JP3608230B2

JP3608230B2 - Receiver

Info

Publication number: JP3608230B2
Application number: JP25506194A
Authority: JP
Inventors: 良雄堀池; 康男吉村; 義幸横網代
Original assignee: Panasonic Corp; Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Corp; Panasonic Holdings Corp
Priority date: 1994-10-20
Filing date: 1994-10-20
Publication date: 2005-01-05
Anticipated expiration: 2020-01-05
Also published as: JPH08125567A

Description

【０００１】
【産業上の利用分野】
本発明は、主として無線通信に用いられる受信装置に関するものである。
【０００２】
【従来の技術】
一般に無線通信における受信方式としてシングルスーパヘテロダイン方式やダブルスーパヘテロダイン方式が用いられている。しかしながら上記従来のヘテロダイン方式ではイメージ周波数を除去するための帯域フィルタや隣接チャンネル信号を除去するための帯域フィルタが必要である。そして前記帯域フィルタとして水晶やセラミックの機械的振動特性を利用したメカニカルフィルタが用いられている。そのため形状が大きいことや高価であること等の諸問題がある。上記課題を解決する受信方式としてダイレクトコンバージョン受信方式がある。ダイレクトコンバージョン方式を用いた受信装置は例えば、特開昭５９−１９６６２９号公報に示されているような方式が知られている。
【０００３】
【発明が解決しようとする課題】
しかしながら上記従来のダイレクトコンバージョン方式では、受信信号の中心周波数にほぼ等しい周波数を有する局部発振信号と受信信号をミキシングすることにより直接ベースバンド帯に受信信号を変換している。変換されたベースバンド信号は直流成分を有することになる。従って上記ベースバンド信号を処理する回路は直流を通す直流増幅回路である必要がある。そして直流増幅回路は温度変化や電源電圧変動により直流バイアスが変動すると、出力の直流成分が大きく変化し受信感度を低下させることや大きな増幅度を実現できないという問題があった。また回路の１／ｆ雑音により直流付近に大きな雑音成分が発生し受信感度を悪化させるという問題も有していた。
【０００４】
またコンデンサで直流阻止を行う場合、コンデンサの容量を小さくすると直流付近のエネルギーが除去されるため受信感度の低下やデータの復調ができなくなってしまうという欠点があった。コンデンサの容量を大きくするとコンデンサを挿入することにより受信回路に電源が供給されてから受信回路が安定するまで長い時間かかってしまうという欠点があった。特に電池駆動の受信装置において電池寿命をのばすために間欠動作方式を採用したい場合、受信回路に電源が供給されてから受信回路が安定するまで長い時間かかってしまうことはシステム設計上大きな問題であった。
【０００５】
本発明は上記課題を解決するもので、直流成分を有しないでかつ従来のダイレクトコンバージョン方式の特徴であるモノリシックＩＣで構成できる受信装置を実現することを目的としたものである。
【０００６】
【課題を解決するための手段】
上記目的を達成するために、本発明の受信装置は、受信信号の中心周波数から前記受信信号の占有帯域以上離れた周波数の信号を出力する第一の信号発生手段と、前記第一の信号発生手段からの信号と前記受信信号の差の周波数となる信号を取り出す第一のミキシング手段と、前記第一の信号発生手段からの信号を位相シフトした信号と前記受信信号の差の周波数となる信号を取り出す第二のミキシング手段と、前記第一のミキシング手段からの信号を入力とする第一の低域遮断フィルタと、前記第二のミキシング手段からの信号を入力とする第二の低域遮断フィルタと、時間的に連続した矩形波信号を発生する第二の信号発生手段と、前記第二の信号発生手段からの矩形波信号により前記第一の低域遮断フィルタからの信号をスイッチする第一のスイッチ手段と、前記第二の信号発生手段からの矩形波信号を位相シフトした矩形波信号により前記第二の低域遮断フィルタからの信号をスイッチする第二のスイッチ手段と、前記第一のスイッチ手段の出力信号と前記第二のスイッチ手段の出力信号とを加算または引算する演算手段と、前記演算手段の前段あるいは後段に設けられ前記第二の信号発生手段で発生する矩形波信号の周波数から前記受信信号と前記第一の信号発生手段の出力信号との差の周波数だけ離れた付近のエネルギーを通過させる第三の帯域通過フィルタを備えている。
【０００７】
さらに上記構成に加え、前記帯域通過フィルタの出力信号の周波数に応じた電圧を発生する周波数−電圧変換手段を備えている。
【０００９】
さらに上記構成に加え、前記周波数−電圧変換手段の出力に生じるパルス状の雑音を除去する雑音除去手段を備え、前記雑音除去手段の出力電圧を復調出力としている。
【００１０】
そして第一または第二のスイッチ手段は、第一の入力端子と第二の入力端子と出力端子と制御端子を有し、前記制御端子に入力する信号により出力端子が第一の入力端子と導通するか第二の入力端子と導通するかが切り替わる電子スイッチと、前記電子スイッチの第一の入力端子に入力する信号と反転した信号を前記電子スイッチの第二の入力端子に出力する反転手段とで構成されている。
【００１１】
さらに、周波数−電圧変換手段は、演算手段からの信号を二値化する二値化手段と、前記二値化手段からの信号を遅延させる遅延手段と、前記二値化手段からの信号と前記遅延手段からの信号の排他的論理和を出力する排他的論理和手段と、前記排他的論理和手段の出力信号の高周波成分を取り除くローパスフィルタとで構成されている。
【００１２】
また、周波数−電圧変換手段は、演算手段からの信号を二値化する二値化手段と、前記二値化手段からの信号のエッジを検出するエッジ検出手段と、前記エッジ検出手段からの信号により起動される単安定マルチバイブレータと、前記単安定マルチバイブレータの出力信号の高周波成分を取り除くローパスフィルタとで構成する。
【００１３】
さらに、雑音除去手段は、周波数−電圧変換手段からの出力電圧がある値を越えた時パルスを出力するパルス出力手段と、前記パルス出力手段からのパルス信号により前記周波数−電圧変換手段からの出力電圧をサンプリングホールドする保持手段とで構成されている。
【００１４】
また、雑音除去手段は、周波数−電圧変換手段に入力する信号の零クロス点の間隔がある値以上の時パルスを発生するパルス出力手段と、前記パルス出力手段からのパルス信号により前記周波数−電圧変換手段からの出力電圧をサンプリングホールドする保持手段とで構成されたものである。
【００１５】
また、雑音除去手段は、周波数−電圧変換手段からの出力電圧がある値を越えた時パルスを出力するパルス出力手段と、前記パルス出力手段からのパルス信号を前記周波数−電圧変換手段からの出力電圧から引算を行う引算手段とで構成されたものでもある。
【００１６】
また、雑音除去手段は、周波数−電圧変換手段に入力する信号の零クロス点の間隔がある値以上の時パルスを発生するパルス出力手段と、前記パルス出力手段からのパルス信号を前記周波数−電圧変換手段に入力する信号の零クロス点の間隔に挿入するパルス挿入手段とで構成されたものでもある。
【００１７】
【作用】
本発明は上記構成によって、ミキシング手段により変換されたベースバンド信号に直流成分が発生しないこととなり、前記ベースバンド信号に含まれる不要な信号を高域通過フィルタあるいは帯域通過フィルタにより除去する。これにより受信回路に電源が供給されてから受信回路が安定するまでの時間を短くできるだけでなく良好な受信感度を実現できることとなる。
【００１８】
【実施例】
以下本発明の一実施例を図１を参照して説明する。１はアンテナ、２は高周波増幅手段、３は第一のミキシング手段、４は直流成分を遮断するための第一の低域遮断フィルタ、６は第一の信号発生手段、７は９０゜位相シフター、８は第二のミキシング手段、９は直流成分を遮断するための第二の低域遮断フィルタ、１５は第一のスイッチ手段、１６は第二のスイッチ手段、１７は第二の信号発生手段、１８は９０゜移相手段、１９は加減算を行う演算手段、２０は第三の帯域通過フィルタ、２１は周波数−電圧変換手段、２２は雑音除去手段、２３は周波数補正手段である。
【００１９】
第一及び第二の低域遮断フィルタ４及び９は隣接チャンネルを除去する目的を兼ねるため帯域通過フィルタを用いている。
【００２０】
さてアンテナ１に入力する信号として、希望信号Ｄ
Ｄ＝ｃｏｓ｛ω＋Δω｝・ｔ
ω：搬送波角周波数 Δω：角周波数偏移であり正負両方の極性を有する
を考える。ここでデータあるいは音声により角周波数偏移Δωは時間的に変化する。すなわち信号Ｄは周波数変調を受けた信号である。また搬送波角周波数ωは信号Ｄの中心角周波数である。第一の信号発生手段６では、
Ｑ＝ＣＯＳ｛ω＋ｘ｝・ｔｘ：搬送波角周波数ωからの角周波数ずれ
で表わされる信号Ｑを発生する。９０゜位相シフター７では信号発生手段６からの信号Ｑが９０゜位相シフトされＱ’＝ＳＩＮ｛ω＋ｘ｝ｔとなる。従って第一の帯域通過フィルタ４および第二の帯域通過フィルタ９の出力端子ａ及びｃには
端子ａ：Ｄ×Ｑ＝ＣＯＳ｛Δωーｘ｝・ｔ
端子ｃ：Ｄ×Ｑ’＝ＳＩＮ｛Δωーｘ｝・ｔ
なる信号が生じる。ここでｘはΔωより大きくなるように設定されている。すなわち信号Ｄの占有帯域以上にＸは設定されている。例えばチャンネル間隔１２．５ｋＨｚで信号が配置されている場合、一般に占有帯域幅は±４．２５ｋＨｚ＝８．５ｋＨｚと決められている。そしてΔωは±２．５ｋＨｚ以下である。そこで占有帯域をはずれた値として、ｘ＝６．２５ｋＨｚあるいは１２．５ｋＨｚ等の値が選ばれる。本実施例ではｘ＝６．２５ｋＨｚとする。
このように設定することにより端子ａ及び端子ｃの信号は直流成分を有しないことになる。
【００２１】
第二の信号発生手段１７では
Ｒ＝ＣＯＳ｛ｒ・ｔ｝−（１／３）・ＣＯＳ｛３・ｒ・ｔ｝＋（１／５）・ＣＯＳ｛５・ｒ・ｔ）−・・・・・・・・
で表される矩形波信号Ｒを発生させる。本実施例ではｒ＝１６ｋＨｚに設定する。
端子ａの信号は第一のスイッチ手段１５において、第二の信号発生手段で発生する矩形波信号Ｒとかけ算される。一方９０゜移相手段１８の出力には
Ｒ’＝ＳＩＮ｛ｒ・ｔ｝＋（１／３）・ＳＩＮ｛３・ｒ・ｔ｝＋（１／５）・ＳＩＮ｛５・ｒ・ｔ）−・・・・・・・・
なる矩形波信号Ｒ’が出力する。従って、端子ｃの信号は第二のスイッチ手段１６において、矩形波信号Ｒ’とかけ算される。よって第一のスイッチ手段１５の出力端子ａ’及び第二のスイッチ手段１６の出力端子ｃ’には

