JP2004297574A

JP2004297574A - Signal detection apparatus, and receiver capable of utilizing the apparatus

Info

Publication number: JP2004297574A
Application number: JP2003088699A
Authority: JP
Inventors: Yuichi Yamazaki; 祐一山崎
Original assignee: Sanyo Electric Co Ltd
Current assignee: Sanyo Electric Co Ltd
Priority date: 2003-03-27
Filing date: 2003-03-27
Publication date: 2004-10-21
Anticipated expiration: 2023-03-27
Also published as: JP4121410B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a signal detection apparatus capable of accurately detecting a DU ratio under a condition wherein a plurality of interference waves exist. <P>SOLUTION: A 100 kHz interference detecting adjacent band summating system filter 30 outputs a 100 kHz interference strength signal 204, a 200 kHz interference detecting adjacent band summating system filter 32 outputs a 200 kHz interference strength signal 206, and a switching filter 34 properly revises the pass band and a method of the filter to apply arithmetic processing to an IF received signal 200. A frequency discrimination section 38 discriminates the frequency of a interference wave from the 100 kHz interference strength signal 204 and the 200 kHz interference strength signal 206 to output a interference frequency signal 208. A strength ratio discrimination section 40 discriminates the DU ratio of the received signal from the 100kHz interference strength signal 204, the 200kHz interference strength signal 206, and an output signal of the switching filter 34 to provide the output of a discrimination result as a DU ratio signal 202. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、ＦＭ放送等の受信装置において、妨害波の状態を自動的に検知可能な信号検出装置およびその装置を利用可能な受信装置に関する。特に、複数の妨害波に対応可能な信号検出装置およびその装置を利用可能な受信装置に関する。
【０００２】
【従来の技術】
一般に、ＦＭラジオ受信機等においては、妨害信号が希望放送局からの放送信号に隣接して発生した場合、いわゆる「隣接妨害」と呼ばれる通信品質の劣化が生じる。したがって、このような隣接妨害が発生した場合、これを検知して、受信装置側で、たとえば受信信号をダウンコンバートした中間周波数信号（ＩＦ信号）を通過させるＩＦフィルタの通過帯域幅を変更するなどして、このような妨害信号の影響を低減する等の対策がとられている。しかしながら、たとえば欧州ではチャネルが１００ＫＨｚの単位で隣接するため、隣接妨害の検知方法によっては、ＩＦフィルタの通過帯域の調整だけでは、妨害信号を除去しきれず、隣接妨害対策がＦＭ受信機等の設計における１つの課題となっている。
【０００３】
このような妨害信号の有無を検知する方法としては、例えば、希望波の周波数を中心として広帯域と狭帯域に含まれるエネルギを比較し、その比較結果に基づいて、隣接妨害の存在を検知する手法がある（例えば、特許文献１参照）。あるいは、中間周波数フィルタにより、受信希望信号の上側および下側の周波数帯域に存在する妨害波を検出し、この検出出力を差動増幅して、この差動増幅出力に応じて、希望信号用ＩＦフィルタの中心周波数を妨害波のエネルギーの小さい方へ移動させる技術がある（例えば、特許文献２参照）。
【０００４】
【特許文献１】
特開平８−９７７３８号公報
【特許文献２】
特開平５−１９１３１２号公報
【０００５】
【発明が解決しようとする課題】
以上説明したような従来技術によれば、特定の条件下において、隣接妨害波を検出することは可能であるものの、以下のような課題がある。まず、特開平８−９７７３８号公報に開示された発明では、所望波と妨害波との間の強度比（以下、ＤＵ比と呼ぶ）について見ると、後述する相互変調が起きると、その検知できるＤＵ比の範囲が狭くなる。一方、もう一方の特開平５−１９１３１２号公報に開示された方法でも、相互変調妨害が発生するような条件下では、本来の妨害局とこのような相互変調によって生じる変調妨害が希望局を挟むように現われてしまうため、誤判定を起こしてしまう。
【０００６】
さらに、上述の技術ではある一種類の隣接妨害についての帯域間隔しか想定しないが、例えば欧州におけるＦＭ放送では、隣接局との隣接帯域間隔１００ｋＨｚに加えて、次隣接の２００ｋＨｚ離れた帯域の局の信号によっても混信妨害が生じる。また、米国における隣接局との隣接帯域間隔は２００ｋＨｚである。一方、以上のような複数の妨害波を検出する検出部がすべての複数の妨害波に対応して備えられると回路規模が増加する。
【０００７】
以下、この相互変調妨害についてさらに詳しく説明する。アンテナからの受信信号を受けて、中間周波数に変換するＦＭ受信機等におけるフロントエンド部では、受信波の増幅も行われるが、このような増幅器を通過した信号では、いわゆる相互変調歪が発生する。高周波増幅器に周波数の異なる２つ以上の信号が入力された場合、入力した信号相互、あるいは増幅器の非直線性により発生した高周波との間で相互変調を起こして、増幅器の出力にいわゆる「スプリアス」を発生させる。すなわち、増幅器に入力された信号の両側に相互変調に伴う新たな妨害信号が発生し得る。
【０００８】
例えば、希望局の周波数Ｆの近傍にその希望局の周波数に対して＋Δｆだけずれた周波数側に妨害局からの妨害信号が発生していると、相互変調の影響により、希望局の信号に対して、妨害局の信号とは反対側の、希望局信号の周波数から−Δｆだけずれた位置にスプリアス信号が発生する。したがって、たとえば、上述した特開平５−１９１３１２号公報に開示されているような発明では、希望局からの信号の両側の信号レベルの差動増幅により妨害波の発生を検知する構成であるため、誤判定を起こしてしまうという問題がある。
【０００９】
本発明者はこうした状況を認識して、本発明をなしたものであり、その目的は妨害局の発生を広いＤＵ比の範囲にわたって正確に検出することが可能な信号検出装置およびその装置を利用可能な受信装置を提供することである。また、複数の妨害波が存在する場合においてもＤＵ比を正確に検出することが可能な信号検出装置およびその装置を利用可能な受信装置を提供することである。
【００１０】
【課題を解決するための手段】
本発明のある態様は信号検出装置に関する。この装置は、希望波の周波数を中心としてそれぞれ第１の周波数離れた２つの周波数領域に対応した第１の強度値を検出する第１検出部と、希望波の周波数を中心としてそれぞれ第２の周波数離れた２つの周波数領域に対応した第２の強度値を検出する第２検出部と、第１の強度値と第２の強度値から、希望波についての妨害波の周波数に対応した第１の周波数の値あるいは第２の周波数の値を選択する周波数判定部と、希望波の周波数を中心としてそれぞれ選択した周波数離れた２つの周波数領域に対応すべき第３の強度値を検出する第３検出部と、第１の周波数の値を選択した場合、第１の強度値および第３の強度値を含む複数の強度値のいずれかを選択し、第２の周波数の値を選択した場合、第２の強度値あるいは第３の強度値を含む複数の強度値のいずれかを選択して、希望波と妨害波の強度比を判定する強度判定部とを含む。この装置において、第３検出部は、第１検出部および第２検出部と比較して、強度値の検出精度の特性が異なってもよい。
【００１１】
第１検出部は、第１の強度値として、希望波の周波数より第１の周波数だけ高い周波数および低い周波数をそれぞれ中心周波数とした２つの帯域フィルタを通過した信号出力の加算値を出力し、第２検出部は、第２の強度値として、希望波の周波数より第２の周波数だけ高い周波数および低い周波数をそれぞれ中心周波数とした２つの帯域フィルタを通過した信号出力の加算値を出力してもよい。
【００１２】
第１検出部は、第１の強度値として、希望波の周波数より第１の周波数だけ高い周波数および低い周波数をそれぞれ中心周波数とした２つの帯域フィルタを通過した信号出力の差分値を出力し、第２検出部は、第２の強度値として、希望波の周波数より第２の周波数だけ高い周波数および低い周波数をそれぞれ中心周波数とした２つの帯域フィルタを通過した信号出力の加算値を出力してもよい。
【００１３】
