JP2004208071A

JP2004208071A - Diversity receiver

Info

Publication number: JP2004208071A
Application number: JP2002375278A
Authority: JP
Inventors: Yukio Otaki; 幸夫大滝
Original assignee: Alps Electric Co Ltd
Current assignee: Alps Alpine Co Ltd
Priority date: 2002-12-25
Filing date: 2002-12-25
Publication date: 2004-07-22

Abstract

<P>PROBLEM TO BE SOLVED: To provide a diversity receiver which can receive digital TV signals and analog TV signals and prevents out-of-synchronization resulting from antenna changeover when receiving digital TV signals and prevents the occurrence of ghosts when receiving analog TV signals and has partial circuits shared to simplify the configuration. <P>SOLUTION: A phase control means 12 is provided which relatively controls phases of first intermediate frequency signals to be inputted to an addition means 5, and approximately opposite phases are given to delay waves respectively included in the first intermediate frequency signals to be inputted to the addition means 5 when receiving analog TV signals, and almost the same phases are given to the first intermediate frequency signals to be inputted to the addition means 5 when receiving digital TV signals. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
この発明は、テレビジョン信号等を受信するダイバーシティ受信装置に関し、特に車載用として好適なダイバーシティ受信装置に関する。
【０００２】
【従来の技術】
図７は例えばアナログＴＶ信号等を受信する従来のダイバーシティ受信装置の構成を示し、複数の受信アンテナ５７と、アンテナ切替部５５と、受信機５６と、受信状態検知回路５３と、切替制御回路５４と、受信機５６から得られる電界強度信号の電界強度を検出する電界強度検出回路５１と、電界強度検出回路５１からの出力信号に基づいて切替閾値を制御する閾値制御回路５２とを有している。
【０００３】
そして、電界強度検出回路５１は、受信機５６から得られる電界強度信号に応じて電界強度を検出して、電界強度信号を閾値制御回路５２に供給する。閾値制御回路５２は、電界強度検出信号に基づいて切替閾値を設定して、閾値設定信号を切替切替制御回路５４の一方の入力に供給する。閾値制御回路５２は、受信電界強度が弱くなるにつれて連続的に切替閾値を上昇させる。
【０００４】
また、受信状態検出回路５３は受信状態を検知して受信状態検知信号を切替制御回路５４の他方の入力に供給する。
切替制御回路５４は、閾値設定信号及び受信状態検知信号に基づいて切替制御信号を生成し、切替制御信号をアンテナ切替部５５に供給する。アンテナ切替部５５は切替制御信号に応じて複数の受信アンテナ５７から択一する（例えば、特許文献１。）。
【０００５】
【特許文献１】
特開平０７−１７０２２０号公報（図１）
【０００６】
一方、図８はデジタルＴＶ信号を受信する従来のダイバーシティ受信装置を示し、複数のアンテナ６１のいずれかがアンテナ切替部６２によって選択され、選択されたアンテナからのデジタルＴＶ信号はチューナ６３で同調をとる。その出力はＩＦ部６４を介して同期再生部６５に送られて、その出力はＯＦＤＭデコーダ６６に加えられる。ＯＦＤＭデコーダ６６の復調出力はＭＰＥＧデコーダ６７に加えられて、これにより得られたビデオ信号で表示部６８に画像が表示される。
【０００７】
ここで、ＯＦＤＭデコーダ６６及びＭＰＥＧデコーダ６７から出力されるエラー率（ＢＥＲ）を制御部６９に入力する。そして、出力されたエラー率が、受信した映像の劣化が始まる時のエラー率（閾値）より大きくなったとき、受信状態が悪化したと判断し、制御部６９はダイバー動作を開始してアンテナ６１の切替を行うためのダイバー制御信号を発生し、この信号をアンテナ切替部６２に与えて、アンテナ６１の切り替えを行うようになっている。
【０００８】
そして、アンテナ切替については、ＯＦＤＭ信号の有効シンボル内でアンテナ切替をすると、データの欠落を招き、再生条件が悪化するので、有効シンボル間に設けられているガードインターバルの受信中で切り替えるようにしている（例えば、特許文献２参照。）。
【０００９】
【特許文献２】
特開２００２−３３６８８号公報（図１）
【００１０】
【発明が解決しようとする課題】
上記図７の構成では、受信するのに最適なアンテナを選択できるが、アンテナで直接波と反射波とが受信された場合は互いの位相関係によって画面にゴーストが現れる。
また、図８の構成では、アンテナの切替はガードインターバルの期間で行っているが、ガードインターバルには、自己相関を検出するために有効シンボル内の一部の信号と同じ信号を挿入しているので、アンテナ切替時にガードインターバル内の信号が乱され、自己相関が検出不可能となるおそれがある。その結果、復調時にデジタル信号の同期がとれず受信障害を招くという問題が発生する。
【００１１】
本発明は、デジタルＴＶ信号とアナログＴＶ信号とを受信でき、しかもデジタルＴＶ信号を受信する場合にアンテナ切替による同期はずれを防止し、アナログＴＶ信号を受信する場合にゴーストの発生を防止し、さらに、回路の一部を供用して構成を簡素化したダイバーシティ受信装置を提供することを目的とする。
【００１２】
【課題を解決するための手段】