が生じる。
端子ａ’及び端子ｃ’の信号は、演算手段１９において加算される。従って演算手段１９の出力端子ｆには

なる信号が出力する。第三の帯域通過フィルタ２０は、第一のスイッチ手段１７及び第二のスイッチ手段１８で発生する角周波数ｒの高調波成分に関係する項、すなわち（１）式の第二項以上を除去する。従って第三の帯域通過フィルタ２０の出力端子ｆ’には
端子ｆ’：ＣＯＳ｛｛｛ｒ＋ｘ｝ーΔω｝・ｔ｝＝ＣＯＳ｛２π×２２．２５ｋＨｚ−Δω｝・ｔ｝・・・（２）式
なる信号が出力する。ここでｒ＋ｘ＞｜Δω｜に設定されているため、（２）式の位相は正の時間において常に正である。すなわち負の周波数が生じることはない。よって（２）式から明かなように端子ｆ’に生じる出力信号は｛ｒ＋ｘ｝なる角周波数を有する搬送波信号がΔωの周波数偏移を受けた周波数変調信号とみなすことができる。従って周波数に比例した出力電圧を発生する周波数−電圧変換手段２１により端子ｆ’に生じた周波数変調信号を復調することができる。さらに端子ｆ’に生じた復調信号は雑音除去手段２２でＦＭ復調において発生するＦＭ復調特有のパルス状の雑音が除去され端子ｇに出力される。第三の帯域通過フィルタ２０は中心周波数が２２．２５ｋＨｚ付近と低いためモノリシックＩＣで構成することができる。もちろんその他の手段についても周波数が低いためモノリシックＩＣで構成することができる。
【００２２】
次にアンテナ１に入力する信号として、希望信号Ｄから２ｘ＝１２．５ｋＨｘ離れた妨害信号Ｕ
Ｕ＝ｃｏｓ｛ω＋２ｘ＋Δω｝・ｔ
を考える。すると端子ａ及び端子ｃには
端子ａ：Ｕ×Ｑ＝ＣＯＳ｛Δω＋ｘ｝・ｔ
端子ｃ：Ｕ×Ｑ’＝ＳＩＮ｛Δω＋ｘ｝・ｔ
なる信号が生じる。この妨害信号は端子ａ及び端子ｃにおいては希望信号と同じ帯域に生じるため第一及び第二の帯域通過フィルタ４及び９では妨害信号を取り除くことは不可能である。しかしながら出力端子ｆには

