data string is further divided into two sub-channels by TDM to form a three-layer structure. As shown in FIG. 131, first, an HDTV signal is converted into two data of a middle-range and a low-range video signal by a 1-1 image encoder 401c and a 1-2 image encoder 401d in a first image encoder 401a._1-1And D1₋2 and is input to the first data string input unit of the input unit 742. Data string D of MPEG grade image quality_1-1Is error-correction-coded with high Code @ gain in ECC @ coder 743a, and D1₋No. 2 is subjected to error correction coding having a normal Code @ gain in the ECC @ Coder 743b. D_1-1And D1₋2 are time-multiplexed by the TDM unit 743c, and one data string D₁And D₁And D2 are modulated by a C-CDM modulator 749 and recorded in two layers on a magnetic tape 855 by a magnetic head 854.
[0306]
At the time of reproduction, the recording signal reproduced by the magnetic head 854 is transmitted to the C-CDM demodulation unit 760 by the operation similar to that described with reference to FIG.₁And D2. First data string D₁Are in the TDM unit 758c in the first data output unit 758._1-1And D1₋2 demodulated. D_1-1Is error-corrected in ECC @ Decoder 758a having a high code @ gain, so that D1₋D compared to 2_1-1Is demodulated even at a low ΔC / N value, and LDTV is decoded and output by the 1-1 image decoder 402a. On the other hand, D1₋2 is error-corrected in the normal ECC @ Decoder 758b of Code @ gain, so that D1₋Since it has a high C / N threshold value as compared with 1, it cannot be reproduced unless the signal level is large. Then, it is demodulated by the 1-2 image encoder 402d,_1-1And an EDTV of wide NTSC grade is output.
[0307]
The second data string D2 is Vitabi decoded by Trellis @ Decoder 759b, error-corrected by ECC759a, becomes a high-frequency image signal by the second image encoder 402b, and_1-1, D1₋2 and an HDTV is output. D in this case₂The threshold value of C / N is D1₋Set larger than 2. Therefore, when the C / N value of the tape 855 is small, D_1-1That is, when the LDTV is reproduced and the tape 855 with the normal C / N value is_1-1, D1₋2 That is, EDTV is reproduced, and if a tape 855 having a high C / N value is used, D_1-1, D1₋2, D2, that is, the HDTV signal is reproduced.
[0308]
Thus, a three-layer magnetic recording / reproducing apparatus is realized. As described above, there is a correlation between the C / N value of the tape 855 and the cost. In the case of the present invention, the user can record and reproduce image signals of three grades of image quality according to the three types of tape cost, so that the user can select a tape grade according to the content of a TV program to be recorded. This has the effect of spreading.
[0309]
Next, as shown in the recording track diagram of FIG. 132 which describes the effect of hierarchical recording during fast-forward reproduction, a recording track 855b of azimuth angle A and a recording track 855b of azimuth angle B opposite to azimuth angle A are recorded on the magnetic tape 855. I have. As shown in the figure, a recording area 855c is provided at the center of the recording track 855a as it is, and the other areas are_1-Two recording areas 855d. This is provided in at least one place for each of several recording tracks. In this, one LDTV frame is recorded. The D2 signal of the high frequency signal is recorded in the D2 recording area 855e of the entire area of the recording track 855a. At the time of recording and reproduction at normal speed, this recording format has no new effect. Now, at the time of tape fast forward reproduction in the forward and reverse directions, the magnetic head trace 855f of the azimuth angle A does not coincide with the magnetic track as shown in the figure. In the present invention shown in FIG. 132, the D set in the narrow area at the center of the tape_1-1A recording area 855c is provided. Thus, with a certain probability, this area is reliably reproduced. Played D_1-1From the signal, it is possible to demodulate an image on the entire screen at the same time, although the image quality is the same as that of MPEG1 LDTV. Thus, when fast-forward playback is performed, when several to several tens of complete LDTV images are played back per second, there is a great effect that the user can check the picture screen during fast-forward.
[0310]
During reverse playback, only a partial area of the magnetic track is traced as shown by the head trace 85g. However, even in this case, when the recording / reproducing format shown in FIG. 132 is used, the D1-1 recording area can be reproduced, so that a moving image of LDTV grade # image quality is intermittently output.
[0311]
Thus, in the present invention, since an LDTV-grade image is recorded in a narrow area of a part of a recording track, the user can intermittently reproduce a nearly complete still image with the LDTV-grade image quality at the time of fast forward in both the forward and reverse directions. There is an effect that the screen can be easily checked at the time of high-speed search.
[0312]
Next, a description will be given of a method of coping with faster-forward reproduction. As shown in the lower right of FIG._1-1A recording area 855C is provided, and one frame of LDTV is recorded._1-1A part of the recording area 855C has a smaller area D_1-1・ D₂A recording area 85 5h is provided. Subchannel D in this area_1-1Records part of one frame of the LDTV. The remaining information of LDTV is D_1-1・ D₂D in recording area 855h₂The data is redundantly recorded in the recording area 855j. Sub channel D₂Is the subchannel D_1-13 to 5 times the data recording amount. Therefore D_1-1And D₂Thus, information of one frame of LDTV on a tape having an area of 1/3 to 1/5 can be recorded. Since the head race can be recorded in the areas 855h and 855j, which are narrower areas, the head trace time T_s1The time and the area are reduced to 1/3 to 1/5 as compared with. Therefore, even if the rapid traverse speed is increased and the trace of the head is further inclined, the probability of tracing the entire area increases. For this reason D_1-1The complete LDTV image is intermittently reproduced even at the time of fast-forwarding which is 3 to 5 times faster than in the case of only.
[0313]
This method uses D₂Since there is no function of reproducing the recording area 855j, it cannot be reproduced at the time of fast forward. On the other hand, in a three-layer high-performance VTR, an image can be confirmed even at a fast forward speed 3 to 5 times faster than in the two layers. That is, a VTR having a different maximum fast-forward speed that can be reproduced according to the cost as well as the number of layers, that is, the image quality according to the cost is realized.
[0314]
In the embodiment, the hierarchical modulation method is used. However, even with a normal modulation method such as 16QAM, if the hierarchical image coding is performed, fast-forward reproduction according to the present invention is realized. Needless to say.
[0315]
In the conventional non-hierarchical digital VTR recording method of the high image compression method, since the image data is uniformly dispersed, it is impossible to reproduce the entire screen image of each frame at the same time during fast forward reproduction. Can not. For this reason, it is possible to reproduce only the image of each block on the screen whose time axis is shifted. However, although the hierarchical HDTV VTR of the present invention is of the LDTV grade, there is an effect that an image in which the time axis of each block of the screen is not shifted can be reproduced at the time of fast forward reproduction.
[0316]
When the three-layered recording of the HDTV of the present invention is performed and the C / N of the recording / reproducing system is high, a high-resolution TV signal such as an HDTV can be reproduced. When the C / N of the recording / reproducing system is low or when reproduction is performed by a magnetic reproducing device having a low function, a TV signal of an EDTV grade such as a wide NTSC or a TV signal of an LDTV grade such as a low resolution NTSC is output.
[0317]
As described above, in the magnetic reproducing apparatus using the present invention, even when the C / N is low or the error rate is high, it is possible to reproduce the video of the same content with low resolution or low image quality. Is obtained.
[0318]
(Example 7)
In the seventh embodiment, the present invention is used for a four-layer video hierarchy transmission. By combining the four-layer transmission scheme and the four-layer video data structure described in the second embodiment, a four-layer reception area is created as shown in the reception interference area diagram of FIG. As shown in the figure, a first reception area 890a is formed on the innermost side, and a second reception area 890b, a third reception area 890c, and a fourth reception area 890d are formed outside the first reception area 890a. A method for realizing the four layers will be described.
[0319]
To realize the four layers, there are a four-layer physical layer by modulation and a four-layer logical layer by differentiating the error correction capability. The former has a large C / N difference due to a large C / N difference between the layers. Is required. The latter is based on the premise that demodulation is possible, so that the C / N difference between layers cannot be made large. It is realistic to perform four-layer transmission using two physical layers and two logical layers. First, a method of separating a video signal into four layers will be described.
[0320]
FIG. 93 is a block diagram of the separation circuit 3. The separation circuit 3 includes a video separation circuit 895 and four compression circuits. The basic configuration inside the separation circuits 404a, 404b, and 404c is the same as the block diagram of the separation circuit 404 in the first image encoder 401 in FIG. The separation circuit 404a and the like convert the video signal into a low-frequency component H_LV_LAnd high frequency component H_HV_HAnd intermediate component H_HV_L, H_LV_HInto four signals. In this case, H_LV_LHas a resolution half that of the original video signal.
[0321]
The input video signal is divided into a high frequency component and a low frequency component by the video separation circuit 404a. Since the image is divided in the horizontal and vertical directions, four components are output. The dividing point of the high band and the low band is at the middle point in this embodiment. Therefore, when the input signal is a vertical HDTV signal of 1000 lines, H_LV_LThe signal is a TV signal with 500 vertical lines and half the horizontal resolution.
[0322]
H of low frequency component_LV_LThe signal is further divided into two in the horizontal and vertical frequency components by a separation circuit 404c. Therefore H_LV_LThe output is, for example, 250 lines vertically and the horizontal resolution is 1/4. When this is defined as an LL signal, the LL component is compressed by the compression unit 405a,_1-1Output as a signal.
[0323]
On the other hand, H_LV_LAre combined into one LH signal by a combiner 772c, compressed by a compression unit 405b, and_1-2Output as a signal. In this case, three compression units may be provided between the separation circuit 404c and the synthesizer 772c.
[0324]
H of high frequency component_HV_H, H_LV_H, H_HV_LAre converted into one H by the synthesizer 772a._HV_H-H signal. If the compression signal is 1000 in both the vertical and horizontal directions, this signal has 500 to 1000 components in the horizontal and vertical directions. Then, the light is separated into four components by the separation circuit 404b.