上記課題に対して、本発明は、複数のアンテナで受信した放送信号をそれぞれ第一中間周波信号に変換する第一ミキサと、一対毎の第一中間周波信号同士を加算する加算手段と、加算された第一中間周波信号に含まれるアナログＴＶ信号を受信するアナログ受信部と、加算された第一中間周波信号に含まれるデジタルＴＶ信号を受信するデジタル受信部とを備え、前記加算手段に入力される第一中間周波信号同士の位相を相対的に制御する位相制御手段を設け、前記アナログＴＶ信号の受信時には前記加算手段に入力される第一中間周波信号にそれぞれ含まれる遅延波同士の位相をほぼ逆相とし、前記デジタルＴＶ信号の受信時には前記加算手段に入力される第一中間周波信号の互いの位相をほぼ同相とした。
【００１３】
また、前記アナログ受信部には前記アナログＴＶ信号のマルチパスを検出してマルチパス検出信号を出力するマルチパス検出手段を設け、前記デジタル受信部は加算された第一中間周波信号を第二中間周波信号に変換する第二ミキサと、第二中間周波信号を復調するＯＦＤＭ復調手段とを有し、前記位相制御手段は前記各第一ミキサに供給される局発振信号同士の相対的な位相を変える第一の移相手段と、前記マルチパス検出信号と前記第二中間周波信号とが入力され、前記マルチパス検出信号が所定の閾値以下のとき又は前記第二中間周波信号がピークレベル以下の時に移相信号を発生する第一の移相信号発生手段とからなり、前記移相信号を前記第一の移相手段に入力した。
【００１４】
また、前記アンテナの数を２とした。
【００１５】
また、前記アンテナの数を４とし、前記加算手段は一対毎の前記第一ミキサから出力される前記第一中間周波信号をそれぞれ加算する二つの第一の加算手段と、前記二つの第一の加算手段から出力される第一中間周波信号を加算する第二の加算手段とからなり、前記第二の加算手段から出力される第一中間周波信号を前記アナログ受信部と前記デジタル受信部とに入力した。
【００１６】
また、前記アンテナの数を４とし、前記加算手段は一対毎の前記第一ミキサから出力される前記第一中間周波信号をそれぞれ加算する二つの第一の加算手段と、前記二つの第一の加算手段から出力される第一中間周波信号を加算する第二の加算手段とからなり、前記第二の加算手段から出力される第一中間周波信号を前記アナログ受信部に入力し、前記二つの第一の加算手段の後段にそれぞれ前記デジタル受信部を設け、前記デジタル受信部の各ＯＦＤＭ復調手段から出力されるベースバンド信号を合成した。
【００１７】
また、前記二つのＯＦＤＭ復調手段から出力されるベースバンド信号同士の位相を比較して移相信号を出力する第二の移相信号発生手段と、前記二つのベースバンド信号同士を加算する第三の加算手段と、一方の前記ＯＦＤＭ復調手段と前記第三の加算手段との間に介挿された第二の移相手段とを設け、前記第二の移相信号発生手段から出力された前記移相信号を前記第二の移相手段に入力した。
【００１８】
【発明の実施の形態】
以下、本発明のダイバーシティ受信装置を図面に従って説明する。図１は第一の実施形態の構成を示す回路図、図２はそれに使用される移相信号発生手段の回路図、図３は第二の実施形態の構成を示す回路図、図４はそれに使用される移相信号発生手段の回路図、図５は第三の実施形態の構成を示す回路図、図６はそれに使用される移相信号発生手段の回路図である。
【００１９】
先ず、図１において、複数のアンテナ１（この実施形態では２個）で受信した放送信号（アナログＴＶ信号及びデジタルＴＶ信号）はそれぞれ二つの第一ミキサ２（２ａと２ｂ）によって第一中間周波信号に変換される。二つの第一ミキサ２ａ、２ｂには発振器３から局部発振信号が供給されるが、一方の第一ミキサ２ａには第一の移相手段４を介して供給される。
【００２０】
二つの第一ミキサ２ａ、２ｂから出力される第一中間周波信号は第一の加算手段５によって加算される。加算された第一中間周波信号はアナログ受信部６とデジタル受信部７とに入力される。アナログ受信部６は音声／映像復調手段（図示せず）、マルチパス検出手段６ａ等を有し、第一中間周波信号におけるアナログＴＶ信号を復調して音声信号Ａ及び映像信号Ｖを出力すると共にマルチパス検出信号Ｍを出力する。マルチパス検出信号ＭはアナログＴＶ信号における直接波と反射波（遅延波ともいう）との相対レベル比として出力される。レベル差が少ないほどマルチパス検出信号のレベルが大きくなる。そして、マルチパス検出信号Ｍは第一の移相信号発生手段８に入力される。この第一の移相信号発生手段８と第一の移相手段４とによって位相制御手段１２が構成されている。
【００２１】
一方、デジタル受信部７は入力された第一中間周波信号を第二中間周波信号に変換する第二ミキサ９と、第二中間周波信号を復調するＯＦＤＭ復調手段１０と復調によって得られたデジタルのベースバンド信号のビットエラーを訂正する誤り訂正手段１１を有し、第二ミキサ９には別の発振器（図示せず）から局部発振信号が供給される。また、ＯＦＤＭ復調手段１０はデジタルＴＶ信号のスペクトラム歪みを検出してその検出信号を出力する。そして、第二中間周波信号ＩＦ２（デジタルＴＶ信号）とスペクトラム歪み信号Ｓとが第一の移相信号発生手段８に入力される。
【００２２】
第一の移相信号発生手段８は図２に示すように、マルチパス検出信号Ｍが入力されるマルチパス判定手段８ａと、第二中間周波信号ＩＦ２が入力される電力判定手段８ｂと、スペクトラム歪み信号Ｓが入力される歪み判定手段８ｃと、移相信号出力手段８ｄとを有する。
なお、マルチパス検出信号ＭはアナログＴＶ信号の受信時に入力され、第二中間周波信号ＩＦ２とスペクトラム歪み信号ＳとはデジタルＴＶ信号の受信時に入力される。
【００２３】
マルチパス判定手段８ａは、マルチパス検出信号Ｍが所定の閾値以上のときには移相信号出力手段８ｄに対して制御信号を出力し、電力判定手段８ｂは第二中間周波信号ＩＦ２がピーク値以下のときには移相信号出力手段８ｄに対して制御信号を出力し、また、歪み判定手段８ｃはスペクトラム歪みが所定レベル以上のときに移相信号出力手段８ｄに対して制御信号を出力する。そして、移相信号出力手段８ｄはマルチパス判定手段８ａ、電力判定手段８ｂ、歪み判定手段８ｃのいずれかから制御信号が入力されている間は移相信号Φを出力する。
そして、移相信号出力手段８ｄから出力された移相信号Φは第一の移相手段４に入力され、その結果、一方の第一ミキサ２ａから出力される第一中間周波信号の位相が変えられる。
【００２４】