第２の周波数の値は、第１の周波数の値より大きく、周波数判定部は、第２の強度値を増幅する増幅部と、希望波の強度値にもとづいて増幅した第２の強度値を補正する補正部と、第１の強度値と補正した第２の強度値から、第１の周波数の値あるいは第２の周波数の値を選択する選択部とを含んでもよい。
【００１４】
第３検出部は、選択した周波数に応じて、第３の強度値として、希望波の周波数より第１の周波数だけ高い周波数および低い周波数をそれぞれ中心周波数とする２つの帯域フィルタを通過した信号出力の差分値、あるいは希望波の周波数を中心に第２の周波数を通過帯域にした帯域フィルタと第２の周波数を非通過帯域にした帯域フィルタをそれぞれ通過した信号出力の差分値を出力してもよい。
【００１５】
本発明の別の態様も信号検出装置に関する。この装置は、希望波の周波数より第１の周波数だけ高い周波数および低い周波数をそれぞれ中心周波数とした２つの帯域フィルタを通過した信号出力の加算値を出力する第１検出部と、希望波の周波数より第２の周波数だけ高い周波数および低い周波数をそれぞれ中心周波数とした２つの帯域フィルタを通過した信号出力の加算値を出力する第２検出部と、希望波の周波数より第１の周波数だけ高い周波数および低い周波数をそれぞれ中心周波数とした２つの帯域フィルタを通過した信号出力の差分値を出力する第３検出部と、希望波の周波数を中心に第２の周波数を通過帯域にした帯域フィルタと第２の周波数を非通過帯域にした帯域フィルタをそれぞれ通過した信号出力の差分値を出力する第４検出部と、第１検出部および第２検出部の出力値から、希望波についての妨害波の周波数に対応すべき第１の周波数の値あるいは第２の周波数の値を選択する周波数判定部と、妨害波に対応すべき周波数および出力レベルに応じて、第１検出部または第３検出部を含む複数の検出部のいずれかひとつの出力値の選択、あるいは第２検出部または第４検出部を含む複数の検出部のいずれかひとつの出力値の選択を実行して、希望波と妨害波の強度比を判定する強度判定部とを含む。
【００１６】
本発明のさらに別の態様は受信装置に関する。この装置は、希望局から受信された無線周波数信号を中間周波数信号に変換するフロントエンド部と、中間周波数信号にもとづいて希望波についての妨害波の強度を検出する妨害検出部と、妨害波の強度に応じて帯域が設定された帯域フィルタによって、中間周波数信号をフィルタリングして出力する中間周波数フィルタ部と、中間周波数フィルタ部からの出力信号を復調処理する検波部とを含む。この装置において、妨害検出部は、希望波の周波数の周辺周波数領域における複数の周波数領域でかつ複数の方法で、中間周波数信号をフィルタリングして妨害波の出力レベルをそれぞれ検出する複数の検出部と、妨害波の出力レベルに応じて、妨害波に対応すべき周波数領域を判定する周波数判定部と、妨害波に対応すべき周波数領域および出力レベルに応じて、複数の検出部のいずれか１つの出力レベルを選択して、希望波と妨害波の強度比を判定する強度判定部とを含んでもよい。
【００１７】
複数の検出部は、希望波の周波数より第１の周波数だけ高い周波数および低い周波数をそれぞれ中心周波数とした２つの帯域フィルタを通過した信号出力の第１加算値を出力する第１検出部と、希望波の周波数より第２の周波数だけ高い周波数および低い周波数をそれぞれ中心周波数とした２つの帯域フィルタを通過した信号出力の第２加算値を出力する第２検出部と、希望波の周波数より第１の周波数だけ高い周波数および低い周波数をそれぞれ中心周波数とした２つの帯域フィルタを通過した信号出力の第１差分値、あるいは希望波の周波数を中心に第２の周波数を通過帯域にした帯域フィルタと第２の周波数を通過帯域にしない帯域フィルタをそれぞれ通過した信号出力の第２差分値を出力する第３検出部とを含んでもよい。この装置において、周波数判定部は、第１加算値と第２加算値から、妨害波に対応すべき周波数領域を判定し、強度判定部は、判定した周波数領域に応じて、第１加算値または第１差分値を含む複数の出力レベルのいずれかの選択、あるいは第２加算値または第２差分値を含む複数の出力レベルのいずれかの選択を実行してもよい。
【００１８】
なお、以上の構成要素の任意の組み合わせ、本発明の表現を方法、装置、システムなどの間で変換したものもまた、本発明の態様として有効である。
【００１９】
【発明の実施の形態】
（実施の形態１）
実施の形態１は、希望波に加えて妨害波を含んだ信号を受信する受信装置に関する。さらに妨害波は、希望波の周波数から１００ｋＨｚ離れた妨害波（以下、「１００ｋＨｚ妨害波」という）、希望波の周波数から２００ｋＨｚ離れた妨害波（以下、「２００ｋＨｚ妨害波」という）を含む。本実施の形態の受信装置は、１００ｋＨｚ妨害波検出用のフィルタと２００ｋＨｚ妨害波検出用のフィルタによって、それぞれ１００ｋＨｚ妨害波と２００ｋＨｚ妨害波に関する信号強度値を測定し、それぞれの信号強度値を比較して、１００ｋＨｚ妨害波と２００ｋＨｚ妨害波のうち希望波の受信処理により影響が強い妨害波を選択する。
【００２０】
さらに、選択した周波数の妨害波に対して、入力した信号のＤＵ比に対してＤＵ比の検出精度の異なった複数のフィルタを用意し、入力した信号におけるＤＵ比のおよそのレベルを測定後、測定した結果に応じて前述の複数のフィルタのうちの最適なフィルタを選択し、ＤＵ比を測定するために、より正確なＤＵ比の検出を可能にする。また、選択した妨害波の周波数および検出したＤＵ比にもとづいて受信した信号を通過させる帯域フィルタの帯域幅を変更するために、複数の妨害波が存在する環境下においても最適なフィルタリングを実行できる。なお、本発明では、妨害波の出力レベルが求まれば、このＩＦ信号レベルのうち残りを占めている希望波の出力レベルがわかるという性質が利用される。
【００２１】
図１は、実施の形態１に係る受信装置１００の構成である。
受信装置１００は、アンテナ２２と、アンテナ２２からの信号を受けて、選局処理、増幅処理および中間周波数への変換処理等を行うフロントエンド部１０と、フロントエンド部１０の出力を受けて、所望帯域の中間周波数信号を通過させる帯域通過型フィルタであるＩＦフィルタ１２と、ＩＦフィルタ１２の出力を受けて、ＦＭ検波を行うＦＭ検波部１６と、フロントエンド部１０の出力から、後に説明するように、ＤＵ比を検出して、ＩＦフィルタ１２にＤＵ比信号２０２を与える妨害検出部１４とを備える。さらに、ＦＭ検波部１６は、検波のために搬送波の位相をロックするＰＬＬ１８と、ＩＦフィルタ１２による信号電力の減衰を補償する利得制御部２０とを備える。
【００２２】
ここで、フロントエンド部１０には、自動利得制御部（図示せず）が設けられており、受信点での電界強度にかかわらずフロントエンド部１０から出力されるＩＦ受信信号２００は一定のレベルとなる。
【００２３】
ＩＦフィルタ１２は、妨害検出部１４からのＤＵ比信号２０２に基づいて、通過帯域を連続的、段階的に切換える。たとえば、妨害信号の発生が検知された場合は、妨害信号を除去可能な帯域までＩＦフィルタ１２の帯域幅を減少させ、このように帯域幅の狭くなったＩＦフィルタ１２からの出力を検波する構成とする。このような制御を行う場合、隣接妨害が発生した場合にのみ、隣接妨害を有効に防止することとなるとともに、隣接妨害がないときは歪率について良好な検波出力を得ることが可能となる。さらに、妨害信号が１００ｋＨｚ妨害波の場合は、２００ｋＨｚ妨害波の場合よりも、希望波に近いため、ＩＦフィルタ１２の帯域幅をより減少させる。
【００２４】
この構成は、ハードウエア的には、任意のコンピュータのＣＰＵ、メモリ、その他のＬＳＩで実現でき、ソフトウエア的にはメモリのロードされた予約管理機能のあるプログラムなどによって実現されるが、ここではそれらの連携によって実現される機能ブロックを描いている。したがって、これらの機能ブロックがハードウエアのみ、ソフトウエアのみ、またはそれらの組合せによっていろいろな形で実現できることは、当業者には理解されるところである。
【００２５】
図２は、妨害検出部１４の構成を示す。妨害検出部１４は、１００ｋＨｚ妨害検出用隣接帯域加算方式フィルタ３０、２００ｋＨｚ妨害検出用隣接帯域加算方式フィルタ３２、切替型フィルタ３４、信号判定部３６を含み、さらに信号判定部３６は、周波数判定部３８、強度比判定部４０を備える。
【００２６】
１００ｋＨｚ妨害検出用隣接帯域加算方式フィルタ３０は、ＩＦ受信信号２００から後述する隣接帯域加算方式の演算処理によって１００ｋＨｚ妨害強度信号２０４を出力し、２００ｋＨｚ妨害検出用隣接帯域加算方式フィルタ３２は、ＩＦ受信信号２００から後述する隣接帯域加算方式の演算処理によって２００ｋＨｚ妨害強度信号２０６を出力し、切替型フィルタ３４は、フィルタの通過帯域および方式を適宜変更して、ＩＦ受信信号２００を演算処理する。
【００２７】
周波数判定部３８は、１００ｋＨｚ妨害強度信号２０４および２００ｋＨｚ妨害強度信号２０６から妨害波の周波数を判定し、妨害周波数信号２０８を出力する。すなわち、妨害波が１００ｋＨｚ妨害波または２００ｋＨｚ妨害波であるかを判定する。切替型フィルタ３４は、妨害周波数信号２０８にもとづいて１００ｋＨｚ妨害波の場合に隣接帯域差分方式、あるいは２００ｋＨｚ妨害波の場合に広狭帯域差分方式にフィルタを切替える。
【００２８】
強度比判定部４０は、１００ｋＨｚ妨害強度信号２０４、２００ｋＨｚ妨害強度信号２０６および切替型フィルタ３４の出力信号から受信信号のＤＵ比を判定して判定結果をＤＵ比信号２０２としてＩＦフィルタ１２に与える。
【００２９】
図３は、１００ｋＨｚ妨害検出用隣接帯域加算方式フィルタ３０の構成を示す。
１００ｋＨｚ妨害検出用隣接帯域加算方式フィルタ３０は、希望波から見て周波数の低い側の隣接周波数付近が通過帯域に規定された下側妨害検出フィルタ５０と、この下側妨害検出フィルタ５０の出力を受けて平滑化するための平滑化処理部５４と、希望局から見て周波数の高い側の隣接周波数付近が通過帯域に規定された上側妨害検出フィルタ５２と、この上側妨害検出フィルタ５２の出力を受けて平滑化するための平滑化処理部５６と、平滑化処理部５４および平滑化処理部５６の出力を受けて、その和の信号を１００ｋＨｚ妨害強度信号２０４として周波数判定部３８または強度比判定部４０に対して出力する加算部５８とを備える。
