JP3588461B2 - Receiver - Google Patents

Description

つまり、４ＰＳＫを送信する場合の２倍の振幅、４倍の送信エネルギーで送信できる。等距離信号点で伝送する一般的な受信機では変形１６値ＱＡＭの復調はできないがＡ_１とＡ_２の２つの閾値を予め設定することにより第２受信機３３で受信できる。図１０の場合、第１分割信号点群９１の中の信号点の最短距離はＡ_１であり、４ＰＳＫの信号点間距離２Ａ_１と比べるとＡ_２／２Ａ_１なる。Ａ_１＝Ａ_２より１／２の信号点間距離となり、同じエラーレートを得ようとすると２倍の振幅の受信感度、エネルギーでは４倍の受信感度が必要となる。４倍の受信感度を得るには、第２受信機３３のアンテナ３２の半径ｒ_２を第１受信機２３のアンテナ２２の半径半径ｒ１に比べて２倍すなわちｒ_２＝２ｒ_１にすればよい。例えば第１受信機２３のアンテナが直径３０ｃｍなら第２受信機３３のアンテナ直径を６０ｃｍにすれば実現できる。このことにより第２データ列の復調により、これをＨＤＴＶの高域成分に割り当てればＨＤＴＶ等の新たなサービスが同一チャンネルで可能となる。サービス内容が倍増することから受信者はアンテナと受信機の投資に見合った分のサービスを受けることができる。従って第２受信機３３はその分高コストでもよい。ここで、４ＰＳＫのモード受信のために最低送信電力が決まっているため、図１０のＡ_１とＡ_２の比率により４ＰＳＫの送信電力に対する変形１６ＡＰＳＫの送信電力比ｎ_１６と第２受信機３３のアンテナ半径ｒ_２が決定する。
【００５０】
この最適化を計るため計算してみると、４ＰＳＫの最低必要な送信エネルギーは｛（Ａ_１＋Ａ_２）／Ａ１｝２倍これをｎ_１６と定義すると、変形１６値ＱＡＭで受信するときの信号点間距離はＡ_２、４ＰＳＫで受信するときの信号点間距離は２Ａ_１、信号点間距離の比率はＡ_２／２Ａ、であるから受信アンテナの半径をｒ_２とすると図１１のような関係となる。曲線１０１は送信エネルギー倍率ｎ_１６と第２受信機２３のアンテナ２２の半径ｒ_２の関係を表す。
【００５１】
点１０２は等距離信号点の場合の１６ＱＡＭを送信する場合で、前述のとおり９倍の送信エネルギーを必要とし実用的ではない。図１１からｎ_１６を５倍以上増やしても第２受信機２３のアンテナ半径ｒ_２はさほど小さくならないことがグラフからわかる。
【００５２】
衛星の場合、送信電力は限定されており、一定値以上はとれない。このことからｎ１６は５倍以下が望ましいことが明らかになる。この領域を図１１の領域１０３の斜線で示す。例えばこの領域内なら例えば点１０４は送信エネルギー４倍で第２受信機２３のアンテナ半径ｒ_２は２倍になる。また、点１０５は送信エネルギーが２倍でｒ_２は約５倍になる。これらは、実用化可能な範囲にある。
【００５３】
ｎ_１６が５より小さいことをＡ１とＡ２で表現すると
ｎ_１６＝（（Ａ_１＋Ａ_２）／Ａ_１）^２≦５
Ａ_２≦１．２３Ａ_１
図１０から分割信号点群間の距離を２Ａ（４），最大振巾を２Ａ（１６）とすると、Ａ（４）とＡ（１６）−Ａ（４）はＡ_１とＡ_２に比例する
従って
｛Ａ（１６）｝^２≦５｛Ａ（１４）｝^２とすればよい
次に変形の６４ＡＰＳＫ変調を用いた例を示す。第３受信機４３は、６４値ＱＡＭ復調ができる。
【００５４】
図１２のベクトル図は図１０のベクトル図の分割信号点群を４値から１６値に増加させた場合である。図１２の第１分割信号点群９１の中には信号点１７０を始めとして４×４＝１６値の信号点が等間隔に配置されている。この場合、４ＰＳＫとの両用性をもたせるため送信振巾のＡ_１≧Ａ_ＴＯに設定しなければならない。第３受信機４３のアンテナの半径をｒ_３として、送信、出力信号ｎ６４と定義した場合のｒ_３の値を、同様にして求めると
ｒ_３ ^２＝｛６^２／（ｎ−１）｝ｒ_１ ^２
となり、図１３ ６４値ＱＡＭの半径ｒ_３−出力倍数ｎのようなグラフとなる。
【００５５】
ただし、図１２のような配置では第２受信機３３で受信した場合４ＰＳＫの２ｂｉｔしか復調できないので第１、第２、第３の３つの両立性を成立させるには、第２受信機３３に変形６４値ＱＡＭ変調波から変形１６値ＱＡＭを復調する機能をもたせることが望ましい。
【００５６】
図１４のように３階層の信号点のグルーピングを行うことにより３つの受信機の両立性が成立する。第１象限だけで説明すると、第１分割分割信号点群９１は第１データ列の２ｂｉｔの（１１）を割りあてたことは述べた。
【００５７】
次に、第１副分割信号点群１８１には第２データ列の２ｂｉｔの（１１）を割りあてる。第２副分割信号点群１８２には（０１）を、第３副分割信号点群１８３には（００）を第４副分割信号点群１８４には（１０）を割りあてる。このことは図７と等価である。
【００５８】
図１５の第１象限のベクトル図を用いて第３データ列の信号点配置を詳しく説明すると例えば信号点２０１，２０５，２０９，２１３を（１１）、信号点２０２，２０６，２１０，２１４を（０１）、信号点２０３，２０７，２１１，２１５を（００）、信号点２０４，２０８，２１２，２１６を（１０）とすれば、第３データ列の２ｂｉｔのデータを第１データ、第２データと独立して、３階層の２ｂｉｔデータが独立して伝送できる。
【００５９】
６ｂｉｔのデータが送るだけでなく本発明の特徴として３つのレベルの性能の異なる受信機で、２ｂｉｔ，４ｂｉｔ，６ｂｉｔの異なる伝送量のデータが伝送できしかも、３つの階層の伝送間の両立性をもたせることができる。
【００６０】
ここで、３階層伝送時の両立性をもたせるために必要な信号点の配置方法を説明する。
【００６１】
図１５にあるように、まず、第１データ列のデータを第１受信機２３で受信させるためには、Ａ_１≧Ａ_ＴＯであることはすでに述べた。
【００６２】
次に第２データ列の信号点、例えば図１０の信号点９１と図１５の副分割信号点群の１８２，１８３，１８４の信号点と区別できるように信号点間距離を確保する必要がある。
【００６３】
図１５では２／３Ａ_２だけ離した場合を示す。この場合第１副分割信号点群１８１の内部の信号点２０１，２０２の信号点間距離はＡ_２／６となる。第３受信機４３で受信する場合に必要な受信エネルギーを計算する。この場合、アンテナ３２の半径をｒ_３として、必要な送信エネルギーを４ＰＳＫ送信エネルギーのｎ６４倍であると定義すると、
ｒ_３ ^２＝（１２ｒ_１）^２／（ｎ−１）となる
このグラフは図１６の曲線２２１で表せる。例えば点２２２，２２３の場合４ＰＳＫ送信エネルギーの６倍の送信エネルギーが得られれば８倍の半径のアンテナで、また９倍の送信エネルギーなら６倍のアンテナで第１、第２、第３のデータ列が復調できることがわかる。この場合、第２データ列の信号点間距離が２／３Ａ_２と近づくため
ｒ_２ ^２＝（３ｒ_１）^２／（ｎ−１）となり
曲線２２３のように若干第２受信機３３のアンテナ３２を大きくする必要がある。
【００６４】
この方法は、現時点のように衛星の送信エネルギーが小さい間は第１データ列と第２データ列を送り、衛星の送信エネルギーが大巾に増加した将来において第１受信機２３や第２受信機３３の受信データを損なうことなく、また改造することなく第３データ列を送ることができるという両立性と発展性の両面の大きな効果が得られる。
【００６５】
受信状態を説明するために、まず第２受信機３３から述べる。前述の第１受信機２３が本来半径ｒ_１の小さいアンテナでデジタル送信機５１の４ＰＳＫ変調信号及び送信機１の第１データ列を復調できるように設定してあるのに対し、第２受信機３３では送信機１の図１０に示した１６値の信号点つまり第２データ列の１６ＱＡＭの２ビットの信号を完全に復調できる。第１データ列と合わせて４ｂｉｔの信号を復調できる。この場合Ａ１，Ａ２の比率が送信機により異なる。このデータを図２１の復調制御部２３１で設定し、復調回路に閾値を送る。これによりＡＭ復調が可能となる。
【００６６】
図２１の第２受信機３３のブロック図と、図１９の第１受信機２３のブロック図はほぼ同じ構成である。違う点は、まずアンテナ３２がアンテナ２２より大きい半径ｒ_２をもっている点にある。このため、より信号点間距離の短い信号を弁別できる。次に、復調器３５の内部に復調制御部２３１と、第１データ列再生部２３２と第２データ列再生部２３３をもつ。第１識別再生回路１３６は変形１６ＱＡＭを復調するためＡＭ復調機能をもっている。この場合、各搬送波は４値の値をもち、零レベルと±各２値の閾値をもつ。本発明の場合、変形１６ＱＡＭ信号のため、図２２の信号ベクトル図のように閾値が送信機の送信出力により異なる。従って、ＴＨ_１６を基準化したスレシホールド値とすると、図２２から明らかなように
ＴＨ_１６＝（Ａ_１＋Ａ_２／２）／（Ａ_１＋Ａ_２）
となる。
【００６７】
このＡ１，Ａ２もしくはＴＨ_１６及び、多値変調の値ｍの復調情報は、送信機１より、第１データ列の中に含めて送信される。また復調制御部２３１が受信信号を統計処理し復調情報を求める方法もとれる。
【００６８】
図２６を用いてシフトファクターＡ_１／Ａ_２の比率を決定していく方法を説明する。Ａ_１／Ａ_２を変えると閾値が変わる。受信機側で設定したＡ_１／Ａ_２が送信機側で設定したＡ_１／Ａ_２の値から離れるに従いエラーは増える。図２６の第２データ列再生部２３３からの復調信号を復調制御回路２３１にフィールドバックしてエラーレートの減る方向にシフトファクターＡ_１／Ａ_２を制御することにより第３受信機４３はシフトファクターをＡ_１／Ａ_２を復調しなくても済むため回路が簡単になる。また送信機はＡ_１／Ａ_２を送る必要がなくなり伝送容量が増えるという効果がある。これを第２受信機３３に用いることもできる。
復調制御回路２３１はメモリー２３１ａを持つ。ＴＶ放送のチャンネル毎に異なるしきい値、つまりシフト比や信号点数や同期ルールを記憶し再びそのチャンネルを受信するとき、この値を呼び出すことにより受信が速く安定するという効果がある。
【００６９】
この復調情報が不明の場合、第２データ列の復調は困難となる。以下、（図２４）のフローチャートを用いて説明する。
【００７０】
復調情報が得られない場合でもステップ３１３の４ＰＳＫの復調及びステップ３０１の第１データ列の復調はできる。そこで、ステップ３０２で第１データ列再生部２３２で得られる復調情報を復調制御部２３１に送る。復調制御部２３１はステップ３０３でｍが４又は２ならステップ３１３の４ＰＳＫもしくは２ＰＳＫの復調を行う。ＮＯならステップ３０４でｍが８又は１６ならステップ３０５へ向う。ＮＯの場合はステップ３１０へ向う。ステップ３０５ではＴＨ８とＴＨ１６の演算を行う。ステップ３０６で復調制御部２３１はＡＭ復調の閾値ＴＨ１６を第１識別再生回路１３６と第２識別再生回路１３７に送り、ステップ３０７、３１５で変形１６ＱＡＭの復調と第２データ列の再生がなされる。ステップ３０８でエラーレートがチェックされ、悪い場合はステップ３１３に戻り、４ＰＳＫ復調を行なう。
【００７１】
またこの場合、図２２の信号点８５．８３はｃｏｓ（ωｔ＋ｎπ／２）の角度上にあるが、信号点８４．８６はこの角度上にない。従って図２１の第２データ列再生部２３３より搬送波再生回路１３１へ第２データ列の搬送波送出情報を送り信号点８４．８６のタイミングの信号からは搬送波を抽出しないように設定してある。
【００７２】
第２データ列が復調不能な場合を想定して送信機１は第１データ列によりを搬送波タイミング信号を間欠的に送っている。この信号により第２データ列が復調できなくても、第１データ列のみでも信号点８３．８５がわかる。このため、搬送波再生回路１３１に搬送波送出情報を送ることにより搬送波が再生できる。
【００７３】
次に送信機１より、図２３に示すような変形６４ＱＡＭの信号が送られてきた場合、図２４のフローチャートに戻るとステップ３０４でｍが１６でないか判断されステップ３１０でｍが６４以下かがチェックされ、ステップ３１１で等距離信号点方式でない場合、ステップ３１２に向かう。ここでは変形６４ＱＡＭ時の信号点間距離ＴＨ_６４を求めると
ＴＨ_６４＝（Ａ_１＋Ａ_２／２）／（Ａ_１＋Ａ_２）
であり、ＴＨ_１６と同じである。しかし、信号点間距離が小さくなる。
【００７４】
第１副分割信号点群１８１の中にある信号点間の距離をＡ_３とすると、第１副分割信号点群１８１と第２副分割信号点群１８２の距離は（Ａ_２−２Ａ_３）、基準化すると（Ａ_２−２Ａ_３）／（Ａ_１＋Ａ_２）となる。これをｄ_６４と定義すると、ｄ_６４が第２受信機３３の弁別能力Ｔ_２以下である場合、弁別できない。この場合、ステップ３１３で判断し、ｄ_６４が許容範囲外であればステップ３１３の４ＰＳＫモードに入る。弁別範囲にある場合はステップ３０５へ向い、ステップ３０７の１６ＱＡＭの復調を行う。ステップ３０８でエラーレートが大きい場合は、ステップ３１３の４ＰＳＫモードに入る。
【００７５】
この場合、送信機１が図２５（ａ）に示すような信号点の変形８ＱＡＭ信号を送信すれば、全ての信号点がｃｏｓ（２πｆ＋ｎ・π／４）の角度上にあるため、４逓倍回路により、全ての搬送波が同じ位相に縮退されるため搬送波の再生が簡単になるという効果が生まれる。この場合、配慮をしていない４ＰＳＫ受信機でも第１データ列の２ｂｉｔは復調でき、第２受信機３３では第２データ列の１ｂｉｔが再生でき、合計３ｂｉｔ再生できる。
【００７６】
次に第３受信機４３について述べる。図２６は第３受信機４３のブロック図で、図２１の第２受信機３３とほぼ同じ構成となる。違う点は第３データ列再生部２３４が追加されていることと識別再生回路に８値の識別能力があることにある。アンテナ４２の半径ｒ_３がｒ_２よりさらに大きくなるため、より信号点間距離の近い信号、例えば３２値ＱＡＭや６４値ＱＡＭも復調できる。このため、６４値ＱＡＭを復調するため、第１識別再生回路１３６は検信号波に対し、８値のレベルを弁別する必要がある。この場合７つの閾値レベルが存在する。このうち１つは０のため１つの象限には３つの閾値が存在する。
【００７７】
図２７の信号スペースダイアグラムに示すように、第１象限では３つの閾値が存在する。
【００７８】
図２７に示すように３つの正規化された閾値、ＴＨ１_６４とＴＨ２_６４とＴＨ３_６４が存在する。
【００７９】
ＴＨ１_６４＝（Ａ_１＋Ａ_３／２）／（Ａ_１＋Ａ_２）
ＴＨ２_６４＝（Ａ_１＋Ａ_２／２）／（Ａ_１＋Ａ_２）
ＴＨ３_６４＝（Ａ_１＋Ａ_２−Ａ_３／２）／（Ａ_１＋Ａ_２）
で表わせる。
【００８０】
この閾値により、位相検波した受信信号をＡＭ復調することにより、図２１で説明した第１データ列と第２データ列と同様にして第３データ列のデータが復調される。図２３のように第３データ列は例えば第１副分割信号群１８１の中の４つの信号点２０１、２０２、２０３、２０４の弁別により、４値つまり２ｂｉｔとれる。こうして６ｂｉｔつまり変形６４値ＱＡＭの復調が可能となる。
【００８１】
この時の復調制御部２３１は第１データ列再生部２３２の第１データ列に含まれる復調情報により、ｍ、Ａ_１、Ａ_２、Ａ_３の値がわかるのでその閾値ＴＨ１_６４とＴＨ２_６４とＴＨ３_６４を計算して第１識別再生回路１３６と第２識別再生回路１３７に送り、変形６４ＱＡＭ復調を確実に行うことができる。この場合復調情報にはスクランブルがかかっているので許可された受信者しか６４ＱＡＭを復調できないようにすることもできる。図２８は変形６４ＱＡＭの復調制御部２３１のフローチャートを示す。（図２４）の１６値ＱＡＭのフローチャートと違う点のみを説明する。図２８のステップ３０４よりステップ３２０になりｍ＝３２ならステップ３２２の３２値ＱＡＭを復調する。ＮＯならステップ３２１でｍ＝６４か判別し、ステップ３２３でＡ_３が設定値以下から再生できないため、ステップ３０５に向い、図２４と同じフローチャートになり、変形１６ＱＡＭの復調を行なう。ここでステップ３２３に戻ると、Ａ_３が設定値以上ならステップ３２４で閾値の計算を行い、ステップ３２５で第１、第２識別再生回路へ３つの閾値を送りステップ３２６で変形６４ＱＡＭの再生を行い、ステップ３２７で第１、第２、第３データの再生を行い、ステップ３２８でエラーレートが大きければステップ３０５に向い１６ＱＡＭ復調をして小さければ６４ＱＡＭ復調を継続する。
【００８２】
ここで、復調に重要な搬送波再生方式について述べる。本発明は変形１６ＱＡＭや、変形６４ＱＡＭの第１データ列を４ＰＳＫ受信機で再生させるところに特徴の一つがある。この場合、通常の４ＰＳＫ受信機を用いた場合は搬送波の再生が困難となり正常な復調ができない。これを防止するため送信機側と受信機側でいくつかの対策が必要となる。
【００８３】
本発明による方法として２通りの方式がある。第１の方式は一定規則基つき間欠的に（２ｎー１）π／４の角度上の信号点を送る方法である。第２の方式はｎπ／８の角度上に略略、全ての信号点を配置し送信する方法である。
【００８４】
第一の方法は、図３８に示したように４つの角度、π／４、３π／４、５π／４、７π／４の角度上にある信号点例えば信号点８３、８５の信号を送る時、図３８の送信信号のタイムチャート図の中のタイムスロット群４５１のうち斜線で示す間欠的に送られる同期タイムスロット４５２、４５３、４５４、４５５をある一定の規則に基ずき設定する。そして、この期間中に必ず上記角度上の８つの信号点の中のひとつの信号点を送信する。それ以外のタイムスロットでは任意の信号点を送信する。そして送信機１は、このタイムスロットを送る上記の規則を図４１に示すデータの同期タイミング情報部４９９に配置して送信する。
【００８５】