なる信号が生じる。上記（３）式で示される妨害信号の周波数帯域は明らかに（１）式で示される希望信号の周波数帯域と異なっている。そのため妨害信号により生じた（３）式の信号は中心周波数ｒ＋ｘ＝２２．２５ｋＨｚ付近の信号のみを通過させるように設計されている第三の帯域通過フィルタ２０により除去され端子ｆ’には何等妨害信号は生じない。本発明の実施例では端子ａ及び端子ｃに生じる信号レベルが同じであるとしたが回路のばらつきにより端子ａの信号レベルと端子ｃの信号レベルに差がある場合、妨害信号Ｕにより端子ｆに生じる信号は（１）式で示す周波数帯域と同じ周波数帯域を有するものが発生する。そこでレベル調整回路を設け端子ａあるいは端子ｃに生じる信号レベルを調整し（１）式で示す周波数帯域に発生する妨害信号成分を打ち消すようにすればよりいっそう妨害に強い受信装置を構成できる。
【００２３】
なお第一のスイッチ手段１５及び第二のスイッチ手段１６のスイッチ構成によっては、角周波数ｒの成分がスイッチ手段１５、１６の出力に生じる場合がある。この時第二の信号発生手段１７からの矩形波信号を第一のスイッチ手段１５あるいは第二のスイッチ手段１６の出力に加え、角周波数ｒの成分を打ち消すようにする。また第一のスイッチ手段１５及び第二のスイッチ手段１６のスイッチ構成によっては、端子ａあるいは端子ｃの信号が第一のスイッチ手段１５あるいは第二のスイッチ手段１６に生じることがある。この場合端子ａあるいは端子ｃの信号を第一のスイッチ手段１５あるいは第二のスイッチ手段１６の出力に加え、端子ａあるいは端子ｃの信号を打ち消すようにする。
【００２４】
本発明の構成を用いれば、第一の信号発生手段６の周波数が温度等の影響で若干ずれた場合であっても周波数補正手段２３を用いなくても信号を復調できるが、さらに受信における安定度を向上させるために、端子ｇの信号の平均直流電圧あるいは端子ｆ’の平均周波数を周波数補正手段２３で検出し、ある基準値になるように第一の信号発生手段６の信号周波数を制御するようにすればなお効果的である。周波数補正手段２３は図１には図示していないが端子ｇの復調出力から信号を受信したことを検知すると、マイクロコンピュータ処理により第一の信号発生手段６の発生周波数を制御する直流電圧をＤ／Ａ変換で発生する。さらに図１には図示していないが端子ｇの復調出力から信号を受信したことを検知すると、第一の帯域通過フィルタ４及び第二の帯域通過フィルタ９の帯域幅を狭くするように切り換える。このようにすればＳ／Ｎ特性を向上することができる。
【００２５】
なお、図１には第一の帯域通過フィルタ４及び第二の帯域通過フィルタ９の後段あるいは前段に増幅手段を図示していないが当然必要に応じて増幅手段を挿入すればよい。またアンテナに大きなレベルの信号が入力し、演算手段１９の出力がクリップしてしまう場合、復調に必要な情報が欠落してしまうことが考えられる。従って少なくとも演算手段１９の出力がクリップしないように例えば高周波増幅手段２の増幅度を調整するように構成すればさらに効果的である。
【００２６】
また図１における演算手段１９を加算動作として説明したが引算動作を行ってもかまわない。この場合端子ｆ’の信号は、ＣＯＳ｛｛｛ｒーｘ｝＋Δω｝・ｔ｝となる。
【００２７】
図２は図１における第一のスイッチ手段１５及び第二のスイッチ手段１６に適用できるスイッチ手段の構成を示す。図２において、２４は端子ａの信号あるいは端子ｃの信号が入力する入力端子、２５は第二の信号発生手段１７からの矩形波信号ＲあるいはＲ’が入力する入力端子、２６は出力端子、２７は増幅度１の反転回路、２８は電子スイッチである。電子スイッチ２８は入力端子２５に入力する矩形波信号Ｒあるいは矩形波信号Ｒ’の位相が正か負かで出力端子と入力端子との接続が切り替わる。このような電子スイッチ２８はアナログスイッチとしてＣＭＯＳで簡単に実現できるし、バイポーラトランジスタを用いても簡単に構成できる。また第一のスイッチ手段１５及び第二のスイッチ手段１６は差動増幅器を組み合わせた構成のものであってもかまわない。
【００２８】
図３は図１における周波数−電圧変換手段２１及び雑音除去手段２２の構成を示す図及び波形図である。図１では周波数−電圧変換手段２１の後段に雑音除去手段２２を配置しているが、図３の例では周波数−電圧変換手段２１の中に雑音除去手段２２を組み込んでいる。図３（ａ）において４０は端子ｆ’に示す周波数変調信号が入力する入力端子、２９は増幅手段、３０はコンパレータで構成された二値化手段、３１は第一の遅延手段であり、抵抗３２とコンデンサ３３とコンパレータ３４で構成される。３５は排他的論理和手段、３６は第二の遅延手段、３７はパルス挿入手段、３８はパルス発生手段、３９はローパスフィルタ、４１は復調出力端子である。入力端子４０に入力した信号の周波数が高くなると排他的論理和手段３５の出力パルス間隔が狭くなり、入力周波数が低くなると排他的論理和手段３５の出力パルス間隔が広くなる。従ってローパスフィルタ３９で不要な高周波成分を取り除くと排他的論理和手段３５の出力パルス間隔に応じた電圧変化を取り出すことができる。復調感度を上げるためには第一の遅延手段３１での遅延量を大きくすればよい。さて次に雑音除去方法について図３（ｂ）の波形図を用いて説明する。ｈ及びｉは排他的論理和手段３５の入力である。従って排他的論理和３５の出力はｊに示すようなパルス列となる。さて入力端子４０に入力する信号に雑音が含まれている場合、雑音の影響により信号ｈ及びｉのパルス列が不規則になり、１パルス分欠落する場合がある。このように信号ｈ及びｉのパルスが欠落すると排他的論理和手段３５の出力ｊのパルスも欠落する。従って、ｊの信号をローパスフィルタに通すとパルスが欠落した部分で大きなパルス状の雑音が生じる。パルス発生手段３８では、信号ｊに通常のパルス間隔Ｔ１より充分長い時間Ｔ２（例えばＴ２＝２・Ｔ１）の間にパルスがなければＴ１毎にＨＩＧＨ／ＬＯＷを繰り返すパルス出力ｌを発生する。パルス出力ｌはｊにパルスが生じるとストップする。信号ｊは第二の遅延手段３６により遅延され、信号ｋとなる。パルス挿入手段３７では、パルス出力ｌの立ち上がり及び立ち下がりエッジにあわせて信号ｋのパルス幅に等しいパルスを信号ｋに挿入する。図３（ｂ）の波形図における信号ｍの○印のパルスが挿入されたパルスである。信号ｍをローパスフィルタに通し復調信号を得る。このようにパルスを挿入することによりパルスの欠落がなくなり復調出力からパルス状の雑音が発生することはなくなる。なお信号ｊにパルスを挿入したが信号ｈにパルスを挿入した後、第一の遅延手段３１で信号ｉをつくり、排他的論理和手段３５でパルスの欠落のない信号ｊを作成するようにしてもよい。
【００２９】
図４は図１における周波数−電圧変換手段２１の他の構成を示す図である。図４において図３と同一の機能ブロックには同一の番号を付与している。４２はエッジ検出手段、４３は単安定マルチバイブレータである。エッジ検出手段４２は図３における遅延手段３１と排他的論理和手段３５で構成されている。単安定マルチバイブレータ４３の出力は、端子４０に入力する信号の周波数に応じてパルス間隔が狭くなったり広くなったりする。従って図３の場合と同様ローパスフィルタ３６で不要な高周波成分を取り除くと単安定マルチバイブレータ４３の出力パルス間隔に応じた電圧変化を取り出すことができる。図４の構成の利点は遅延手段３１での遅延量を大きくとる必要がないという点である。そのためコンデンサ３３と抵抗３２で構成される回路の時定数を大きくする必要がない。そして復調感度は単安定マルチバイブレータ４３の出力のパルス幅を適当に選べば復調感度を最適に設定できる。雑音除去の方法については図３と同じである。
【００３０】
図５は雑音除去手段２２の他の構成及び波形図を示す。図５（ａ）において４４は周波数−電圧変換手段２１の復調出力が入力する入力端子、４５はデータ信号等の希望信号を取り除いて雑音成分だけを取り出すハイパスフィルタ、４６はあるレベル以上の雑音を取り出すコンパレータ、４７はパルス幅延長手段であり、４５、４６、４７でパルス発生手段４８を構成している。４９は遅延手段、５０は保持手段、５１は出力端子である。図５（ｂ）の波形図を参照しながら雑音除去手段２２の動作を説明する。入力端子４４に入力した信号ｖはハイパスフィルタ４５により信号ｗとなる。コンパレータ４６でパルス状の雑音だけが取り出され信号ｘとなる。信号ｘはパルス幅延長手段４７でパルス幅が広げられ信号ｙとなる。一方信号ｖは遅延手段４９で遅延され、保持手段５０では信号ｙのパルス出力期間中、遅延された信号ｖの値がサンプリングホールドされる。従って出力端子５１の出力は信号ｚとなる。この信号ｚを図示していないがローパスフィルタを通すことによりなめらかな変化にすることができる。また保持手段５０の代わりに引算手段を用い、信号ｚと信号ｙの引算を行って雑音を除去するように構成してもよい。なおパルス発生手段の出力信号ｙとして図３の信号ｌを用いてもよい。
【００３１】
図６に第二の信号発生手段１７と９０゜移相手段１８の構成を示す。５２はマイクロコンピュータの基準クロックより作成したクロック信号が入力する入力端子、５３、５４、５５はＤ−フリップフロップであり、それぞれ１／２分周器を構成している。５６、５７は出力端子であり、端子５６から矩形波信号Ｒ、端子５７から矩形波信号Ｒに直交した矩形波信号Ｒ’が出力する。図６の回路を用いれば簡単にＩＣ化が可能である。なお入力端子５２に入力する信号として双安定マルチバイブレータ等で発振させた信号を用いてもよい。
【００３２】
なお図１の実施例では周波数変調信号の復調について説明したが、周波数変調信号だけでなく振幅変調信号や位相変調信号の復調も図１の周波数−電圧変換手段２１のかわりに入力する変調信号に対応した復調手段を用いることにより可能である。
【００３３】
高周波増幅手段２からの信号を本発明の構成装置の入力信号としているが、高周波増幅手段２の出力信号を周波数変換した中間周波数信号を本発明の構成装置の入力信号としてもかまわない。
【００３４】
【発明の効果】
以上説明したように本発明の受信装置によれば、信号の復調に直流成分を必要としないため電源供給時の立ち上がり時間を短くすることができると同時に、温度等による直流ドリフトの影響や回路の１／ｆ雑音の影響を除去し受信感度の悪化を防ぐことのできる信頼性の高い受信装置を提供することができる。もちろん高価なメカニカルフィルタも必要がなくかつＩＣ化しやすいため安価に受信装置を実現できることとなる。なお回路の増幅度ばらつきを考慮してレベル調整回路を設けて不要な妨害信号を打ち消すようにすればより妨害に強い受信装置を提供できる。
【００３５】
また周波数変調信号の復調をはじめ、振幅変調信号や位相変調信号の復調に本発明を適用することができる。
【００３７】
さらに雑音除去手段を用いることによりパルス状の雑音を取り除くことができるためＳ／Ｎ特性の改善をはかることができる。
【００３８】
もちろん第一及び第二のスイッチや周波数−電圧変換手段、雑音除去手段は簡単な構成で実現でき、ＩＣ化することは簡単である。
【００３９】
電池駆動で長時間動作させるために送信側と受信側で同期をとって間欠的に送受信を行う間欠動作方式においては相手から自分あてに信号があるかどうかをチェックするのに出来る限り短時間に行う必要があり、受信装置に電源を供給してから受信装置の動作が安定するまでの時間をできるだけ短くしなければならない。本発明はこのような間欠動作方式に適用でき、電池寿命を伸ばすことに大きな効果を発揮することができる。特に、ガスメータ等の自動検針システムにおいてガスメータ内に無線の送受信装置を組み込む場合、小型でかつ電池駆動で１０年間動作可能な受信装置が必要である。自動検針システムに限らずガス給湯器と台所を無線で接続するリモコン装置を初めとして住宅設備システムに用いる無線式のリモコン装置においては小型かつ電池駆動は必須条件である。上記課題に対して本発明は非常に有効な受信装置を提供することができる。
【図面の簡単な説明】
【図１】本発明の一実施例における受信装置のブロック図
【図２】本発明の一実施例におけるスイッチ手段のブロック図
【図３】（ａ）本発明の一実施例における周波数−電圧変換手段及び雑音除去手段のブロック図と波形図
（ｂ）同実施例における周波数−電圧変換手段及び雑音除去手段の波形図
【図４】本発明の一実施例における周波数−電圧変換手段及び雑音除去手段の他のブロック図
【図５】（ａ）本発明の一実施例における雑音除去手段のブロック図
（ｂ）同実施例における雑音除去手段の波形図
【図６】本発明の一実施例における第二の信号発生手段と９０゜移相手段のブロック図
【符号の説明】
１アンテナ
２高周波増幅手段
３第一のミキシング手段
４第一の帯域通過フィルタ
６第一の信号発生手段
７９０゜シフター
８第二のミキシング手段
９第二の帯域通過フィルタ
１５第一のスイッチ手段
１６第二のスイッチ手段
１７第二の信号発生手段
１８９０゜移相手段
１９演算手段
２０第三の帯域通過フィルタ
２１周波数−電圧変換手段
２２周波数補正手段
２２雑音除去手段[0001]
[Industrial application fields]
The present invention relates to a receiving apparatus mainly used for wireless communication.
[0002]
[Prior art]
In general, a single superheterodyne system or a double superheterodyne system is used as a reception system in wireless communication. However, the conventional heterodyne method requires a band filter for removing image frequencies and a band filter for removing adjacent channel signals. A mechanical filter using mechanical vibration characteristics of quartz or ceramic is used as the band filter. Therefore, there are various problems such as large shape and high price. There is a direct conversion reception method as a reception method for solving the above-mentioned problems. As a receiving apparatus using the direct conversion method, for example, a method as disclosed in Japanese Patent Application Laid-Open No. 59-196629 is known.
[0003]
[Problems to be solved by the invention]
However, in the above conventional direct conversion method, the received signal is directly converted into the baseband by mixing the local oscillation signal having a frequency substantially equal to the center frequency of the received signal and the received signal. The converted baseband signal has a DC component. Therefore, the circuit for processing the baseband signal needs to be a direct current amplifier circuit that passes direct current. When the DC bias fluctuates due to temperature changes or power supply voltage fluctuations, the DC amplifier circuit has a problem that the DC component of the output is greatly changed and the reception sensitivity is lowered and a large amplification degree cannot be realized. In addition, there is a problem that a large noise component is generated in the vicinity of the direct current due to 1 / f noise of the circuit to deteriorate reception sensitivity.
[0004]
In addition, when direct current blocking is performed with a capacitor, if the capacity of the capacitor is reduced, energy near the direct current is removed, so that reception sensitivity is lowered and data cannot be demodulated. When the capacitance of the capacitor is increased, there is a drawback that it takes a long time until the receiving circuit is stabilized after the power is supplied to the receiving circuit by inserting the capacitor. Especially when adopting the intermittent operation method to extend the battery life in a battery-powered receiver, it takes a long time for the receiver circuit to stabilize after power is supplied to the receiver circuit. It was.
[0005]