そして、アナログＴＶ信号の受信時には一方の第一ミキサ２ａから出力される第一中間周波信号に含まれる遅延波の位相が他方の第一ミキサ２ｂから出力される第一中間周波信号に含まれる遅延波の位相とは逆相となるように制御されて第一の加算手段５では遅延波同士はキャンセルされる。すなわち、マルチパス検出信号Ｍのレベルが閾値以下になるまで、一方の第一ミキサ２ａに供給される局部発振信号の位相、従って第一ミキサ２ａから出力される第一中間周波信号の位相が制御されて、その結果として一方の第一ミキサ２ａから出力される第一中間周波信号に含まれる遅延波の位相が他方の第一ミキサ２ｂから出力される第一中間周波信号に含まれる遅延波の位相とはほぼ逆相となる。よって、アナログ受信部６ではマルチパス検出信号Ｍのレベルが下がり映像信号Ｖにはゴーストが発生しない。
【００２５】
また、デジタルＴＶ信号の受信時では、第二中間周波信号ＩＦ２の電力がピークとなるよう一方の第一ミキサ２ａから出力される第一中間周波信号の位相が制御される。よって、第二中間周波信号ＩＦ２はピークとなるように制御され、同期はずれが無くＳ／Ｎの向上したデジタルＴＶ信号の可能となる。また、第二中間周波信号におけるスペクトラム歪みも軽減される。
【００２６】
図３においては、４個のアンテナ１で受信した放送信号（アナログＴＶ信号及びデジタルＴＶ信号）はそれぞれ４個の第一ミキサ２（２ａ〜２ｄ）によって第一中間周波信号に変換される。各第一ミキサ２には発振器３から局部発振信号が供給されるが、このうちの３個の第一ミキサ２ａ〜２ｃにはそれぞれ第一の移相手段４ａ〜４ｃを介して供給される。
【００２７】
四個のミキサ２ａ〜２ｄのうちの一方の対の第一ミキサ２ａ、２ｂから出力される第一中間周波信号は一方の第一の加算手段５ａよって加算され、他方の対の第一ミキサ２ｃ、２ｄから出力される第一中間周波信号は他方の第一の加算手段５ｂよって加算される。加算されたそれぞれの第一中間周波信号は更に第２の加算手段１３によって加算される。第二の加算手段１３から出力された第一中間周波信号はアナログ受信部６と、デジタル受信部７とに入力される。そして、マルチパス検出手段６ａから出力されたマルチパス検出信号Ｍと第二ミキサ９から出力された第二中間周波信号ＩＦ２とＯＦＤＭ復調手段１０から出力されたスペクトラム歪み信号Ｓとが第一の移相信号発生手段１４に入力される。第一の移相信号発生手段１４と第一の移相手段４ａ〜４ｃとによって位相制御手段１５が構成されている。
【００２８】
第一の移相信号発生手段１４は図４に示すように、マルチパス検出信号Ｍが入力されるマルチパス判定手段１４ａと、第二中間周波信号ＩＦ２が入力される電力判定手段１４ｂと、スペクトラム歪み検出信号Ｓが入力される歪み判定手段１４ｃと、移相信号出力手段１４ｅとを有する。そして、マルチパス判定手段１４ａ、電力判定手段１４ｂ、歪み判定手段１４ｃから移相信号出力手段１４ｅに制御信号が入力されることは図２と同じである。ただし、移相信号出力手段１４ｅは三つの出力端を有し、各出力端から順次に移相信号Φ１〜Φ３が出力され、それらは第一の移相手段４ａ〜４ｃに順次入力される。その結果、三つの第一ミキサ２ａ〜２ｃから出力される第一中間周波信号の位相が残りの第一ミキサ２ｄから出力される第一中間周波信号の位相を基準として順次変えられる。
【００２９】
そして、アナログＴＶ信号の受信時には一方の対の第一ミキサ２ａ、２ｂからそれぞれ出力される第一中間周波信号に含まれる遅延波同士の移相が互いにほぼ逆相となるように制御され、同様に他方の対の第一ミキサ２ｃ、２ｄからそれぞれ出力される第一中間周波信号に含まれる遅延波同士の移相が互いにほぼ逆相となるように制御され、さらに、二つの第一の加算手段５ａ、５ｂからそれぞれ出力される第一中間周波信号に含まれる遅延波同士の移相が互いにほぼ逆相となるように制御される。よって、第二の加算手段１３では遅延波同士はキャンセルされ、アナログ受信部６ではマルチパス検出信号のレベルが下がり映像信号Ｖにはゴーストが発生しない。
【００３０】
また、デジタルＴＶ信号の受信時では、同様に一方の対の第一ミキサ２ａ、２ｂからそれぞれ出力される第一中間周波信号の位相がほぼ同相となると共に、他方の対の第一ミキサ２ｃ、２ｄからそれぞれ出力される第一中間周波信号の位相がほぼ同相となり、さらに、一方の第一の加算手段５ａから出力される第一中間周波信号の位相と他方の第一の加算手段５ｂから出力される第一中間周波信号の位相とがほぼ同相となるように制御される。よって、第二中間周波信号ＩＦ２の電力がピークとなる。さらに、スペクトラム歪みも軽減される。
【００３１】
図５においては、４個のアンテナ１で受信した放送信号（アナログＴＶ信号及びデジタルＴＶ信号）はそれぞれ４個の第一ミキサ２（２ａ〜２ｄ）によって第一中間周波信号に変換される。各第一ミキサ２には発振器３から局部発振信号が供給されるが、３個の第一ミキサ２ａ〜２ｃにはそれぞれ第一の移相手段４ａ〜４ｃを介して供給される。
【００３２】
一方の対の第一ミキサ２ａ、２ｂからそれぞれ出力される第一中間周波信号は一方の第一の加算手段５ａよって加算され、他方の対の第一ミキサ２ｃ、２ｄからそれぞれ出力される第一中間周波信号は他方の第一の加算手段５ｂよって加算される。加算されたそれぞれの第一中間周波信号は更に第２の加算手段１３によって加算される。第二の加算手段１３から出力された第一中間周波信号はアナログ受信部６に入力される。
【００３３】
また、一方の第一の加算手段５ａから出力された第一中間周波信号と他方の第一の加算手段５ｂから出力された第一中間周波信号とはデジタル受信部７に入力される。デジタル受信部７は二つの第二ミキサ９ａ、９ｂと二つのＯＦＤＭ復調手段１０ａ、１０ｂと、各復調手段１０ａ、１０ｂから出力されるベースバンド信号の周波数軸の位相を比較してその位相差信号を出力する第二の移相信号発生手段１６と、他方のＯＦＤＭ復調手段１０ｂからのベースバンド信号の位相を変える第二の移相手段１７と、ベースバンド信号を加算する第三の加算手段１７等を有する。そして、一方の加算手段５ａから出力された第一中間周波信号は一方の第二ミキサ９ａに入力され、他方の加算手段５ｂから出力された第一中間周波信号は他方の第二ミキサ９ｂに入力される。二つの第二ミキサ９ａ、９ｂには別の発振器（図示せず）から局部発振信号が供給されている。
【００３４】
ここで、アナログ受信部６のマルチパス検出手段６ａから出力されるマルチパス検出信号Ｍと、二つの第二ミキサ９ａ、９ｂから出力される第二中間周波信号ＩＦ２と二つのＯＦＤＭ復調手段１０ａ。１０ｂから出力されるスペクトラム歪み信号Ｓとが第一の移相信号発生手段１９に入力される。第一の移相信号発生手段１９と第一の移相手段４ａから４ｃとによって位相制御手段２０が構成される。
【００３５】
第一の移相信号発生手段１９は図６に示すように、マルチパス検出信号Ｍが入力されるマルチパス判定手段１９ａと、二つの第二中間周波信号ＩＦ２が入力される電力判定手段１９ｂ１、１９ｂ２と、スペクトラム歪み検出信号Ｓが入力される歪み判定手段１９ｃ１、１９ｃ２と、移相信号出力手段１９ｆとを有する。電力判定手段１９ｂ１及び１９ｂ２と、歪み判定手段１９ｃ１及び１９ｃ２は図２に示すものと同一構成である。そして、マルチパス判定手段１９ａ、二つの電力判定手段１９ｂ１、１９ｂ２、二つの歪み判定手段１９ｃ１、１９ｃ２からそれぞれ移相信号出力手段１９ｆに制御信号が入力される。