[0325]
Therefore H_LV_LAs output, 500 to 750 horizontal and vertical components are separated. This is called an HH signal. And H_HV_H, H_LV_H, H_HV_LThe three components have 750 to 1000 components, are combined by a combiner 772b, become HH signals, are compressed by a compression unit 405d, and are_2-2Output as a signal. On the other hand, the HL signal is D_2-1Output as a signal. Therefore, LL, that is, D_1-1The signal is, for example, a component of 0 to 250 lines or less, LH, that is, D_1-2The signal is a frequency component HL that is 250 or more and 500 or less, ie, D_2-1The signal is a component of 500 or more and 750 or less, HH, that is, D_2-2The signal has frequency components of 750 or more and 1000 or less. This separation circuit 3 has an effect that a hierarchical data structure can be formed. By using the separation circuit 3 of FIG. 93 to replace the part of the separation circuit 3 in the transmitter 1 of FIG. 87 described in the second embodiment, four-layer hierarchical transmission can be performed.
[0326]
Thus, by combining the hierarchical data structure and the hierarchical transmission, it is possible to realize the image transmission in which the image quality gradually decreases as the C / N deteriorates. This has a great effect of expanding the service area in broadcasting. Next, the receiver for demodulating and reproducing this signal has the same configuration and operation as the second receiver in FIG. 88 described in the second embodiment. Therefore, the entire operation is omitted. However, the configuration of the synthesizing unit 37 differs from that of data transmission because it handles video signals. Here, the synthesizing unit 37 will be described in detail.
[0327]
As described with reference to the block diagram of the receiver in FIG. 88 in the second embodiment, the received signal is demodulated, error-corrected, and D_1-1, D_1-2, D_2-1, D_2-2And these signals are input to the synthesizing unit 37.
[0328]
FIG. 94 is a block diagram of the synthesizing unit 33. D entered_1-1, D_1-2, D_2-1, D_2-2The signal is expanded in the expansion units 523a, 523b, 523c, and 523d, and becomes the LL, LH, HL, and HH signals described in the separation circuit in FIG. This signal has a band of 1/4 for LL, 1/2 for LL + LH, 3/4 for LL + LH + HL, and 1 for LL + LH + HL + HH, assuming that the band in the horizontal and vertical directions of the original video signal is 1. The LH signal is separated by the separator 531a, combined with the LL signal in the image combining unit 548a, and output from the image combining unit 548c._LV_LInput to the terminal. The description of the example of the image synthesizing unit 531a has been described with reference to the image decoder 527 in FIG. On the other hand, the HH signal is separated by the separator 531b and input to the image combining unit 548b. The HL signal is combined with the HH signal in the image combining unit 548b,_HV_HThe signal becomes a −H signal, is separated by the separator 531 c, is combined with the combined signal of LH and LL in the image combining section 548 c, becomes a video signal, and is output from the combining section 33. Then, the output signal 36 of the second receiver shown in FIG. 88 is output as a TV signal. In this case, if the original signal is HDTV signals of about 1050 vertical lines and about 1000 lines, TV signals of four image quality are received under the four reception conditions shown in the reception interference diagram of FIG.
[0329]
The image quality of the TV signal will be described in detail. FIG. 92 is a transmission hierarchical structure diagram in which FIG. 91 and FIG. 86 are combined. As described above, with the improvement of C / N, D in the reception areas 862d, 862c, 862b, and 862a._1-1, D_1-2, D_2-1, D_2-2And the hierarchical channel which can be reproduced one after another is added, and the data amount increases.
[0330]
In the case of the hierarchical transmission of the video signal, as shown in the transmission hierarchical structure diagram of FIG. 95, the hierarchical channels of the LL, LH, HL, and HH signals are reproduced with the improvement of the C / N. Therefore, as the distance from the transmitting antenna decreases, the image quality improves. The LL signal is reproduced when L = Ld, the LL + LH signal when L = Lc, the LL + LH + HL signal when L = Lb, and the LL + LH + HL + HH signal when L = La. Therefore, if the band of the original signal is 1, the image quality of the bands of 1/4, 1/2, 3/4 and 1 can be obtained in each receiving area. When the original signal is an HDTV with 1000 vertical scanning lines, 250, 500, 750, and 1000 TV signals are obtained. In this way, hierarchical video transmission in which image quality gradually deteriorates becomes possible. FIG. 96 is a reception interference diagram in the case of a conventional digital HDTV broadcast. As is clear from the figure, in the conventional method, CN is V_OIn the following, the reproduction of the TV signal becomes completely impossible. Therefore, even within the service area distance R, reception is not possible as shown by the mark x in a competitive area with another station, a building shadow, or the like. FIG. 97 shows a reception state diagram of the HDTV hierarchical broadcast using the present invention. As shown in FIG. 97, C / N = a at distance La, C / N = b at Lb, C / N = c at Lc, C / N = d at Ld, and 250/500 in each reception area. , 750 lines and 1000 lines. Even within the distance La, the C / N is inferior, and there are areas where reproduction is not possible with the HDTV image quality itself. However, even in that case, reproduction can be performed even if the image quality is deteriorated. For example, there are 750 lines at the point B of the building, 250 lines at the point D on the train, 750 lines at the point F receiving the ghost, 250 lines at the point G in the car, and 250 lines at the point L which is a competitive area with other stations. You can play with the image quality of. As described above, by using the hierarchical transmission of the present invention, it is possible to receive even in an area where reception and reproduction cannot be performed by the conventionally proposed method, and there is a remarkable effect that the service area of the TV station is greatly expanded. . Also, as shown in the hierarchical transmission diagram of FIG._1-1Broadcast D on the channel, which is the same program as the analog broadcast in the area,_1-2, D_2-1, D_2-2By broadcasting other programs C, B, and A on the channel, the simulcast of program D can be reliably broadcast in all regions, and the other three programs can be served while fulfilling the role of simulcast. Is also obtained.
[0331]
(Example 8)
Hereinafter, a seventh embodiment will be described with reference to the drawings. Embodiment 8 is an embodiment in which the hierarchical transmission system of the present invention is applied to a transceiver of a cellular telephone system. In the block diagram of the transmitter / receiver of the mobile phone shown in FIG. 115, the voice of the caller input from the microphone 762 is compressed by the compression unit 405 into the data D having the hierarchical structure described above.₁, D₂, D₃The time division unit 765 time-divides the signal into predetermined time slots based on the timing, receives the above-described hierarchical modulation such as SRQAM in the modulator 4, takes one carrier wave, and passes through the antenna duplexer 764. The signal is transmitted from the antenna 22, received by a base station described later, transmitted to another base station or a telephone station, and can communicate with another telephone.
[0332]
On the other hand, a communication signal from another telephone is received by the antenna 22 as a transmission radio wave from the base station. This received signal is transmitted to a hierarchical demodulator 45 such as SRQAM by D₁, D₂, D₃Is demodulated. A timing signal is detected from the demodulated signal in a timing circuit 76 # 7, and the timing signal is sent to a time division unit 765. Demodulated signal D₁, D₂, D₃Are decompressed by the decompression unit 503 and turned into a sound signal, sent to the speaker 65, and turned into sound.
[0333]
Next, as shown in the block diagram of the base station in FIG. 116, base stations 771, 772, and 773 at the center of three hexagonal or circular receiving cells 768, 769, and 770 are the same as those in FIG. It has a plurality of 761a to 761j, and transmits and receives data of the same number of channels as the number of transceivers. The base station control unit 774 connected to each base station constantly monitors the traffic volume of communication of each base station, and allocates a channel frequency to each base station and adjusts the size of the reception cell of each base station accordingly. It controls the whole system such as control.
[0334]
As shown in the conventional communication capacity traffic distribution diagram of FIG. 117, in the conventional digital communication system such as QPSK, the transmission capacity of Ach of the reception cells 768 and 770 is the same-wave number utilization efficiency of 2 bits as shown in the diagram of d = A. The data 774d is a combination of the data 774d and 774b of // Hz and the data 774c of the diagram of d = B, and has a uniform frequency use efficiency of 2 bits / Hz at any point. On the other hand, in an actual urban area, where the buildings are concentrated as in the densely populated areas 775a, 775b, and 775c, the population density is high, and the communication traffic volume also shows a peak as indicated by the data 774e. There is little traffic in other surrounding areas. As compared with the actual traffic volume TF data 774e, the capacity of the conventional cellular telephone has the same frequency efficiency of 2 bits / Hz in all regions as shown by the data 774d. In other words, there is an inefficiency that the same frequency efficiency is applied to places where the traffic volume is small and places where the traffic volume is small. In the conventional method, in an area with a large traffic volume, the frequency allocation is increased to increase the number of channels, or the size of the receiving cell is reduced. However, increasing the number of channels is limited by the frequency spectrum. In addition, the transmission power has been increased by multi-leveling such as 16QAM and 64QAM in the conventional method. Decreasing the size of the reception cell and increasing the number of cells increases the number of base stations and increases installation costs. There are the above problems.
[0335]
Ideally, the efficiency of the entire system can be increased by increasing the frequency efficiency in an area with a large amount of traffic, increasing the frequency efficiency in an area with a small amount of traffic, and decreasing the frequency efficiency in an area with a small amount of traffic. The above can be realized by employing the hierarchical transmission system of the present invention. This will be described with reference to the communication capacity / traffic distribution diagram according to the eighth embodiment of the present invention shown in FIG. The distribution diagram in FIG. 118 shows the communication capacities on the A-A 'line of the reception cells 770B, 768, 769, 770, and 770a in order from the top. Reception cells 768 and 770 use channel group A. Reception cells 770b, 769, and 770a use the frequency of channel group B that does not overlap with channel group A. The number of these channels is increased or decreased by the base station controller 774 in FIG. 116 according to the traffic volume of each reception cell. In FIG. 118, d = A indicates the distribution of the communication capacity of the A channel. d = B is the communication capacity of the B channel, d = A + B is the communication capacity of all the channels, TF is the communication traffic amount, and P is the distribution of buildings and population. Since the receiving cells 768, 769, and 770 use the multilayer hierarchical transmission system such as SRQAM described in the previous embodiment, as shown in the data 776a, 776b, and 776c, the frequency utilization efficiency of QPSK is 2 bits / Hz and 3 bits. Doubled 6 bit / Hz can be obtained in the periphery of the base station. It decreases to 4 bit / Hz and 2 bit / Hz toward the periphery. If the transmission power is not increased, the area of 2 bit / Hz becomes narrower than the size of the QPSK reception cell indicated by the dotted lines 777a, 777b, and 777c. Is obtained. A slave station supporting 64 SRQAM transmits / receives data using a modified QPSK in which the shift amount of SRQAM is S = 1 at a location far from the base station, transmits / receives 16 SRQAM at a location near the base station, and transmits / receives a 64 SRQAM at a location near the base station. Therefore, the maximum transmission power does not increase as compared with QPSK. Also, a 4SRQAM transceiver as shown in the block diagram of FIG. 121 with a simplified circuit can communicate with another telephone while maintaining compatibility. The same applies to the case of 16 SRQAM shown in the block diagram of FIG. Therefore, there are slave units of three modulation systems. For mobile phones, small weighability is important. In the case of 4SRQAM, the frequency usage efficiency is reduced and the call charge is increased. However, the circuit is simpler, so that it is suitable for users who need to reduce the size and weight. Thus, this method can be used for a wide range of applications.