SUMMARY OF THE INVENTION The present invention solves the above-described problems, and an object of the present invention is to realize a receiving apparatus that does not have a direct current component and can be configured by a monolithic IC that is a feature of a conventional direct conversion system.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the receiving apparatus of the present invention comprises: first signal generating means for outputting a signal having a frequency separated from the center frequency of the received signal by a frequency not less than the occupied band of the received signal; and the first signal generating A first mixing means for extracting a signal having a frequency difference between the signal from the means and the received signal, and a signal having a frequency difference between the signal obtained by phase-shifting the signal from the first signal generating means and the received signal. Second mixing means for taking out the signal, a first low-frequency cutoff filter that receives the signal from the first mixing means, and a second low-frequency cutoff that receives the signal from the second mixing means A filter, second signal generating means for generating a rectangular wave signal continuous in time, and a signal from the first low-frequency cutoff filter by a rectangular wave signal from the second signal generating means A first switching means, a second switching means for switching a signal from the second low-frequency cutoff filter by a rectangular wave signal obtained by phase-shifting the rectangular wave signal from the second signal generating means, and the first A calculating means for adding or subtracting the output signal of the switch means and the output signal of the second switch means, and a rectangular wave signal provided in the preceding stage or the succeeding stage of the calculating means and generated by the second signal generating means A third band-pass filter that passes energy in the vicinity of the difference frequency between the received signal and the output signal of the first signal generating means from the frequency of the first signal.
[0007]
Further, in addition to the above configuration, frequency-voltage conversion means for generating a voltage corresponding to the frequency of the output signal of the band pass filter is provided.
[0009]
Further, in addition to the above-described configuration, noise removal means for removing pulse noise generated at the output of the frequency-voltage conversion means is provided, and the output voltage of the noise removal means is used as a demodulated output.
[0010]
The first or second switch means has a first input terminal, a second input terminal, an output terminal, and a control terminal, and the output terminal is electrically connected to the first input terminal by a signal input to the control terminal. An electronic switch for switching whether to conduct or to conduct with the second input terminal; and an inverting means for outputting a signal input to the first input terminal of the electronic switch and an inverted signal to the second input terminal of the electronic switch; It consists of
[0011]
Further, the frequency-voltage converting means includes a binarizing means for binarizing a signal from the computing means, a delay means for delaying a signal from the binarizing means, a signal from the binarizing means, and the An exclusive OR means for outputting an exclusive OR of the signals from the delay means and a low pass filter for removing a high frequency component of the output signal of the exclusive OR means.
[0012]
The frequency-voltage converting means includes a binarizing means for binarizing the signal from the computing means, an edge detecting means for detecting an edge of the signal from the binarizing means, and a signal from the edge detecting means. And a low-pass filter that removes high-frequency components of the output signal of the monostable multivibrator.
[0013]
Further, the noise removing means includes a pulse output means for outputting a pulse when the output voltage from the frequency-voltage conversion means exceeds a certain value, and an output from the frequency-voltage conversion means by a pulse signal from the pulse output means. And holding means for sampling and holding the voltage.
[0014]
The noise removing means includes a pulse output means for generating a pulse when the interval of zero cross points of the signal input to the frequency-voltage converting means is greater than a certain value, and the frequency-voltage by the pulse signal from the pulse output means. And holding means for sampling and holding the output voltage from the conversion means.
[0015]
The noise removing means outputs a pulse when the output voltage from the frequency-voltage converting means exceeds a certain value, and outputs a pulse signal from the pulse outputting means from the frequency-voltage converting means. It is also composed of subtraction means for subtracting from the voltage.
[0016]
The noise removing means includes a pulse output means for generating a pulse when the interval between zero cross points of the signal input to the frequency-voltage converting means is a certain value or more, and the pulse signal from the pulse output means is converted to the frequency-voltage. It is also composed of pulse insertion means for inserting the signal input to the conversion means at intervals of zero cross points.
[0017]
[Action]
According to the present invention, a DC component is not generated in the baseband signal converted by the mixing means, and unnecessary signals included in the baseband signal are removed by the high-pass filter or the band-pass filter. As a result, not only the time from when power is supplied to the receiving circuit until the receiving circuit is stabilized can be shortened, but also good receiving sensitivity can be realized.
[0018]
【Example】
An embodiment of the present invention will be described below with reference to FIG. 1 is an antenna, 2 is a high frequency amplifying means, 3 is a first mixing means, 4 is a first low-frequency cutoff filter for blocking DC components, 6 is a first signal generating means, and 7 is a 90 ° phase shifter. , 8 is a second mixing means, 9 is a second low-frequency cutoff filter for cutting off the DC component, 15 is a first switch means, 16 is a second switch means, and 17 is a second signal generating means. , 18 is a 90 ° phase shift means, 19 is an arithmetic means for performing addition / subtraction, 20 is a third band pass filter, 21 is a frequency-voltage conversion means, 22 is a noise removal means, and 23 is a frequency correction means.
[0019]
The first and second low-frequency cutoff filters 4 and 9 use bandpass filters in order to serve the purpose of removing adjacent channels.
[0020]
Now, as a signal input to the antenna 1, the desired signal D
D = cos {ω + Δω} · t
ω: Angular frequency of carrier wave Δω: Angular frequency shift with both positive and negative polarities
think of. Here, the angular frequency deviation Δω varies with time depending on data or voice. That is, the signal D is a signal subjected to frequency modulation. The carrier angular frequency ω is the center angular frequency of the signal D. In the first signal generating means 6,
Q = COS {ω + x} · t x: Angular frequency deviation from carrier angular frequency ω
A signal Q represented by In the 90 ° phase shifter 7, the signal Q from the signal generating means 6 is phase-shifted by 90 ° so that Q ′ = SIN {ω + x} t. Therefore, the output terminals a and c of the first bandpass filter 4 and the second bandpass filter 9 are
Terminal a: D × Q = COS {Δω−x} · t
Terminal c: D × Q ′ = SIN {Δω−x} · t
A signal is generated. Here, x is set to be larger than Δω. That is, X is set to be equal to or greater than the occupied band of the signal D. For example, when signals are arranged with a channel spacing of 12.5 kHz, the occupied bandwidth is generally determined to be ± 4.25 kHz = 8.5 kHz. Δω is ± 2.5 kHz or less. Therefore, a value such as x = 6.25 kHz or 12.5 kHz is selected as a value out of the occupied band. In this embodiment, x = 6.25 kHz.
By setting in this way, the signals at the terminals a and c do not have a DC component.
[0021]
In the second signal generating means 17,
R = COS {r · t} − (1/3) · COS {3 · r · t} + (1/5) · COS {5 · r · t) −
A rectangular wave signal R represented by In this embodiment, r = 16 kHz is set.
The signal at the terminal a is multiplied by the rectangular wave signal R generated by the second signal generating means in the first switch means 15. On the other hand, the output of the 90 ° phase shift means 18
R ′ = SIN {r · t} + (1/3) · SIN {3 · r · t} + (1/5) · SIN {5 · r · t) −
The rectangular wave signal R ′ is output. Therefore, the signal at the terminal c is multiplied by the rectangular wave signal R ′ in the second switch means 16. Therefore, the output terminal a ′ of the first switch means 15 and the output terminal c ′ of the second switch means 16 are