この場合の送信信号の内容を図４１を用いてさらに詳しく説明すると同期タイムスロット４５２、４５３、４５４、４５５を含むタイムスロット群４５１は１つの単位データ列４９１、Ｄｎを構成する。
【００８６】
この信号には同期タイミング情報の規則に基づき間欠的に同期タイムスロットが配置されているので、この配置規則がわかれば、同期タイムスロットにある情報を抽出することにより搬送波再生は容易にできる。
【００８７】
一方データ列４９２のフレームの先頭部分には、Ｓで示す同期領域４９３がありこれは斜線で示す同期タイムスロットだけで構成されている。この構成により上記の搬送波再生用の抽出情報が多くなるので４ＰＳＫ受信機の搬送波再生が確実にしかも早くできるという効果がある。
【００８８】
この同期領域４９３は、Ｓ１、Ｓ２、Ｓ３で示す同期部４９６、４９７、４９８、等を含み、この部分には、同期のためのユニークワードや前述の復調情報が入っている。さらにＩ_Ｔで示す位相同期信号配置情報部４９９もあり、この中には、位相同期タイムスロットの配置間隔の情報や配置規則の情報等の情報が入っている。
【００８９】
位相同期タイムスロットの領域の信号点は特定の位相しかもたないため搬送波は４ＰＳＫ受信機でも再生できるため、位相同期部配置情報Ｉ_Ｔの内容は確実に再生できるため、この情報入手後は搬送波を確実に再生できる。
【００９０】
図４１の同期領域４９３の次に復調情報部５０１があり、変形多値ＱＡＭ信号を復調するときに必要なスレシホルド電圧に関する復調情報が入っている。この情報は多値ＱＡＭの復調に重要なので、図４１の同期領域５０２のように同期領域の中に復調情報５０２を入れると復調情報の入手がより確実になる。
【００９１】
図４２はＴＤＭＡ方式によりバースト状の信号を送る場合の信号配置図である。図４１との違いはデータ列４９２、Ｄｎと他のデータ列との間にガードタイム５２１が設けられ、この期間中、送信信号は送信されない。またデータ列４９２の先頭部には同期をとるための同期部５２２が設けられている。この期間中は前述の（２ｎ−１）π／４の位相の信号点しか送信されない。従って４ＰＳＫの復調器でも搬送波が再生できる。こうしてＴＤＭＡ方式でも同期及び搬送波再生が可能となる。
【００９２】
次に図１９の第１受信機２３の搬送波再生方式について図４３と図４４を用いて詳しく述べる。図４３において入力した受信信号は入力回路２４に入り、同期検波回路５４１で同期検波された復調信号の１つは出力回路５４２に送られ出力され、第１データ列が再生される。抽出タイミング制御回路５４３で図４１の位相同期部配置情報部４９９が再生され、どのタイミングで（２ｎ−１）π／４の位相同期部の信号が入ってくるかわかり、図４４のような間欠的な位相同期制御信号５６１が送られる。復調信号は逓倍回路５４５に送られ、４逓倍されて搬送波再生制御回路５４に送られる。図４４の信号５６２のように真の位相情報５６３の信号とそれ以外の信号を含む。タイミングチャート５６４の中の斜線に示すように（２ｎー１）π／４の位相の信号点からなる位相同期タイムスロット４５２が間欠的に含まれる。これを位相同期制御信号５６４を用いて搬送波再生制御回路５４４により、サンプリングすることにより位相標本信号５６５が得られる。これをサンプリングホールドすることにより、所定の位相信号５６６が得られる。この信号はループフィルタ５４６を通り、ＶＣＯ５４７に送られ搬送波が再生され、同期検波回路５４１に送られる。こうして図３９の斜線に示すような（２ｎー１）π／４の位相の信号点が抽出される。この信号を基に４逓倍方式により正確な搬送波が再生できる。この時、複数の位相が再生されるが図４１の同期部４９６にユニークワードを入れることににより、搬送波の絶対位相を特定できる。
【００９３】
図４０のように変形６４ＱＡＭ信号を送信する場合、略略（２ｎー１）π／４の位相の斜線で示す位相同期領域４７１の中の信号点に対してのみ位相同期タイムスロット４５２、４５２ｂ等を送信機は送る。このため通常の４ＰＳＫ受信機では搬送波は再生できないが、４ＰＳＫの第１受信機２３でも、本発明の搬送波再生回路を装備することのより搬送波が再生できるという効果がある。
【００９４】
以上はコスタス方式の搬送波再生回路を用いた場合である。次に逆変調方式搬送波再生回路に本発明を用いた場合を説明する。
【００９５】
図４５は本発明の逆変調方式搬送波再生回路を示す。入力回路２４からの受信信号は同期検波回路５４１により、復調信号が再生される。一方、第１遅延回路５９１により遅延された入力信号は４相位変調器５９２において上記復調信号により逆復調され搬送波信号となる。搬送波再生制御回路５４４を通過できた上記搬送波信号は、位相比較器５９３に送られる。一方ＶＣＯ５４７からの再生搬送波は第２遅延回路５９４により、遅延され、位相比較器５９３で前述の逆変調搬送波信号と位相比較され、位相差信号はループフィルタ５４６を通してＶＣＯ５４７に供給され、受信搬送波と同位相の搬送波が再生される。この場合、図４３のコスタス形搬送波再生回路と同様にして、抽出タイミング制御回路５４３は図３９の斜線で示した領域の信号点のみの位相情報をサンプリングさせるので１６ＱＡＭでも６４ＱＡＭでも、第１受信機２３の４ＰＳＫの変調器で搬送波を再生できる。
【００９６】
次に、１６逓倍方式により搬送波を再生する方式について述べる。図２の送信機１は、図４６に示すように変形１６ＱＡＭの信号点をｎπ／８の位相に配置して変調および送信を行なう。図１９の第１受信機２３の方では、図４８に示すような１６逓倍回路６６１をもつコスタス型の搬送波再生回路を用いることにより、搬送波が再生できる。１６逓倍回路６６１により、図４６のようなｎπ／８の位相の信号点は第１象現に縮退されるためループフィルタ５４６とＶＣＯ５４１により搬送波が再生できる。ユニークワードを同期領域に配置することにより１６相から絶対位相を抽出することもできる。
【００９７】
次に１６逓倍回路の構成を説明する。復調信号から和回路６６２と差回路６６３により、和信号、差信号を作り、乗算器６６４で掛け合わせてｃｏｓ２θをつくる。また乗算器６６５ではｓｉｎ２θをつくる。これらを乗算器６６６で乗算し、ｓｉｎ４θをつくる。
【００９８】
ｓｉｎ２θとｃｏｓ２θから、同様にして、和回路６６７差回路６６８と乗算器６７０によりｓｉｎ８θをつくる。和回路６７１と差回路６７２と乗算器によりｃｏｎ８θをつくる。そして乗算器６７４によりｓｉｎ１６θをつくることにより１６逓倍ができる。
【００９９】
以上のような１６逓倍方式により、図４６のような信号点配置をした変形１６ＱＡＭ信号の全ての信号点の搬送波を特定の信号点を抽出することなしに再生できるという大きな効果がある。
【０１００】
また図４７のような配置をした変形６４ＱＡＭ信号の搬送波も再生できるが、いくつかの信号点は同期領域４７１より若干ずれているので、復調時エラーレートが増えてしまう。
【０１０１】
この対策として２つの方法がある。１つは同期領域をはずれた信号点の信号を送信しないことである情報量は減るが構成は簡単になるという効果がある。もう１つは図３８で説明したように同期タイムスロットを設けることである。タイムスロット群４５１の中の同期タイムスロットの期間中に斜線で示すｎπ／８の位相の同期位相領域４７１、４７１ａ等の信号点を送ることにより、この期間中に正確に同期をとることができるため位相誤差がすくなくなる。
【０１０２】
以上のようにして１６逓倍方式により、簡単な受信機の構成で４ＰＳＫ受信機により変形１６ＱＡＭや変形６４ＱＡＭの信号の搬送波を再生できるという大きな効果がある。また、さらに同期タイムスロットを設定した場合、変形６４ＱＡＭの搬送波再生時の位相精度を上げるという効果が得られる。
【０１０３】
以上詳しく述べたように本発明の伝送装置を用いることにより、１つの電波帯域で複数のデータを階層構造で同時に伝送することができる。
【０１０４】
この場合に、一つの送信機に対し異なる受信感度と復調能力をもつ３つの階層の受信機を設定することにより、受信機の投資に見合ったデータ量を復調できるという特長がある。まず小さなアンテナと低分解能であるが低コストの第１受信機を購入した人受信者は第１データ列を復調再生できる。次に、中型のアンテナと中分解能の高コストの第２受信機を購入した受信者は第１、第２データ列を再生できる。また、大型のアンテナと高分解能の、かなり高コストの第３受信機を購入した人は第１、第２、第３データ列の全て復調再生できる。
【０１０５】
もし第１受信機を家庭用デジタル衛星放送受信機にすれば多数の一般消費者に受け容れられるような低い価格で受信機を実現できる。第２受信機は当初は大型のアンテナを必要とする上に高コストのため消費者全般には受け容れられるものではないがＨＤＴＶを視聴したい人々には多少高くても意味がある。第３受信機は衛星出力が増加するまでの間かなり大型の産業用アンテナが必要で家庭用には現実的でなく産業用途に当初は適している。例えば超高解像ＨＤＴＶ信号を送り、衛星により各地の映画館に伝送すれば、映画館をビデオにより電子化できる。このばあい映画館やビデオシアターの運営コストが安くなるという効果もある。
【０１０６】
以上のように本発明をＴＶ伝送に応用した場合、３つの画質の映像サービスを１つの電波の周波数帯域で提供でき、しかもお互いに両立するという大きな効果がある。実施例では４ＰＳＫ、変形８ＱＡＭ、変形１６ＱＡＭ、変形６４ＱＡＭの例を示したが、３２ＱＡＭや２５６ＱＡＭでも実現できる。又、８ＰＳＫや１６ＰＳＫ、３２ＰＳＫでも実施できる。また実施例では衛星伝送の例を示したが地上伝送や有線伝送でも同様にして実現できることはいうまでもない。
【０１０７】
（実施例２）
実施例２は実施例１で説明した物理階層構造をエラー訂正能力の差別化等により論理的にさらに分割し、論理的な階層構造を追加したものである。実施例１の場合それぞれの階層チャンネルは電気信号レベルつまり物理的な復調能力が異なる。これに対し実施例２ではエラー訂正能力等の論理的な再生能力が異なる。具体的には例えばＤ１の階層チャンネルの中のデータを例えばＤ_１−１とＤ_１−２の２つに分割し、この分割データの１つ例えばＤ_１−１データのエラー訂正能力をＤ_１−２データより高め、エラー訂正能力を差別化することより、復調再生時にＤ_１−１とＤ_１−２のデータのエラー後調能力が異なるため、送信信号のＣ／Ｎ値を低くしていった場合、Ｄ_１−２が再生できない信号レベルにおいてもＤ_１−１は設定したエラーレート内に収まり原信号を再生できる。これは論理的な階層構造ということができる。 つまり、変調階層チャンネルのデータを分割し、誤り訂正符号と積符号の使用等の誤り訂正の符号間距離の大きさを差別化することによ誤り訂正能力による論理的な階層構造が追加され、さらに細かい階層伝送が可能となる。
【０１０８】
これを用いると、Ｄ１チャンネルはＤ_１−１，Ｄ_１−２の２つのサブチャンネル，_{Ｄ ２}チャンネルはＤ_２−１，Ｄ_２−２の２つのサブチャンネルに増える。
【０１０９】
これを入力信号のＣ／Ｎ値と階層チャンネル番号の図８５を用いて説明すると、階層チャンネルＤ_１−１は最も低い入力信号で再生できる。このＣＮ値をｄとすると、ＣＮ＝ｄの時、Ｄ_１−１は再生されるがＤ_１−２，Ｄ_２−１，Ｄ_２−２は再生されない。次にＣＮ＝ｃ以上になるとＤ_１−２がさらに再生され、ＣＮ＝ｂの時Ｄ_２−１が加わり、ＣＮ＝ａの時Ｄ_２−２が加わる。このようにＣＮが上がるにつれて、再生可能な階層の総数が増えていく。逆をいうとＣＮが下がるにつれて、再生可能な階層の総数が減っていく。これを図８６の伝送距離と再生可能ＣＮ値の図で説明する。一般的に図８６の実線８６１に示すように伝送距離が長くなるに従い、受信信号のＣ／Ｎ値は低下する。図８５で説明したＣＮ＝ａとなる地点の送信アンテナからの距離をＬａとし，ＣＮ＝ｂではＬｂ，ＣＮ＝ｃではＬｃ，ＣＮ＝ｄではＬｄ，ＣＮ＝ｅではＬｅとなるとする。送信アンテナよりＬｄの距離より迫い地域は図８５で説明したようにＤ_１−１チャンネルのみが再生できる。このＤ_１−１の受信可能範囲を斜線の領域８６２で示す。図から明らかなようにＤ_１−１チャンネルは一番広い領域で再生できる。同様にしてＤ_１−２チャンネルは送信アンテナより距離Ｌｃ以内の領域８６３で再生できる。距離Ｌｃ以内の範囲では領域８６２も含まれるためＤ_１−１チャンネルも再生できる。同様にして領域８６４ではＤ_２−１チャンネルが再生でき、領域８６５ではＤ_２−２チャンネルが再生可能となる。このようにして、ＣＮ値の劣化に伴い伝送チャンネルが段階的に減少する階層型伝送ができる。データ構造を分離して階層構造にし、本発明の階層伝送を用いることにより、アナログ伝送のようにＣ／Ｎの劣化に伴いデータ量が次第に減少する階層型の伝送が可能となるという効果がある。
【０１１０】
次に、具体的な構成を述べる。ここでは物理階層２層、論理階層２層の実施例を述べる。図８７は送信機１のブロック図である。基本的には実施例１で説明した図２の送信機のブロック図と同じなので詳しい説明は省略するが、エラー訂正符号エンコーダが付加されている点が異なる。これをＥＣＣエンコーダと略す。分離回路３は１−１、１−２、２−１、２−２の４つの出力をもち、入力信号をＤ_１−１、Ｄ_１−２、Ｄ_２−１、Ｄ_２−２の４つの信号に分離して出力する。このうち、Ｄ_１−１、Ｄ_１−２信号は第１ＥＣＣエンコーダ８７１ａに入力され、各々、主ＥＣＣエンコーダ８７２ａと副ＥＣＣエンコーダ８７３ａに送られ、誤り訂正の符号化がなされる。
【０１１１】
ここで主ＥＣＣエンコーダ８７２ａは副ＥＣＣエンコーダ８７３ａよりも強力なエラー訂正能力をもっている。このため、図８５のＣＮ−階層チャンネルのグラフで説明したように、復調再生時、Ｄ_１−１チャンネルはＤ_１−２チャンネルより低いＣ／Ｎ値においてもＤ_１−１は基準エラーレート以下で再生できる。Ｄ_１−１はＤ_１−２よりＣ／Ｎの低下に強い論理的な階層構造となっている。誤り訂正されたＤ_１−１、Ｄ_１−２信号は合成器８７４ａでＤ１信号に合成され、変調器４に入力される。一方、Ｄ_２−１、Ｄ_２−２信号は第２ＥＣＣエンコーダ８７１ｂの中の各々主エンコーダ８７２ｂと副ＥＣＣエンコーダ８７３ｂにより誤り訂正符号化され合成器８７４ｂによりＤ２信号に合成され、変調器４により入力される。主ＥＣＣエンコーダ８７２ｂは副ＥＣＣエンコーダ８７３ｂよりエラー訂正能力が高い。この場合、変調器４はＤ_１信号、Ｄ_２信号より階層型の変調信号を作り、送信部５より送信される。以上のように図８７の送信機１はまず実施例１で説明した変調によるＤ_１、Ｄ_２の２層の物理階層構造をもっている。この説明は既に述べた。次に、エラー訂正能力の差別化によりＤ_１−１とＤ_１−２叉はＤ_２−１、Ｄ_２−２の各々２層の論理的階層構造をもっている。
【０１１２】
次にこの信号を受信する状態を説明する。図８８は受信機のブロック図である。図８７の送信機の送信信号を受信した第２受信機３３の基本構成は、実施例１の図２１で説明した第２受信機３３とほぼ同じ構成である。ＥＣＣデコーダ８７６ａ、８７６ｂを追加した点が異なる。この場合、ＱＡＭ変復調の例を示すが、ＡＳＫもしくはＰＳＫ、ＦＳＫ変復調でもよい。
【０１１３】
さて、図８８において、受信された信号は復調器３５によりＤ_１、Ｄ_２信号として再生され分離器３ａ、３ｂにより、各々Ｄ_１−１とＤ_１−２、Ｄ_２−１、Ｄ_２−２の４つの信号がつくられ、第１ＥＣＣデコーダ８７６ａと第２ＥＣＣデコーダ８７６ｂに入力される。第１ＥＣＣデコーダ８７６ａでは、Ｄ_１−１信号が主ＥＣＣデコーダ８７７ａにより誤り訂正されて合成部３７に送られる。一方、Ｄ_１−２信号は副ＥＣＣデコーダ８７８ａにより誤り訂正され合成部３７に送られる。同様にして第２ＥＣＣデコーダ８７６ｂにおいてＤ_２−１信号は主ＥＣＣデコーダ８７７ｂにおいて、Ｄ_２−２信号は副ＥＣＣデコーダ８７８ｂにおいて誤り訂正され、合成部３７に入力される。誤り訂正されたＤ_１−１、Ｄ_１−２、Ｄ_２−１、Ｄ_２−２信号は合成部３７において１つの信号となり出力部３６より出力される。
【０１１４】
この場合、論理階層構造によりＤ_１−１はＤ_１−２より、またＤ_２−１はＤ_２−２より誤り訂正能力が高いため図８５で説明したように、入力信号のＣ／Ｎ値がより低い状態においても所定の誤り率が得られ、原信号を再生できる。
【０１１５】
具体的に主ＥＣＣデコーダ８７７ａ，８７７ｂと副ＥＣＣデコーダ８７８ａ，８７８ｂの間に誤り訂正能力の差別化を行う方法を述べる。副ＥＣＣデコーダにリードソロモン符号やＢＣＨ符号のような標準的な符号間距離の符号化方式を用いた場合、主ＥＣＣデコーダにリードソロモン符号とリードソロモン符号の両者の積符号や長符号化方式を用いた誤り訂正の符号間距離の大きい符号化方式を用いることにより誤り訂正能力に差をつけることができる。こうして論理的階層構造を実現できる。符号間距離を大きくする方法は様々な方法が知られているため他の方式に関しては省略する。本発明は基本的にはどの方式も適用できる。
【０１１６】
ここで論理的な階層構造を図８９のＣ／Ｎと誤り訂正後のエラーレートの関係図を用いて説明する。図８９において、直線８８１はＤ_１−１チャンネルのＣ／Ｎとエラーレートの関係を示し、直線８８２はＤ_１−２チャンネルのＣ／Ｎと訂正後のエラーレートの関係を示す。
【０１１７】
入力信号のＣ／Ｎ値が小さくなればなる程、訂正後のデータのエラーレートは大きくなる。一定のＣ／Ｎ値以下では誤り訂正後のエラーレートがシステム設計時の基準エラーレートＥｔｈ以下に収まらず原データが正常に再生されない。さて、図８９において徐々にＣ／Ｎを上げてゆくとＤ_１−１信号の直線８８１が示すようにＣ／Ｎがｅ以下の場合Ｄ_１チャンネルの復調ができない。ｅ≦Ｃ／Ｎ＜ｄの場合Ｄ_１チャンネルの復調はできるが、Ｄ_１−１チャンネルのエラーレートはＥｔｈを上回り、原データを正常に再生できない。