【００３６】
移相信号出力手段１９ｆは三つの出力端を有し、各出力端から移相信号Φ１〜Φ３が順次出力され、それがそれぞれ第一の移相手段４ａ〜４ｃに順次入力される。その結果、三つの第一ミキサ２ａ〜２ｃから出力される第一中間周波信号の位相が残りの第一ミキサ２ｄから出力される第一中間周波信号の位相を基準として順次変えられる。
【００３７】
そして、アナログＴＶ信号の受信時には一方の対の第一ミキサ２ａ、２ｂからそれぞれ出力される第一中間周波信号に含まれる遅延波同士の移相が互いにほぼ逆相となるように制御され、同様に他方の対の第一ミキサ２ｃ、２ｄからそれぞれ出力される第一中間周波信号に含まれる遅延波同士の移相が互いにほぼ逆相となるように制御され、さらに、二つの第一の加算手段５ａ、５ｂからそれぞれ出力される第一中間周波信号に含まれる遅延波同士の移相が互いにほぼ逆相となるように制御される。よって、第二の加算手段１３では遅延波同士はキャンセルされ、アナログ受信部６ではマルチパス検出信号のレベルが下がり映像信号Ｖにはゴーストが発生しない。
【００３８】
また、デジタルＴＶ信号の受信時では、同様に第一ミキサ２ａ〜２ｃからそれぞれ出力される第一中間周波信号の位相が制御されて、一方の第二ミキサ９ａから出力される第二中間周波信号ＩＦ２の電力と他方の第二ミキサ９ｂから出力される第二中間周波信号ＩＦ２の電力とがそれぞれピークとなるように制御される。さらに、スペクトラム歪みも軽減するように制御される。
【００３９】
そして、第二の移相信号発生手段１６からの移相信号によって第二の移相手段１７が制御され、第三の加算手段１８に入力される二つのベースバンド信号の周波数軸の位相が一致する。これによって、第三の加算手段１８からはビットエラーの少ないベースバンド信号が出力されるが、ビットエラーが有れば誤り訂正手段１１によって訂正される。
【００４０】
【発明の効果】
以上のように、本発明は、加算手段に入力される第一中間周波信号同士の位相を相対的に制御する位相制御手段を設け、アナログＴＶ信号の受信時には加算手段に入力される第一中間周波信号にそれぞれ含まれる遅延波同士の位相をほぼ逆相とし、デジタルＴＶ信号の受信時には加算手段に入力される第一中間周波信号の互いの位相をほぼ同相としたので、ゴーストのないアナログＴＶ信号が受信できると共に同期はずれがなくしかもＳ／Ｎの向上したアナログＴＶ信号が受信できるダイバーシティ受信装置を簡単な構成で実現できる。
【００４１】
また、位相制御手段は各第一ミキサに供給される局発振信号同士の相対的な位相を変える第一の移相手段と、マルチパス検出信号と第二中間周波信号とが入力され、マルチパス検出信号が所定の閾値以下のとき又は第二中間周波信号がピークレベル以下の時に移相信号を発生する第一の移相信号発生手段とからなり、移相信号を第一の移相手段に入力したので、アナログＴＶ信号の受信時には第一の加算手段に入力される一対の第一中間周波信号にそれぞれ含まれる遅延波同士の位相をほぼ逆相とし、デジタルＴＶ信号の受信時には一対の第一中間周波信号の互いの位相をほぼ同相とすることができる。
【００４２】
また、アンテナの数を２としたので、最も簡単なダイバーシティ受信装置を構成できる。
【００４３】
また、アンテナの数を４とし、加算手段は一対毎の第一ミキサから出力される第一中間周波信号をそれぞれ加算する二つの第一の加算手段と、二つの第一の加算手段から出力される第一中間周波信号を加算する第二の加算手段とからなり、第二の加算手段から出力される第一中間周波信号をアナログ受信部とデジタル受信部とに入力したので、アナログＴＶ信号の受信時とデジタルＴＶ信号の受信時共にＳ／Ｎを大幅に向上できる。また、デジタル受信部が１系統で構成できる。
【００４４】
また、アンテナの数を４とし、加算手段は一対毎の第一ミキサから出力される第一中間周波信号をそれぞれ加算する二つの第一の加算手段と、二つの第一の加算手段から出力される第一中間周波信号を加算する第二の加算手段とからなり、第二の加算手段から出力される第一中間周波信号をアナログ受信部に入力し、二つの第一の加算手段の後段にそれぞれデジタル受信部を設け、デジタル受信部の各ＯＦＤＭ復調手段から出力されるベースバンド信号を合成したので、復調されるベースバンド信号のＳ／Ｎが一層改善される。
【００４５】
また、二つのＯＦＤＭ復調手段から出力されるベースバンド信号同士の位相を比較して移相信号を出力する第二の移相信号発生手段と、二つのベースバンド信号同士を加算する第三の加算手段と、一方のＯＦＤＭ復調手段と第三の加算手段との間に介挿された第二の移相手段とを設け、第二の移相信号発生手段から出力された移相信号を第二の移相手段に入力したので、第三の加算手段に入力されるベースバンド信号の周波数軸の位相を同相とすることができてビットエラーを少なくできる。
【図面の簡単な説明】
【図１】本発明のダイバーシティ受信装置の第一の実施形態の構成を示す回路図である。
【図２】本発明の第一の実施形態に使用される第一の移相信号発生手段の回路図である。
【図３】本発明のダイバーシティ受信装置の第二の実施形態の構成を示す回路図である。
【図４】本発明の第二の実施形態に使用される第一の移相信号発生手段の回路図である。
【図５】本発明のダイバーシティ受信装置の第三の実施形態の構成を示す回路図である。
【図６】本発明の第三の実施形態に使用される第一の移相信号発生手段の回路図である。
【図７】従来のダイバーシティ受信装置の構成を示す回路図である。
【図８】従来のダイバーシティ受信装置の他の構成を示す回路図である。
【符号の説明】
１アンテナ
２、２ａ、２ｂ、２ｃ、２ｄ第一ミキサ
３発振器
４、４ａ、４ｂ、４ｃ第一の移相手段
５、５ａ、５ｂ第一の加算手段
６アナログ受信部
６ａマルチパス信号検出手段
７デジタル受信部
８、１４、１９第一の移相信号発生手段
９、９ａ、９ｂ第二ミキサ
１０、１０ａ、１０ｂＯＦＤＭ復調手段
１１誤り訂正手段
１２、１５、２０位相制御手段
１３第二の加算手段
１６第二の移相信号発生手段
１７第二の移相手段
１８第三の加算手段[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a diversity receiver for receiving a television signal or the like, and more particularly to a diversity receiver suitable for use in a vehicle.