【００３０】
図４は、図３の２つのバンドパスフィルタ、すなわち下側妨害検出フィルタ５０と上側妨害検出フィルタ５２の通過帯域特性を示す。
図４に示すとおり、下側妨害検出フィルタ５０は、希望局の周波数ＦよりもΔｆだけ低い周波数を中心周波数とする領域に通過帯域を有し、通過帯域の上限は希望波の中心周波数未満であり、希望波を含まないように、比較的狭い通過帯域に設定される。上側妨害検出フィルタ５２は、希望局の周波数ＦよりもΔｆだけ高い周波数を中心周波数とする領域に通過帯域を有し、通過帯域の下限は希望波の中心周波数を超え、希望波を含まないように、比較的狭い通過帯域に設定される。これら２つの下側妨害検出フィルタ５０および上側妨害検出フィルタ５２とも、その通過帯域幅は、妨害波の領域に相当しているものとする。ここで、希望波の中心周波数と検出すべき妨害波の中心周波数との差であるΔｆの値は、１００ｋＨｚ妨害検出用隣接帯域加算方式フィルタ３０について１００ＫＨｚとする。一方、２００ｋＨｚ妨害検出用隣接帯域加算方式フィルタ３２については、下側妨害検出フィルタ５０および上側妨害検出フィルタ５２におけるΔｆを２Δｆとした２００ｋＨｚに設定する。
【００３１】
図５は、切替型フィルタ３４における広狭帯域差分方式フィルタの構成を示す。これは、妨害周波数信号２０８によって２００ｋＨｚ妨害波が指定された場合に使用される。
切替型フィルタ３４は、希望局の周波数を中心に通過帯域が広帯域である広帯域フィルタ６０と、広帯域フィルタ６０の出力を平滑化するための平滑化処理部５４と、希望波の周波数を中心として通過帯域が狭帯域の狭帯域フィルタ６２と、狭帯域フィルタ６２の出力を平滑化するための平滑化処理部５６と、平滑化処理部５４および平滑化処理部５６の出力の差分を算出するための加算部５８とを備える。妨害の程度は、この加算部５８の出力となって、強度比判定部４０に与えられる。
【００３２】
図６は、切替型フィルタ３４における広帯域バンドパスフィルタおよび狭帯域バンドパスフィルタの通過特性を示す。
希望局の周波数Ｆを中心周波数として、広帯域バンドパスフィルタの通過帯域は、その両側の妨害波を含み得るほどに広い通過帯域を有している。一方、狭帯域バンドパスフィルタは、希望局の周波数Ｆを中心として、その妨害波を含まないように狭い通過帯域を有している。ただし、この狭帯域バンドパスフィルタまで通過帯域幅を狭くしてしまった場合、このような狭帯域バンドパスフィルタを通過した信号を、仮に検波回路で検波すればその歪率が大きくなってしまうために、このような狭帯域バンドパスフィルタを、変調度が大きいときは受信装置１００のＩＦフィルタ１２として用いることは妥当ではない。ここでは、狭帯域バンドパスフィルタの通過帯域幅を−２Δｆから＋２Δｆ、すなわち−２００ｋＨｚから＋２００ｋＨｚより狭くする。
【００３３】
図７は、切替型フィルタ３４における隣接帯域差分方式フィルタの構成を示す。これは、妨害周波数信号２０８によって１００ｋＨｚ妨害波が指定された場合に使用される。
【００３４】
切替型フィルタ３４は、希望波から見て周波数の低い側の隣接周波数付近が通過帯域となる下側妨害検出フィルタ５０と、この下側妨害検出フィルタ５０の出力を受けて平滑化するための平滑化処理部５４と、希望局から見て周波数の高い側の隣接周波数付近が通過帯域となる上側妨害検出フィルタ５２と、この上側妨害検出フィルタ５２の出力を受けて平滑化するための平滑化処理部５６と、平滑化処理部５４および平滑化処理部５６の出力を受けて、その差の信号を出力する加算部５８と、加算部５８の出力の絶対値を強度比判定部４０に対して出力する絶対値計算部６４とを備える。下側妨害検出フィルタ５０と上側妨害検出フィルタ５２の通過帯域特性は、図４と同一である。さらに、希望波の中心周波数と検出すべき妨害波の中心周波数との差であるΔｆの値は１００ＫＨｚとする。
【００３５】
図８は、周波数判定部３８の構成を示す。１００ｋＨｚ妨害検出用隣接帯域加算方式フィルタ３０は、増幅部７０、希望波成分加算部７２、比較部７４、決定部７６を備える。
【００３６】
増幅部７０は、フロントエンド部１０による信号の減衰を補償するために２００ｋＨｚ妨害強度信号２０６を増幅する。すなわち、一般にフロントエンド部１０からの出力は希望波の周波数帯域から離れるほど利得が低くなるように設計されているため、これを補償する。
【００３７】
希望波成分加算部７２は、希望波の中心周波数から１００ｋＨｚ離れた帯域と２００ｋＨｚ離れた帯域における希望波の強度が異なるためにこの差分を加える。
比較部７４は、１００ｋＨｚ妨害強度信号２０４と希望波成分加算部７２からの出力を比較し、大きい方を決定部７６が選択して、妨害波の周波数を選択する。さらに決定部７６は、選択結果を妨害周波数信号２０８として出力する。
【００３８】
図２における強度比判定部４０は、前述の通り１００ｋＨｚ妨害強度信号２０４、２００ｋＨｚ妨害強度信号２０６および切替型フィルタ３４の出力信号から受信信号のＤＵ比を判定する。周波数判定部３８が２００ｋＨｚ妨害波を指定した場合、強度比判定部４０は、切替型フィルタ３４における広狭帯域差分方式フィルタの出力信号と２００ｋＨｚ妨害検出用隣接帯域加算方式フィルタ３２からの２００ｋＨｚ妨害強度信号２０６より、ＤＵ比を検出する。切替型フィルタ３４における広狭帯域差分方式フィルタからの出力信号は、例えばＤＵ比が−３０〜０ｄＢの範囲において、妨害波の信号レベルに正確に対応しているが、ＤＵ比が０ｄＢを超えるあたりからその出力レベルは急激に減少し、ＤＵ比の正確な判定ができなくなる。
【００３９】
一方、２００ｋＨｚ妨害検出用隣接帯域加算方式フィルタ３２からの２００ｋＨｚ妨害強度信号２０６は、ＤＵ比が０〜３０ｄＢにおいても妨害波の信号レベルに正確に対応しているが、逆にＤＵ比が０ｄＢ以下ではＤＵ比の正確な判定ができなくなる。したがって、ＤＵ比の判定には、ＤＵ比が−３０〜０ｄＢの範囲は切替型フィルタ３４における広狭帯域差分方式フィルタの出力結果を、ＤＵ比が０〜＋３０ｄＢの範囲では、２００ｋＨｚ妨害検出用隣接帯域加算方式フィルタ３２の２００ｋＨｚ妨害強度信号２０６を用いることで、広いＤＵ比の範囲にわたって、良好な妨害波の検出が可能となる。
【００４０】
すなわち、強度比判定部４０は、２００ｋＨｚ妨害波の場合に、ＤＵ比の第１の所定範囲、たとえば上述したように−３０〜０ｄＢの範囲では、切替型フィルタ３４における広狭帯域差分方式フィルタの出力結果に基づいて妨害波の検出を行い、ＤＵ比が第１の所定範囲よりも大きくなる第２の所定範囲、たとえば、上述したような０〜＋３０ｄＢの範囲では、２００ｋＨｚ妨害検出用隣接帯域加算方式フィルタ３２の２００ｋＨｚ妨害強度信号２０６に基づいて妨害波の検出を行う。
【００４１】
一方、周波数判定部３８が１００ｋＨｚ妨害波を指定した場合、強度比判定部４０は、切替型フィルタ３４における隣接帯域差分方式フィルタの出力信号と１００ｋＨｚ妨害検出用隣接帯域加算方式フィルタ３０からの１００ｋＨｚ妨害強度信号２０４より、ＤＵ比を検出する。１００ｋＨｚ妨害検出用隣接帯域加算方式フィルタ３０からの１００ｋＨｚ妨害強度信号２０４については、２００ｋＨｚ妨害検出用隣接帯域加算方式フィルタ３２からの２００ｋＨｚ妨害強度信号２０６と同一である。希望波信号の変調度が高い場合には、妨害波がない状態でも、１００ｋＨｚ妨害検出用隣接帯域加算方式フィルタ３０からの１００ｋＨｚ妨害強度信号２０４が、大きな値となってしまい、妨害波があると誤判定される。
【００４２】
そのため、ＤＵ比が＋３０ｄＢ以上の範囲では、切替型フィルタ３４における隣接帯域差分方式フィルタの出力信号を用いる。すなわち、強度比判定部４０は、１００ｋＨｚ妨害波の場合に、ＤＵ比の第２の所定範囲、たとえば上述したように０〜＋３０ｄＢの範囲では、１００ｋＨｚ妨害検出用隣接帯域加算方式フィルタ３０からの１００ｋＨｚ妨害強度信号２０４に基づいて妨害波の検出を行い、ＤＵ比が第２の所定範囲よりも大きくなる第３の所定範囲、たとえば、上述したような＋３０ｄＢ以上の範囲では、切替型フィルタ３４における隣接帯域差分方式フィルタの出力結果に基づいて妨害波の検出を行う。
【００４３】
図９は、ＩＦフィルタ１２の構成を示す。ＩＦフィルタ１２は、広帯域ＩＦフィルタ７８、中帯域ＩＦフィルタ８０、狭帯域ＩＦフィルタ８２を選択部８４により切り替えて、ＩＦ受信信号２００を通過させた後に、フィルタリング信号２１０をＦＭ検波部１６へ与える。選択部８４の切り替えは、ＤＵ比信号２０２に応じて行われる。１００ｋＨｚ妨害波のＤＵ比が小さい、すなわち妨害波のレベルが高い場合、選択性の高い狭帯域ＩＦフィルタ８２に切り替え、２００ｋＨｚ妨害波のＤＵ比が大きい、すなわち妨害波のレベルが低い場合、広帯域ＩＦフィルタ７８に切り替え、この他の場合、中帯域ＩＦフィルタ８０に切り替える。
【００４４】
図１０は、ＤＵ比判定手順を示すフローチャートである。１００ｋＨｚ妨害検出用隣接帯域加算方式フィルタ３０はＩＦ受信信号２００から１００ｋＨｚ妨害強度信号２０４を出力し、２００ｋＨｚ妨害検出用隣接帯域加算方式フィルタ３２はＩＦ受信信号２００から２００ｋＨｚ妨害強度信号２０６を出力し、周波数判定部３８は両者を比較し、１００ｋＨｚ妨害検出用隣接帯域加算方式フィルタ３０の出力信号の強度が２００ｋＨｚ妨害検出用隣接帯域加算方式フィルタ３２の出力信号の強度より大きい場合（Ｓ１０のＹ）、切替型フィルタ３４を隣接帯域差分方式フィルタに設定する。強度比判定部４０は、隣接帯域差分値がしきい値を超えた場合（Ｓ１２のＹ）、強度比判定部４０は、１００ｋＨｚ妨害検出用隣接帯域加算方式フィルタ３０を選択してＤＵ比を出力し（Ｓ１６）、隣接帯域差分値がしきい値を超えない場合（Ｓ１２のＮ）、強度比判定部４０は、切替型フィルタ３４を選択してＤＵ比を出力する（Ｓ１８）。
【００４５】