Occurs.
The signals at the terminals a ′ and c ′ are added by the computing means 19. Accordingly, the output terminal f of the computing means 19 is connected to the output terminal f.

Is output. The third band pass filter 20 removes a term related to the harmonic component of the angular frequency r generated by the first switch means 17 and the second switch means 18, that is, the second term or more of the expression (1). . Therefore, the output terminal f ′ of the third bandpass filter 20 has
Terminal f ′: COS {{{r + x} −Δω} · t} = COS {2π × 22.25 kHz−Δω} · t} (2)
Is output. Here, since r + x> | Δω | is set, the phase of the equation (2) is always positive at the positive time. That is, no negative frequency occurs. Therefore, as is clear from the equation (2), the output signal generated at the terminal f ′ can be regarded as a frequency modulation signal in which a carrier signal having an angular frequency of {r + x} undergoes a frequency shift of Δω. Therefore, the frequency modulation signal generated at the terminal f ′ can be demodulated by the frequency-voltage conversion means 21 that generates an output voltage proportional to the frequency. Further, the demodulated signal generated at the terminal f ′ is subjected to noise removal means 22 to remove pulsed noise peculiar to FM demodulation generated in FM demodulation, and is output to the terminal g. Since the third band pass filter 20 has a low center frequency of around 22.25 kHz, it can be constituted by a monolithic IC. Of course, other means can also be constituted by a monolithic IC because the frequency is low.
[0022]
Next, as a signal to be input to the antenna 1, an interference signal U 2x = 12.5 khx away from the desired signal D
U = cos {ω + 2x + Δω} · t
think of. Then terminal a and terminal c have
Terminal a: U × Q = COS {Δω + x} · t
Terminal c: U × Q ′ = SIN {Δω + x} · t
A signal is generated. Since this interference signal is generated in the same band as the desired signal at the terminals a and c, the interference signals cannot be removed by the first and second bandpass filters 4 and 9. However, the output terminal f