[0002]
[Prior art]
FIG. 7 shows a configuration of a conventional diversity receiving apparatus for receiving, for example, an analog TV signal or the like. A plurality of receiving antennas 57, an antenna switching unit 55, a receiver 56, a reception state detecting circuit 53, a switching control circuit 54 And an electric field intensity detection circuit 51 for detecting the electric field intensity of the electric field intensity signal obtained from the receiver 56, and a threshold control circuit 52 for controlling a switching threshold based on an output signal from the electric field intensity detection circuit 51. I have.
[0003]
Then, the electric field strength detection circuit 51 detects the electric field strength according to the electric field strength signal obtained from the receiver 56 and supplies the electric field strength signal to the threshold value control circuit 52. The threshold control circuit 52 sets a switching threshold based on the electric field strength detection signal, and supplies a threshold setting signal to one input of the switching control circuit 54. The threshold control circuit 52 continuously increases the switching threshold as the received electric field strength decreases.
[0004]
The reception state detection circuit 53 detects a reception state and supplies a reception state detection signal to the other input of the switching control circuit 54.
The switching control circuit 54 generates a switching control signal based on the threshold setting signal and the reception state detection signal, and supplies the switching control signal to the antenna switching unit 55. The antenna switching unit 55 selects one of the plurality of receiving antennas 57 according to the switching control signal (for example, Patent Document 1).
[0005]
[Patent Document 1]
JP-A-07-170220 (FIG. 1)
[0006]
On the other hand, FIG. 8 shows a conventional diversity receiving apparatus for receiving a digital TV signal, in which one of a plurality of antennas 61 is selected by an antenna switching unit 62, and the digital TV signal from the selected antenna is tuned by a tuner 63. Take. The output is sent to the synchronous reproduction unit 65 via the IF unit 64, and the output is applied to the OFDM decoder 66. The demodulated output of the OFDM decoder 66 is applied to an MPEG decoder 67, and an image is displayed on a display unit 68 with the video signal obtained by this.
[0007]
Here, the error rate (BER) output from the OFDM decoder 66 and the MPEG decoder 67 is input to the control unit 69. Then, when the output error rate becomes larger than the error rate (threshold) when the degradation of the received video starts, it is determined that the reception state has deteriorated, and the control unit 69 starts the diver operation and starts the antenna 61. A diver control signal for switching the antenna 61 is generated, and this signal is supplied to the antenna switching unit 62 to switch the antenna 61.
[0008]
As for the antenna switching, if the antenna is switched within the effective symbol of the OFDM signal, data is lost and the reproduction condition deteriorates. Therefore, the antenna is switched during reception of the guard interval provided between the effective symbols. (For example, see Patent Document 2).
[0009]
[Patent Document 2]
JP-A-2002-33688 (FIG. 1)
[0010]
[Problems to be solved by the invention]
In the configuration of FIG. 7, the most suitable antenna for reception can be selected. However, when a direct wave and a reflected wave are received by the antenna, a ghost appears on the screen due to the mutual phase relationship.
Further, in the configuration of FIG. 8, the antenna switching is performed during the guard interval, but the same signal as a part of the signal in the effective symbol is inserted into the guard interval in order to detect the autocorrelation. Therefore, when the antenna is switched, the signal within the guard interval may be disturbed, and the autocorrelation may not be detected. As a result, there arises a problem that a digital signal cannot be synchronized at the time of demodulation and a reception failure occurs.
[0011]
The present invention is capable of receiving a digital TV signal and an analog TV signal, preventing loss of synchronization due to antenna switching when receiving a digital TV signal, preventing ghosting when receiving an analog TV signal, It is an object of the present invention to provide a diversity receiving apparatus whose configuration is simplified by using a part of a circuit.
[0012]
[Means for Solving the Problems]
In order to solve the above problem, the present invention provides a first mixer that converts broadcast signals received by a plurality of antennas into first intermediate frequency signals, an adding unit that adds the first intermediate frequency signals of each pair, and an addition unit. An analog receiving section that receives an analog TV signal included in the added first intermediate frequency signal; and a digital receiving section that receives a digital TV signal included in the added first intermediate frequency signal. Phase control means for relatively controlling the phase of the first intermediate frequency signals to be provided, and the phase of the delayed waves included in the first intermediate frequency signal input to the addition means when the analog TV signal is received. Are substantially in opposite phases, and the phase of the first intermediate frequency signal input to the adding means is substantially the same when receiving the digital TV signal.
[0013]
Further, the analog receiving section is provided with multipath detecting means for detecting a multipath of the analog TV signal and outputting a multipath detection signal, and the digital receiving section converts the added first intermediate frequency signal into a second intermediate signal. A second mixer that converts the signal into a frequency signal, and an OFDM demodulator that demodulates the second intermediate frequency signal, wherein the phase control means adjusts the relative phase between the local oscillation signals supplied to each of the first mixers. First phase shifting means for changing, the multipath detection signal and the second intermediate frequency signal are input, and when the multipath detection signal is below a predetermined threshold or the second intermediate frequency signal is below a peak level. And a first phase shift signal generating means for generating a phase shift signal at times. The phase shift signal is input to the first phase shift means.
[0014]
Further, the number of the antennas was set to two.
[0015]
In addition, the number of the antennas is set to 4, the adding means includes two first adding means for respectively adding the first intermediate frequency signals output from the pair of first mixers, and the two first adding means. The second intermediate means for adding the first intermediate frequency signal output from the adding means, the first intermediate frequency signal output from the second adding means to the analog receiving unit and the digital receiving unit I input it.
[0016]
In addition, the number of the antennas is set to 4, the adding means includes two first adding means for respectively adding the first intermediate frequency signals output from the pair of first mixers, and the two first adding means. And a second adding means for adding the first intermediate frequency signal output from the adding means, inputting the first intermediate frequency signal output from the second adding means to the analog receiving section, The digital receivers are provided at respective stages subsequent to the first adder, and baseband signals output from the respective OFDM demodulators of the digital receiver are synthesized.