一方、周波数判定部３８において、１００ｋＨｚ妨害検出用隣接帯域加算方式フィルタ３０の出力信号の強度が２００ｋＨｚ妨害検出用隣接帯域加算方式フィルタ３２の出力信号の強度より大きくない場合（Ｓ１０のＮ）、切替型フィルタ３４を広狭帯域差分方式フィルタに設定する。強度比判定部４０は、広狭帯域差分値がしきい値を超えた場合（Ｓ１４のＹ）、強度比判定部４０は、切替型フィルタ３４を選択してＤＵ比を出力し（Ｓ２０）、広狭帯域差分値がしきい値を超えない場合（Ｓ１４のＮ）、強度比判定部４０は、２００ｋＨｚ妨害検出用隣接帯域加算方式フィルタ３２を選択してＤＵ比を出力する（Ｓ２２）。
【００４６】
以上の構成による受信装置１００の動作を説明する。受信信号は、フロントエンド部１０でＩＦ受信信号２００に変換され、１００ｋＨｚ妨害検出用隣接帯域加算方式フィルタ３０と２００ｋＨｚ妨害検出用隣接帯域加算方式フィルタ３２に入力される。１００ｋＨｚ妨害検出用隣接帯域加算方式フィルタ３０は１００ｋＨｚ妨害強度信号２０４を出力し、２００ｋＨｚ妨害検出用隣接帯域加算方式フィルタ３２は２００ｋＨｚ妨害強度信号２０６を出力し、周波数判定部３８は、１００ｋＨｚ妨害強度信号２０４と２００ｋＨｚ妨害強度信号２０６の強度を比較する。２００ｋＨｚ妨害強度信号２０６の強度が大きい場合、周波数判定部３８は、２００ｋＨｚ妨害波を選択し、妨害周波数信号２０８として出力する。
【００４７】
切替型フィルタ３４は、妨害周波数信号２０８をもとに切替型フィルタ３４を広狭帯域差分方式フィルタに設定し、強度比判定部４０は、広狭帯域差分値がしきい値を超えないため、切替型フィルタ３４の出力信号と２００ｋＨｚ妨害検出用隣接帯域加算方式フィルタ３２の２００ｋＨｚ妨害強度信号２０６から後者を選択してＤＵ比を決定し、ＤＵ比信号２０２を出力する。ＩＦフィルタ１２は、選択部８４によって中帯域ＩＦフィルタ８０を選択し、フィルタリング信号２１０を出力する。さらにフィルタリング信号２１０はＦＭ検波部１６によって復調される。
【００４８】
本実施の形態によれば、受信信号の複数のフィルタ出力から、妨害波の周波数を選択し、さらに選択された周波数ごとに異なったタイプのフィルタの出力を選択して信号のＤＵ比を検出するため、複数の周波数において、より広いＤＵ比の範囲にわたって、隣接妨害の状態を検知可能になる。さらに、選択した周波数に応じてフィルタの特性を切替えるため、回路規模の小型化が可能である。
【００４９】
（実施の形態２）
実施の形態２は、実施の形態１と同様に、希望波に加えて妨害波を含んだ信号を受信する受信装置に関する。実施の形態１では、妨害波の周波数を選択後、当該選択に使用したフィルタ以外のフィルタの特性を切替えて、入力した信号のＤＵ比を測定していた。しかし、実施の形態２では、妨害波の周波数によらず処理に必要な複数のフィルタを予め用意しておき、前述の複数のフィルタによって、入力した信号のＤＵ比を測定するために、より正確なＤＵ比をより迅速に検出可能にする。
【００５０】
実施の形態２に係る受信装置１００の構成としては、図１に示されるものが有効であるため、受信装置１００の構成の説明は省略する。
【００５１】
図１１は、実施の形態２に係る妨害検出部１４の構成を示す。図１１の妨害検出部１４は、図２の妨害検出部１４と比較して、切替型フィルタ３４の代わりに１００ｋＨｚ妨害検出用隣接帯域差分方式フィルタ９０と２００ｋＨｚ妨害検出用広狭帯域差分方式フィルタ９２を備える。なお、１００ｋＨｚ妨害検出用隣接帯域差分方式フィルタ９０と２００ｋＨｚ妨害検出用広狭帯域差分方式フィルタ９２は、実施の形態１における切替型フィルタ３４についての隣接帯域差分方式フィルタと広狭帯域差分方式フィルタと同一の処理を実行する。図２の妨害検出部１４では、周波数判定部３８が妨害波の周波数を決定後、切替型フィルタ３４を所定の特性のフィルタに設定し、強度比判定部４０がＤＵ比を検出していたが、図１１の妨害検出部１４では、１００ｋＨｚ妨害検出用隣接帯域差分方式フィルタ９０と２００ｋＨｚ妨害検出用広狭帯域差分方式フィルタ９２を独立して備えることによって、周波数判定部３８が妨害波の周波数を決定すると直ちにいずれかのフィルタ出力を使用できるため、処理がより高速になる。
【００５２】
以上の構成による受信装置１００の動作を説明する。受信信号は、フロントエンド部１０でＩＦ受信信号２００に変換され、１００ｋＨｚ妨害検出用隣接帯域加算方式フィルタ３０、２００ｋＨｚ妨害検出用隣接帯域加算方式フィルタ３２、１００ｋＨｚ妨害検出用隣接帯域差分方式フィルタ９０、２００ｋＨｚ妨害検出用広狭帯域差分方式フィルタ９２に入力される。周波数判定部３８は、１００ｋＨｚ妨害検出用隣接帯域加算方式フィルタ３０と２００ｋＨｚ妨害検出用隣接帯域加算方式フィルタ３２の出力信号の強度を比較する。
【００５３】
２００ｋＨｚ妨害検出用隣接帯域加算方式フィルタ３２の出力信号の強度が大きい場合、強度比判定部４０は、２００ｋＨｚ妨害検出用広狭帯域差分方式フィルタ９２の出力信号の強度がしきい値を超えないため、２００ｋＨｚ妨害検出用隣接帯域加算方式フィルタ３２と２００ｋＨｚ妨害検出用広狭帯域差分方式フィルタ９２の出力信号から前者を選択してＤＵ比を決定し、ＤＵ比信号２０２を出力する。ＩＦフィルタ１２は、選択部８４によって中帯域ＩＦフィルタ８０を選択し、フィルタリング信号２１０を出力する。さらにフィルタリング信号２１０はＦＭ検波部１６によって復調される。
【００５４】
本実施の形態によれば、複数の妨害波の周波数のそれぞれに対応して複数のフィルタを予め用意し、入力した信号から妨害波の周波数と使用するフィルタのタイプを選択して信号のＤＵ比を検出するため、複数の周波数において、より広いＤＵ比の範囲にわたって、さらにより迅速に隣接妨害の状態を検知可能になる。
【００５５】
以上、本発明を実施の形態をもとに説明した。これらの実施の形態は例示であり、それらの各構成要素や各処理プロセスの組み合わせにいろいろな変形例が可能なこと、またそうした変形例も本発明の範囲にあることは当業者に理解されるところである。
【００５６】
実施の形態１において、妨害検出部１４は妨害波の周波数として１００ｋＨｚと２００ｋＨｚを対象としている。しかしこれに限らず例えば、妨害波の周波数を別に設定してもよいし、３種類以上の妨害波の周波数を対象としてもよい。本変形例によれば、３種類以上の妨害波が存在する環境下においても妨害検出部１４を使用可能である。つまり、複数の妨害波が存在すればよい。
【００５７】
実施の形態１において、妨害検出部１４は例えばひとつの妨害波の周波数に対してそれぞれ２つの特性を有したフィルタを使用している。しかしこれに限らず例えば、他のタイプのフィルタの組み合わせであってもよいし、３種類以上のフィルタの組み合わせであってもよい。本変形によれば、ＤＵ比の正確な検出範囲が拡大される。つまり、ＤＵ比の検出精度に対する特性が異なったフィルタを使用すればよい。
【００５８】
実施の形態１または２において、妨害波の周波数を選択するためにも使用する１００ｋＨｚ妨害検出用隣接帯域加算方式フィルタ３０と２００ｋＨｚ妨害検出用隣接帯域加算方式フィルタ３２は、同じタイプのフィルタを使用している。しかしこれに限らずたとえば、１００ｋＨｚ妨害検出用隣接帯域加算方式フィルタ３０に隣接帯域差分方式フィルタを使用してもよい。つまり、入力された信号の強度を考慮して、フィルタのタイプが選択されればよい。
【００５９】
【発明の効果】
本発明によれば、妨害局の発生を広いＤＵ比の範囲にわたって正確に検出することができる。また、複数の妨害波が存在する場合においてもＤＵ比を正確に検出できる。
【図面の簡単な説明】
【図１】実施の形態１に係る受信装置の構成図である。
【図２】図１の妨害検出部の構成を示す図である。
【図３】図２の１００ｋＨｚ妨害検出用隣接帯域加算方式フィルタの構成を示す図である。
【図４】図３の２つのバンドパスフィルタの通過帯域特性を示す図である。
【図５】図２の切替型フィルタにおける広狭帯域差分方式フィルタの構成を示す図である。
【図６】図５の広帯域バンドパスフィルタおよび狭帯域バンドパスフィルタの通過特性を示す図である。
【図７】図２の切替型フィルタにおける隣接帯域差分方式フィルタの構成を示す図である。
【図８】図２の周波数判定部の構成を示す図である。
【図９】図１のＩＦフィルタの構成を示す図である。
【図１０】図２によるＤＵ比判定手順を示すフローチャートである。
【図１１】実施の形態２に係る妨害検出部の構成を示す図である。
【符号の説明】
１０フロントエンド部、１２ＩＦフィルタ、１４妨害検出部、１６ＦＭ検波部、１８ＰＬＬ、２０利得制御部、２２アンテナ、３０１００ｋＨｚ妨害検出用隣接帯域加算方式フィルタ、３２２００ｋＨｚ妨害検出用隣接帯域加算方式フィルタ、３４切替型フィルタ、３６信号判定部、３８周波数判定部、４０強度比判定部、５０下側妨害検出フィルタ、５２上側妨害検出フィルタ、５４平滑化処理部、５６平滑化処理部、５８加算部、６０広帯域フィルタ、６２狭帯域フィルタ、６４絶対値計算部、７０増幅部、７２希望波成分加算部、７４比較部、７６決定部、７８広帯域ＩＦフィルタ、８０中帯域ＩＦフィルタ、８２狭帯域ＩＦフィルタ、８４選択部、９０１００ｋＨｚ妨害検出用隣接帯域差分方式フィルタ、９２２００ｋＨｚ妨害検出用広狭帯域差分方式フィルタ、１００受信装置、２００ＩＦ受信信号、２０２ＤＵ比信号、２０４１００ｋＨｚ妨害強度信号、２０６２００ｋＨｚ妨害強度信号、２０８妨害周波数信号、２１０フィルタリング信号。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a signal detection device capable of automatically detecting a state of an interference wave in a reception device such as an FM broadcast, and a reception device that can use the signal detection device. In particular, the present invention relates to a signal detection device that can cope with a plurality of interference waves and a reception device that can use the device.