A signal is generated. Obviously, the frequency band of the disturbing signal expressed by the above expression (3) is different from the frequency band of the desired signal expressed by the expression (1). Therefore, the signal of the expression (3) generated by the interference signal is removed by the third band-pass filter 20 designed to pass only the signal in the vicinity of the center frequency r + x = 22.25 kHz, and there is no interference at the terminal f ′. No signal is generated. In the embodiment of the present invention, the signal levels generated at the terminal a and the terminal c are the same. However, when there is a difference between the signal level of the terminal a and the signal level of the terminal c due to circuit variations, the interference signal U causes the terminal f to The generated signal is generated having the same frequency band as the frequency band shown in the equation (1). Therefore, if a level adjustment circuit is provided to adjust the signal level generated at the terminal a or the terminal c and cancel the interference signal component generated in the frequency band shown by the equation (1), a receiver that is more resistant to interference can be configured.
[0023]
Depending on the switch configuration of the first switch means 15 and the second switch means 16, an angular frequency r component may occur at the outputs of the switch means 15 and 16. At this time, the rectangular wave signal from the second signal generating means 17 is added to the output of the first switch means 15 or the second switch means 16 so as to cancel the component of the angular frequency r. Depending on the switch configuration of the first switch means 15 and the second switch means 16, a signal at the terminal a or terminal c may be generated at the first switch means 15 or the second switch means 16. In this case, the signal at the terminal a or the terminal c is added to the output of the first switch means 15 or the second switch means 16 to cancel the signal at the terminal a or the terminal c.
[0024]
If the configuration of the present invention is used, the signal can be demodulated without using the frequency correcting means 23 even when the frequency of the first signal generating means 6 is slightly shifted due to the influence of temperature or the like. In order to improve the frequency, the average DC voltage of the signal at the terminal g or the average frequency of the terminal f ′ is detected by the frequency correcting means 23, and the signal frequency of the first signal generating means 6 is controlled so as to become a certain reference value. This is still effective. When the frequency correction means 23 detects that a signal has been received from the demodulated output of the terminal g (not shown in FIG. 1), the DC voltage for controlling the frequency generated by the first signal generation means 6 is converted to D by microcomputer processing. / A conversion occurs. Further, although not shown in FIG. 1, when it is detected that a signal is received from the demodulated output of the terminal g, the bandwidths of the first bandpass filter 4 and the second bandpass filter 9 are switched so as to be narrowed. In this way, the S / N characteristic can be improved.
[0025]
In FIG. 1, the amplifying means is not shown after or before the first band-pass filter 4 and the second band-pass filter 9, but naturally the amplifying means may be inserted if necessary. In addition, when a large level signal is input to the antenna and the output of the calculation means 19 is clipped, it is considered that information necessary for demodulation is lost. Accordingly, it is more effective to adjust the amplification degree of the high-frequency amplification means 2 so that at least the output of the calculation means 19 is not clipped.
[0026]
1 has been described as an addition operation, a subtraction operation may be performed. In this case, the signal at the terminal f ′ is COS {{{r−x} + Δω} · t}.
[0027]
FIG. 2 shows a configuration of switch means applicable to the first switch means 15 and the second switch means 16 in FIG. In FIG. 2, 24 is an input terminal for receiving a signal at terminal a or a signal at terminal c, 25 is an input terminal for receiving a rectangular wave signal R or R ′ from the second signal generating means 17, 26 is an output terminal, Reference numeral 27 denotes an inverting circuit having an amplification factor of 1, and 28 denotes an electronic switch. In the electronic switch 28, the connection between the output terminal and the input terminal is switched depending on whether the phase of the rectangular wave signal R or the rectangular wave signal R ′ input to the input terminal 25 is positive or negative. Such an electronic switch 28 can be easily realized by CMOS as an analog switch, and can also be easily configured by using a bipolar transistor. The first switch means 15 and the second switch means 16 may have a configuration in which a differential amplifier is combined.
[0028]
FIG. 3 is a diagram and a waveform diagram showing the configuration of the frequency-voltage converting means 21 and the noise removing means 22 in FIG. In FIG. 1, the noise removal unit 22 is arranged at the subsequent stage of the frequency-voltage conversion unit 21, but in the example of FIG. 3, the noise removal unit 22 is incorporated in the frequency-voltage conversion unit 21. In FIG. 3A, 40 is an input terminal for inputting the frequency modulation signal shown at terminal f ′, 29 is an amplifying means, 30 is a binarizing means composed of a comparator, 31 is a first delay means, and a resistor 32, a capacitor 33, and a comparator 34. 35 is exclusive OR means, 36 is second delay means, 37 is pulse insertion means, 38 is pulse generation means, 39 is a low pass filter, and 41 is a demodulation output terminal. When the frequency of the signal input to the input terminal 40 increases, the output pulse interval of the exclusive OR unit 35 becomes narrower, and when the input frequency decreases, the output pulse interval of the exclusive OR unit 35 becomes wider. Accordingly, if unnecessary high-frequency components are removed by the low-pass filter 39, a voltage change corresponding to the output pulse interval of the exclusive OR means 35 can be taken out. In order to increase the demodulation sensitivity, the delay amount in the first delay means 31 may be increased. Next, the noise removal method will be described with reference to the waveform diagram of FIG. h and i are inputs to the exclusive OR means 35. Therefore, the output of the exclusive OR 35 is a pulse train as shown in j. When noise is included in the signal input to the input terminal 40, the pulse train of the signals h and i may become irregular due to the influence of noise, and one pulse may be lost. Thus, if the pulses of the signals h and i are lost, the pulse of the output j of the exclusive OR means 35 is also lost. Accordingly, when the signal j is passed through the low-pass filter, a large pulse noise is generated at the portion where the pulse is missing. The pulse generation means 38 generates a pulse output 1 that repeats HIGH / LOW every T1 if there is no pulse in the signal j for a time T2 (for example, T2 = 2 · T1) sufficiently longer than the normal pulse interval T1. The pulse output l stops when a pulse occurs at j. The signal j is delayed by the second delay means 36 to become a signal k. In the pulse insertion means 37, a pulse equal to the pulse width of the signal k is inserted into the signal k in accordance with the rising and falling edges of the pulse output l. This is a pulse in which a pulse marked with a circle in the signal m in the waveform diagram of FIG. The signal m is passed through a low-pass filter to obtain a demodulated signal. By inserting a pulse in this way, there is no missing pulse, and no pulse-like noise is generated from the demodulated output. Although a pulse is inserted into the signal j, a signal i is generated by the first delay means 31 after a pulse is inserted into the signal h, and a signal j having no missing pulse is generated by the exclusive OR means 35. Also good.
[0029]
FIG. 4 is a diagram showing another configuration of the frequency-voltage converting means 21 in FIG. 4, the same functional blocks as those in FIG. 3 are given the same numbers. 42 is an edge detection means, and 43 is a monostable multivibrator. The edge detection means 42 includes the delay means 31 and the exclusive OR means 35 in FIG. The output of the monostable multivibrator 43 has a narrower or wider pulse interval depending on the frequency of the signal input to the terminal 40. Accordingly, when unnecessary high-frequency components are removed by the low-pass filter 36 as in the case of FIG. The advantage of the configuration of FIG. 4 is that there is no need to increase the delay amount in the delay means 31. For this reason, it is not necessary to increase the time constant of the circuit composed of the capacitor 33 and the resistor 32. The demodulation sensitivity can be optimally set by appropriately selecting the pulse width of the output of the monostable multivibrator 43. The method for removing noise is the same as in FIG.
[0030]
FIG. 5 shows another configuration and waveform diagram of the noise removing means 22. In FIG. 5A, 44 is an input terminal to which the demodulated output of the frequency-voltage converting means 21 is input, 45 is a high-pass filter that removes a desired signal such as a data signal and extracts only noise components, and 46 is a noise of a certain level or higher. A comparator 47 to be taken out is a pulse width extending means, and 45, 46 and 47 constitute a pulse generating means 48. Reference numeral 49 is a delay means, 50 is a holding means, and 51 is an output terminal. The operation of the noise removing unit 22 will be described with reference to the waveform diagram of FIG. The signal v input to the input terminal 44 becomes a signal w by the high pass filter 45. Only pulsed noise is taken out by the comparator 46 and becomes a signal x. The pulse width of the signal x is expanded by the pulse width extension means 47 to become a signal y. On the other hand, the signal v is delayed by the delay means 49, and the holding means 50 samples and holds the value of the delayed signal v during the pulse output period of the signal y. Therefore, the output of the output terminal 51 is the signal z. Although this signal z is not shown, it can be changed smoothly by passing through a low-pass filter. Further, subtraction means may be used in place of the holding means 50, and noise may be removed by subtracting the signal z and the signal y. Note that the signal 1 in FIG. 3 may be used as the output signal y of the pulse generating means.
[0031]
FIG. 6 shows the configuration of the second signal generating means 17 and the 90 ° phase shifting means 18. 52 is an input terminal for receiving a clock signal generated from a reference clock of the microcomputer, 53, 54 and 55 are D-flip flops, each of which constitutes a 1/2 frequency divider.