[0017]
A second phase shift signal generator for comparing the phases of the baseband signals output from the two OFDM demodulators and outputting a phase shift signal; and a third phase adder for adding the two baseband signals together. Adder means, and second phase shift means interposed between one of the OFDM demodulator means and the third adder means, wherein the output from the second phase shift signal generating means The phase shift signal was input to the second phase shift means.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a diversity receiver according to the present invention will be described with reference to the drawings. FIG. 1 is a circuit diagram showing the configuration of the first embodiment, FIG. 2 is a circuit diagram of a phase shift signal generating means used in the first embodiment, FIG. 3 is a circuit diagram showing the configuration of the second embodiment, and FIG. FIG. 5 is a circuit diagram showing a configuration of a third embodiment, and FIG. 6 is a circuit diagram of a phase shift signal generating means used therein.
[0019]
First, in FIG. 1, broadcast signals (an analog TV signal and a digital TV signal) received by a plurality of antennas 1 (two in this embodiment) are first intermediate frequency signals by two first mixers 2 (2a and 2b). Converted to a signal. A local oscillation signal is supplied from the oscillator 3 to the two first mixers 2a and 2b, and supplied to one of the first mixers 2a via the first phase shift means 4.
[0020]
The first intermediate frequency signals output from the two first mixers 2a and 2b are added by the first adding means 5. The added first intermediate frequency signal is input to the analog receiving unit 6 and the digital receiving unit 7. The analog receiving section 6 has an audio / video demodulating means (not shown), a multipath detecting means 6a and the like, and outputs an audio signal A and a video signal V by demodulating an analog TV signal in the first intermediate frequency signal. It outputs a multipath detection signal M. The multipath detection signal M is output as a relative level ratio between a direct wave and a reflected wave (also called a delayed wave) in the analog TV signal. The smaller the level difference, the higher the level of the multipath detection signal. Then, the multipath detection signal M is input to the first phase shift signal generating means 8. The first phase shift signal generator 8 and the first phase shifter 4 constitute a phase controller 12.
[0021]
On the other hand, the digital receiving unit 7 has a second mixer 9 for converting the input first intermediate frequency signal into a second intermediate frequency signal, an OFDM demodulating means 10 for demodulating the second intermediate frequency signal, and a digital demodulated signal obtained by the demodulation. An error correction means 11 for correcting a bit error of the baseband signal is provided. The second mixer 9 is supplied with a local oscillation signal from another oscillator (not shown). Further, the OFDM demodulation means 10 detects spectrum distortion of the digital TV signal and outputs a detection signal. Then, the second intermediate frequency signal IF2 (digital TV signal) and the spectrum distortion signal S are input to the first phase shift signal generating means 8.
[0022]
As shown in FIG. 2, the first phase shift signal generating means 8 includes a multipath determining means 8a to which a multipath detection signal M is input, a power determining means 8b to which a second intermediate frequency signal IF2 is input, and a spectrum The apparatus includes a distortion determination unit 8c to which the distortion signal S is input and a phase shift signal output unit 8d.
Note that the multipath detection signal M is input when receiving an analog TV signal, and the second intermediate frequency signal IF2 and the spectrum distortion signal S are input when receiving a digital TV signal.
[0023]
The multipath determination means 8a outputs a control signal to the phase shift signal output means 8d when the multipath detection signal M is equal to or greater than a predetermined threshold, and the power determination means 8b determines that the second intermediate frequency signal IF2 is equal to or less than the peak value. Sometimes, a control signal is output to the phase shift signal output means 8d, and the distortion determination means 8c outputs a control signal to the phase shift signal output means 8d when the spectrum distortion is equal to or higher than a predetermined level. Then, the phase shift signal output unit 8d outputs the phase shift signal Φ while the control signal is being input from any of the multipath determination unit 8a, the power determination unit 8b, and the distortion determination unit 8c.
The phase shift signal Φ output from the phase shift signal output means 8d is input to the first phase shift means 4, and as a result, the phase of the first intermediate frequency signal output from one of the first mixers 2a changes. Can be
[0024]
When the analog TV signal is received, the phase of the delay wave included in the first intermediate frequency signal output from one first mixer 2a is the same as the delay included in the first intermediate frequency signal output from the other first mixer 2b. The first adding means 5 cancels the delayed waves so that the phases are opposite to each other. That is, until the level of the multipath detection signal M becomes equal to or less than the threshold, the phase of the local oscillation signal supplied to one of the first mixers 2a, that is, the phase of the first intermediate frequency signal output from the first mixer 2a is controlled. Then, as a result, the phase of the delay wave included in the first intermediate frequency signal output from one first mixer 2a is changed to the phase of the delay wave included in the first intermediate frequency signal output from the other first mixer 2b. The phase is almost opposite to the phase. Therefore, in the analog receiving unit 6, the level of the multipath detection signal M decreases and no ghost occurs in the video signal V.
[0025]
Further, at the time of receiving the digital TV signal, the phase of the first intermediate frequency signal output from one of the first mixers 2a is controlled so that the power of the second intermediate frequency signal IF2 becomes a peak. Therefore, the second intermediate frequency signal IF2 is controlled so as to be a peak, and a digital TV signal with improved S / N without synchronization loss can be obtained. Also, spectrum distortion in the second intermediate frequency signal is reduced.
[0026]
In FIG. 3, broadcast signals (analog TV signal and digital TV signal) received by four antennas 1 are converted into first intermediate frequency signals by four first mixers 2 (2a to 2d). Each of the first mixers 2 is supplied with a local oscillation signal from an oscillator 3, and three local mixers 2a to 2c are supplied with the local oscillation signals via first phase shift means 4a to 4c, respectively.
[0027]
The first intermediate frequency signals output from one pair of first mixers 2a and 2b of the four mixers 2a to 2d are added by one first adding means 5a, and the other pair of first mixers 2c are added. , 2d are added by the other first adding means 5b. Each of the added first intermediate frequency signals is further added by the second adding means 13. The first intermediate frequency signal output from the second adding means 13 is input to the analog receiving unit 6 and the digital receiving unit 7. Then, the multipath detection signal M output from the multipath detection means 6a, the second intermediate frequency signal IF2 output from the second mixer 9, and the spectrum distortion signal S output from the OFDM demodulation means 10 are first shifted. The signal is input to the phase signal generating means 14. The phase control means 15 is constituted by the first phase shift signal generation means 14 and the first phase shift means 4a to 4c.