[0002]
[Prior art]
Generally, in an FM radio receiver or the like, when an interference signal is generated adjacent to a broadcast signal from a desired broadcast station, communication quality called "adjacent interference" deteriorates. Therefore, when such adjacent interference occurs, it is detected, and the receiving apparatus changes the pass bandwidth of an IF filter that passes an intermediate frequency signal (IF signal) obtained by down-converting the received signal, for example. Then, measures such as reducing the influence of such an interfering signal are taken. However, for example, in Europe, channels are adjacent in units of 100 KHz. Therefore, depending on the method of detecting adjacent interference, it is not possible to completely remove the interference signal only by adjusting the pass band of the IF filter. Is one of the issues.
[0003]
As a method of detecting the presence or absence of such an interference signal, for example, a method of comparing the energy included in a wide band and a narrow band around the frequency of a desired signal, and detecting the presence of adjacent interference based on the comparison result (For example, see Patent Document 1). Alternatively, the interference signal present in the upper and lower frequency bands of the desired reception signal is detected by the intermediate frequency filter, the detection output is differentially amplified, and the desired signal IF There is a technique for moving the center frequency of a filter to a side where the energy of an interference wave is smaller (for example, see Patent Document 2).
[0004]
[Patent Document 1]
JP-A-8-97738
[Patent Document 2]
JP-A-5-191213
[0005]
[Problems to be solved by the invention]
According to the related art described above, it is possible to detect an adjacent interference wave under a specific condition, but there are the following problems. First, in the invention disclosed in Japanese Patent Application Laid-Open No. 8-97738, the intensity ratio between a desired wave and an interfering wave (hereinafter, referred to as a DU ratio) can be detected when an intermodulation described later occurs. The range of the DU ratio becomes narrow. On the other hand, even in the method disclosed in Japanese Patent Application Laid-Open No. Hei 5-191312, under conditions where intermodulation interference occurs, the original interfering station and the modulation interference caused by such intermodulation sandwich the desired station. Erroneous judgment is caused.
[0006]
Further, the above technique assumes only a band interval for one type of adjacent interference. For example, in FM broadcasting in Europe, in addition to an adjacent band interval of 100 kHz with an adjacent station, a station of a band 200 kHz away from the next adjacent station is added. Signals also cause interference. Also, the interval between adjacent bands in the United States is 200 kHz. On the other hand, if the detection unit for detecting a plurality of interference waves as described above is provided corresponding to all the plurality of interference waves, the circuit scale increases.
[0007]
Hereinafter, this intermodulation interference will be described in more detail. In a front-end part of an FM receiver or the like that receives a signal received from an antenna and converts the signal into an intermediate frequency, a received wave is also amplified. However, a signal passing through such an amplifier causes so-called intermodulation distortion. . When two or more signals having different frequencies are input to a high-frequency amplifier, intermodulation occurs between the input signals or a high frequency generated by the non-linearity of the amplifier, so-called "spurious" occurs at the output of the amplifier. Generate. That is, a new interfering signal accompanying the intermodulation may be generated on both sides of the signal input to the amplifier.
[0008]
For example, if a disturbing signal from the disturbing station is generated near the frequency F of the desired station on the frequency side shifted by + Δf from the frequency of the desired station, the signal of the desired station is affected by the intermodulation. As a result, a spurious signal is generated at a position opposite to the signal of the interfering station and shifted by -Δf from the frequency of the desired station signal. Therefore, for example, in the invention as disclosed in the above-mentioned Japanese Patent Application Laid-Open No. H5-191312, the generation of the interference wave is detected by the differential amplification of the signal level on both sides of the signal from the desired station. There is a problem that an erroneous determination is made.
[0009]
The present inventor has recognized the above situation and made the present invention, and an object of the present invention is to use a signal detection device and a device capable of accurately detecting the occurrence of an interfering station over a wide range of DU ratio. It is to provide a possible receiving device. Another object of the present invention is to provide a signal detection device capable of accurately detecting a DU ratio even when a plurality of interference waves are present, and a receiving device that can use the device.
[0010]
[Means for Solving the Problems]
One embodiment of the present invention relates to a signal detection device. The apparatus includes a first detection unit that detects a first intensity value corresponding to two frequency regions separated by a first frequency around a frequency of a desired wave, and a second detection unit that centers around a frequency of the desired wave. A second detection unit that detects a second intensity value corresponding to two frequency regions separated by a frequency; and a first intensity value corresponding to a frequency of an interfering wave with respect to a desired wave from the first intensity value and the second intensity value. A frequency judging unit for selecting the value of the second frequency or the value of the second frequency, and a third detecting unit for detecting a third intensity value corresponding to two frequency regions separated by the selected frequency from the frequency of the desired wave. When the detection unit and the value of the first frequency are selected, any one of a plurality of intensity values including the first intensity value and the third intensity value is selected, and the value of the second frequency is selected. Contains the second intensity value or the third intensity value By selecting one of the number of intensity values, and a determining intensity determination unit the intensity ratio of the desired wave and the interfering wave. In this device, the third detection unit may have a different characteristic of detection accuracy of the intensity value as compared with the first detection unit and the second detection unit.
[0011]
The first detection unit outputs, as a first intensity value, an added value of signal outputs that have passed through two band-pass filters each having a center frequency of a frequency higher and lower than the frequency of the desired wave by a first frequency, The second detection unit outputs, as a second intensity value, an added value of signal outputs that have passed through two band filters each having a center frequency of a frequency higher and lower by a second frequency than the frequency of the desired wave. Is also good.
[0012]
The first detection unit outputs, as a first intensity value, a difference value between signal outputs that have passed through two band filters each having a center frequency of a frequency higher and lower than the frequency of the desired wave by a first frequency, The second detection unit outputs, as a second intensity value, an added value of signal outputs that have passed through two band filters each having a center frequency of a frequency higher and lower by a second frequency than the frequency of the desired wave. Is also good.
[0013]
The value of the second frequency is greater than the value of the first frequency, and the frequency determination unit determines an amplification unit that amplifies the second intensity value and a second intensity value amplified based on the intensity value of the desired wave. The image processing apparatus may include a correction unit that corrects and a selection unit that selects a value of the first frequency or a value of the second frequency from the first intensity value and the corrected second intensity value.
[0014]
The third detection unit outputs, as a third intensity value, a signal output that has passed through two band-pass filters each having a center frequency higher and lower than the frequency of the desired wave by a first frequency according to the selected frequency. Or the difference between the signal output of a signal passing through a band-pass filter with the second frequency as the pass band and the signal output of the signal passing through a band-pass filter with the second frequency as the non-pass band around the frequency of the desired wave. Good.
[0015]
Another embodiment of the present invention also relates to a signal detection device. The apparatus includes a first detection unit that outputs an added value of signal outputs that have passed through two band-pass filters having a center frequency of a frequency higher and a frequency lower by a first frequency than a frequency of a desired wave; A second detection unit that outputs an added value of signal outputs that have passed through two band filters each having a center frequency of a higher frequency and a lower frequency by a second frequency, and a frequency higher by a first frequency than the frequency of the desired wave And a third detection unit that outputs a difference value of signal outputs that have passed through two band filters each having a center frequency of a low frequency and a band filter that has a second frequency as a pass band around the frequency of the desired wave. A fourth detection unit that outputs a difference value of a signal output that has passed through a band-pass filter having a frequency of 2 as a non-pass band, and a first detection unit and a second detection unit. A frequency determination unit that selects a first frequency value or a second frequency value that should correspond to the frequency of the interference wave for the desired wave from the force value, and a frequency and an output level that should correspond to the interference wave Selection of any one of the plurality of detection units including the first detection unit or the third detection unit, or selection of the output value of any one of the plurality of detection units including the second detection unit or the fourth detection unit An intensity determination unit that performs the selection and determines an intensity ratio between the desired wave and the interference wave.
[0016]
Yet another embodiment of the present invention relates to a receiving device. The apparatus includes a front end unit that converts a radio frequency signal received from a desired station into an intermediate frequency signal, an interference detection unit that detects the intensity of an interference wave of a desired wave based on the intermediate frequency signal, An intermediate frequency filter unit that filters and outputs an intermediate frequency signal with a band filter whose band is set according to the intensity, and a detection unit that demodulates an output signal from the intermediate frequency filter unit. In this device, the interference detection unit includes a plurality of detection units that filter the intermediate frequency signal and detect the output level of the interference wave in a plurality of frequency regions and a plurality of methods in a frequency region around the frequency of the desired wave. A frequency determining unit that determines a frequency region that should correspond to the interference wave according to the output level of the interference wave, and one of a plurality of detection units according to the frequency region and the output level that should correspond to the interference wave. An intensity determination unit for selecting an output level and determining an intensity ratio between the desired wave and the interference wave may be included.