【０１１８】
Ｃ／Ｎ＝ｄの時、Ｄ_１−１は誤り訂正能力がＤ_１−２より高いため、誤り訂正後のエラーレートは点８８５ｄに示すようにＥｔｈ以下になり、データを再生できる。一方、Ｄ_１−２の誤り訂正能力はＤ１−１ほど高くないため訂正後のエラーレートがＤ_１−１ほど低くないため訂正後のエラーレートがＥ_２とＥｔｈを上回るため再生できない。従ってこの場合Ｄ_１−１のみが再生できる。
【０１１９】
Ｃ／Ｎが向上してＣ／Ｎ＝Ｃになった時、Ｄ_１−２の誤り訂正後のエラーレートが点８８５Ｃに示すようにＥｔｈに達するため、再生可能となる。この時点ではＤ_２−１、Ｄ_２−２つまりＤ_２チャンネルの復調は不確実な状況にある。Ｃ／Ｎの向上に伴い、Ｃ／Ｎ＝ｂ’においてＤ_２チャンネルが確実に復調できるようになる。
【０１２０】
さらにＣ／Ｎが向上しＣ／Ｎ＝ｂになった時点で、Ｄ_２−１のエラーレートが点８８５ｂに示すようにＥｔｈまで減少し、Ｄ_２−１が再生できるようになる。この時、Ｄ_２−２のエラーレートはＥｔｈより大きいため再生できない。Ｃ／Ｎ＝ａになって点８８５ａに示すようにＤ_２−２のエラーレートがＥｔｈにまで減少しＤ_２−２チャンネルが再生できるようになる。
【０１２１】
このようにして、誤り訂正能力の差別化を用いることにより物理階層Ｄ_１、Ｄ_２チャンネルをさらに２層の論理階層２分割し、計４層の階層伝送ができるという効果が得られる。
【０１２２】
この場合、データ構造を高階層のデータが欠落しても原信号の一部が再生できるような階層構造にし、本発明の階層伝送と組み合わせることにより、アナログ伝送のようにＣ／Ｎの劣化に伴いデータ量が次第に減少する階層型伝送が可能となるという効果がある。特に、近年の画像圧縮技術は急速に進歩しているため、画像圧縮データを階層構造とし階層伝送と組み合わせた場合、同一地点間において、アナログ伝送よりはるかに高画質の映像を伝送すると同時に、アナログ伝送のように段階的に受信信号レベルに応じて画質を低くしながら広い地域で受信できる。このように従来のデジタル映像伝送にはなかった階層伝送の効果をデジタルによる高画質を保ちながら得ることができる。
【０１２３】
（実施例３）
以下本発明の第３の実施例について図面を参照しながら説明する。
【０１２４】
図２９は実施例３の全体図である。実施例３は本発明の伝送装置をデジタルＴＶ放送システムに用いた例を示し、超高解像度の入力映像４０２は、第１画像エンコーダー４０１の入力部４０３に入力し、分離回路４０４により、第１データ列と第２データ列と第３データ列に分離され、圧縮回路４０５により圧縮され出力される。
【０１２５】
他の入力映像４０６，４０７，４０８は各々第１画像エンコーダー４０１と同様の構成の第２画像エンコーダー４０９，４１０，４１１により圧縮され出力される。
【０１２６】
これらの４組のデータのうち、第１データ列の４組の信号は、多重器４１２の第１多重器４１３によりＴＤＭ方式等の時間的に多重化されて、第１データ列として、送信機１に送られる。
【０１２７】
第２データ列の信号群の全部もしくは１部は多重器４１４により多重化され、第２データ列として送信機１に送られる。また、第３データ列の信号群の全部もしくは１部は多重器４１５により多重化され、第３データ列として送信機１に送られる。
【０１２８】
これらを受けて送信機１では３つのデータ列を変調器４により実施例１で述べた変調を行い、送信部５によりアンテナ６と伝送路７により、衛星１０に送り中継器１２により、第１受信機２３等の３種の受信機に送られる。
【０１２９】
第１受信機２３では伝送路２１により半径ｒ_１の小径のアンテナ２２で受けて、受信信号の中の第１データ列のみを第１データ列再生部２３２で再生し、第１画像デコーダー４２１によりＮＴＳＣ信号もしくはワイドＮＴＳＣ信号等の低解像度の映像出力４２５と４２６を再生し出力させる。
【０１３０】
第２受信機３３では、半径ｒ_２の中径のアンテナ３２で受けて、第１データ列再生部２３２と第２データ列再生部２３３により第１データ列と第２データ列を再生し、第２画像デコーダー４２２により、ＨＤＴＶ信号等の高解像度の映像出力４２７もしくは映像出力４２５、４２６を再生し出力させる。
【０１３１】
第３受信機４３では、半径ｒ３の大径のアンテナ３３で受けて、第１データ列再生部２３２と第２データ列再生部２３３と第３データ列再生部２３４により、第１データ列と第２データ列と第３データ列を再生し、ビデオシアターや映画館用の超高解像度ＨＤＴＶ等の超高解像度の映像出力４２８を出力する。映像出力４２５、４２６６，４２７も出力できる。一般のデジタルＴＶ放送は、デジタル送信機５１から放送され、第１受信機２３で受信した場合、ＮＴＳＣ等の低解像の映像出力４２６として出力される。
【０１３２】
では、次に図３０の第１画像エンコーダー４０１のブロック図に基ずき、構成を詳しく述べる。超高解像度の映像信号は入力部４０３に入力され、分離回路４０４に送られる。分離回路４０４ではサブバンドコーディング方式により４つの信号に分離する。ＱＭＦ等の水平ローパスフィルタ４５１と水平ハイパスフィルタ４５２により、水平低域成分と水平高域成分に分離され、サブサンプリング部４５３，４５４により、各々の成分はサンプリングレートを半分にした後、水平低域成分は垂直ローパスフィルタ４５５と垂直ハイパスフィルタ４５６により、各々水平低域垂直低域信号、略してＨ_ＬＶ_Ｌ信号と水平低域垂直高域信号、略してＨ_ＬＶ_Ｈ信号に分離され、サブサンプリング部４５７と４５８により、サンプリングレートを落として圧縮部４０５に送られる。
【０１３３】
水平高域成分は、垂直ローパスフィルタ４５９と垂直ハイパスフィルタ４６０により、水平高域垂直低域信号、略してＨ_ＨＶ_Ｌ信号と、水平高域垂直低域信号、略してＨ_ＨＬ_Ｈ信号に分離され、サブサンプリング部４６１，４６２によりサンプリングレートを下げて、圧縮部４０５に送られる。
【０１３４】
圧縮部４０５ではＨ_ＬＶ_Ｌ信号を第１圧縮部４７１でＤＣＴ等の最適の圧縮を行い第１出力部４７２より第１データ列として出力する。
【０１３５】
Ｈ_ＬＶ_Ｈ信号は第２圧縮部４７３で圧縮され第２出力部４６４に送られる。Ｈ_ＨＶ_Ｌ信号は第３圧縮部４６３により圧縮され第２出力部４６４へ送られる。Ｈ_ＨＶ_Ｈ信号は分離回路４６５により高解像度映像記号（Ｈ_ＨＶ_Ｈ１）と超高解像度映像信号（Ｈ_ＨＶ_Ｈ２）に分けられ、Ｈ_ＨＶ_Ｈ１は第２出力部４６４へ、Ｈ_ＨＶ_Ｈ２は第３出力部４６８へ送られる。
【０１３６】
次に図３１を用いて第１画像デコーダー４２１を説明する。第１画像デコーダー４２１は第１受信機２３からの出力、第１データ列つまりＤ_１を入力部５０１に入力しデスクランブル部５０２によりスクランブルを解いた後伸長部５０３により、前述のＨ_ＬＶ_Ｌ信号に伸長した後画面比率変更回路５０４と出力部５０５により画面比率を変更してＮＴＳＣ信号の画像５０６、ＮＴＳＣ信号でストライプ画面の画像５０７、ワイドＴＶのフル画面の画像５０８もしくは、ワイドＴＶのサイドパネル画面の画像５０９を出力する。この場合、ノンインタレースもしくはインタレースの２つの走査線のタイプが選べる。走査線もＮＴＳＣの場合５２５本と二重描画による１０５０本が得られる。また、デジタル送信機５１からの４ＰＳＫの一般のデジタルＴＶ放送を受信した場合は、第１受信機２３と第１画像デコーダ４２１によりＴＶ画像を復調、再生できる。次に図３２の第２画像デコーダーのブロック図を用いて第２画像デコーダーを説明する。まず第２受信機３３からのＤ１信号は第１入力部５２１より入力し、第１伸長部５２２で伸長され、オーバーサンプリング部５２３により２倍のサンプリングレートになり垂直ローパスィルタ５２４により、Ｈ_ＬＶ_Ｌ信号が再生される。Ｄ_２信号は第２入力部５３０より入力し、分離回路５３１により３つの信号に分離され、第２伸長部５３２と第３伸長部５３３と、第３伸長部５３４により各々伸長及び、デスクランブルされ、オーバーサンプリング部５３５、５３６、５３７により２倍のサンプリングレートとなり、垂直ハイパスフィルター５３８、垂直ローパスフィルタ５３９、垂直ハイパスフィルタ５４０により送られる。Ｈ_ＬＶ_Ｌ信号とＨ_ＬＶ_Ｈ信号は加算器５２５で加算され、オーバーサンプリング部５４１と水平ローパスフィルター５４２により水平低域映像信号となり、加算器５４３に送られる。Ｈ_ＨＶ_Ｌ信号とＨ_ＨＶ_Ｈ１信号は加算器５２６により加算され、オーバーサンプリング部５４４と水平ハイパスフィルター５４５により水平高域映像信号になり加算器５４３によりＨＤＴＶ等の高解像度映像信号ＨＤ信号となり出力部５４６からＨＤＴＶ等の画像出力５４７が出力される。場合によりＮＴＳＣ信号も出力される。
【０１３７】
図３３は第３画像デコーダーのブロック図でＤ_１信号は第１入力部５２１からＤ_２信号は第２入力部５３０から入力し高域画像デコーダー５２７により前述の手順でＨＤ信号が再生される。Ｄ３信号は第３入力部５５１より入力し超高域部画像デコーダー５５２により伸長、デスクランブル、および合成されＨ_ＨＶ_Ｈ２信号が再生される。この信号はＨＤ信号と合成器５５３で合成され超高解像度ＴＶ信号、Ｓ−ＨＤ信号となり出力部５５４より超高解像度映像信号５５５が出力される。
【０１３８】
次に図２９の説明で触れた多重器４０１の具体的な多重化方法について述べる。図３４はデータ配列図であり、第１データ列、Ｄ_１と第２データ列、Ｄ_２と第３データ列Ｄ_３に６つのＮＴＳＣチャンネルＬ１、Ｌ２、Ｌ３、Ｌ４、Ｌ５、Ｌ６と６つのＨＤＴＶチャンネルＭ１〜Ｍ６と６つのＳ−ＨＤＴＶチャンネルＨ１〜Ｈ６をＴの期間中に、時間軸上にどう配置するかを描いたものである。図３４はまずＴの期間にＤ_１信号にＬ１からＬ６をＴＤＭ方式等で時間多重により配置するものである。Ｄ_１のドメイン６０１に第１チャンネルのＨ_ＬＶ_Ｌ信号を送る。次にＤ_２信号のドメイン６０２には第１チャンネルに相当する時間領域に第１チャンネルのＨＤＴＶとＮＴＳＣとの差分情報Ｍ１つまり、前述のＨ_ＬＶ_Ｈ信号とＨ_ＨＶ_Ｌ信号とＨ_ＨＶ_Ｈ１信号を送る。またＤ_３信号のドメイン６０３には第１チャンネルのスーパーＨＤＴＶ差分情報Ｈ１，すなわち図３０で説明したＨ_ＨＶ_Ｈー２Ｈ１を送る。
【０１３９】
ここで第１チャンネルのＴＶ局を選択した場合を説明する。まず小型アンテナと第１受信機２３と第１画像デコーダ４２１のシステムをもつ一般の受信者は図３１のＮＴＳＣもしくはワイドＮＴＳＣのＴＶ信号が得られる。次に中型アンテナと第２受付信機３３と第２画像エンコーダ４２２をもつ特定の受信者はチャンネル１を選択した場合第１データ列、Ｄ_１のドメイン６０１と第２データ列、Ｄ_２のドメイン６０２の信号を合成してチャンネル１のＮＴＳＣ番組と同じ番組内容のＨＤＴＶ信号を得る。
【０１４０】
大型アンテナと多値復調できる第３受信機４３と第３画像デコーダー４２３をもつ映画館等の一部の受信者はＤ_１のドメイン６０１とＤ_２のドメイン６０２とＤ_３のドメイン６０３の信号を合成し、チャンネル１のＮＴＳＣと同じ番組内容で映画館用の画質の超解像度ＨＤＴＶ信号を得る。２から３までの他のチャンネルも同様にして再生される。
【０１４１】
図３５は別のドメインの構成である。まずＮＴＳＣの第１チャンネルはＬ１に配置されている。このＬ１はＤ１信号の第１タイムドメインのドメイン６０１の位置にあり、先頭部にＮＴＳＣ間のデスクランブル情報と実施例１で説明した復調情報を含む情報Ｓ１１が入っている。次にＨＤＴＶの第１チャンネルはＬ１とＭ１に分割されて入っている。Ｍ１はＨＤＴＶとＮＴＳＣとの差分情報であり、Ｄ_２のドメイン６０２とドメイン６１１の両方に入っている。この場合６ＭｂｐｓのＮＴＳＣ圧縮信号を採用しＬ１に収容すると、Ｍ１の帯域は２倍の１２Ｍｂｐｓになる。Ｌ１とＭ１とを合わせると１８Ｍｂｐｓの帯域が第２受信機３３と第２画像デコーダ４２３から復調再生可能である。一方、現在提案されている圧縮方法を用い約１５Ｍｂｐｓの帯域でＨＤＴＶ圧縮信号を実現することができる。従って図３５の配置でチャンネル１でＨＤＴＶとＮＴＳＣを同時に放送できる。この場合チャンネル２ではＨＤＴＶの再生はできない。Ｓ２１はＨＤＴＶのデスクランブル情報である。また、スーパーＨＤＴＶ信号はＬ１とＭ１とＨ１に分割して放送される。スーパーＨＤＴＶの差分情報はＤ_３のドメイン６０３，６１２，６１３を用い、ＮＴＳＣを６Ｍｂｐｓに設定した場合、合計３６Ｍｂｐｓ送れ、圧縮を高くすれば映画館用画質の走査線約２０００本のスーパーＨＤＴＶ信号も伝送できる。
【０１４２】
図３６の配置図はＤ_３で６つのタイムドメインを占有させスーパーＨＤＴＶ信号を伝送した場合を示す。ＮＴＳＣ圧縮信号を６Ｍｂｐｓに設定した場合９倍の５４Ｍｂｐｓが伝送できる。このためより高画質のスーパーＨＤＴＶを伝送できる。
【０１４３】
以上は、送信信号の電波の水平もしくは垂直の偏波面の片方を利用する場合である。ここで水平と垂直の２つの偏波面を使うことにより、周波数利用効率は２倍となる。以下に説明をする。
【０１４４】
図４９は第１データ列の水平偏波信号Ｄ_Ｖ１と垂直偏波信号ＤＨ１及び第２データ列の同じくＤ_Ｖ２とＤ_Ｈ２、第３データ列のＤ_Ｖ３とＤ_Ｈ３の信号配置図を示す。この場合、第１データ列の垂直偏波信号Ｄ_Ｖ１にＮＴＳＣ等の低域ＴＶ信号が入っており第１データ列の水平偏波信号Ｄ_Ｈ１に高域ＴＶ信号が入っている。従って、垂直偏波アンテナしかもっていない第１受信機２３は，ＮＴＳＣ等の低域信号を再生できる。一方、垂直、水平の両方向の偏波アンテナをもつ第１受信機２３は、例えば、Ｌ_１とＭ_１信号を合成しＨＤＴＶ信号を得ることができる。つまり、第１受信機２３を用いた場合、アンテナの能力により、一方ではＮＴＳＣが、他方ではんＴＳＣとＨＤＴＶが再生できるため２方式が両立するという大きな効果がある。
【０１４５】
図５０はＴＤＭＡ方式にした場合で、各データバースト７２１の先頭部に同期部７３１とカード部７４１が設けられている。又、フレームの先頭部には同期情報部７２０が設けられている。この場合は、各タイムスロット群が、各々１つのチャンネルが割りあてられている。例えば、第１タイムスロット７５０で第１チャンネルの全く同じ番組のＮＴＳＣ、ＨＤＴＶ、スーパーＨＤＴＶを送ることができる。各々のタイムスロット７５０〜７５０ｅが完全に独立している。従って特定の放送局が特定のタイムスロットを用いてＴＤＭＡ方式で放送する場合、他局と独立してＮＴＳＣ、ＨＤＴＶ、スーパーＨＤＴＶの放送ができるという効果がある。又、受信側も水平偏波アンテナで第１受信機２３をもつ構成の場合ＮＴＳＣ ＴＶ信号を両偏波アンテナなら、ＨＤＴＶを再生できる。第２受信機３３にすると低解像度のスーパーＨＤＴＶを再生できる。第３受信機４３にするとスーパーＨＤＴＶ信号を完全に再生できる。以上のように両立性のある放送システムを構築出来る。この場合、図５０のような配置で、バースト状のＴＤＭＡ方式でなく、図４９のような連続信号の時間多重も可能である。また図５１に示すような信号配置にすればより高解度のＨＤＴＶ信号を再生できる。
【０１４６】
以上述べたように実施例３により超高解像度型ＨＤＴＶ、ＨＤＴＶとＮＴＳＣ−ＴＶの３つの信号の両立性のあるデジタルＴＶ放送が可能になるという顕著な効果がある。とくに映画館等に伝送した場合、映像を電子化することができるという新たな効果がある。
【０１４７】
ここで、本発明による変形ＱＡＭをＳＲＱＡＭと呼び、具体的なエラーレートについて述べる。
【０１４８】
まず、１６ＳＲＱＡＭのエラーレートを計算する。図９９は１６ＳＲＱＡＭの信号点のベクトル図である。第１象限において、１６ＱＡＭの場合、信号点８３ａ、８３ｂ、８４ａ、８５、８３ａ等の各１６ヶの信号点の間隔は等間隔であり、全て２δである。
【０１４９】
１６ＱＡＭの信号点８３ａは座標軸のＩ軸、Ｑ軸よりδの距離にある。ここで１６ＳＲＱＡＭにする場合、ｎをシフト値と定義すると、信号点８３ａはシフトして、座標軸からの距離をｎδの位置の信号点８３へ移動させる。この場合ｎは
０＜ｎ＜３
である。また他の信号点８４ａ、８６ａもシフトして信号点８４、８６の位置に移動する。
第１データ列の誤り率をＰｅ１とすると
【０１５０】
【数１】

【０１５１】
第２データ列の誤り率をＰｅ２とすると
【０１５２】
【数２】

【０１５３】
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。
【０１５４】
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
【０１５５】
【数３】

【０１５６】
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。
【０１５７】
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。
【０１５８】
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。
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Ｄ１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。
【０１５９】
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。
【０１６０】