[0028]
As shown in FIG. 4, the first phase shift signal generating means 14 includes a multipath determining means 14a to which the multipath detection signal M is input, a power determining means 14b to which the second intermediate frequency signal IF2 is input, and a spectrum The apparatus includes a distortion determination unit 14c to which the distortion detection signal S is input and a phase shift signal output unit 14e. The control signal is input from the multipath determining means 14a, the power determining means 14b, and the distortion determining means 14c to the phase shift signal output means 14e as in FIG. However, the phase shift signal output means 14e has three output terminals, and the phase shift signals Φ1 to Φ3 are sequentially output from each output terminal, and these are sequentially input to the first phase shift means 4a to 4c. As a result, the phases of the first intermediate frequency signals output from the three first mixers 2a to 2c are sequentially changed based on the phases of the first intermediate frequency signals output from the remaining first mixers 2d.
[0029]
During reception of the analog TV signal, the delayed waves included in the first intermediate frequency signals output from the pair of first mixers 2a and 2b are controlled so that the phase shifts of the delayed waves are substantially opposite to each other. Are controlled so that the phase shifts of the delayed waves included in the first intermediate frequency signals respectively output from the other pair of first mixers 2c and 2d are substantially opposite to each other. Control is performed so that the phase shifts of the delayed waves included in the first intermediate frequency signals output from the means 5a and 5b are substantially opposite to each other. Therefore, the second adder 13 cancels out the delayed waves, and the analog receiving unit 6 lowers the level of the multipath detection signal so that no ghost occurs in the video signal V.
[0030]
Also, at the time of receiving the digital TV signal, the phases of the first intermediate frequency signals output from the pair of first mixers 2a and 2b are substantially the same, and the other pair of the first mixers 2c and 2c are similarly in phase. The phase of the first intermediate frequency signal output from each of the second intermediate frequency signals 2d and 2d becomes substantially the same, and the phase of the first intermediate frequency signal output from the first first adding means 5a and the phase output from the other first adding means 5b The first intermediate frequency signal is controlled so as to be substantially in phase. Therefore, the power of the second intermediate frequency signal IF2 reaches a peak. Further, spectrum distortion is reduced.
[0031]
In FIG. 5, broadcast signals (an analog TV signal and a digital TV signal) received by four antennas 1 are converted into first intermediate frequency signals by four first mixers 2 (2a to 2d). Each of the first mixers 2 is supplied with a local oscillation signal from the oscillator 3, but is supplied to the three first mixers 2a to 2c via first phase shift means 4a to 4c, respectively.
[0032]
The first intermediate frequency signals output from one pair of first mixers 2a and 2b are added by one first adding means 5a, and the first intermediate frequency signals output from the other pair of first mixers 2c and 2d, respectively. The intermediate frequency signal is added by the other first adding means 5b. Each of the added first intermediate frequency signals is further added by the second adding means 13. The first intermediate frequency signal output from the second adding means 13 is input to the analog receiving section 6.
[0033]
Further, the first intermediate frequency signal output from one first adding means 5a and the first intermediate frequency signal output from the other first adding means 5b are input to the digital receiving unit 7. The digital receiver 7 compares the phases of the frequency axes of the two second mixers 9a and 9b, the two OFDM demodulators 10a and 10b, and the baseband signals output from the demodulators 10a and 10b, and compares the phase difference signals. , A second phase shifter 17 for changing the phase of the baseband signal from the other OFDM demodulator 10b, and a third adder 17 for adding the baseband signal. Etc. The first intermediate frequency signal output from one adding means 5a is input to one second mixer 9a, and the first intermediate frequency signal output from the other adding means 5b is input to the other second mixer 9b. Is done. A local oscillator signal is supplied to the two second mixers 9a and 9b from another oscillator (not shown).
[0034]
Here, a multipath detection signal M output from the multipath detection means 6a of the analog receiving unit 6, a second intermediate frequency signal IF2 output from the two second mixers 9a and 9b, and two OFDM demodulation means 10a. The spectrum distortion signal S output from 10b is input to the first phase shift signal generation means 19. The phase control means 20 is constituted by the first phase shift signal generation means 19 and the first phase shift means 4a to 4c.
[0035]
As shown in FIG. 6, the first phase shift signal generating means 19 includes a multi-path determining means 19a to which the multi-path detection signal M is input, a power determining means 19b1 to which two second intermediate frequency signals IF2 are input, 19b2, distortion determination means 19c1 and 19c2 to which the spectrum distortion detection signal S is input, and phase shift signal output means 19f. The power determining units 19b1 and 19b2 and the distortion determining units 19c1 and 19c2 have the same configuration as that shown in FIG. Then, control signals are input to the phase shift signal output unit 19f from the multipath determination unit 19a, the two power determination units 19b1 and 19b2, and the two distortion determination units 19c1 and 19c2.
[0036]
The phase shift signal output means 19f has three output terminals, and phase shift signals Φ1 to Φ3 are sequentially output from the respective output terminals, and are sequentially input to the first phase shift means 4a to 4c, respectively. As a result, the phases of the first intermediate frequency signals output from the three first mixers 2a to 2c are sequentially changed based on the phases of the first intermediate frequency signals output from the remaining first mixers 2d.
[0037]
During reception of the analog TV signal, the delayed waves included in the first intermediate frequency signals output from the pair of first mixers 2a and 2b are controlled so that the phase shifts of the delayed waves are substantially opposite to each other. Are controlled so that the phase shifts of the delayed waves included in the first intermediate frequency signals respectively output from the other pair of first mixers 2c and 2d are substantially opposite to each other. Control is performed so that the phase shifts of the delayed waves included in the first intermediate frequency signals output from the means 5a and 5b are substantially opposite to each other. Therefore, the second adder 13 cancels out the delayed waves, and the analog receiving unit 6 lowers the level of the multipath detection signal so that no ghost occurs in the video signal V.
[0038]
When a digital TV signal is received, the phases of the first intermediate frequency signals output from the first mixers 2a to 2c are similarly controlled, and the second intermediate frequency signal output from one of the second mixers 9a is similarly controlled. The power of the IF2 and the power of the second intermediate frequency signal IF2 output from the other second mixer 9b are controlled so as to peak respectively. Further, control is performed so as to reduce spectrum distortion.
[0039]
Then, the second phase shifting means 17 is controlled by the phase shifting signal from the second phase shifting signal generating means 16, and the phases of the two baseband signals input to the third adding means 18 coincide with each other on the frequency axis. I do. As a result, a baseband signal with few bit errors is output from the third adding means 18, but if there is a bit error, it is corrected by the error correcting means 11.