[0017]
A plurality of detection units, a first detection unit that outputs a first addition value of a signal output that has passed through two band filters each having a center frequency of a frequency higher and lower than the frequency of the desired wave by a first frequency, A second detector that outputs a second addition value of signal outputs that have passed through two band-pass filters each having a center frequency of a frequency higher and lower by a second frequency than the frequency of the desired wave; A first difference value of a signal output having passed through two band filters each having a center frequency of a higher frequency and a lower frequency by one frequency, or a band filter having a pass band of a second frequency centering on the frequency of a desired wave; A third detection unit that outputs a second difference value of a signal output that has passed through a bandpass filter that does not use the second frequency as a passband. In this device, the frequency determination unit determines a frequency region that should correspond to the interfering wave from the first addition value and the second addition value, and the intensity determination unit determines the first addition value or Selection of any of a plurality of output levels including the first difference value, or selection of any of a plurality of output levels including the second addition value or the second difference value may be performed.
[0018]
Note that any combination of the above-described components and any conversion of the expression of the present invention between a method, an apparatus, a system, and the like are also effective as embodiments of the present invention.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
(Embodiment 1)
Embodiment 1 relates to a receiving apparatus that receives a signal including an interference wave in addition to a desired wave. Further, the interference wave includes an interference wave that is 100 kHz away from the frequency of the desired wave (hereinafter, referred to as “100 kHz interference wave”) and an interference wave that is 200 kHz away from the frequency of the desired wave (hereinafter, “200 kHz interference wave”). The receiving apparatus according to the present embodiment measures the signal strength values of the 100 kHz and 200 kHz interference waves using a filter for detecting the 100 kHz interference wave and a filter for detecting the 200 kHz interference wave, and compares the respective signal strength values. Then, of the 100 kHz interference wave and the 200 kHz interference wave, the interference wave having a stronger influence by the reception processing of the desired wave is selected.
[0020]
Further, for the interference wave of the selected frequency, a plurality of filters having different detection accuracy of the DU ratio with respect to the DU ratio of the input signal are prepared, and after measuring the approximate level of the DU ratio in the input signal, According to the measurement result, an optimum filter is selected from the above-mentioned plurality of filters, and the DU ratio is measured, so that the DU ratio can be detected more accurately. Further, since the bandwidth of the band-pass filter that passes the received signal is changed based on the frequency of the selected interference wave and the detected DU ratio, optimal filtering can be performed even in an environment where a plurality of interference waves exist. . In the present invention, the property that the output level of the desired wave that occupies the rest of the IF signal level can be determined if the output level of the interference wave is obtained.
[0021]
FIG. 1 shows the configuration of the receiving apparatus 100 according to the first embodiment.
Receiving apparatus 100 receives antenna 22, a front-end unit 10 that receives a signal from antenna 22, performs a tuning process, an amplification process, a conversion process to an intermediate frequency, and the like, and an output of front-end unit 10. An IF filter 12 that is a band-pass filter that passes an intermediate frequency signal in a desired band, an FM detection unit 16 that receives an output of the IF filter 12 and performs FM detection, and an output of the front end unit 10 will be described later. Thus, the interference detection unit 14 that detects the DU ratio and supplies the IF filter 12 with the DU ratio signal 202 is provided. Further, the FM detection unit 16 includes a PLL 18 that locks the phase of a carrier wave for detection, and a gain control unit 20 that compensates for signal power attenuation caused by the IF filter 12.
[0022]
Here, the front end unit 10 is provided with an automatic gain control unit (not shown), and the IF reception signal 200 output from the front end unit 10 has a constant level regardless of the electric field strength at the reception point. It becomes.
[0023]
The IF filter 12 switches the passband continuously and stepwise based on the DU ratio signal 202 from the interference detection unit 14. For example, when the occurrence of an interference signal is detected, the bandwidth of the IF filter 12 is reduced to a band in which the interference signal can be removed, and the output from the IF filter 12 having the reduced bandwidth is detected. And When such control is performed, adjacent interference can be effectively prevented only when adjacent interference occurs, and when there is no adjacent interference, it is possible to obtain a good detection output with respect to the distortion factor. Further, when the interference signal is a 100 kHz interference wave, it is closer to the desired wave than when the interference signal is a 200 kHz interference wave, so that the bandwidth of the IF filter 12 is further reduced.
[0024]
This configuration can be realized in hardware by a CPU, a memory, or other LSI of any computer, and is realized in software by a program having a reservation management function loaded into a memory. The functional blocks realized by their cooperation are drawn. Therefore, it is understood by those skilled in the art that these functional blocks can be realized in various forms by hardware only, software only, or a combination thereof.
[0025]
FIG. 2 shows the configuration of the interference detection unit 14. The interference detection unit 14 includes a 100 kHz interference detection adjacent band addition filter 30, a 200 kHz interference detection adjacent band addition filter 32, a switchable filter 34, and a signal determination unit 36. 38, an intensity ratio determination unit 40 is provided.
[0026]
The 100 kHz interference detection adjacent band addition method filter 30 outputs a 100 kHz interference intensity signal 204 from the IF reception signal 200 by an adjacent band addition method calculation process described later, and the 200 kHz interference detection adjacent band addition method filter 32 outputs the IF reception signal. The 200 kHz interference strength signal 206 is output from the signal 200 by an arithmetic processing of an adjacent band addition method described later, and the switching filter 34 changes the pass band and the method of the filter as appropriate, and arithmetically processes the IF reception signal 200.
[0027]
The frequency determination unit 38 determines the frequency of the interference wave from the 100 kHz interference intensity signal 204 and the 200 kHz interference intensity signal 206 and outputs an interference frequency signal 208. That is, it is determined whether the interference wave is a 100 kHz interference wave or a 200 kHz interference wave. The switchable filter 34 switches the filter based on the interference frequency signal 208 to the adjacent band difference method in the case of a 100 kHz interference wave or the wide band narrow difference method in the case of a 200 kHz interference wave.
[0028]
The intensity ratio determination unit 40 determines the DU ratio of the received signal from the 100 kHz interference intensity signal 204, the 200 kHz interference intensity signal 206, and the output signal of the switching filter 34, and provides the determination result to the IF filter 12 as a DU ratio signal 202.
[0029]
FIG. 3 shows a configuration of the 100 kHz interference detection adjacent band addition filter 30.
The 100 kHz interference detection adjacent band addition filter 30 includes a lower interference detection filter 50 in which the vicinity of a lower frequency adjacent to the desired wave is defined as a pass band, and an output of the lower interference detection filter 50. A smoothing processing unit 54 for receiving and smoothing the received signal, an upper interference detection filter 52 in which the vicinity of a higher frequency adjacent to the desired station is defined as a passband, and an output of the upper interference detection filter 52 A smoothing processing unit 56 for receiving and smoothing, and receiving the outputs of the smoothing processing unit 54 and the smoothing processing unit 56, and using the sum signal as a 100 kHz interference intensity signal 204, the frequency determination unit 38 or the intensity ratio determination. And an addition unit 58 that outputs the result to the unit 40.
[0030]
FIG. 4 shows the pass band characteristics of the two band-pass filters of FIG. 3, namely, the lower interference detection filter 50 and the upper interference detection filter 52.
As shown in FIG. 4, the lower interference detection filter 50 has a pass band in a region whose center frequency is a frequency lower by Δf than the frequency F of the desired station, and the upper limit of the pass band is lower than the center frequency of the desired wave. Yes, it is set to a relatively narrow passband so as not to include the desired wave. The upper interference detection filter 52 has a pass band in a region whose center frequency is a frequency higher by Δf than the frequency F of the desired station, and the lower limit of the pass band exceeds the center frequency of the desired wave and does not include the desired wave. In addition, a relatively narrow pass band is set. It is assumed that the pass bandwidth of each of the two lower interference detection filters 50 and the upper interference detection filter 52 corresponds to the area of the interference wave. Here, the value of Δf, which is the difference between the center frequency of the desired wave and the center frequency of the interference wave to be detected, is 100 KHz for the 100 kHz interference detection adjacent band addition filter 30. On the other hand, the 200 kHz interference detection adjacent band addition filter 32 is set to 200 kHz where Δf in the lower interference detection filter 50 and the upper interference detection filter 52 is 2Δf.
[0031]
FIG. 5 shows a configuration of a wide-and-narrow band difference type filter in the switching filter 34. This is used when a 200 kHz interference wave is specified by the interference frequency signal 208.
The switchable filter 34 includes a broadband filter 60 having a wide passband centered on the frequency of the desired station, a smoothing processing unit 54 for smoothing the output of the wideband filter 60, and a passband centered on the frequency of the desired wave. A narrow-band filter 62 having a narrow band, a smoothing processing unit 56 for smoothing the output of the narrow-band filter 62, and a difference between outputs of the smoothing processing unit 54 and the smoothing processing unit 56. And an adder 58. The degree of the interference is output from the adder 58 and supplied to the intensity ratio determiner 40.
[0032]
FIG. 6 shows pass characteristics of the wideband bandpass filter and the narrowband bandpass filter in the switching filter 34.
With the frequency F of the desired station as the center frequency, the passband of the wideband bandpass filter has a passband wide enough to include interfering waves on both sides thereof. On the other hand, the narrow band-pass filter has a narrow pass band around the frequency F of the desired station so as not to include the interference wave. However, if the pass band width is narrowed down to this narrow band pass filter, if the signal passing through such a narrow band pass filter is detected by a detection circuit, the distortion rate becomes large. In addition, it is not appropriate to use such a narrow band-pass filter as the IF filter 12 of the receiving apparatus 100 when the degree of modulation is large. Here, the pass band width of the narrow-band bandpass filter is narrowed from −2Δf to + 2Δf, that is, from −200 kHz to +200 kHz.
[0033]
FIG. 7 shows a configuration of the adjacent band difference type filter in the switching filter 34. This is used when a 100 kHz interference wave is specified by the interference frequency signal 208.
[0034]
The switching filter 34 includes a lower interference detection filter 50 having a pass band near an adjacent frequency on the lower frequency side as viewed from the desired wave, and a smoothing device for receiving and smoothing the output of the lower interference detection filter 50. Processing unit 54, an upper interference detection filter 52 having a passband near the adjacent frequency on the higher frequency side as viewed from the desired station, and a smoothing process for receiving and smoothing the output of the upper interference detection filter 52. Unit 56, an adding unit 58 that receives the outputs of the smoothing processing unit 54 and the smoothing processing unit 56 and outputs a signal of the difference, and outputs the absolute value of the output of the adding unit 58 to the intensity ratio determining unit 40. And an absolute value calculating section 64 for outputting. The pass band characteristics of the lower interference detection filter 50 and the upper interference detection filter 52 are the same as those in FIG. Further, the value of Δf, which is the difference between the center frequency of the desired wave and the center frequency of the interference wave to be detected, is set to 100 KHz.