Reference numerals

56 and 57 denote output terminals, which output a rectangular wave signal R from the terminal 56 and a rectangular wave signal R ′ orthogonal to the rectangular wave signal R from the terminal 57. If the circuit of FIG. 6 is used, an IC can be easily formed. Note that a signal oscillated by a bistable multivibrator or the like may be used as a signal input to the input terminal 52.
[0032]
In the embodiment of FIG. 1, the demodulation of the frequency modulation signal has been described. However, not only the frequency modulation signal but also the amplitude modulation signal and the phase modulation signal are demodulated in place of the frequency-voltage conversion means 21 shown in FIG. This is possible by using corresponding demodulation means.
[0033]
Although the signal from the high frequency amplifying means 2 is used as the input signal of the constituent device of the present invention, an intermediate frequency signal obtained by frequency conversion of the output signal of the high frequency amplifying means 2 may be used as the input signal of the constituent device of the present invention.
[0034]
【The invention's effect】
As described above, according to the receiver of the present invention, since no DC component is required for signal demodulation, the rise time at the time of power supply can be shortened, and at the same time, the influence of DC drift due to temperature or the like It is possible to provide a highly reliable receiving apparatus that can remove the influence of 1 / f noise and prevent deterioration of reception sensitivity. Of course, an expensive mechanical filter is not necessary, and it is easy to make an IC, so that a receiving apparatus can be realized at low cost. If a level adjustment circuit is provided in consideration of variations in the amplification degree of the circuit so as to cancel unnecessary interference signals, it is possible to provide a receiver that is more resistant to interference.
[0035]
In addition, the present invention can be applied to demodulation of frequency modulation signals and demodulation of amplitude modulation signals and phase modulation signals.
[0037]
Furthermore, since the noise in the pulse form can be removed by using the noise removing means, the S / N characteristic can be improved.
[0038]
Of course, the first and second switches, the frequency-voltage converting means, and the noise removing means can be realized with a simple configuration, and it is easy to make an IC.
[0039]
In the intermittent operation method in which transmission and reception are performed intermittently in order to operate for a long time with battery drive, it is as short as possible to check whether there is a signal from the other party to yourself It is necessary to perform this, and the time from when the power is supplied to the receiving apparatus until the operation of the receiving apparatus is stabilized must be as short as possible. The present invention can be applied to such an intermittent operation method, and can exert a great effect in extending the battery life. In particular, in the case of incorporating a wireless transmission / reception device in a gas meter in an automatic meter reading system such as a gas meter, a receiving device that is small and can be operated for 10 years by battery operation is required. Not only the automatic meter reading system but also a wireless remote control device used in a housing equipment system including a remote control device that connects a gas water heater and a kitchen wirelessly, a small size and battery drive are indispensable conditions. The present invention can provide a very effective receiver for the above-mentioned problems.
[Brief description of the drawings]
FIG. 1 is a block diagram of a receiving apparatus according to an embodiment of the present invention.
FIG. 2 is a block diagram of switch means in one embodiment of the present invention.
3A is a block diagram and a waveform diagram of a frequency-voltage conversion unit and a noise removal unit in an embodiment of the present invention. FIG.
(B) Waveform diagram of frequency-voltage converting means and noise removing means in the same embodiment
FIG. 4 is another block diagram of frequency-voltage converting means and noise removing means in one embodiment of the present invention.
FIG. 5A is a block diagram of noise removal means in an embodiment of the present invention.
(B) Waveform diagram of noise removing means in the same embodiment
FIG. 6 is a block diagram of second signal generating means and 90 ° phase shifting means in an embodiment of the present invention.
[Explanation of symbols]
1 Antenna
2 High frequency amplification means
3 First mixing means
4 First bandpass filter
6 First signal generating means
7 90 ° shifter
8 Second mixing means
9 Second bandpass filter
15 First switch means
16 Second switch means
17 Second signal generating means
18 90 ° phase shift means
19 Calculation means
20 Third bandpass filter
21 Frequency-voltage conversion means
22 Frequency correction means
22 Noise removal means

Claims

A first signal generating means for outputting a signal having a frequency separated from a center frequency of the received signal by an occupied band of the received signal, or a signal having a frequency that is a difference between the signal from the first signal generating means and the received signal First mixing means for taking out the signal, second mixing means for taking out a signal having a frequency that is the difference between the signal obtained by phase-shifting the signal from the first signal generating means and the received signal, and the first mixing means A first low-frequency cutoff filter that receives a signal from the first low-frequency cutoff filter, a second low-frequency cutoff filter that receives a signal from the second mixing means, and a first that generates a rectangular wave signal that is temporally continuous. Second signal generating means, first switch means for switching a signal from the first low-frequency cutoff filter by a rectangular wave signal from the second signal generating means, and the second signal generating means A second switch means for switching a signal from the second low-frequency cutoff filter by a rectangular wave signal obtained by phase-shifting the rectangular wave signal, an output signal of the first switch means, and a second switch means An arithmetic means for adding or subtracting the output signal, and the received signal and the first signal generating means from the frequency of the rectangular wave signal provided in the preceding stage or the subsequent stage of the arithmetic means and generated by the second signal generating means And a band pass filter that passes energy in the vicinity of the difference frequency with respect to the output signal of the output signal , wherein the first or second switch means includes a first input terminal and a second input device. The electronic switch has a first input terminal, an output terminal, and a control terminal, and the output terminal is switched to the first input terminal or the second input terminal according to a signal input to the control terminal. Ji and, first second receiving apparatus is composed of a reversing means for outputting to an input terminal of the electronic switch the signal and inverted signal to be input to the input terminal of the electronic switch.

A first signal generating means for outputting a signal having a frequency separated from a center frequency of the received signal by an occupied band of the received signal, or a signal having a frequency that is a difference between the signal from the first signal generating means and the received signal First mixing means for taking out the signal, second mixing means for taking out a signal having a frequency that is the difference between the signal obtained by phase-shifting the signal from the first signal generating means and the received signal, and the first mixing means A first low-frequency cutoff filter that receives a signal from the first low-frequency cutoff filter, a second low-frequency cutoff filter that receives a signal from the second mixing means, and a first that generates a rectangular wave signal that is temporally continuous. Second signal generating means, first switch means for switching a signal from the first low-frequency cutoff filter by a rectangular wave signal from the second signal generating means, and the second signal generating means A second switch means for switching a signal from the second low-frequency cutoff filter by a rectangular wave signal obtained by phase-shifting the rectangular wave signal, an output signal of the first switch means, and a second switch means An arithmetic means for adding or subtracting the output signal, and the received signal and the first signal generating means from the frequency of the rectangular wave signal provided in the preceding stage or the subsequent stage of the arithmetic means and generated by the second signal generating means A band-pass filter that passes energy in the vicinity of a difference frequency with respect to the output signal of the output signal, and a frequency-voltage conversion unit that generates a voltage according to the frequency of the output signal of the band-pass filter, the frequency - a receiver for the output voltage of the voltage converting means and the demodulated output, the frequency - voltage converting means includes a binarizing means for binarizing the signal from said operation means Delay means for delaying a signal from the binarization means, exclusive OR means for outputting an exclusive OR of the signal from the binarization means and the signal from the delay means, and the exclusive OR And a low-pass filter that removes a high-frequency component of the output signal of the means.