[0040]
【The invention's effect】
As described above, the present invention provides the phase control means for relatively controlling the phase between the first intermediate frequency signals input to the addition means, and the first intermediate frequency signal input to the addition means when receiving the analog TV signal. Since the phases of the delay waves included in the respective frequency signals are substantially opposite to each other, and the phase of the first intermediate frequency signal input to the adding means is substantially the same when receiving the digital TV signal, the ghost-free analog TV is used. It is possible to realize a diversity receiving apparatus which can receive a signal, has no loss of synchronization, and can receive an analog TV signal having an improved S / N with a simple configuration.
[0041]
Further, the phase control means is provided with a first phase shift means for changing a relative phase between the local oscillation signals supplied to each first mixer, a multipath detection signal and a second intermediate frequency signal, and When the detection signal is equal to or less than a predetermined threshold value or when the second intermediate frequency signal is equal to or less than the peak level, the first intermediate signal includes a first phase shift signal generating means for generating a phase shift signal. Therefore, when the analog TV signal is received, the phases of the delay waves included in the pair of first intermediate frequency signals input to the first adding means are substantially reversed, and when the digital TV signal is received, the pair of first and second intermediate frequency signals are paired. The phases of one intermediate frequency signal can be substantially the same.
[0042]
Also, since the number of antennas is set to 2, the simplest diversity receiving apparatus can be configured.
[0043]
In addition, the number of antennas is set to four, and the adding means are two first adding means for adding the first intermediate frequency signals output from the paired first mixers, and the two output means are output from the two first adding means. And a second adding means for adding the first intermediate frequency signal, and the first intermediate frequency signal output from the second adding means is input to the analog receiving section and the digital receiving section. The S / N can be greatly improved both during reception and when receiving a digital TV signal. Further, the digital receiving section can be constituted by one system.
[0044]
In addition, the number of antennas is set to four, and the adding means are two first adding means for adding the first intermediate frequency signals output from the paired first mixers, and the two output means are output from the two first adding means. And a second adding means for adding the first intermediate frequency signal to the analog receiving unit. Since a digital receiving unit is provided and a baseband signal output from each OFDM demodulating unit of the digital receiving unit is synthesized, the S / N of the demodulated baseband signal is further improved.
[0045]
A second phase-shifted signal generator for comparing the phases of the baseband signals output from the two OFDM demodulators and outputting a phase-shifted signal; and a third addition for adding the two baseband signals together. Means, and second phase shifting means interposed between one of the OFDM demodulating means and the third adding means, and the phase shifting signal output from the second phase shifting signal generating means is provided to the second phase shifting signal generating means. , The phase of the frequency band of the baseband signal input to the third adding means can be made in-phase, and the bit error can be reduced.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing a configuration of a first embodiment of a diversity receiver according to the present invention.
FIG. 2 is a circuit diagram of a first phase shift signal generating means used in the first embodiment of the present invention.
FIG. 3 is a circuit diagram showing a configuration of a second embodiment of the diversity receiver according to the present invention.
FIG. 4 is a circuit diagram of a first phase shift signal generating means used in a second embodiment of the present invention.
FIG. 5 is a circuit diagram showing a configuration of a third embodiment of the diversity receiver according to the present invention.
FIG. 6 is a circuit diagram of a first phase shift signal generating means used in a third embodiment of the present invention.
FIG. 7 is a circuit diagram showing a configuration of a conventional diversity receiver.
FIG. 8 is a circuit diagram showing another configuration of the conventional diversity receiver.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Antenna 2, 2a, 2b, 2c, 2d First mixer 3 Oscillator 4, 4a, 4b, 4c First phase shifting means 5, 5a, 5b First adding means 6 Analog receiving unit 6a Multipath signal detecting means 7 Digital receivers 8, 14, 19 First phase-shifted signal generators 9, 9a, 9b Second mixers 10, 10a, 10b OFDM demodulators 11 Error corrections 12, 15, 20 Phase controller 13 Second adder 16 second phase shift signal generation means 17 second phase shift means 18 third addition means

Claims

A first mixer for converting the broadcast signals received by the plurality of antennas into first intermediate frequency signals, an adding unit for adding the pair of first intermediate frequency signals, and a first intermediate frequency signal included in the added first intermediate frequency signals An analog receiving section for receiving an analog TV signal; and a digital receiving section for receiving a digital TV signal included in the added first intermediate frequency signal. Phase control means for relatively controlling the digital TV signal when the analog TV signal is received, the phases of the delay waves included in the first intermediate frequency signal input to the addition means are substantially reversed. Wherein the first intermediate frequency signal input to the addition means is substantially in phase with each other during reception.

The analog receiving section is provided with multipath detecting means for detecting a multipath of the analog TV signal and outputting a multipath detection signal, and the digital receiving section converts the added first intermediate frequency signal into a second intermediate frequency signal. And a OFDM demodulating means for demodulating a second intermediate frequency signal, wherein the phase control means changes a relative phase between the local oscillation signals supplied to each of the first mixers. One phase shifter, the multipath detection signal and the second intermediate frequency signal are input, and the phase shifter is operated when the multipath detection signal is lower than a predetermined threshold or when the second intermediate frequency signal is lower than a peak level. 2. The diversity receiving apparatus according to claim 1, further comprising first phase shift signal generating means for generating a phase signal, wherein said phase shift signal is input to said first phase shift means.

The diversity receiver according to claim 1, wherein the number of the antennas is two.

The number of the antennas is set to 4, the adding means includes two first adding means for respectively adding the first intermediate frequency signals output from the pair of first mixers, and the two first adding means. And second adding means for adding the first intermediate frequency signal output from the first intermediate frequency signal output from the second adding means was input to the analog receiving unit and the digital receiving unit The diversity receiving apparatus according to claim 2, wherein:

The number of the antennas is set to 4, the adding means includes two first adding means for respectively adding the first intermediate frequency signals output from the pair of first mixers, and the two first adding means. And a second adding means for adding a first intermediate frequency signal output from the second intermediate frequency signal, the first intermediate frequency signal output from the second adding means is input to the analog receiving unit, the two first 3. The diversity receiving apparatus according to claim 2, wherein the digital receiving sections are provided at respective stages subsequent to the adding section, and the baseband signals output from the OFDM demodulating sections of the digital receiving section are combined.

A second phase shift signal generator for comparing the phases of the baseband signals output from the two OFDM demodulators and outputting a phase shift signal; and a third addition for adding the two baseband signals. Means, and second phase shifting means interposed between one of the OFDM demodulating means and the third adding means, wherein the phase shift output from the second phase shifting signal generating means is provided. 6. The diversity receiver according to claim 5, wherein a signal is input to said second phase shift means.