[0035]
FIG. 8 shows a configuration of the frequency determination unit 38. The 100 kHz interference detection adjacent band addition filter 30 includes an amplification unit 70, a desired wave component addition unit 72, a comparison unit 74, and a determination unit 76.
[0036]
The amplification unit 70 amplifies the 200 kHz disturbance intensity signal 206 to compensate for the signal attenuation by the front end unit 10. That is, since the output from the front end unit 10 is generally designed so that the gain becomes lower as the frequency departs from the frequency band of the desired wave, this is compensated for.
[0037]
Desired wave component adding section 72 adds this difference because the intensity of the desired wave differs between the band 100 kHz away from the center frequency of the desired wave and the band 200 kHz away from the center frequency of the desired wave.
The comparing unit 74 compares the 100 kHz interference intensity signal 204 with the output from the desired wave component adding unit 72, and the determining unit 76 selects the larger one, and selects the frequency of the interference wave. Further, the determination unit 76 outputs the selection result as the interference frequency signal 208.
[0038]
The intensity ratio determination unit 40 in FIG. 2 determines the DU ratio of the received signal from the 100 kHz interference intensity signal 204, the 200 kHz interference intensity signal 206, and the output signal of the switching filter 34 as described above. When the frequency determination unit 38 specifies a 200 kHz interference wave, the intensity ratio determination unit 40 outputs the output signal of the wide / narrow band difference type filter in the switching filter 34 and the 200 kHz interference intensity signal from the 200 kHz interference detection adjacent band addition type filter 32. From 206, the DU ratio is detected. The output signal from the wide / narrow band difference type filter in the switching filter 34 exactly corresponds to the signal level of the interfering wave, for example, when the DU ratio is in the range of -30 to 0 dB. The output level sharply decreases, making it impossible to accurately determine the DU ratio.
[0039]
On the other hand, the 200 kHz interference intensity signal 206 from the 200 kHz interference detection adjacent band addition filter 32 accurately corresponds to the signal level of the interference wave even when the DU ratio is 0 to 30 dB, but on the contrary, the DU ratio is 0 dB or less. In this case, the DU ratio cannot be accurately determined. Accordingly, in the determination of the DU ratio, the output result of the wide / narrow band difference type filter in the switching filter 34 is in the range of -30 to 0 dB, and the 200 kHz interference detection adjacent band is in the range of 0 to +30 dB. By using the 200 kHz interference intensity signal 206 of the addition filter 32, it is possible to detect an excellent interference wave over a wide range of the DU ratio.
[0040]
That is, in the case of a 200 kHz interference wave, the intensity ratio determination unit 40 outputs the output of the wide / narrow band differential filter in the switchable filter 34 in the first predetermined range of the DU ratio, for example, in the range of −30 to 0 dB as described above. An interference wave is detected based on the result, and in a second predetermined range where the DU ratio is larger than the first predetermined range, for example, in the range of 0 to +30 dB as described above, a 200 kHz interference detection adjacent band addition method is used. An interference wave is detected based on the 200 kHz interference intensity signal 206 of the filter 32.
[0041]
On the other hand, when the frequency determination unit 38 specifies the 100 kHz interference wave, the intensity ratio determination unit 40 determines whether the output signal of the adjacent band difference type filter in the switching filter 34 and the 100 kHz interference from the adjacent band addition type filter 30 for 100 kHz interference detection. The DU ratio is detected from the intensity signal 204. The 100 kHz interference intensity signal 204 from the 100 kHz interference detection adjacent band addition filter 30 is the same as the 200 kHz interference intensity signal 206 from the 200 kHz interference detection adjacent band addition filter 32. When the modulation degree of the desired wave signal is high, the 100 kHz interference strength signal 204 from the 100 kHz interference detection adjacent band addition filter 30 has a large value even when there is no interference wave, and there is an interference wave. An incorrect determination is made.
[0042]
Therefore, when the DU ratio is in the range of +30 dB or more, the output signal of the adjacent band difference type filter in the switching filter 34 is used. That is, in the case of a 100 kHz interference wave, the intensity ratio determination unit 40 determines that the 100 kHz interference detection adjacent band addition filter 30 in the second predetermined range of the DU ratio, for example, the range of 0 to +30 dB as described above. An interference wave is detected based on the interference intensity signal 204, and in the third predetermined range where the DU ratio is larger than the second predetermined range, for example, in the range of +30 dB or more as described above, the adjacent filter in the switching filter 34 An interference wave is detected based on the output result of the band difference filter.
[0043]
FIG. 9 shows a configuration of the IF filter 12. The IF filter 12 switches the wide band IF filter 78, the middle band IF filter 80, and the narrow band IF filter 82 by the selection unit 84, passes the IF reception signal 200, and then supplies the filtering signal 210 to the FM detection unit 16. Switching of the selector 84 is performed according to the DU ratio signal 202. When the DU ratio of the 100 kHz interference wave is small, that is, when the level of the interference wave is high, switching to the highly selective narrow band IF filter 82 is performed. When the DU ratio of the 200 kHz interference wave is large, that is, when the level of the interference wave is low, the wide band IF Switch to filter 78, otherwise switch to mid-band IF filter 80.
[0044]
FIG. 10 is a flowchart showing a DU ratio determination procedure. The 100 kHz interference detection adjacent band addition filter 30 outputs a 100 kHz interference intensity signal 204 from the IF reception signal 200, the 200 kHz interference detection adjacent band addition filter 32 outputs a 200 kHz interference intensity signal 206 from the IF reception signal 200, The frequency determination unit 38 compares the two, and if the intensity of the output signal of the 100 kHz interference detection adjacent band addition filter 30 is greater than the intensity of the output signal of the 200 kHz interference detection adjacent band addition filter 32 (Y in S10). The switching type filter 34 is set as an adjacent band difference type filter. When the adjacent band difference value exceeds the threshold value (Y in S12), the intensity ratio determination unit 40 selects the 100 kHz interference detection adjacent band addition filter 30 and outputs the DU ratio. When the adjacent band difference value does not exceed the threshold value (N in S12), the intensity ratio determination unit 40 selects the switchable filter 34 and outputs the DU ratio (S18).
[0045]
On the other hand, if the frequency of the output signal of the 100 kHz interference detection adjacent band addition filter 30 is not greater than the output signal of the 200 kHz interference detection adjacent band addition filter 32 in the frequency determination unit 38 (N in S10), the switching is performed. The type filter 34 is set as a wide / narrow band difference type filter. When the wide / narrow band difference value exceeds the threshold value (Y in S14), the intensity ratio determination unit 40 selects the switchable filter 34 and outputs the DU ratio (S20), and When the band difference value does not exceed the threshold value (N in S14), the intensity ratio determination unit 40 selects the 200 kHz interference detection adjacent band addition filter 32 and outputs the DU ratio (S22).
[0046]
The operation of the receiving apparatus 100 having the above configuration will be described. The reception signal is converted into an IF reception signal 200 by the front end unit 10 and input to the 100 kHz interference detection adjacent band addition filter 30 and the 200 kHz interference detection adjacent band addition filter 32. The 100 kHz interference detection adjacent band addition filter 30 outputs a 100 kHz interference intensity signal 204, the 200 kHz interference detection adjacent band addition filter 32 outputs a 200 kHz interference intensity signal 206, and the frequency determination unit 38 outputs a 100 kHz interference intensity signal. Compare the intensity of the 204 and 200 kHz disturbance intensity signals 206. When the intensity of the 200 kHz interference intensity signal 206 is high, the frequency determination unit 38 selects the 200 kHz interference wave and outputs it as the interference frequency signal 208.
[0047]
The switching filter 34 sets the switching filter 34 to a wide-and-narrow band difference filter based on the interference frequency signal 208, and the intensity ratio determination unit 40 determines that the wide-and-narrow band difference value does not exceed the threshold value. The latter is selected from the output signal of the filter 34 and the 200 kHz interference strength signal 206 of the 200 kHz interference detection adjacent band addition filter 32 to determine the DU ratio, and the DU ratio signal 202 is output. The IF filter 12 selects the middle band IF filter 80 by the selection unit 84 and outputs a filtering signal 210. Further, the filtered signal 210 is demodulated by the FM detector 16.
[0048]
According to the present embodiment, the frequency of the interference wave is selected from the plurality of filter outputs of the received signal, and the output of a different type of filter is selected for each of the selected frequencies to detect the DU ratio of the signal. Therefore, at a plurality of frequencies, the state of adjacent interference can be detected over a wider range of the DU ratio. Further, since the characteristics of the filter are switched according to the selected frequency, the circuit size can be reduced.
[0049]
(Embodiment 2)
The second embodiment relates to a receiving apparatus that receives a signal containing an interference wave in addition to a desired wave, as in the first embodiment. In the first embodiment, after selecting the frequency of the interference wave, the characteristics of the filters other than the filter used for the selection are switched, and the DU ratio of the input signal is measured. However, in the second embodiment, a plurality of filters necessary for processing are prepared in advance irrespective of the frequency of the interfering wave, and the DU ratio of the input signal is measured by the above-described plurality of filters. DU ratio can be detected more quickly.
[0050]
As the configuration of the receiving apparatus 100 according to Embodiment 2, the configuration shown in FIG. 1 is effective, and thus the description of the configuration of the receiving apparatus 100 is omitted.