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。しかし、天候等の受信条件の悪化により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。
【０１６１】
一方、本発明の３２ＳＲＱＡＭの場合、前述のように第１階層Ｄ_１でＮＴＳＣ等の中解像度ＴＶ成分を送り、第２階層Ｄ_２でＨＤＴＶの高域成分のみを送ることができる。例えば図１０５において第１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は図５３をより具体的に説明したものである。図１０６において領域７０８、７０３ａ、７０３ｂ、７１２は各々従来方式の３２ＱＡＭのサービスエリア、第１階層Ｄ_１のサービスエリア、第２層Ｄ２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。
【０１６２】
つまり、従来方式の３２ＱＡＭでは各目上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。
【０１６３】
しかし、本発明の３２ＳＲＱＡＭを用い、第１階層Ｄ１でＮＴＳＣグレードの中低域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サービスエリアの半径が５マイル縮小するものの、中低解像度グレードのサービスエリアの半径が１０マイル以上拡大するという効果が生まれる。
【０１６４】
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地域において受信不能地域が大巾に減少し、これに伴い受信者数が増加する。
【０１６５】
二番目に従来方式では高価なＨＤＴＶ受信機と受像機をもつ受信者しか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。
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。
【０１６６】
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。
【０１６７】
さて、図１０７の３２ＳＲＱＡＭのサービスエリア図にみるように、ｎ＝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。
【０１６８】
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。
【０１６９】
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。
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。
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。
【０１７０】
また、実施例では時間分割多重（ＴＤＭ）方式と組み合わせてＴＤＭによるサブチャンネルを設け、その各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ることができた。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。このような優れた効果をもつ多重化技術である。
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には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考えられる。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。
【０１７１】
この時、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を追加する。次にこの閾値の低いサブチャンネルにさらに低解像度の成分をのせる。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が生まれる。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。
【０１７２】
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。
【０１７３】
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。
【０１７４】
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。
【０１７５】
（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。
【０１７６】
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。
【０１７７】
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。
【０１７８】
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。
【０１７９】
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。
【０１８０】
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。
【０１８１】
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。
【０１８２】
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。
【０１８３】
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。
【０１８４】
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。
【０１８５】
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。
【０１８６】
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。
【０１８７】
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。
【０１８８】
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。
【０１８９】
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。
【０１９０】
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。
【０１９１】
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。
【０１９２】
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。
【０１９３】
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。
【０１９４】
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。
【０１９５】
（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。４値の場合２ｂｉｔのデータを１周期で送ることができる。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。
【０１９６】
本発明による階層型伝送を行うために、図５８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ＬｏはＬより大きく設定する。
【０１９７】
つまり Ｌｏ＞Ｌ
と設定する。これが本発明の階層型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＝Ｌｏになっても良い。
【０１９８】
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。
【０１９９】
このように信号点を配置することにより、ＡＳＫ方式で本発明の階層型伝送が可能となる。階層型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、信号点７２１と信号点７２２、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。
【０２００】
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のみが再生される階層型伝送ができるという効果がある。
【０２０１】
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さらにフィルタ７４７により帯域制限されＶＳＢ信号等のＡＳＫ信号となり出力部７４８から出力される。
【０２０２】
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方式を用いると同一周波数帯域で１６ＱＡＭの４ｂｉｔ／シンボルに相当する情報量が伝送できる。
【０２０３】
次に図６３のブロック図で示す受信機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。
【０２０４】
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。
【０２０５】
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。
【０２０６】
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。
【０２０７】
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。
【０２０８】
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場合は自動的にＨ_ＬＶ_Ｌ信号の低解像度の映像信号を出力させる。
【０２０９】
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。
【０２１０】
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。
【０２１１】
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ＡＳＫ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。
【０２１２】
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の階層型伝送を行った。しかし、図６８のように８値のＡＳＫ信号を用いるとＤ_１、Ｄ_２、Ｄ_３の３層の各１ｂｉｔの階層型伝送を行うことができる。図６８ではＤ_３信号の信号点は信号点７２１ａと７２１ｂ、７２２ａと７２２ｂ、７２３ａと７２３ｂ、７２４ａと７２４ｂの２値つまり１ｂｉｔである。次にＤ２の信号点は信号点群７２１と７２２、信号点群７２３と７２４の２値の１ｂｉｔ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３層の階層型伝送が可能となる。
【０２１３】
この３層の階層型伝送システムを用いて３層の映像伝送を行うことは実施例３と３で説明したもので動作の詳しい説明は省略する。
【０２１４】
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、ＨＬＶ_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。
【０２１５】
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。
【０２１６】
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。
【０２１７】
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。
【０２１８】
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，ＨＬＶ_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。
【０２１９】
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。
【０２２０】
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，ＨＨＶ_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。
【０２２１】
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。
【０２２２】
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。
【０２２３】
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。
【０２２４】
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_ＬＶ_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。
【０２２５】
ここでは、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。
【０２２６】
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ＨＬＶＬ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。
【０２２７】
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。
【０２２８】
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_ＬＶ_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５５６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。
【０２２９】
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_ＬＶ_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。
【０２３０】
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。
【０２３１】
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。
【０２３２】
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。
【０２３３】
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。
【０２３４】
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。
【０２３５】
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。
【０２３６】
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。
【０２３７】
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１ｂｉｔ、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の階層型伝送方式を用いることもできる。
【０２３８】
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。
【０２３９】
図８４を説明すると、磁気記録再生装置８５１は、入力した映像信号を画像エンコーダ４０１により分離および圧縮し、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。これまでの動作は実施例５の図６４の送信機とほぼ同じである。変調信号は記録再生回路８５３と磁気ヘッド８５４により磁気テープ８５５に記録される。この記録の手法は従来のデジタルの多値記録を変形して物理的な階層記録もできるし、実施例１、３のような位相変調や位相振巾変調による階層記録もできる。磁気テープ上の多トラックによる階層記録もできる。データ送信レートの変更による階層記録もできる。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。
【０２４０】