[0336]
As described above, a transmission system having different distributions of capacities such as d = A + B in FIG. 118 can be obtained. By installing the base station according to the traffic volume of the TF, there is a great effect that the overall frequency use efficiency is improved. In particular, in the micro cell system with a small cell, a large number of sub base stations can be installed, so that the sub base stations can be easily installed at a location where traffic is high, and the effect of the present invention is high.
[0337]
Next, the data arrangement of each time slot will be described using the data time arrangement diagram of FIG. FIG. 119A shows a conventional time slot, and FIG. 119B shows a time slot according to the eighth embodiment. As shown in FIG. 119 (a), in the conventional transmission / reception-based frequency scheme, the synchronization signal S is transmitted at the time slot 780a at the frequency A at the time of Down, that is, at the time of transmission from the base station to the child station, A transmission signal to each of the slave units of the A, B, and C channels is sent. Next, when transmitting from the Up side, that is, the slave unit to the base station, the synchronization signal and the a, b, and c channels are transmitted in time slots 781a, 781b, 781c, 781d at the frequency B.
[0338]
In the case of the present invention, as shown in FIG. 119 (b), since a hierarchical transmission system such as the aforementioned 64 SRQAM is used, D₁, D₂, D₃Have three layers of 2bit / Hz data. A₁, A₂Since the data is transmitted by 16 SRQAM, the data rate becomes about twice as shown in the slots 782b and 782c and the slots 783b and 783c. When sending with the same sound quality, it can be sent in half the time. Therefore, the time slots 782b and 782c are half the time. In this way, twice the transmission capacity can be obtained in the area of the second hierarchy of 776c in FIG. 118, that is, in the vicinity of the base station. Similarly, in time slots 782g and 783g, E₁Data transmission and reception are performed by 64 SRQAM. Since it has a transmission capacity of about three times ３, three times E in the same time slot₁, E₂, E₃3 channels can be secured. In this case, transmission / reception is required in an area near the base station. In this way, there is an effect that a maximum of about three times the call can be obtained in the same frequency band. However, in this case, the call is performed as it is in the vicinity of the base station, and is actually lower than this number. Also, the actual transmission efficiency drops to about 90%. In order to improve the effect of the present invention, it is desirable that the regional distribution of the traffic volume and the transmission capacity distribution according to the present invention match. However, as shown in the TF diagram of FIG. 118, in an actual city, a green belt is arranged around a building street. Even in the suburbs, fields and forests are located around residential areas. Therefore, the distribution is close to the TF diagram. Therefore, the effect of applying the present invention is high.
[0339]
In the TDMA time slot diagram of FIG. 120, (a) shows the conventional system and (b) shows the system of the present invention. As shown in FIG. 120 (a), transmission to the slave units of the A and B channels is performed in time slots 786a and 786b in the same frequency band, and transmission from the slave units of the A and B channels respectively in time slots 787a and 787b. Send. As shown in FIG. 120 (b), in the case of the present invention, in the case of 16 SRQAM,₁A channel is received, and A is received in slot 788c.₁Perform channel transmission. The time slot width becomes about 1/2. In the case of 64 SRQAM, D₁The channel is received, and D is₁Perform channel transmission. The time slot width becomes about 1/3.
[0340]
In particular, in order to reduce the power consumption, the E of 16 SRQAM in a half time slot in slot 788p is used.₁, But transmission is performed in the normal time slot 4 SRQAM in the slot 788r. Since 4 SRQAM consumes less power than 16 SRQAM, there is an effect that power consumption during transmission is reduced. However, the longer the occupancy time, the higher the communication fee. It is highly effective when the battery is small and lightweight, and when the remaining battery power is low.
[0341]
As described above, since the transmission capacity distribution can be set according to the actual traffic distribution, there is an effect that the substantial transmission capacity can be increased. In addition, since the base station and the slave station can select the transmission capacity of three or two transmission capacities, the frequency efficiency is reduced to reduce the power consumption, or conversely, the efficiency is increased to reduce the call charge, and the degree of freedom is high. Is obtained. In addition, by using a method such as 4SRQAM with a low transmission capacity, it is possible to set a slave unit whose circuit is simplified and whose size and cost are reduced. In this case, one of the features of the present invention is that transmission compatibility between all models can be obtained as described in the previous embodiment. In this way, with the increase in transmission capacity, a wide variety of models from microminiature machines to high-performance machines can be developed.
[0342]
(Example 9)
Hereinafter, a ninth embodiment will be described with reference to the drawings. Embodiment 9 is an embodiment in which the present invention is applied to an OFDM transmission system. A block diagram of the OFDM transceiver shown in FIG. 123 and an operation principle diagram of the OFDM shown in FIG. 124 are shown. OFDM, which is a type of FDM, has higher frequency band use efficiency than general FDM by making adjacent carriers orthogonal. In addition, it has been studied for digital music broadcasting and digital TV broadcasting because of its resistance to multipath interference such as ghosts. As shown in the principle diagram of OFDM in FIG. 124, in the case of OFDM, an input signal is arranged on a frequency axis 793 by a serial / parallel conversion unit 791 at an interval of 1 / ts to create sub-channels 794a to 794e. This signal is inverse-FFT-transformed to the time axis 799 by the modulator 4 having the inverse FFT unit 40 to generate a transmission signal 795. The inverse FFT signal is transmitted during the ts effective symbol period 796, and a tg guard period 797 is provided between each symbol.
[0343]
The operation of the ninth embodiment when transmitting and receiving HDTV signals will be described with reference to a block diagram of the OFDM-CCDM hybrid system shown in FIG. The input HDTV signal is converted into a low-frequency signal D by the image encoder 401._1-1And (mid-low) D_1-2And (high-mid-low) D₂, And is input to the input unit 742. In the first data string input unit 743, D_1-1The signal is ECC encoded with a high code @ gain, and D_1-2The signal is ECC encoded with normal code gain. D_1-1And D_2-2Are time-division multiplexed by the TDM unit 743, and D₁Into a signal and the D of the modulator 852a₁The signal is input to the serial / parallel converter 791a. D₁The signal becomes n parallel data and is input to the first input units of the n C-CDM modulators 4a, 4b,.
[0344]
On the other hand, D of the high frequency component signal₂Is encoded by an ECC (Error Correction Code) in an ECC unit 744a in a second data string input unit 744 of an input unit 742, is trellis encoded in a trellis encoder 744b, and is input to a D of the modulator 852a.₂.. Are input to the serial-parallel parallel unit 791b and become n parallel data, which are input to the second input units of the C-CDM modulators 4a, 4b,. D of the first input unit₁Data and D at the second input₂The data is C-CDM-modulated to 16 SRQAM or the like in each of the C-CDM modulators 4a, 4b, 4c,. The n C-CDM modulators have carriers of different frequencies, and the adjacent carriers are orthogonal on the frequency axis 793 as shown by 794a, 794b, 794c,... In FIG. Thus, the n-number of modulated signals subjected to the C-CDM modulation are mapped from the frequency axis dimension 793 to the time axis dimension 790 by the inverse FFT circuit 40, and are converted into time signals 796a and 796b having an effective symbol length of ts. Become. A guard time zone 797a of Tg seconds is provided between the effective symbol time zones 796a and 796b to reduce multipath interference. This is expressed by a time axis and a signal level, which is a time axis-signal level diagram in FIG. 129. The Tg of the guard time zone 797a is determined according to the application from the multipath influence time. By setting Tg longer than the influence time of a multipath such as a TV ghost, the modulated signal from the inverse FFT circuit 40 becomes one signal by the parallel / serial converter 40b at the time of reception, and is transmitted as an RF signal by the transmission unit 5 at the time of reception.
[0345]
Next, the operation of the receiver 43 will be described. This is shown in the time axis symbol signal 796e of FIG. The received signal is input to the input unit 24 in FIG. 123, input to the modulation unit 852b, digitized, expanded into Fourier coefficients by the FFT unit 40a, and mapped from the time axis 799 to the frequency axis 793a as shown in FIG. Is done. The time axis symbol signal shown in FIG. 124 is converted into a carrier 794a, 794b of a frequency axis signal. Since these carriers are orthogonal to each other, each modulated signal can be separated. The 16 SRQAM and the like shown in FIG. 125 (b) are demodulated and sent to the respective C-CDM demodulators 45a and 45b. Then, in each of the C-CDM demodulators 45a, 45b, etc. of the C-CDM demodulator 45, the demodulated data is hierarchically demodulated.₁, D₂Are demodulated and D₁Parallel-to-serial converter 852a and D₂The parallel D / S converter 852b converts the signal into a serial signal and the original D signal.₁, D₂The signal is demodulated. In this case, since a hierarchical transmission method using C-CDM as shown in FIG. 125 (b) is used, under reception conditions with a poor C / N value, D₁Only the signal is demodulated, and in good reception conditions, D₁And D2 signal are demodulated. Demodulated D₁The signal is demodulated at output 757. D_1-2D compared to the signal_1-Since the code cane for one-signal error correction is high, D_1-An error signal of one signal is reproduced even under conditions of worse reception conditions. D_1-The 1 signal is converted into a low-frequency signal of LDTV by the 1-1-1 image decoder 402c._1-The two signals are converted into signals of the mid-range component of the EDTV by the 1-2 image decoder 402d, and output.