A first signal generating means for outputting a signal having a frequency separated from a center frequency of the received signal by an occupied band of the received signal, or a signal having a frequency that is a difference between the signal from the first signal generating means and the received signal First mixing means for taking out the signal, second mixing means for taking out a signal having a frequency that is the difference between the signal obtained by phase-shifting the signal from the first signal generating means and the received signal, and the first mixing means A first low-frequency cutoff filter that receives a signal from the first low-frequency cutoff filter, a second low-frequency cutoff filter that receives a signal from the second mixing means, and a first that generates a rectangular wave signal that is temporally continuous. Second signal generating means, first switch means for switching a signal from the first low-frequency cutoff filter by a rectangular wave signal from the second signal generating means, and the second signal generating means A second switch means for switching a signal from the second low-frequency cutoff filter by a rectangular wave signal obtained by phase-shifting the rectangular wave signal, an output signal of the first switch means, and a second switch means An arithmetic means for adding or subtracting the output signal, and the received signal and the first signal generating means from the frequency of the rectangular wave signal provided in the preceding stage or the subsequent stage of the arithmetic means and generated by the second signal generating means A band-pass filter that passes energy in the vicinity of a difference frequency with respect to the output signal of the output signal, and a frequency-voltage conversion unit that generates a voltage according to the frequency of the output signal of the band-pass filter, the frequency - a receiver for the output voltage of the voltage converting means and the demodulated output, the frequency - voltage converting means includes a binarizing means for binarizing the signal from said operation means Edge detection means for detecting an edge of a signal from the binarization means, a monostable multivibrator activated by a signal from the edge detection means, and a low-pass filter for removing a high frequency component of an output signal of the monostable multivibrator And a receiving device.

A first signal generating means for outputting a signal having a frequency separated from a center frequency of the received signal by an occupied band of the received signal, or a signal having a frequency that is a difference between the signal from the first signal generating means and the received signal First mixing means for taking out the signal, second mixing means for taking out a signal having a frequency that is the difference between the signal obtained by phase-shifting the signal from the first signal generating means and the received signal, and the first mixing means A first low-frequency cutoff filter that receives a signal from the first low-frequency cutoff filter, a second low-frequency cutoff filter that receives a signal from the second mixing means, and a first that generates a rectangular wave signal that is temporally continuous. Second signal generating means, first switch means for switching a signal from the first low-frequency cutoff filter by a rectangular wave signal from the second signal generating means, and the second signal generating means A second switch means for switching a signal from the second low-frequency cutoff filter by a rectangular wave signal obtained by phase-shifting the rectangular wave signal, an output signal of the first switch means, and a second switch means An arithmetic means for adding or subtracting the output signal, and the received signal and the first signal generating means from the frequency of the rectangular wave signal provided in the preceding stage or the subsequent stage of the arithmetic means and generated by the second signal generating means A band-pass filter that passes energy in the vicinity of a difference frequency from the output signal of the output signal, a frequency-voltage conversion means that generates a voltage according to the frequency of the output signal of the band-pass filter, and the frequency-voltage conversion is composed of a noise removing means for removing a pulse-like noise occurring in the output means, the output voltage of said noise removing means comprising a receiving unit for a demodulation output, the The sound removal means includes a pulse output means for outputting a pulse when the output voltage from the frequency-voltage conversion means exceeds a certain value, and an output voltage from the frequency-voltage conversion means by a pulse signal from the pulse output means. And a holding device for sampling and holding.

A first signal generating means for outputting a signal having a frequency separated from a center frequency of the received signal by an occupied band of the received signal, or a signal having a frequency that is a difference between the signal from the first signal generating means and the received signal First mixing means for taking out the signal, second mixing means for taking out a signal having a frequency that is the difference between the signal obtained by phase-shifting the signal from the first signal generating means and the received signal, and the first mixing means A first low-frequency cutoff filter that receives a signal from the first low-frequency cutoff filter, a second low-frequency cutoff filter that receives a signal from the second mixing means, and a first that generates a rectangular wave signal that is temporally continuous. Second signal generating means, first switch means for switching a signal from the first low-frequency cutoff filter by a rectangular wave signal from the second signal generating means, and the second signal generating means A second switch means for switching a signal from the second low-frequency cutoff filter by a rectangular wave signal obtained by phase-shifting the rectangular wave signal, an output signal of the first switch means, and a second switch means An arithmetic means for adding or subtracting the output signal, and the received signal and the first signal generating means from the frequency of the rectangular wave signal provided in the preceding stage or the subsequent stage of the arithmetic means and generated by the second signal generating means A band-pass filter that passes energy in the vicinity of a difference frequency from the output signal of the output signal, a frequency-voltage conversion means that generates a voltage according to the frequency of the output signal of the band-pass filter, and the frequency-voltage conversion is composed of a noise removing means for removing a pulse-like noise occurring in the output means, the output voltage of said noise removing means comprising a receiving unit for a demodulation output, the The sound removing means includes a pulse output means for generating a pulse when a zero cross point interval of a signal input to the frequency-voltage conversion means is greater than a certain value, and the frequency-voltage conversion by a pulse signal from the pulse output means. And a holding means for sampling and holding the output voltage from the means .

A first signal generating means for outputting a signal having a frequency separated from a center frequency of the received signal by an occupied band of the received signal, or a signal having a frequency that is a difference between the signal from the first signal generating means and the received signal First mixing means for taking out the signal, second mixing means for taking out a signal having a frequency that is the difference between the signal obtained by phase-shifting the signal from the first signal generating means and the received signal, and the first mixing means A first low-frequency cutoff filter that receives a signal from the first low-frequency cutoff filter, a second low-frequency cutoff filter that receives a signal from the second mixing means, and a first that generates a rectangular wave signal that is temporally continuous. Second signal generating means, first switch means for switching a signal from the first low-frequency cutoff filter by a rectangular wave signal from the second signal generating means, and the second signal generating means A second switch means for switching a signal from the second low-frequency cutoff filter by a rectangular wave signal obtained by phase-shifting the rectangular wave signal, an output signal of the first switch means, and a second switch means An arithmetic means for adding or subtracting the output signal, and the received signal and the first signal generating means from the frequency of the rectangular wave signal provided in the preceding stage or the subsequent stage of the arithmetic means and generated by the second signal generating means A band-pass filter that passes energy in the vicinity of a difference frequency from the output signal of the output signal, a frequency-voltage conversion means that generates a voltage according to the frequency of the output signal of the band-pass filter, and the frequency-voltage conversion is composed of a noise removing means for removing a pulse-like noise occurring in the output means, the output voltage of said noise removing means comprising a receiving unit for a demodulation output, the The sound removal means includes a pulse output means for outputting a pulse when the output voltage from the frequency-voltage conversion means exceeds a certain value, and a pulse signal from the pulse output means for outputting an output voltage from the frequency-voltage conversion means. And a subtracting means for subtracting from the receiver.

A first signal generating means for outputting a signal having a frequency separated from a center frequency of the received signal by an occupied band of the received signal, or a signal having a frequency that is a difference between the signal from the first signal generating means and the received signal First mixing means for taking out the signal, second mixing means for taking out a signal having a frequency that is the difference between the signal obtained by phase-shifting the signal from the first signal generating means and the received signal, and the first mixing means A first low-frequency cutoff filter that receives a signal from the first low-frequency cutoff filter, a second low-frequency cutoff filter that receives a signal from the second mixing means, and a first that generates a rectangular wave signal that is temporally continuous. Second signal generating means, first switch means for switching a signal from the first low-frequency cutoff filter by a rectangular wave signal from the second signal generating means, and the second signal generating means A second switch means for switching a signal from the second low-frequency cutoff filter by a rectangular wave signal obtained by phase-shifting the rectangular wave signal, an output signal of the first switch means, and a second switch means An arithmetic means for adding or subtracting the output signal, and the received signal and the first signal generating means from the frequency of the rectangular wave signal provided in the preceding stage or the subsequent stage of the arithmetic means and generated by the second signal generating means A band-pass filter that passes energy in the vicinity of a difference frequency from the output signal of the output signal, a frequency-voltage conversion means that generates a voltage according to the frequency of the output signal of the band-pass filter, and the frequency-voltage conversion is composed of a noise removing means for removing a pulse-like noise occurring in the output means, the output voltage of said noise removing means comprising a receiving unit for a demodulation output, the The sound removing means includes a pulse output means for generating a pulse when a zero cross point interval of a signal input to the frequency-voltage converting means is greater than a certain value, and a pulse signal from the pulse output means for the frequency-voltage conversion. And a pulse inserting means for inserting at intervals of zero cross points of signals inputted to the means.