次に、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により再生信号を変復調器８５２に送る。以下は実施例１，３，４とほぼ同様な動作をする。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、画像デコーダー４２２により映像信号を出力する。この場合、階層記録を行っているためＣ／Ｎが高いときはＨＤＴＶ等の信号高解像度ＴＶ信号を再生できる。一方Ｃ／Ｎが低い場合もしくは機能の低い磁気再生装置で再生した場合、ＮＴＳＣ、ＴＶ信号もしくは低解像度ＮＴＳＣＴＶ信号が出力される。
【０２４１】
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が低くなったり、エラーレートが高く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。
【０２４２】
（実施例６）
実施例６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。
【０２４３】
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。
【０２４４】
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。
【０２４５】
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。
【０２４６】
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。
【０２４７】
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。
【０２４８】
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。
【０２４９】
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Ｄ２−１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。
【０２５０】
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。
【０２５１】
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。
【０２５２】
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。
【０２５３】
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。
【０２５４】
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。
【０２５５】
本発明の階層型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。
【０２５６】
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。
【０２５７】
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。
【０２５８】
また本発明の階層型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と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。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。
【０２５９】
【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。
【０２６０】
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】本発明の実施例５における送信機のブロック図
【図６２】（ａ）は本発明の実施例５におけるＡＳＫ変調信号の周波数分布図、（ｂ）は本発明の実施例５におけるＡＳＫ変調信号の周波数分布図
【図６３】本発明の実施例５における受信機のブロック図
【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】本発明の実施例５における８値ＡＳＫ信号の信号点配置図
【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の関係図
【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】本発明による実施例３のＴＶ信号周波数分布図
【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
【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
７０８ 従来方式の受信可能地域
７２２ キャリア
７２５ スペクトラム[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 broadcasting system, a signal obtained by compressing an NTSC-TV signal to approximately 6 Mbps is multiplexed by a TDM system using quaternary PSK modulation, and one transponder broadcasts a 4 to 20 channel NTSC TV program or a 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 apparatus of the present invention modulates a signal input portion and a plurality of carriers having different phases with an input signal from the input portion to generate an m-value signal point on a signal vector diagram. A transmitter for performing data transmission, comprising a modulator for transmitting a modulated signal, a transmitting unit for transmitting a modulated signal, an input unit for the transmitted signal, a demodulator and an output unit for demodulating a QAM modulated wave of a l-value signal point on a vector diagram. The receiving device has two configurations.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
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 signal point groups, and the signal point groups are assigned to n data in the first data string, and m / n signal points or A transmission signal is transmitted by the transmitting device by allocating each data of the second data sequence to the sub-signal point group. In some cases, 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. 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]
【Example】
(Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings.
[0017]
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 transmitter 5 as a modulated signal 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.
[0018]
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.
[0019]
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.
[0020]
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.
[0021]
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.
[0022]
In this case, a receiver capable of demodulation using an NTSC-TV signal in a receiver capable of demodulation using a small antenna using a small antenna, an HDTV signal using a receiver capable of medium-value demodulation using a medium antenna, and a receiver capable of multi-level demodulation using a large antenna 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.
[0023]
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.
[0024]
Now, each part will be described. FIG. 2 is a block diagram of the transmitter 1.
[0025]
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.
[0026]
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 carriers 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_cIn the state of t), the signal is sent to the second AM modulator 63 and subjected to multi-level amplitude modulation. Then, the signal 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.
[0027]
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. When the tip of the combined vector from the zero point is defined as a signal point, in the case of 16-value QAM, a₁, A₂, A₃, A₄Quaternary amplitude value and b₁, B₂, B₃, B₄A total of 16 signal points can be set by the combination of the four amplitude values. In the first quadrant of FIG.₁₁, C at signal point 84₁₂, Signal point 85 C₂₂, C at signal point 86₂₁There are four signals:
[0028]
C₁₁Is the vector 0-a₁And the vector 0-b₁Is a composite vector of₁₁= A₁cos2πf_ctb₁sin2πf_ct = Acos (2πf_ct + dπ / 2).
[0029]
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.
[0030]
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.
[0031]
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.
[0032]
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.
[0033]
Here, FIG. 8 shows an example of allocation of 2 bits of the first data string and 2 bits of the second data string.
[0034]
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.
[0035]
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. Assuming that the threshold distance is ATO, if only 4PSK is sent, the amplitude of ATO may be used. However, when trying to transmit 16QAM while maintaining ATO, 3ATO, that 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.
[0036]
A 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.
[0037]
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.
[0038]
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 section 121 divides the input signal into two signals and modulates the phase of the reference carrier by a 1-2 phase modulation circuit 122, and modulates the carrier by 90 ° out of phase with the reference carrier. The signals are sent to the two-phase modulation circuit 123, and these phase-modulated waves are combined by the combiner 65 and transmitted by the transmission unit 55.
[0039]
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_TOIf the signal is transmitted at the minimum amplitude ATO of the transmission limit or more, the first receiver 23 can receive.
[0040]
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.
[0041]
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.
[0042]
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 without any transmission distortion or noise.
[0043]