[0346]
D₂The signal is trellis-decoded and output as a high-frequency component of HDTV by the second image decoder 402b. An LDTV is output only with the above low-frequency signal, and an EDTV signal of a wide NTSC grade is output by adding the above middle frequency component, and an HDTV signal is synthesized by adding the above high frequency component. As in the previous embodiment, a TV signal having an image quality corresponding to the reception C / N can be received. In the case of the ninth embodiment, by using OFDM and C-CDM in combination, it is possible to realize hierarchical transmission that cannot be realized by OFDM itself. As shown in the error rate C / N of FIG. 130, the curve 805 of the conventional OFDM-TCM modulation signal is different from the curve 805 of the conventional OFDM-TCM modulation signal in that the error rate of the sub-channel 1 807a is reduced and the sub-channel 2 807b is reduced. Error rate goes up. Thus, a hierarchical type is realized.
[0347]
OFDM is robust against multipaths such as TV ghosts because multipath interference signals are contained in the guard period Tg. Therefore, it can be used for digital TV broadcasting for an automobile TV receiver. However, since it is not a hierarchical transmission, it is not possible to receive signals below a certain C / N threshold. By combining with the C-CDM of the present invention, it is possible to realize two types of image reception (Gradational Degradation) that are resistant to multipath and correspond to C / N deterioration. When receiving a TV in a car, not only the multipath but also the C / N value deteriorates. Therefore, the service area of the TV broadcasting station does not widen so much only with the multipath measures. However, by combining with C-CDM of the hierarchical transmission, even if the C / N is considerably deteriorated, it is possible to receive the signal in the LDTV grade. On the other hand, in the case of an automobile TV, since the screen size is usually 100 dimensions or less, sufficient image quality can be obtained with the LDTV grade. There is an effect that the service area of the LDTV grade of the automobile TV is greatly expanded. If OFDM is used for the entire HDTV band, the DSP circuit scale becomes large in the current semiconductor technology. Therefore, the low-frequency TV signal D_1-1Only the method of sending only OFDM is shown. As shown in the block diagram of FIG. 138, the DTV of the mid-range component and the high-range component of HDTV_1-2And D₂Two of the signals are C-CDM multiplexed according to the present invention and transmitted in frequency band A by FDM 40D. On the other hand, the signal received on the receiver side is frequency-separated by the FDM 4oe, demodulated by the C-CDM demodulator 4b of the present invention, and the HDTV middle band component and high band component are reproduced in the same manner as in FIG. The operation of the image decoder in this case is the same as that of the first, second, and third embodiments, and thus will not be described.
[0348]
Next, D, which is a low-frequency signal of the HDTV MPEG1 grade,_1-1The signal is converted into a parallel signal by the serial / parallel converter 791, undergoes QPSK or 16 QAM modulation in the OFDM converter 852 </ b> C, is converted into a time-axis signal by the inverse FFT unit 40, and is transmitted in the frequency band B by the FDM 40 d.
[0349]
On the other hand, the signal received by the receiver 43 is frequency-separated by the FDM unit 40e, becomes a signal of many frequency axes by the FFT 40a in the OFDM demodulation unit 852d, is demodulated by the demodulators 45a, 45b, etc., and is converted into the parallel-serial converter 852a By D_1-1The signal is demodulated, and in the same manner as in FIG._1-1The signal is output from the receiver 43.
[0350]
In this way, the hierarchical transmission in which only the LDTV signal is subjected to the OFDM is realized. By using the method of FIG. 138, the complex circuit of OFDM needs only the LDTV signal. The LDTV signal has a 1/20 bit rate compared to the HDTV signal. Therefore, the circuit scale of OFDM is 1/20, and the overall circuit scale is greatly reduced.
[0351]
OFDM is a transmission method that is resistant to multipath, and is intended to be applied to mobile stations, such as when receiving a mobile TV or an automobile TV, or when receiving a digital music broadcast from an automobile, where the multipath interference is large and fluctuates. . In such applications, a small screen size of 10 inches or less from 4 inches to 8 inches is mainly used. Therefore, the method of OFDM-modulating all high-resolution TV signals such as HDTV and EDTV is ineffective for the cost involved, and it is sufficient to receive LDTV Great グ TV signals for automobile TV. On the other hand, in a fixed station such as a home TV, since the multipath is always constant, it is easy to take measures against the multipath. Therefore, the effect of OFDM is not high except in a strong ghost area. It is not advisable to use OFDM for the middle and high frequency components of HDTV in the current situation where the circuit scale of OFDM is large. Accordingly, the method of using OFDM shown in FIG. 138 of the present invention only for low-frequency TV signals does not lose the effect of OFDM that significantly reduces multipath interference of LDTV received in a mobile station such as an automobile. And OFDM circuit size can be greatly reduced to 1/10 or less.
[0352]
In FIG. 138, D_1-1Only OFDM modulation, but D_1-1And D_1-2 can also be OF DM modulated. In this case, D_1-1And D_1-2 can perform C-CDM two-layer transmission, so that hierarchical broadcasting that is resistant to multi-pulses is realized even in a mobile body such as an automobile, and in the mobile body, the LDTV and SDTV can display images with image quality corresponding to the reception level and antenna sensitivity. The effect of the Gradational Degradation that can be received.
[0353]
Thus, the hierarchical transmission of the present invention becomes possible, and the various effects described above can be obtained. In the case of OFDM, which is particularly resistant to multipath, by combining with the hierarchical transmission of the present invention, it is possible to obtain an effect that it is resistant to multipath and the data transmission grade is deteriorated according to the deterioration of the reception level.
[0354]
As a method of realizing the hierarchical transmission system, as shown in FIG. 126 (a), each sub-channel 794a-c of the FDM is a first layer 801a, and sub-channels 794d-f are a second layer 801b. By providing a frequency guard band 802a and a power difference 802b of Pg as shown in FIG. 126 (b), the transmission power of the first layer 801a and the second layer 801b can be differentiated.
[0355]
By utilizing this, it is possible to increase the power of the first layer 801a within a range that does not interfere with analog TV broadcasting, as shown in FIG. In this case, as shown in FIG. 108 (e), the threshold value of the receivable C / N value of the first layer 801a is lower than that of the second layer 801b. Therefore, the effect that the reception of the first layer 801a becomes possible even in an area with a low signal level or an area with much noise is obtained. As shown in FIG. 147, two-layer hierarchical transmission is realized. This is referred to herein as the Power-Weighted-OFDM scheme (PW-OFDM). By combining the P-OFDM of this embodiment with the above-described C-CDM scheme of the present invention, the number of hierarchies is increased to three as shown in FIG. 108 (e), which has the effect of further expanding the coverage area. .
[0356]
As a specific circuit, as shown in FIG. 144, the first layer data is passed through a first data string circuit 791a to a modulator 4a to 4c having a large amplitude and a carrier f.₁~ F₃The OFDM modulation is performed by the inverse FFT 40, and the second layer data is passed through the second data string circuit 791b to the modulators 4d to 4f having normal amplitudes and the carrier f.₆~ F₈OFDM modulated by the inverse FFT 40 and transmitted.
[0357]
The received signal is converted by the FFT 40a of the receiver 43 into f₁~ F_nInto a signal having a carrier of₁~ F₃Is the first data string D by the demodulators 45a to 45c.₁That is, the first layer 801a is demodulated and the carrier f₆~ F₈From the second data string D₂That is, the second layer 801b is demodulated.
[0358]
Since the power of the first layer 801a is large, it can be received even in an area where the signal is weak. In this way, two-layer hierarchical transmission is realized by PW-OFDM. When PW-OFDM is combined with C-CDM, three to four layers are realized. The other operations in FIG. 144 are the same as those in the case of the block diagram in FIG. 123, and thus description thereof is omitted.
[0359]
Next, the hierarchical system of the Time-Weighted-OFDM (TW-OFDM) system of the present invention will be described. Since the OFDM system has the guard time zone tg as described above, the ghost, that is, the delay time t_MIs t_MIf the conditional expression <tg is satisfied, the effect of ghost can be eliminated. In a fixed station such as an ordinary household TV receiver, t_MIs as small as several μs and is constant, so that it is easy to cancel. However, in the case of a mobile station such as an in-vehicle TV receiver, there are many reflected waves._MIs not only close to several tens of microseconds but also changes with movement, making cancellation difficult. Therefore, it is expected that hierarchies for multipaths will be required.
[0360]
146. The layering method according to the present embodiment will be described. As shown in FIG. 146, by making the guard time tga of the A layer larger than the guard time tgb of the B layer, the symbol of the subchannel of the A layer becomes ghost. Become stronger. Thus, the hierarchical transmission for the multipath is realized by the weighting of the guard time. This method is called Guard-Time-Weighted-OFDM (GTW-OFDM).
[0361]
Further, when the number of symbols in the symbol time Ts of the A-th layer and the B-th layer is set to the same number, the symbol time tsa of A is set to be longer than the symbol time tsb of B. As a result, if the intervals of the carriers A and B on the frequency axis are respectively △ fa and △ fb, △ fa> △ fb. Therefore, the error rate when demodulating the symbol of A is lower than that of the symbol of B. In this way, by layering the weighting of the symbol time Ts, a two-layer hierarchy for the multi-layer of the A-th layer and the B-th layer is realized. This method is called Carrier-Spacing-Weighted-OFDM (CSW-OFDM). By realizing two-layer transmission using GTW-0FDM and transmitting a low-resolution TV signal in the A-layer and a high-frequency component in the B-layer, there are many ghosts like an in-vehicle TV receiver. Stable reception of a low-resolution TV is possible even under the conditions. Also, by combining the symbol time ts using the CSW-OFDM and the layering for the C / N of the layer A and the layer B with the GTW-OFDM, more stable reception can be achieved in an in-vehicle TV having a low reception signal level. The big effect that can be achieved is realized. High resolution is not required for in-vehicle and portable TVs. Since the time ratio of the symbol time including the low-resolution TV signal is small, increasing the guard time alone does not significantly lower the overall transmission efficiency. Therefore, by using the GTW-OFDM of the present embodiment and taking multipath measures with emphasis on a low-resolution TV signal, a mobile station such as a portable TV or an in-vehicle TV and a home station with almost no effect on transmission efficiency can be obtained. There is a great effect of realizing a hierarchical TV broadcast compatible with a fixed station such as a TV. In this case, as described above, by combining with CSW-OFDM or C-CDM, hierarchies for C / N are added, and more stable mobile station reception becomes possible.