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 defined as 2ARO. 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 the 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 r₀If so, 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. For this reason, as shown in FIG. 25A, if the transmitter 1 arranges and transmits eight signal points at positions on an angle of (π / 4 + nπ / 2), a carrier wave can be reproduced by the quadruple system. 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 the 16-multiplier carrier recovery method in the carrier recovery 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) 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.
[0044]
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. 9, the amplitude A1 of the signal point 83 in the horizontal vector direction is converted to the digital transmitter of FIG. 51 4PSK minimum transmission power A_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 which of the signal points 83, 84, 85, and 86 in FIG. 9 is received, 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.
[0045]
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.
[0046]
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 outside area efficiency. However, considering a system in which receiver groups of antennas having different sizes are combined, a new transmission system can be configured.
[0047]
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, provides 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.
[0048]
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
[0049]

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 A₁And the distance between 4PSK signal points is 2A₁A compared to₂/ 2A₁Become. A₁= A₂If the distance between signal points is further reduced to １ ／, and the same error rate is to be obtained, the receiving sensitivity of twice the amplitude and the receiving sensitivity of four times in energy are required. To obtain four times the receiving sensitivity, the radius r of the antenna 32 of the second receiver 33₂Is twice as large as the radius r1 of the antenna 22 of the first receiver 23, that is, 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.
[0050]
When calculating to measure this optimization, the minimum required transmission energy of 4PSK is ｛(A₁+ A₂) / A1｝ 2 times this to 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
[0051]
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 23₂It can be seen from the graph that does not become so small.
[0052]
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. Also, the point 105 has the transmission energy doubled and r₂Becomes about 5 times. These are in a range that can be put to practical use.
[0053]
n₁₆Is smaller than 5 by A1 and A2
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, A (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.
[0054]
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 A is used in order to have compatibility with 4PSK.₁≧ A_TOMust be set to Let the radius of the antenna of the third receiver 43 be r₃Where r is the transmission and output signal n64₃Is calculated in the same way.
r₃ ²= $ 6²/ (N-1)｝ r₁ ²
Fig. 13 Radius r of 64-value QAM₃A graph such as the output multiple n.
[0055]
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.
[0056]
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.
[0057]
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.
[0058]
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), the signal points 203, 207, 211, and 215 are (00), and the 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.
[0059]
In addition to the transmission of 6-bit data, a feature of the present invention is that a receiver having three levels of different performance 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.
[0060]
Here, a method of arranging signal points necessary for achieving compatibility during three-layer transmission will be described.
[0061]
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.
[0062]
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. .
[0063]
In FIG. 15, 2 / 3A₂Only when they are separated. In this case, the signal point distance between signal points 201 and 202 inside first sub-divided signal point group 181 is A₂/ 6. The reception energy required for reception 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 defined as n64 times the 4PSK transmission energy,
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 an antenna having an eight-fold radius if six times the transmission energy of the 4PSK transmission energy is obtained, and using a six-times antenna if the transmission energy is nine 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.
[0064]
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 23 is used. The third data stream can be sent without damaging the received data of No. 33 and without any modification, and thus a great effect of both compatibility and development can be obtained.
[0065]
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 so as to be demodulated by an antenna having a smaller size, whereas the second receiver 33 uses the 16 of the transmitter 1 shown in FIG. The signal point of the value, that is, the 2-bit signal of 16QAM of the second data string can be completely demodulated. 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.
[0066]
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.
[0067]
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.
[0068]
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.
[0069]
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.
[0070]
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.
[0071]
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 second data stream reproducing unit 233 in FIG. 21 is set to transmit the carrier wave transmission information of the second data stream to the carrier wave reproducing circuit 131 so that the carrier wave is not extracted from the signal at the timing of the signal point 84.86.
[0072]
Assuming a case where the second data sequence cannot be demodulated, the transmitter 1 intermittently transmits a 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.
[0073]
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 64QAM₆₄Ask for
TH₆₄= (A₁+ A₂/ 2) / (A₁+ A₂)
And TH₁₆Is the same as However, the distance between signal points becomes smaller.
[0074]
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, the determination is made in step 313, and 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.
[0075]
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 a 4PSK receiver that is not considered, and 1 bit of the second data string can be reproduced by the second receiver 33, so that a total of 3 bits can be reproduced.
[0076]
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. Therefore, in order to demodulate 64-value QAM, it is necessary for the first discriminating / reproducing circuit 136 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.
[0077]
As shown in the signal space diagram of FIG. 27, there are three thresholds in the first quadrant.
[0078]
As shown in FIG. 27, three normalized thresholds, TH1₆₄And TH2₆₄And TH3₆₄Exists.
[0079]
TH1₆₄= (A₁+ A₃/ 2) / (A₁+ A₂)
TH2₆₄= (A₁+ A₂/ 2) / (A₁+ A₂)
TH3₆₄= (A₁+ A₂-A₃/ 2) / (A₁+ A₂)
Can be represented by
[0080]
By demodulating the received signal subjected to phase detection with this threshold value, the 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.
[0081]
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 at step 321 whether m = 64, and A is determined at step 323.₃Cannot be reproduced from the set value or less, the process proceeds to step 305, and the same flowchart as in FIG. 24 is performed, and the demodulation of the modified 16QAM is performed. Here, returning to step 323, A₃Is greater than or equal to the set value, the threshold is calculated in step 324, the three thresholds are sent to the first and second discriminating and 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.