[0362]
The effect of multipath will be specifically described. As shown in FIG. 145 (a), in the case of multipaths 810a to 810d having a short delay time, the first transmission and the second layer signals can be received, and the HDTV signal is demodulated. it can. However, in the case of long multipaths 811a to 811d as shown in FIG. 145 (b), demodulation cannot be performed because the guard time and Tgb of the B signal of the second layer are short. In this case, the A signal of the first layer has a long guard time Tga and is not affected by a multipath having a long delay time. As described above, the B signal contains the high-frequency component of the TV, and the A signal contains the low-frequency component of the TV. For example, an in-vehicle TV can reproduce an LDTV. Further, since the symbol time Tsa of the first layer is set to be longer than Tsb, the first layer is also strong against deterioration of C / N.
[0363]
By differentiating the guard time and the symbol time in this manner, a two-dimensional hierarchical OFDM can be realized with a simple configuration. By combining guard time differentiation and C-CDM in a configuration as shown in FIG. 123, it is possible to achieve both hierarchies of multipath and C / N value deterioration.
[0364]
This will be described in detail using a specific example.
Multipath delay time T_MThe smaller the D / U ratio, the larger the reflected wave and the larger the direct wave. For example, as shown in FIG. 148, when D / U <30 dB, the influence of the reflected wave becomes large and becomes 30 μs or more. By taking a Tg of 50 μs or more as shown in FIG. 148, it is possible to receive even the worst conditions. Therefore, as specifically shown in FIG. 149 (a), each symbol of the first layer 801a, the second layer 801b, and the third layer 801c in the period of 2 ms shown in FIG. It is divided into three hierarchical groups, and is shown in FIG. 149 (c). By setting the guard times 797a, 797b, and 797c of each group, that is, Tga, Tgb, and Tgc with weights of, for example, 50 .mu.s, 5 .mu.s, and 1 .mu.s, the three layers of layers 801a, 801b, and 801c as shown in FIG. Of multi-path broadcasting is realized. If GTW-OFDM is applied to all image qualities, transmission efficiency naturally drops. However, by taking the GTW-OFDM multi-path measure only for the LDTV picture quality signal having a small amount of information, there is an effect that the overall transmission efficiency is not significantly reduced. Particularly, in the first layer 801a, the guard time Tg is set to 30 μs or more and 50 μs, so that the in-vehicle TV receiver can receive. The circuit shown in the block diagram of FIG. 127 is used. In particular, an in-vehicle TV may have an image quality of an LDTV grade, and thus may have a transmission capacity of about 1 Mbps of the MPEG1 class. Therefore, as shown in FIG. 149, if the symbol time 796a Tsa is set to 200 μs with respect to the period of 2 ms, 2 Mbps can be obtained, and even if the symbol rate is reduced by half, it becomes close to 1 Mbps, and the image quality of LDTV grade can be obtained. However, the transmission efficiency is slightly lower than that of CSW-OFDM, but the error rate is lower. In particular, when the C-CDM of the present invention is combined with GTW-OFDM, the effect is further enhanced because the transmission efficiency does not decrease. In FIG. 149, the symbol times 796a, 796b, and 796c are differentiated into 200 μs, 150 μs, and 100 μs for the same number of symbols. Accordingly, hierarchical transmission is performed in which the error rate increases in the order of the first layer, the second layer, and the third layer.
[0365]
At the same time, hierarchical transmission is realized for C / N. As shown in FIG. 151, two-dimensional hierarchical transmission of multipath and C / N is realized by a combination of CSW-OFDM and CSW-OFDM. As described above, the present invention can also be realized by combining the CSW-OFDM and the C-CDM of the present invention, and in this case, there is an effect that a decrease in the overall transmission efficiency is small. In the first layer 801a, the first-second layer 851a, and the first-third layer 851a, the multipath T_MIn applications where the TV signal is large and the C / N is low, for example, in an in-vehicle TV receiver #, stable reception of an LDTV grade can be performed. In the second layer 801b and the second to third layers 851b, the C / N is low as in the fringe area of the service area, and the fixed station in the reception area with many ghosts can receive the SDTV grade of the standard resolution. In the third layer 801c occupying more than half of the service area, the C / N is high, the direct wave is large, and the number of ghosts is small, so that the image can be received with HDTV grade image quality. In this way, two-dimensional hierarchical broadcasting of C / N and multipath is realized. Such a large effect can be obtained by the combination of GTW-OFDM and C-CDM of the present invention or the combination of GTW-OFDM and CSW-C-CDM. Conventionally, a hierarchical broadcasting system for C / N has been proposed, but the present invention realizes a two-dimensional matrix hierarchical broadcasting of C / N and multipath.
[0366]
FIG. 152 shows a specific time allocation diagram of three-layer TV signals of HDTV, SDTV, and LDTV of two-dimensional hierarchical broadcasting of three layers of C / N and three layers of multipath. As shown in the figure, an LDTV is arranged in the slot 796a1 of the first layer of the A layer that is strong against the first multipath, and an SDTV synchronization signal is provided in the slot 796a2 that is strong against multipath and the slot 796b1 that is strong against C / N deterioration. And important HP signals such as address signals. In the second and third layers of the B layer, general SDTV signals, that is, LP signals and HDTV HP signals are arranged. In the C layer, high-frequency component TV signals such as SDTV, EDTV, and HDTV are arranged in the first, second, and third layers.
[0367]
In this case, as the transmission rate decreases as CN resistance or multipath becomes stronger, the resolution of the TV signal decreases, and a three-dimensional Graceful Degradation is realized as shown in FIG. 153. Can be FIG. 153 expresses a three-dimensional hierarchical broadcasting of the present invention by using three parameters of CNR, multipath delay time, and transmission rate.
[0368]
The embodiment has been described using an example in which a two-dimensional hierarchical structure can be obtained by a combination of the GTW-OFDM of the present invention and the above-described C-CDM of the present invention or a combination of the GTW-OFDM and the CSW-C-CDM. -Two-dimensional hierarchical broadcasting can be realized by a combination of OFDM and Power-Weighted-OFDM or a combination of GTW-OFDM and another CNR hierarchical transmission system.
[0369]
FIG. 154 is a diagram in which the power of the carriers 794a, 794c, and 794e is transmitted with a smaller weight compared to the carriers 794b, 794d, and 794f, and two-layered Power-Weighted-OFDM is realized. Similarly, the power of the carriers 795a and 795c orthogonal to the carrier 794a is weighted with respect to the carriers 795b and 795d to obtain two layers. When combined, a four-layer hierarchy is obtained, but FIG. 154 shows an embodiment in the case of two layers. As shown in the figure, the frequency distribution of the carriers is dispersed, so that interference with other analog broadcasts and the like in the same frequency band is dispersed, so that the effect is reduced.
[0370]
Further, as shown in FIG. 155, by adopting a time arrangement in which the time width of the guard time 797a, 797b, 797c is changed for each symbol 796a, 796b, 796c, hierarchical multi-level transmission for three-layer multipath can be performed. Realize. With the time arrangement of FIG. 155, the data of the A layer, the B layer, and the C layer are dispersed on the time axis. Therefore, even if burst noise occurs at a specific time, the data in each layer is interleaved to prevent data destruction and to stably demodulate the TV signal. In particular, by dispersing and interleaving the data in the A layer, it is possible to greatly reduce the interference of burst noise generated from the ignition device of another vehicle, which is generated at the time of receiving a vehicle-mounted TV.
[0371]
160 (a) and 160 (b) show block diagrams of specific ECC encoders 744j and ECC decoders 749j in this case. FIG. 167 is a block diagram of the de-interleave unit 936b. FIG. 168 (a) shows the interleave table 954 processed in the de-interleave RAM 936a of the de-interleave section 936b, and FIG. 168 (b) shows the interleave distance L1.
[0372]
By interleaving the data in this manner, the disturbance of the burst noise can be reduced. As shown in the block diagram of the VSB receiver in FIG. 161 and the block diagram of the VSB transmitter in FIG. 162, in the transmission device of 4VSB, 8VSB, 16VSB and the embodiments 1 and 2 described in Embodiments 4, 5, and 6 etc. By using the above-described QAM or PSK transmission apparatus, interference of burst noise can be reduced, so that there is an effect that TV reception with less noise can be performed in terrestrial broadcasting.
[0373]
By performing the three-layer broadcasting by the method shown in FIG. 155, the layer A can reduce the disturbance of the burst noise in addition to the above-described multipath and C / N deterioration, so that the LDTV by the mobile station such as the on-vehicle TV receiver or the pocket TV can be performed. This has the effect of stabilizing grade TV reception.
[0374]
Although the embodiment of the present invention has been described using the modulation schemes of ASK, QAM, PSK, and OFDM, similar effects can be obtained with other modulation schemes. Also, by using the partial response, the error rate can be reduced not only in the recording system but also in the transmission system.
[0375]
One feature of the multilevel transmission scheme of the present invention is to improve the frequency use efficiency, but for some receivers the power use efficiency is considerably reduced. Therefore, it cannot be applied to all transmission systems. For example, in the case of a satellite communication system between specific receivers, the most economical method is to replace the equipment with the highest frequency use efficiency and the highest power use efficiency obtained at that time. In such a case, it is not always necessary to use the present invention.