[0082]
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.
[0083]
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.
[0084]
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.
[0085]
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.
[0086]
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.
[0087]
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.
[0088]
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, which contains information such as information on the arrangement interval of the phase synchronization time slot and information on the arrangement rule.
[0089]
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.
[0090]
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.
[0091]
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.
[0092]
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.
[0093]
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.
[0094]
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.
[0095]
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.
[0096]
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.
[0097]
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.
[0098]
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.
[0099]
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.
[0100]
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.
[0101]
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.
[0102]
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.
[0103]
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.
[0104]
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.
[0105]
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.
[0106]
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. 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.
[0107]
(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, data in the hierarchical channel of D1 is_1-1And D_1-2And 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. 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.
[0108]
Using this, the D1 channel is D_1-1, D_1-2Two sub-channels,_{D 2}Channel is D_2-1, D_2-2To two sub-channels.
[0109]
This will be described with reference to FIG. 85 showing the C / N value of the input signal and the hierarchical channel number._1-1Can be reproduced with the lowest input signal. When 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. As described above, as the CN increases, the total number of reproducible hierarchies 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 Lc from the transmitting antenna. Since the area 862 is also included in the range within the distance Lc, D_1-1Channels can also be played. Similarly, in area 864, D_2-1The channel can be played, and the D_2-2The channel can be played. In this manner, hierarchical transmission in which the number of transmission channels decreases stepwise with the deterioration of the CN value can be performed. By separating the data structure into a hierarchical structure and using the hierarchical 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. .
[0110]
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.
[0111]
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 combined with the D1 signal by the combiner 874a and input to the modulator 4. On the other hand, D_2-1, D_2-2The signal is error-correction-coded by the main encoder 872b and the sub-ECC encoder 873b in the second ECC encoder 871b, synthesized into a D2 signal by the synthesizer 874b, and input by the modulator 4. The main ECC encoder 872b 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.
[0112]
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, but ASK, PSK, or FSK modulation / demodulation may be used.
[0113]
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 the main ECC decoder 877a and sent to the combining unit 37. On the other hand, D_1-2The signal is error-corrected by the sub ECC decoder 878a and sent to the synthesizing unit 37. Similarly, in the second ECC decoder 876b, D_2-1The signal is sent to the main ECC decoder 877b by the D_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.
[0114]
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.
[0115]
Specifically, a method for differentiating the error correction capability between the main ECC decoders 877a and 877b and the sub ECC decoders 878a and 878b will be described. When a standard inter-code distance coding method such as Reed-Solomon code or BCH code is used for the sub ECC decoder, the product code or long coding method of both Reed-Solomon code and Reed-Solomon code is used for the main ECC decoder. By using an encoding method with a large inter-code distance for error correction, it is possible to make a difference in error correction capability. 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.
[0116]
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._1-24 shows the relationship between the C / N of the channel and the error rate after correction.
[0117]
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_1-1If the C / N is less than or equal to e, as 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.
[0118]
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 not as high as D1-1, the 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-Only 1 can be played.
[0119]
When C / N is improved and C / N = C, D_1-2Since the error rate 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.
[0120]
When C / N is further improved and C / N = b, D_2-1Decreases 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. As C / N = a, as shown at point 885a, D_2-2Error rate decreases to Eth and D_2-2The channel can be played.
[0121]
In this way, by using the error correction capability differentiation, the physical layer D₁, D₂The effect is obtained that the channel is further divided into two logical hierarchies and two hierarchical hierarchies can be transmitted.
[0122]
In this case, the data structure is made to be a hierarchical structure in which a part of the original signal can be reproduced even if the data of the high hierarchy is lost, and by combining with the hierarchical transmission of the present invention, the C / N is deteriorated like the analog transmission. 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.
[0123]
(Example 3)
Hereinafter, a third embodiment of the present invention will be described with reference to the drawings.
[0124]
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.
[0125]
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.
[0126]
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.
[0127]
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.
[0128]
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.
[0129]
In the first receiver 23, the radius r₁, And reproduces only the first data sequence in the received signal by the first data sequence reproducing unit 232, and outputs a low-resolution video signal such as an NTSC signal or a wide NTSC signal by the first image decoder 421. 425 and 426 are reproduced and output.
[0130]
In the second receiver 33, the radius r₂, And the first and second data streams are reproduced by the first data stream reproducing section 232 and the second data stream reproducing section 233, and the second image decoder 422 outputs an HDTV signal or the like. The high-resolution video output 427 or the video outputs 425 and 426 are reproduced and output.
[0131]
In the third receiver 43, the signal is received by the large-diameter antenna 33 having a radius r3, and the first data sequence reproducing unit 232, the second data sequence reproducing unit 233, and the third data sequence reproducing unit 234 transmit the first data sequence and the third data sequence. The second data stream and the third data stream are reproduced, and an ultra-high-resolution video output 428 such as an ultra-high-resolution HDTV for a video theater or a movie theater is output. 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.
[0132]
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.
[0133]
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.
[0134]
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.
[0135]
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 an ultra-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.
[0136]
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, the D1 signal from the second receiver 33 is input from the first input unit 521, expanded by the first expansion unit 522, becomes a double sampling rate by the oversampling unit 523, and becomes H by the vertical low-pass filter 524._LV_LThe signal is reproduced. D₂The signal is input from a second input unit 530, separated into three signals by a separation circuit 531, expanded and descrambled by a second expansion unit 532, a third expansion unit 533, and a 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, and becomes a horizontal high-frequency video signal by an oversampling unit 544 and a horizontal high-pass filter 545, and becomes a high-resolution video signal HD signal such as an HDTV by an adder 543. 547 is output. In some cases, an NTSC signal is also output.
[0137]
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-described procedure. The D3 signal is input from a third input unit 551, decompressed, descrambled, and synthesized by an ultra-high frequency band image decoder 552, and H_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 the output unit 554 outputs an ultra-high resolution video signal 555.
[0138]
Next, a specific multiplexing method of the multiplexer 401 mentioned in the description of FIG. 29 will be described. 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 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. Then D₂In the signal domain 602, difference information M1 between the HDTV and the NTSC of the first channel in the time domain corresponding to the first channel, that is, the aforementioned 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.
[0139]
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.
[0140]
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 D₃Of the domain 603 to obtain a super-resolution HDTV signal having the same program contents as the NTSC of channel 1 and having the image quality for a movie theater. The other channels 2 to 3 are reproduced in the same manner.
[0141]
FIG. 35 shows the configuration of another domain. First, the first channel of NTSC is arranged in L1. This L1 is located at the position of the domain 601 of the first time domain of the D1 signal, and at the head thereof, the information S11 including the descrambling information between NTSC and the demodulation information described in the first embodiment is entered. 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 a 6 Mbps NTSC compressed signal 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, 612, 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.
[0142]
36 is D₃Shows a case where six time domains are occupied and a super HDTV signal is transmitted. 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.
[0143]
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.
[0144]
FIG. 49 shows the horizontal polarization signal D of the first data string._V1And D of the vertical polarization signal DH1 and 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 TSC and HDTV can be reproduced on the other hand, so that there is a great effect that the two systems are compatible.
[0145]
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 NTSC TV 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.
[0146]
As described above, according to the third embodiment, there is a remarkable effect that ultra-high resolution HDTV, and digital TV broadcasting compatible with three signals of HDTV and NTSC-TV can be realized. In particular, when transmitted to a movie theater or the like, there is a new effect that images can be digitized.
[0147]
Here, the modified QAM according to the present invention is called SRQAM, and a specific error rate will be described.
[0148]
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.
[0149]
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.
If the error rate of the first data string is Pe1,
[0150]
(Equation 1)

[0151]
If the error rate of the second data string is Pe2
[0152]
(Equation 2)

[0153]
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.
[0154]
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.₁Only the error rate at the time of 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,
[0155]
(Equation 3)

[0156]
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 curve 900, D₁Has the effect that it can be reproduced at the same error rate.
[0157]
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. In summary, when the error rate is 22n = 1.5, 2.0, 2.5 at a value of 10 to the power of -1.5, D is smaller than that of 32QAM.₁Is improved by 5, 8, 10 dB and D₂Degrades by 2.5 dB.
[0158]
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.
In FIG. 102, a curve 900 indicates an error rate of 16QAM. Curves 901a, 901b, and 901c indicate error rates of the first data string D1 when n = 1.2, 1.5, and 1.8, respectively. Curves 902a, 902b, and 902c are each a second data string D₂Are the error rates when n = 1.2, 1.5, 1.8.
[0159]
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 apparent 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.
[0160]
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 currently 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. However, there is a problem that when the C / N is reduced due to the deterioration of the reception conditions such as the weather, the reception of the HDTV 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.
[0161]
On the other hand, in the case of the 32 SRQAM of the present invention, the first layer D₁Sends a medium resolution TV component such as NTSC,₂Can send only the high frequency component of HDTV. For example, in FIG. 105, the service area of the first layer expands to a point 70 miles as indicated by a point 910a, and the second layer retreats to a point 55 miles as indicated by 910b. The service area diagram of 32 SRQAM in FIG. 106 shows the difference in the service area area in this case. FIG. 106 illustrates FIG. 53 more specifically. In FIG. 106, areas 708, 703a, 703b, and 712 are respectively a 32QAM service area of the conventional system and a first layer D₁, The service area of the second layer D2, and the service area of the adjacent analog station.
[0162]
That is, in the conventional 32QAM, a service area of approximately 60 miles can be set. However, in practice, reception conditions were extremely unstable near the reception limit area due to changes in weather and topographic conditions.
[0163]
However, using the 32 SRQAM of the present invention, the NTSC grade mid-low range TV component is transmitted in the first layer D1, and the second layer D1 is transmitted.₂By transmitting the high-frequency TV component of HDTV, the radius of the service area of the high-resolution grade is reduced by 5 miles as shown in FIG. 106, but the radius of the service area of the medium-low resolution grade is increased by 10 miles or more as shown in FIG. Is born.
[0164]
As a result, by applying the SRQAM method of the present invention even in the unreceivable area which existed in the area where reception conditions were poor in the conventional method, at least in most of the receivers at least within the set service area. Transmission that enables reception of TV broadcasts at a low resolution grade becomes possible. Accordingly, the unreceivable area in the unreceivable area of a building or a lowland and the area which is affected by an adjacent analog station greatly decreases, and the number of receivers increases accordingly.
[0165]
Secondly, in the conventional method, only a receiver having an expensive HDTV receiver and a receiver can be received, so that only a part of the receiver can be viewed in the service area. However, according to the present invention, even a receiver having a conventional TV receiver of the conventional NTSC, PAL or SECAM system can receive a digital HDTV broadcast program in NTSC grade by adding only a digital receiver. It has the effect of becoming. Therefore, the receiver can view the program with less economic burden.
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.
[0166]
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.
[0167]
Now, as shown in the service area diagram of 32 SRQAM in FIG. 107, the same effect can be obtained when n = 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 SRQAM D₁And 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.
[0168]
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.
[0169]
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
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.
When used for PCM broadcasting, radio, and mobile phones, there is an effect that the service area is expanded.
[0170]
Further, in the embodiment, a sub-channel based on TDM is provided in combination with a time division multiplexing (TDM) system, and a code gain of error correction of each sub-channel is differentiated, so that a threshold value of each sub-channel can be differentiated. did it. SRQAM applies the signal point code division multiplexing (Constellation-Code Division Multiplex) of the present invention called "C-CDM" to 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. A multiplexing technique having such excellent effects.
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, a method of dividing a digital broadcast signal into two frequencies by FDM is considered. 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.
[0171]
At this time, a subchannel is first added to the first signal 720 using 32 SRQAM obtained by C-CDM. Next, a lower resolution component is added to the sub-channel having the lower threshold value. 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.
[0172]
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.
[0173]
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.
[0174]
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, other modulation schemes having signal points, for example, other forms of QAM, PSK, ASK, and the frequency domain can be regarded as signal points, and FSK can be multiplexed similarly.
[0175]
(Example 4)
Hereinafter, a fourth embodiment of the present invention will be described with reference to the drawings.
[0176]
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.
[0177]
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.
[0178]
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.
[0179]
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.
[0180]
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.
[0181]
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.
[0182]
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.
[0183]
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.
[0184]
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.
[0185]
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.
[0186]
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.
[0187]
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.
[0188]
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.