[0376]
However, in the case of a satellite broadcasting system or a terrestrial broadcasting system, a hierarchical transmission system as in the present invention is required. This is because satellite broadcasting standards require persistence of 50 years or more. During this period, the broadcasting standard is not changed, but the transmission power of the satellite is dramatically improved with technological innovation. Broadcasting stations must perform compatible broadcasting so that manufactured receivers can receive and view TV programs in the future several decades from now. According to the present invention, effects such as compatibility between existing NTSC broadcasting and HDTV broadcasting and expandability of future information transmission amount can be obtained.
[0377]
Although the present invention emphasizes frequency efficiency rather than power efficiency, the power of the transmitter is set by setting several types of receivers each having a designed receiving sensitivity according to each transmission stage on the receiver side. Need not be increased much. For this reason, even a current satellite with a small power can transmit sufficiently. Further, even if the transmission power increases in the future, transmission can be performed according to the same standard, so that future expandability and compatibility between new and old receivers can be obtained. As described above, the present invention has a remarkable effect when used in the satellite broadcasting standard.
[0378]
Further, when the multi-level transmission system of the present invention is used for terrestrial broadcasting, the present invention is easier to implement than satellite broadcasting because there is no need to consider power use efficiency at all. As described above, the conventional digital HDTV broadcasting system has a remarkable effect of greatly reducing the unreceivable area in the service area and the effect of compatibility between the NTSC and the HDTV receiver or the receiver. Also, there is an effect that the service area as viewed from the sponsor of the TV program is substantially expanded. Although the embodiment has been described using an example using the modulation schemes of QPSK, 16QAM, 32QAM and 4VSB, 8VSB, 16VSB, it goes without saying that the present invention can be applied to 64QAM, 128QAM, 256QAM, 32VSB, 64VSB and the like. It goes without saying that the present invention can be applied to multi-valued PSK, ASK, and FSK as described with reference to the drawings. Although the embodiment in which the present invention is combined with TDM for transmission has been described, transmission may also be carried out in combination with FDM, CDMA and spread communication systems.
[0379]
One feature of the multilevel transmission scheme of the present invention is to improve the frequency use efficiency, but for some receivers the power use efficiency is considerably reduced. Therefore, it cannot be applied to all transmission systems. For example, in the case of a satellite communication system between specific receivers, the most economical method is to replace the equipment with the highest frequency use efficiency and the highest power use efficiency obtained at that time. In such a case, it is not always necessary to use the present invention.
[0380]
However, in the case of a satellite broadcasting system or a terrestrial broadcasting system, a multilevel transmission system as in the present invention is required. This is because satellite broadcasting standards require persistence of 50 years or more. During this period, the broadcasting standard is not changed, but the transmission power of the satellite is dramatically improved with technological innovation. Broadcasting stations must perform compatible broadcasting so that manufactured receivers can receive and view TV programs in the future several decades from now. According to the present invention, effects such as compatibility between existing NTSC broadcasting and HDTV broadcasting and expandability of future information transmission amount can be obtained.
[0381]
Although the present invention emphasizes frequency efficiency rather than power efficiency, the power of the transmitter is set by setting several types of receivers each having a designed receiving sensitivity according to each transmission stage on the receiver side. Need not be increased much. For this reason, even a current satellite with a small power can transmit sufficiently. Further, even if the transmission power increases in the future, transmission can be performed according to the same standard, so that future expandability and compatibility between new and old receivers can be obtained. As described above, the present invention has a remarkable effect when used in the satellite broadcasting standard.
[0382]
Further, when the multi-level transmission system of the present invention is used for terrestrial broadcasting, the present invention is easier to implement than satellite broadcasting because there is no need to consider power use efficiency at all. As described above, the conventional digital HDTV broadcasting system has a remarkable effect of greatly reducing the unreceivable area in the service area and the effect of compatibility between the NTSC and the HDTV receiver or the receiver. Also, there is an effect that the service area as viewed from the sponsor of the TV program is substantially expanded. Although the embodiment has been described using the example using the modulation schemes of 16QAM and 32QAM, it is needless to say that the present invention can be applied to 64QAM, 128QAM, 256QAM and the like. It goes without saying that the present invention can be applied to multi-valued PSK, ASK, and FSK as described with reference to the drawings.
[0383]
【The invention's effect】
As described above, the present invention provides a signal input unit, a modulation unit that modulates a plurality of carriers having different phases with an input signal from the input unit to generate an m-valued signal point on a signal vector diagram, The first and second data strings of n values are input to a transmission device that performs data transmission and includes a transmitting unit that transmits the signal, and divides the signal into n signal point groups. Allocating each data of the second data group to each signal point in the signal point group by allocating the data to one data string, transmitting a signal by a transmitting transmitter, In a receiving apparatus having a demodulator for demodulating a QAM modulated wave of a p-value signal point on a diagram and an output unit, the signal point is divided into n-value signal point groups, and a first data string of each signal point group n-value Are demodulated in correspondence with each other, and approximately p / By demodulating and reproducing the data of the second data string of the p / n value at the signal point of the value and transmitting the data using the receiving device, for example, the first data string of the n value is transmitted by the modulator 4 of the transmitter 1. , The second data string and the third data string are assigned to signal point groups to transmit data, and a modified m-value QAM modulated signal is transmitted. In the first receiver 23, the n-valued first data string is demodulated by the demodulator 25. The second receiver 33 demodulates the first data sequence and the second data sequence, and the third receiver 43 demodulates the first data sequence, the second data sequence, and the third data sequence. Even a receiver having a demodulation capability of n-valued data of a multilevel modulated wave obtained by modulating data can provide a compatible and expandable transmission device capable of demodulating n-valued data. Further, when the distance between the signal point closest to the origin and the I-axis or the Q-axis among the signal points of the QAM system is f, the signal point is shifted so that the distance becomes nf such that n> 1. , Hierarchical transmission becomes possible.
[0384]
By transmitting an NTSC signal to the transmission system as a first data sequence and a difference signal between HDTV and NTSC as a second data sequence, in satellite broadcasting, NTSC broadcasting and HDTV broadcasting are compatible, and the amount of information can be expanded. Digital broadcasting with high performance is possible, and terrestrial broadcasting has a remarkable effect of expanding the service area and eliminating unreceivable areas.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an entire transmission device system according to a first embodiment of the present invention;
FIG. 2 is a block diagram of a transmitter 1 according to the first embodiment of the present invention.
FIG. 3 is a vector diagram of a transmission signal according to the first embodiment of the present invention.
FIG. 4 is a vector diagram of a transmission signal according to the first embodiment of the present invention.
FIG. 5 is a diagram illustrating code allocation to signal points according to the first embodiment of the present invention.
FIG. 6 is a coding diagram for a signal point cloud according to the first embodiment of the present invention.
FIG. 7 is a coding diagram for signal points in a signal point group according to the first embodiment of the present invention.
FIG. 8 is a diagram illustrating coding of signal points and signal points according to the first embodiment of the present invention.
FIG. 9 is a threshold state diagram of a signal point group of a transmission signal according to the first embodiment of the present invention.
FIG. 10 is a vector diagram of modified 16-value QAM according to the first embodiment of the present invention.
FIG. 11 illustrates an antenna radius r according to the first embodiment of the present invention.₂Diagram of relationship between transmission power ratio and transmission power ratio n
FIG. 12 is a diagram of signal points of modified 64-QAM according to the first embodiment of the present invention;
FIG. 13 illustrates an antenna radius r according to the first embodiment of the present invention.₃Diagram of relationship between transmission power ratio and transmission power ratio n
FIG. 14 is a vector diagram of a modified 64-value QAM signal group and sub-signal point group according to the first embodiment of the present invention.
FIG. 15 shows the ratio A of the modified 64-QAM of the first embodiment of the present invention.₁, A₂Illustration of
FIG. 16 illustrates an antenna radius r according to the first embodiment of the present invention.₂, R₃And transmission power ratio n₁₆, N₆₄Relationship diagram
FIG. 17 is a block diagram of a digital transmitter according to the first embodiment of the present invention.
FIG. 18 is a signal space diagram diagram of 4PSK modulation according to the first embodiment of the present invention.
FIG. 19 is a block diagram of a first receiver according to the first embodiment of the present invention.
FIG. 20 is a signal space diagram diagram of a 4PSK modulated signal according to the first embodiment of the present invention.
FIG. 21 is a block diagram of a second receiver according to the first embodiment of the present invention.
FIG. 22 is a signal vector diagram of modified 16-value QAM according to the first embodiment of the present invention.
FIG. 23 is a signal vector diagram of modified 64-value QAM according to the first embodiment of the present invention.
FIG. 24 is a flowchart of the first embodiment of the present invention.
FIG. 25 (a) is an 8-ary QAM signal vector diagram according to the first embodiment of the present invention,
(B) is a signal vector diagram of 16-level QAM according to the first embodiment of the present invention.
FIG. 26 is a block diagram of a third receiver according to the first embodiment of the present invention.
FIG. 27 is a diagram of signal points of modified 64-ary QAM according to the first embodiment of the present invention.
FIG. 28 is a flowchart of the first embodiment of the present invention.
FIG. 29 is an overall configuration diagram of a transmission system according to a third embodiment of the present invention.
FIG. 30 is a block diagram of a first image encoder according to Embodiment 3 of the present invention.
FIG. 31 is a block diagram of a first image decoder according to a third embodiment of the present invention;
FIG. 32 is a block diagram of a second image decoder according to the third embodiment of the present invention.
FIG. 33 is a block diagram of a third image decoder according to the third embodiment of the present invention.
FIG. 34 shows D of Example 3 of the present invention.₁, D₂, D₃Illustration of time multiplexing of signals
FIG. 35 shows D of Example 3 of the present invention.₁, D₂, D₃Illustration of time multiplexing of signals
FIG. 36 shows D of Example 3 of the present invention.₁, D₂, D₃Illustration of time multiplexing of signals
FIG. 37 is a configuration diagram of an entire system of a transmission device according to a fourth embodiment of the present invention.
FIG. 38 is a vector diagram of signal points of modified 16QAM in Embodiment 3 of the present invention.
FIG. 39 is a vector diagram of signal points of modified 16QAM in Embodiment 3 of the present invention.
FIG. 40 is a vector diagram of signal points of modified 64QAM in Embodiment 3 of the present invention.