[0189]
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.
[0190]
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.
[0191]
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.
[0192]
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.
[0193]
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.
[0194]
By the way, the regulation conditions will be further relaxed in the full-scale spread of digital broadcasting in the future, and the hierarchical broadcasting of the present invention will enable HDTV broadcasting over a wide service area. Even at this time, by adopting the hierarchical broadcasting system of the present invention, an HDTV reception range as wide as that of the conventional system can be ensured, and NTSCTV can be used in a remote area or a competitive area which cannot be received by the conventional system. Since the program can be received with a high quality, there is an effect that the defective portion of the service area is greatly reduced.
[0195]
(Example 5)
Embodiment 5 is an embodiment in which the present invention is applied to amplitude modulation, that is, the ASK method. FIG. 57 is a diagram showing the arrangement of quaternary ASK signal signal points according to Embodiment 5, showing four signal points 721, 722, and 723. , 724. In the case of four values, 2-bit data can be transmitted in one cycle. The signal points 721, 722, 723, 724 can correspond to 00, 01, 10, 11 for example.
[0196]
To perform hierarchical transmission according to the present invention, as shown in FIG. 58, signal points 721 and 722 are treated as one group, that is, a first signal point group 725, and signal points 723 and 724 are treated as another group and a second group. Is defined as a 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 Lo between the signal point 722 and the signal point 723 is set to be larger than L.
[0197]
That is, Lo> L
And set. This is a feature of the hierarchical transmission system of the present invention. However, depending on the system design, L = Lo may be temporarily or permanently set depending on conditions and settings.
[0198]
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 724 are D₂= 1, the second data string D₂Data can be defined. Also in this case, it is 2 bits / symbol.
[0199]
By arranging the signal points in this way, the hierarchical transmission according to 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 transmission system is no different from the conventional equally spaced signal point method. 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 where the C / N ratio has deteriorated can be shown as 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 and between the signal points 723 and 724. That is, the second data string D₂Error rate becomes very high. However, as is clear 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 with a low error rate.
[0200]
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 hierarchical transmission in which only the information is reproduced can be performed.
[0201]
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 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 further band-limited by a filter 747 to become an ASK signal such as a VSB signal from an output unit 748. Is output.
[0202]
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 band-pass filtered by a filter 747. One sideband is removed while leaving a small carrier component like a transmission signal 749 in FIG. 62 (b). 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, an information amount corresponding to 4 bits / symbol of 16QAM can be transmitted in the same frequency band.
[0203]
Next, in the receiver 751 shown in the block diagram of FIG. 63, the signal received by the terrestrial antenna 32a passes through the input unit 752, is mixed with the signal from the variable oscillator 754 variable by channel selection in the mixer 753, Converted to frequency. Next, the signal is detected by a detector 755, becomes a baseband signal by an LPF 756, and becomes a first data string D by an identification reproducer 757.₁And the second data string D₂Is reproduced and output from the first data string output unit 758 and the second data string output unit 759.
[0204]
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 is input to 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.
[0205]
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 an input unit 752 of a receiver 751 in a TV receiver 781, and a signal of an arbitrary channel desired by the receiver is selected and demodulated by a 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 second 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.
[0206]
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.
[0207]
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.
[0208]
The 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 outputs H when the error rate is high._LV_LOutput a low-resolution video signal of the signal.
[0209]
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.
[0210]
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.
[0211]
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 an ASK 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.
[0212]
In the embodiment, the quaternary ASK signal is divided into two groups,₁, D₂The hierarchical transmission of each 1 bit of the two layers was performed. However, if an 8-level ASK signal is used as shown in FIG.₁, D₂, D₃1-bit hierarchical transmission of each of the three layers can be performed. In FIG. 68, D₃The signal points of the signal are binary points of signal points 721a and 721b, 722a and 722b, 723a and 723b, 724a and 724b, that is, 1 bit. Next, the signal point of D2 is a binary 1 bit of the signal point groups 721 and 722 and the signal point groups 723 and 724. D₃Are 1-bit binary values of the 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 By separating them, three-layer hierarchical transmission becomes possible.
[0213]
Performing three-layer video transmission using the three-layer hierarchical transmission system has been described in the third and third embodiments, and a detailed description of the operation will be omitted.
[0214]
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, HLV_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.
[0215]
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.
[0216]
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.
[0217]
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.
[0218]
Now, in this method, first, at timing 1, H_HV_H, H_HV_L, HLV_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.
[0219]
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.
[0220]
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, HHV_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.
[0221]
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.
[0222]
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.
[0223]
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.
[0224]
FIG. 77 is a time allocation diagram in the case where hierarchical 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. Is shown. 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 arranged in the data 823, 823a, 823b.
[0225]
Here, a logical hierarchical transmission by differentiating the error correction capability described in the second embodiment is added. 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_1-1The data 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.
[0226]
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, in addition to HLVL, 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.
[0227]
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.
[0228]
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_LIs input to the decompression section 503 and decompressed. Next, H of the first channel_LV_H, H_HV_L, H_HV_HAre decompressed, input to a predetermined input unit of the synthesizer 556 via the switch 812a, are 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.
[0229]
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 each signal is 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.
[0230]
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.
[0231]
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.
[0232]
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.
[0233]
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.
[0234]
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.
[0235]
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.
[0236]
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.
[0237]
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 1 bit each of D1 and D2, that is, 2 bits in total, 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 transmission method of FSK can be used for the hierarchical broadcasting of the video signal described in the third, fourth, and fifth embodiments.
[0238]
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.
[0239]
Referring to FIG. 84, the magnetic recording / reproducing device 851 separates and compresses an input video signal by the image encoder 401, and outputs the H signal to the first data string input unit 743 in the input unit 742._LV_LThe low-frequency video signal such as the component is input to the second data string input unit 744 as H_HV_HA high-frequency video signal including components and the like is input and input to a modulation unit 749 in the modem 852. The operation so far is almost the same as the transmitter of the fifth embodiment shown in FIG. The modulated signal is recorded on a magnetic tape 855 by a recording / reproducing circuit 853 and a magnetic head 854. This recording method can be a physical hierarchical recording by modifying the conventional digital multi-level recording, or a hierarchical recording by phase modulation or phase amplitude modulation as in the first and third embodiments. Hierarchical recording with multiple tracks on a magnetic tape is also possible. Hierarchical recording by changing the data transmission rate is also possible. Further, it is also possible to perform logical hierarchical recording by differentiating data by changing the error correction capability.
[0240]
Next, when reproducing, the magnetic tape 855 sends a reproduction signal to the modem 852 by the magnetic head 854 and the magnetic reproduction circuit 853. The following operations are substantially the same as those of the first, third, and fourth embodiments. The first data sequence D1 and the second data sequence D2 are reproduced by the demodulation unit 760, and a video signal is output by the image decoder 422. In this case, since the hierarchical recording is performed, when the C / N is high, a high-resolution TV signal such as an HDTV can be reproduced. On the other hand, when the C / N is low or when reproduction is performed by a magnetic reproducing device having a low function, an NTSC, TV signal or a low-resolution NTSCTV signal is output.
[0241]
As described above, in the magnetic reproducing apparatus using the present invention, even when the C / N ratio is low or the error rate is high, it is possible to reproduce an image having the same content with a low resolution or a low image quality.
[0242]
(Example 6)
In the sixth embodiment, the present invention is applied to 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.
[0243]
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.
[0244]
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.
[0245]
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.
[0246]
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.
[0247]
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.
[0248]
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.
[0249]
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 or less, LH, ie, D_1-2The signal is a frequency component HL of 250 or more and 500 or less, that is, the D2-1 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.
[0250]
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.
[0251]
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.
[0252]
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.
[0253]
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.
[0254]
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 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_OBelow, 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._1-1Channel D broadcasts program D, 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 a channel, a 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. The effect is also obtained.
[0255]
One feature of the hierarchical transmission scheme of the present invention is to improve the frequency utilization efficiency, but for some receivers the power utilization efficiency is significantly 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.
[0256]
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.
[0257]
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.
[0258]
In addition, when the hierarchical 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, 16 QAM and 32 QAM, it goes without saying that the present invention can be applied to 64 QAM, 128 QAM, 256 QAM, 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.
[0259]
【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 if the receiver has only n-m demodulation capability of n <m for a multi-level modulated wave obtained by modulating data, it is possible to obtain a compatible and developable transmission device capable of demodulating n-value 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.
[0260]
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.
25A is a signal vector diagram of 8-level QAM according to the first embodiment of the present invention, and FIG. 25B 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 is a block diagram of a transmitter according to a fifth embodiment of the present invention.
FIG. 62 (a) is a frequency distribution diagram of an ASK modulation signal according to the fifth embodiment of the present invention, and FIG. 62 (b) is a frequency distribution diagram of the ASK modulation signal according to the fifth embodiment of the present invention.
FIG. 63 is a block diagram of a receiver according to a fifth embodiment of the present invention.
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 is a signal point arrangement diagram of an 8-level ASK signal in Embodiment 5 of the present invention.
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.
74 (a) is a block diagram of an image decoder according to Embodiment 5 of the present invention, and FIG. 74 (b) is a time allocation diagram of transmission signals of Embodiment 5 according to 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 showing 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 is a diagram illustrating a relationship between a distance from a transmission 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.
FIG. 108 is a TV signal frequency distribution diagram according to the third embodiment of the present invention.
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.
[Explanation of symbols]
1 transmitter
4 Modulator
6 Antenna
6a Ground antenna
10 satellites
12 Repeater
23 1st receiver
25 Demodulator
33 Second receiver
35 Demodulator
43 Third receiver
51 Digital transmitter
85 signal points
91 First divided signal point cloud
401 First Image Encoder
703 SRQAM coverage area
708 Reception area of the conventional method
722 carrier
725 Spectrum

Claims (5)

A receiving device for receiving a terrestrial digital broadcast signal and a satellite digital broadcast signal,
The satellite digital broadcast signal includes at least information on a first data sequence and a second data sequence,
The first data sequence is m-valued PSK-modulated, the second data sequence is n-valued PSK-modulated,
The first data sequence has demodulation information for demodulating a modulation signal corresponding to the second data sequence, and the demodulation information includes information on the value of n.
A first demodulation unit for demodulating the terrestrial digital broadcast signal;
A second demodulation unit that demodulates the modulated signal corresponding to the first data sequence to m-value PSK and demodulates the modulated signal corresponding to the second data sequence to n-value PSK.
The receiving device, wherein the second demodulation unit demodulates a modulation signal corresponding to the second data sequence based on the demodulation information. A receiving device for receiving a digital modulation signal and a satellite digital broadcast signal,
The digital modulation signal is ASK modulation or PSK modulation or QAM modulation,
The satellite digital broadcast signal includes at least information on a first data sequence and a second data sequence,
The first data sequence is m-valued PSK-modulated, the second data sequence is n-valued PSK-modulated,
The first data sequence has demodulation information for demodulating a modulation signal corresponding to the second data sequence, and the demodulation information includes information on the value of n.
A first demodulation unit that performs ASK demodulation, PSK demodulation, or QAM demodulation on the digital modulation signal;
A second demodulation unit that demodulates the modulated signal corresponding to the first data sequence to m-value PSK and demodulates the modulated signal corresponding to the second data sequence to n-value PSK.
The receiving device, wherein the second demodulation unit demodulates a modulation signal corresponding to the second data sequence based on the demodulation information. A receiving device for receiving a digital modulation signal and a terrestrial digital broadcast signal,
  The digital modulation signal is ASK modulation or PSK modulation or QAM modulation,
  The terrestrial digital broadcast signal includes information on at least a first data stream and a second data stream,
  The first data string is m-value PSK modulation or m-value QAM modulation, and the second data string is n-value PSK modulation or n-value QAM modulation;
  The first data sequence has demodulation information for demodulating a modulation signal corresponding to the second data sequence, and the demodulation information includes information on the value of n.
  A first demodulation unit that performs ASK demodulation, PSK demodulation, or QAM demodulation on the digital modulation signal;
  The modulation signal corresponding to the first data sequence is subjected to m-value PSK demodulation or m-value QAM demodulation, and the modulation signal corresponding to the second data sequence is subjected to n-value PSK demodulation or n-value QAM demodulation. And two demodulation units,
  The receiving device, wherein the second demodulation unit demodulates a modulation signal corresponding to the second data sequence based on the demodulation information. 4. The receiving device according to claim 1 , wherein the value of m is 4 or less. The receiving device according to claim 1 , wherein the value of n is 4 or more.

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