FIG. 41 is a signal arrangement diagram on a time axis according to the third embodiment of the present invention.
FIG. 42 is a signal arrangement diagram on the time axis in the TDMA system according to the third embodiment of the present invention.
FIG. 43 is a block diagram of a carrier recovery circuit according to a third embodiment of the present invention.
FIG. 44 is a view showing the principle of carrier recovery according to the third embodiment of the present invention;
FIG. 45 is a block diagram of an inverse modulation type carrier recovery circuit according to a third embodiment of the present invention;
FIG. 46 is a signal point arrangement diagram of a 16QAM signal according to the third embodiment of the present invention.
FIG. 47 is a signal point arrangement diagram of a 64QAM signal according to the third embodiment of the present invention.
FIG. 48 is a block diagram of a 16-multiplier carrier recovery circuit according to a third embodiment of the present invention;
FIG. 49 shows D of Example 3 of the present invention._V1, D_H1, D_V2, D_H2, D_V3, D_H3Illustration of time multiplexing of signals
FIG. 50 shows D of Example 3 of the present invention._V1, D_H1, D_V2, D_H2, D_V3, D_H3Explanatory diagram of TDMA time multiplexing of signals
FIG. 51 shows D of Example 3 of the present invention._V1, D_H1, D_V2, D_H2, D_V3, D_H3Explanatory diagram of TDMA time multiplexing of signals
FIG. 52 is a diagram of a reception interference area of the conventional system in the fourth embodiment of the present invention.
FIG. 53 is a diagram of a reception interference area in the case of a hierarchical broadcasting system according to the fourth embodiment of the present invention.
FIG. 54 is a diagram showing a reception disturbance area of the conventional system in the fourth embodiment of the present invention.
FIG. 55 is a diagram of a reception obstruction area in the case of the hierarchical broadcasting system according to the fourth embodiment of the present invention.
FIG. 56 is a reception interference area diagram of two digital broadcasting stations according to the fourth embodiment of the present invention.
FIG. 57 is a signal point arrangement diagram of a modified 4ASK signal according to the fifth embodiment of the present invention.
FIG. 58 is a signal point arrangement diagram of modified 4ASK in the fifth embodiment of the present invention.
FIG. 59 (a) is a signal point arrangement diagram of modified 4ASK in Embodiment 5 of the present invention, and (b) is a signal point arrangement diagram of modified 4ASK in Embodiment 5 of the present invention.
FIG. 60 is a signal point arrangement diagram of a modified 4ASK signal in the case of a low C / N value in the fifth embodiment of the present invention.
FIG. 61 shows a 4VSB, 8VSB transmitter according to the fifth embodiment.
FIG. 62 (a) is a spectrum diagram of an ASK signal, that is, a filtered multi-level VSB signal according to the fifth embodiment of the present invention, and FIG. 62 (b) is a frequency distribution diagram of the VSB signal according to the fifth embodiment of the present invention.
FIG. 63 is a block diagram of a receiver of 4VSB, 8VSB, and 16VSB in the fifth embodiment.
FIG. 64 is a block diagram of a video signal transmitter according to a fifth embodiment of the present invention.
FIG. 65 is a block diagram of an entire TV receiver according to a fifth embodiment of the present invention.
FIG. 66 is a block diagram of another TV receiver according to the fifth embodiment of the present invention.
FIG. 67 is a block diagram of a satellite / terrestrial TV receiver according to a fifth embodiment of the present invention.
FIG. 68 (a) is an 8VSB Constellation diagram in Examples 5 and 6, (b) is an 8VSB Constellation diagram in Examples 5 and 6, and (c) is an 8VSB signal-time waveform in Examples 5 and 6. Figure
FIG. 69 is another block diagram of an image encoder in Embodiment 5 of the present invention.
FIG. 70 is a block diagram of an image encoder with one separation circuit in Embodiment 5 of the present invention.
FIG. 71 is a block diagram of an image decoder according to Embodiment 5 of the present invention.
FIG. 72 is a block diagram of an image decoder with one synthesizer according to a fifth embodiment of the present invention.
FIG. 73 is a time allocation diagram of a transmission signal according to the fifth embodiment of the present invention.
FIG. 74 (a) is a block diagram of an image decoder according to Embodiment 5 of the present invention;
(B) is a time allocation diagram of a transmission signal according to the fifth embodiment of the present invention.
FIG. 75 is a time allocation diagram of a transmission signal according to the fifth embodiment of the present invention.
FIG. 76 is a time allocation diagram of a transmission signal according to the fifth embodiment of the present invention.
FIG. 77 is a time allocation diagram of a transmission signal according to the fifth embodiment of the present invention.
FIG. 78 is a block diagram of an image decoder according to a fifth embodiment of the present invention.
FIG. 79 is a timing diagram of transmission signals of three layers according to the fifth embodiment of the present invention.
FIG. 80 is a block diagram of an image decoder according to Embodiment 5 of the present invention.
FIG. 81 is a time allocation diagram of a transmission signal according to the fifth embodiment of the present invention.
FIG. 82 is a block diagram of a D1 image decoder according to Embodiment 5 of the present invention;
FIG. 83 is a frequency-time diagram of the frequency modulation signal of the fifth embodiment according to the present invention.
FIG. 84 is a block diagram of a magnetic recording / reproducing apparatus according to a fifth embodiment of the present invention.
FIG. 85 is a diagram showing the relationship between the C / N and the layer number according to the second embodiment of the present invention.
FIG. 86 is a diagram showing the relationship between the transmission distance and C / N according to the second embodiment of the present invention.
FIG. 87 is a block diagram of a transmitter according to a second embodiment of the present invention.
FIG. 88 is a block diagram of a receiver according to a second embodiment of the present invention.
FIG. 89 is a relationship diagram of C / N-error rate according to the second embodiment of the present invention.
FIG. 90 is a diagram of a three-layer reception interference area according to the fifth embodiment of the present invention.
FIG. 91 is a diagram of a four-layer reception interference area according to the sixth embodiment of the present invention.
FIG. 92 is a hierarchical transmission diagram according to the sixth embodiment of the present invention.
FIG. 93 is a block diagram of a separation circuit according to a sixth embodiment of the present invention.
FIG. 94 is a block diagram of a synthesis unit according to a sixth embodiment of the present invention.
FIG. 95 is a transmission hierarchical structure diagram of Embodiment 6 according to the present invention.
FIG. 96 is a reception state diagram of a conventional digital TV broadcast.
FIG. 97 is a reception state diagram of digital TV hierarchical broadcasting according to Embodiment 6 of the present invention.
FIG. 98 is a transmission hierarchical structure diagram of Embodiment 6 according to the present invention.
FIG. 99 is a vector diagram of 16 SRQAM of Embodiment 3 according to the present invention.
FIG. 100 is a vector diagram of 32 SRQAM of Embodiment 3 according to the present invention.
FIG. 101 is a relationship diagram of C / N-error rate according to the third embodiment of the present invention.
FIG. 102 is a diagram illustrating a relationship between C / N and an error rate according to the third embodiment of the present invention.
FIG. 103 is a diagram illustrating a relationship between a shift amount n and C / N required for transmission according to a third embodiment of the present invention.
FIG. 104 is a diagram illustrating a relationship between a shift amount n and C / N required for transmission according to a third embodiment of the present invention.
FIG. 105 shows a distance from a transmitting antenna and a signal level during terrestrial broadcasting according to the third embodiment of the present invention.
FIG. 106 is a service area diagram of 32 SRQAM of Embodiment 3 according to the present invention.
FIG. 107 is a 32SRQAM service area diagram of Embodiment 3 according to the present invention.
108A is a frequency distribution diagram of a conventional TV signal, FIG. 108B is a frequency distribution diagram of a conventional two-layer TV signal, FIG. 108C is a diagram showing threshold values of the third embodiment of the present invention, (D) is a frequency distribution diagram of the carrier group of the two-layered OFDM of the ninth embodiment, and (e) is a diagram showing three threshold values of the three-remodeled OFDM of the ninth embodiment.
FIG. 109 is a diagram illustrating a TV signal time arrangement according to the third embodiment of the present invention.
FIG. 110 is a diagram showing the principle of the C-CDM according to the third embodiment of the present invention.
FIG. 111 is a diagram showing a code assignment according to the third embodiment of the present invention.
FIG. 112 is a diagram showing a code assignment in a case where 36QAM of the third embodiment is extended.
FIG. 113 is a diagram illustrating a modulation signal frequency arrangement according to a fifth embodiment of the present invention.
FIG. 114 is a block diagram of a magnetic recording / reproducing apparatus according to a fifth embodiment of the present invention.
FIG. 115 is a block diagram of a transceiver of a mobile phone according to a seventh embodiment of the present invention.
FIG. 116 is a block diagram of a base station according to a seventh embodiment of the present invention.
FIG. 117: Distribution diagram of communication capacity and traffic of the conventional method
FIG. 118 is a distribution diagram of communication capacity and traffic according to the seventh embodiment of the present invention.
FIG. 119 (a) is a conventional time slot layout, and FIG. 119 (b) is a time slot layout according to the seventh embodiment of the present invention.
FIG. 120 (a) is a layout diagram of a conventional TDMA time slot, and FIG. 120 (b) is a layout diagram of a TDMA time slot according to a seventh embodiment of the present invention.
FIG. 121 is a block diagram of a one-layer transceiver according to a seventh embodiment of the present invention.
FIG. 122 is a block diagram of a two-layer transceiver according to a seventh embodiment of the present invention.
FIG. 123 is a block diagram of an OFDM transceiver according to an eighth embodiment of the present invention.
FIG. 124 is an operation principle diagram of an OFDM system according to an eighth embodiment of the present invention.
FIG. 125 (a) is a frequency allocation diagram of a conventional modulation signal, and FIG. 125 (b) is a frequency allocation diagram of a modulation signal according to the eighth embodiment of the present invention.
126A is a diagram illustrating a state in which the OFDM is not weighted in the ninth embodiment, FIG. 126B is a diagram illustrating two subchannels of a two-layer OFDM weighted by transmission power in the ninth embodiment, and FIG. ) Is a frequency distribution diagram of OFDM in which the carrier spacing is doubled in the ninth embodiment, and (e) is a frequency distribution diagram of OFDM in the ninth embodiment where the carrier spacing is not weighted.
FIG. 127 is a block diagram of a transceiver according to a ninth embodiment of the present invention.
128A is a block diagram of Trellis @ Encoder (Ratio1 / 2) in Examples 2, 4, and 5; FIG. 128B is a block diagram of Trellis @ Encoder (Ratio2 / 3) in Examples 2, 4, and 5; (C) is a block diagram of Trellis @ Encoder (Ratio3 / 4) in Examples 2, 4, and 5, (d) is a block diagram of Trellis @ Decoder (Ratio1 / 2) in Examples 2, 4, and 5, and (e) is a block diagram. Block diagram of Trellis @ Decoder (Ratio 2/3) in Embodiments 2, 4, and 5, (f) is a block diagram of Trellis @ Decoder (Ratio 3/4) in Embodiments 2, 4, and 5.
FIG. 129 is a time allocation diagram of an effective symbol period and a guard period according to the ninth embodiment;
FIG. 130 is a diagram showing the relationship between C / N and error rate in the conventional example and the ninth embodiment.
FIG. 131 is a block diagram of a magnetic recording / reproducing apparatus according to a fifth embodiment.
FIG. 132 is a diagram illustrating a recording format of a track on a magnetic tape and a running pattern of a head according to a fifth embodiment.
FIG. 133 is a block diagram of a transceiver according to a third embodiment.
FIG. 134 is a diagram showing frequency allocation of a conventional broadcasting system.
FIG. 135 is a diagram showing the relationship between service areas and image quality when the three-layer hierarchical transmission system according to the third embodiment is used.
FIG. 136 is a frequency allocation diagram when the hierarchical transmission system according to the third embodiment is combined with FDM.
FIG. 137 is a block diagram of a transceiver when trellis coding is used in Embodiment 3.
FIG. 138 is a block diagram of a transceiver when a part of a low-frequency signal is transmitted by OFDM in Embodiment 9.
FIG. 139 is a signal point arrangement diagram of 8-PS-APSK in the first embodiment.
FIG. 140 is a signal point arrangement diagram of 16-PS-APSK in the first embodiment.
FIG. 141 is a signal point arrangement diagram of 8-PS-PSK in the first embodiment.
FIG. 142 is a view showing a signal point arrangement of 16-PS-PSK (PS type) in the first embodiment.
FIG. 143 is a diagram illustrating the relationship between the radius of the satellite antenna and the transmission capacity according to the first embodiment;
FIG. 144 is a block diagram of a Weighted OFDM transceiver according to a ninth embodiment.
FIG. 145A is a waveform diagram of the guard time and symbol time hierarchical OFDM in the ninth embodiment when the multipath is short, and FIG. 145B is a guard time and symbol time hierarchy in the ninth embodiment where the multipath is long. Diagram of type OFDM
FIG. 146 (a) is a diagram illustrating the principle of guard time and symbol time hierarchical OFDM according to the ninth embodiment.
FIG. 147 is a diagram illustrating a sub-channel layout of a two-layer transmission system using power weighting in a ninth embodiment;
FIG. 148 is a diagram illustrating the relationship between D / V conversion, a multipath delay time, and a guard time according to the ninth embodiment.
FIG. 149A is a time slot diagram of each layer according to the ninth embodiment;
(B) is a time distribution diagram of the guard time of each layer in the ninth embodiment, and (c) is a time distribution diagram of the guard time of each layer in the ninth embodiment.
FIG. 150 is an explanatory diagram of a three-layer hierarchical broadcasting system for a multipath in a relation diagram between a multipath delay time and a transmission rate diagram according to the ninth embodiment.
FIG. 151 is an explanatory diagram of a hierarchical broadcasting system having a two-dimensional matrix structure in a relationship diagram between a delay time and a CN value in a case where GTW-OFDM and C-CDM (or CSW-OFDM) according to the ninth embodiment are combined.
[FIG. 152] FIG. 152 is a time allocation diagram of a three-layer TV signal in each time slot when GTW-OFDM and C-CDM (or CSW-OFDM) according to the ninth embodiment are combined.
FIG. 153 is a diagram showing a hierarchical broadcast of a three-dimensional matrix structure in a relationship diagram between a multipath signal delay time, a CN value, and a transmission rate when GTW-OFDM and C-CDM (or CSW-OFDM) according to the ninth embodiment are combined. Illustration of the method
FIG. 154 is a frequency distribution diagram of Power-Weighted-OFDM of the ninth embodiment.
[FIG. 155] FIG. 155 is an arrangement diagram on the time axis of a three-layer TV signal in each time slot when Guard-Time-OFDM and C-CDM according to the ninth embodiment are combined.
Fig. 156 is a block diagram of a transmitter and a receiver according to the fourth and fifth embodiments.
FIG. 157 is a block diagram of a transmitter and a receiver in Embodiments 4 and 5.
FIG. 158 is a block diagram of a transmitter and a receiver in Embodiments 4 and 5.
159 (a) is a 16VSB signal point arrangement diagram in the fifth embodiment, (b) is a 16VSB signal point arrangement diagram in the fifth embodiment (8VSB), and (c) is a 16VSB signal point arrangement in the fifth embodiment. FIGS. 4D and 4D are signal point arrangement diagrams of 16 VSB in the fifth embodiment (16 VSB).
FIG. 160 (a) is a block diagram of ECC @ Encoder in Embodiments 5 and 6, and FIG. 160 (b) is a block diagram of ECC @ Encoder in Embodiments 5 and 6.
FIG. 161 is an overall block diagram of a VSB receiver according to a fifth embodiment.
FIG. 162 is a diagram illustrating a transmitter according to a fifth embodiment.
FIG. 163: Error rate / C / N value curve of Example 4 VSB and TC-8VSB
FIG. 164 is an error rate curve of subchannel 1 and subchannel 2 of Embodiment 4 VSB and TC-8VSB;
FIG. 165 (a) is a block diagram of Reed Solomon Encoder in Embodiments 2, 4 and 5, and FIG. 165 (B) is Reed in Embodiments 2, 5 and 6;
Block diagram of Solomon @ Decoder
FIG. 166 is a flowchart of a Reed @ Solomon error correction and operation according to the second, fourth, and fifth embodiments.
FIG. 167 is a block diagram of a deinterleave unit according to the second, third, fourth, fifth, and sixth embodiments.
FIG. 168 (a) is a diagram of an interleave and deinterleave table in Embodiments 2, 3, 4, and 5, and FIG. 168 is a diagram showing an interleave distance in Embodiments 2, 3, 4, and 5;
FIG. 169 is a comparison diagram of 4-VSB, 8-VSB, and 16-VSB Redundancy in Example 5;
FIG. 170 is a block diagram of a TV Receiver that receives a High Priority signal in the second, third, fourth, and fifth embodiments.
FIG. 171 is a block diagram of a transmitter and a receiver in Embodiments 2, 3, 4, and 5;
FIG. 172 is a block diagram of a transmitter and a receiver in Embodiments 2, 3, 4, and 5;
FIG. 173 is a block diagram of an ASK type magnetic recording / reproducing apparatus according to a sixth embodiment.
[Explanation of symbols]
1 Transmitter
4 modulator
6 antenna
6a @ ground antenna
10 satellite
12 repeater
23 first receiver
25 ° demodulator
33 second receiver
35 ° demodulator
43 3rd receiver
51 Digital transmitter
85 ° signal point
91 1st divided signal point cloud
401 first image encoder
703 SRQAM coverage area

Claims (5)

A receiving device for receiving a terrestrial digital broadcast signal and a satellite digital broadcast signal,
The terrestrial digital broadcast signal includes information on at least a first data stream and a second data stream,
The first data string and the second data string are digitally modulated;
The power of the modulation signal corresponding to the first data sequence is greater than the power of the modulation signal corresponding to the second data sequence,
A first demodulation unit for demodulating the satellite digital broadcast signal;
A second demodulation unit for demodulating the terrestrial digital broadcast signal;
A first error correction decoding unit that performs a first error correction decoding process on an output of the second demodulation unit corresponding to the second data sequence;
A deinterleaver for deinterleaving the output of the first error correction decoder;
A receiving device comprising: a second error correction decoding unit that performs a second error correction decoding process on an output of the deinterleaving unit. A receiving device for receiving a terrestrial digital broadcast signal and a satellite digital broadcast signal,
The terrestrial digital broadcast signal includes information on at least a first data stream and a second data stream,
The first data sequence is m-value PSK modulation or m-value QAM modulation, and the second data sequence is n-value PSK modulation or n-value QAM modulation.
The modulated signal corresponding to the first data sequence and the modulated signal corresponding to the second data sequence are subjected to inverse Fourier transform,
The power of the modulation signal corresponding to the first data sequence is greater than the power of the modulation signal corresponding to the second data sequence,
The first data sequence has demodulation information for demodulating a modulation signal corresponding to the second data sequence,
A first demodulation unit for demodulating the satellite digital broadcast signal;
Fourier transform unit for Fourier transforming the terrestrial digital broadcast signal,
The output of the Fourier transform unit corresponding to the first data sequence is subjected to m-value PSK demodulation or m-value QAM demodulation, and the output of the Fourier transform unit corresponding to the second data sequence is subjected to n-value PSK demodulation. Or a second demodulation unit for performing n-value QAM demodulation,
A first error correction decoding unit that performs a first error correction decoding process on an output of the second demodulation unit corresponding to the second data sequence;
A deinterleaver for deinterleaving the output of the first error correction decoder;
A second error correction decoding unit that performs a second error correction decoding process on an output of the deinterleaving unit,
The receiving device, wherein the second demodulation unit demodulates an output of the Fourier transform unit corresponding to the second data sequence based on the demodulation information. 3. The receiving device according to claim 2, wherein the value of m is 4 or less. 4. The receiving device according to claim 2, wherein the value of n is 4 or more. The receiving device according to claim 2, wherein the demodulation information includes information on the value of n.

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