[0051]
FIG. 11 shows a configuration of the interference detection unit 14 according to the second embodiment. The interference detection unit 14 of FIG. 11 is different from the interference detection unit 14 of FIG. 2 in that a 100 kHz interference detection adjacent band difference filter 90 and a 200 kHz interference detection wide and narrow band difference filter 92 are used instead of the switchable filter 34. Prepare. The 100 kHz interference detection adjacent band difference filter 90 and the 200 kHz interference detection wide and narrow band difference filter 92 are the same as the adjacent band difference filter and the wide and narrow band difference filter of the switching filter 34 in the first embodiment. Execute the process. In the interference detection unit 14 of FIG. 2, after the frequency determination unit 38 determines the frequency of the interference wave, the switching type filter 34 is set to a filter having a predetermined characteristic, and the intensity ratio determination unit 40 detects the DU ratio. In the interference detection unit 14 shown in FIG. 11, the frequency determination unit 38 determines the frequency of the interference wave by independently including the adjacent band difference filter 90 for detecting 100 kHz interference and the wide and narrow band difference filter 92 for detecting 200 kHz interference. Then, since either filter output can be used immediately, the processing becomes faster.
[0052]
The operation of the receiving apparatus 100 having the above configuration will be described. The reception signal is converted into an IF reception signal 200 by the front end unit 10, and a 100 kHz interference detection adjacent band addition filter 30, a 200 kHz interference detection adjacent band addition filter 32, a 100 kHz interference detection adjacent band difference filter 90, The signal is input to a 200 kHz interference detection wide / narrow band difference filter 92. The frequency determination unit 38 compares the output signal strengths of the 100 kHz interference detection adjacent band addition filter 30 and the 200 kHz interference detection adjacent band addition filter 32.
[0053]
If the intensity of the output signal of the 200 kHz interference detection adjacent band addition filter 32 is large, the intensity ratio determination unit 40 determines that the intensity of the output signal of the 200 kHz interference detection wide / narrow band difference filter 92 does not exceed the threshold value. The former is selected from the output signals of the 200 kHz interference detection adjacent band addition filter 32 and the 200 kHz interference detection wide and narrow band difference filter 92, the DU ratio is determined, and the DU ratio signal 202 is output. The IF filter 12 selects the middle band IF filter 80 by the selection unit 84 and outputs a filtering signal 210. Further, the filtered signal 210 is demodulated by the FM detector 16.
[0054]
According to the present embodiment, a plurality of filters are prepared in advance corresponding to the respective frequencies of a plurality of interference waves, and the frequency of the interference wave and the type of filter to be used are selected from the input signal to thereby determine the DU ratio of the signal. , It is possible to more quickly detect the state of adjacent interference at a plurality of frequencies over a wider range of DU ratios.
[0055]
The present invention has been described based on the embodiments. These embodiments are exemplifications, and it is understood by those skilled in the art that various modifications can be made to the combination of each component and each processing process, and such modifications are also within the scope of the present invention. By the way.
[0056]
In the first embodiment, the interference detector 14 targets 100 kHz and 200 kHz as the frequency of the interference wave. However, the present invention is not limited to this. For example, the frequency of the interference wave may be set separately, or the frequencies of three or more types of interference waves may be targeted. According to the present modification, the interference detection unit 14 can be used even in an environment where three or more types of interference waves exist. That is, it is only necessary that a plurality of interference waves exist.
[0057]
In the first embodiment, the interference detection unit 14 uses, for example, a filter having two characteristics for each frequency of one interference wave. However, the present invention is not limited to this. For example, a combination of other types of filters may be used, or a combination of three or more types of filters may be used. According to this modification, the accurate detection range of the DU ratio is expanded. In other words, filters having different characteristics with respect to the DU ratio detection accuracy may be used.
[0058]
In the first and second embodiments, the same type of filter is used for the 100 kHz interference detection adjacent band addition filter 30 and the 200 kHz interference detection adjacent band addition filter 32 which are also used to select the frequency of the interference wave. ing. However, the present invention is not limited to this. For example, an adjacent band difference type filter may be used as the 100 kHz interference detection adjacent band addition type filter 30. That is, the type of the filter may be selected in consideration of the strength of the input signal.
[0059]
【The invention's effect】
According to the present invention, the occurrence of an interfering station can be accurately detected over a wide range of the DU ratio. Further, even when a plurality of interference waves exist, the DU ratio can be accurately detected.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a receiving apparatus according to Embodiment 1.
FIG. 2 is a diagram illustrating a configuration of a disturbance detection unit in FIG. 1;
FIG. 3 is a diagram showing a configuration of a 100 kHz interference detection adjacent band addition type filter of FIG. 2;
FIG. 4 is a diagram illustrating pass band characteristics of two band pass filters of FIG. 3;
5 is a diagram showing a configuration of a wide-and-narrow band difference type filter in the switching filter of FIG.
FIG. 6 is a diagram illustrating pass characteristics of the wideband bandpass filter and the narrowband bandpass filter of FIG. 5;
FIG. 7 is a diagram showing a configuration of an adjacent band difference type filter in the switching filter of FIG. 2;
FIG. 8 is a diagram illustrating a configuration of a frequency determination unit in FIG. 2;
FIG. 9 is a diagram illustrating a configuration of an IF filter of FIG. 1;
FIG. 10 is a flowchart showing a DU ratio determination procedure according to FIG. 2;
FIG. 11 is a diagram showing a configuration of a disturbance detection unit according to the second embodiment.
[Explanation of symbols]
Reference Signs List 10 front-end section, 12 IF filter, 14 interference detection section, 16 FM detection section, 18 PLL, 20 gain control section, 22 antenna, 30 100 kHz interference detection adjacent band addition filter, 32 200 kHz interference detection adjacent band addition method Filter, 34 switching type filter, 36 signal judgment unit, 38 frequency judgment unit, 40 intensity ratio judgment unit, 50 lower interference detection filter, 52 upper interference detection filter, 54 smoothing processing unit, 56 smoothing processing unit, 58 addition Unit, 60 wide band filter, 62 narrow band filter, 64 absolute value calculation unit, 70 amplification unit, 72 desired wave component addition unit, 74 comparison unit, 76 decision unit, 78 wide band IF filter, 80 middle band IF filter, 82 narrow band IF filter, 84 selection unit, 90 100kHz adjacent band difference for interference detection Method filter, 92 200kHz interference detection wide and narrow band differential method filter 100 receiving apparatus, 200 IF received signal, 202 DU ratio signal, 204 100kHz interference intensity signal, 206 200kHz interference intensity signal, 208 interference frequency signals, 210 filtered signal.

Claims

A first detection unit configured to detect a first intensity value corresponding to each of two frequency regions separated by a first frequency around a frequency of a desired wave;
A second detection unit that detects a second intensity value corresponding to two frequency regions separated by a second frequency around the frequency of the desired wave,
From the first intensity value and the second intensity value, a frequency determination unit that selects the value of the first frequency or the value of the second frequency corresponding to the frequency of the interfering wave for the desired wave,
A third detection unit that detects a third intensity value that should correspond to two frequency regions separated by the selected frequency from the frequency of the desired wave,
When selecting the value of the first frequency, selecting one of the plurality of intensity values including the first intensity value and the third intensity value, and selecting the value of the second frequency, An intensity determination unit that selects any one of the plurality of intensity values including the second intensity value or the third intensity value and determines an intensity ratio between the desired wave and the interfering wave,
The signal detector according to claim 3, wherein the third detector has a characteristic of detecting accuracy of an intensity value different from that of the first detector and the second detector.

The first detection unit calculates, as the first intensity value, an addition value of a signal output that has passed through two band-pass filters each having a center frequency higher and lower than the frequency of the desired wave by the first frequency. And output
The second detection unit calculates, as the second intensity value, an addition value of a signal output that has passed through two band-pass filters each having a center frequency of a frequency higher and lower by the second frequency than the frequency of the desired wave. The signal detection device according to claim 1, wherein the signal is output.

The first detection unit is configured to determine, as the first intensity value, a difference value of a signal output that has passed through two band-pass filters each having a center frequency higher and lower than the frequency of the desired wave by the first frequency. And output
The second detection unit calculates, as the second intensity value, an addition value of a signal output that has passed through two band-pass filters each having a center frequency of a frequency higher and lower by the second frequency than the frequency of the desired wave. The signal detection device according to claim 1, wherein the signal is output.

The value of the second frequency is greater than the value of the first frequency;
The frequency determination unit,
An amplification unit that amplifies the second intensity value;
A correction unit that corrects the amplified second intensity value based on the intensity value of the desired wave;
A selection unit that selects the value of the first frequency or the value of the second frequency from the first intensity value and the corrected second intensity value;
The signal detection device according to any one of claims 1 to 3, further comprising:

The third detection unit includes two band filters each having, as the third intensity value, a center frequency of a frequency higher and lower than the frequency of the desired wave by the first frequency, according to the selected frequency. Or the difference between the signal outputs passing through the bandpass filter centering on the frequency of the desired wave and the bandpass filter using the second frequency as the passband and the bandpass filter using the second frequency as the nonpassband. The signal detection device according to claim 1, wherein the signal detection device outputs a difference value.

A first detection unit that outputs an added value of signal outputs that have passed through two band filters each having a center frequency of a frequency higher and lower than the frequency of the desired wave by a first frequency,
A second detection unit that outputs an addition value of signal outputs that have passed through two band filters each having a center frequency of a frequency higher and a frequency lower by a second frequency than the frequency of the desired wave,
A third detection unit that outputs a difference value of a signal output that has passed through two band-pass filters each having a frequency higher and lower than the frequency of the desired wave by the first frequency as a center frequency,
A fourth detection unit that outputs a difference value of a signal output that has passed through a band filter that has the second frequency as a pass band and a band filter that has the second frequency as a non-pass band centering on the frequency of the desired wave. When,
A frequency determination unit that selects, from output values of the first detection unit and the second detection unit, a value of the first frequency or a value of the second frequency to correspond to a frequency of an interference wave for the desired wave When,
According to the frequency and the output level corresponding to the interfering wave, selection of one of the output values of the plurality of detection units including the first detection unit or the third detection unit, or the second detection unit or the An intensity determination unit that performs selection of any one output value of the plurality of detection units including the fourth detection unit and determines an intensity ratio between the desired wave and the interference wave;
A signal detection device comprising:

A front end unit for converting a radio frequency signal received from a desired station into an intermediate frequency signal,
An interference detection unit that detects the intensity of an interference wave for a desired wave based on the intermediate frequency signal,
An intermediate frequency filter unit that filters and outputs the intermediate frequency signal by a band filter whose band is set according to the intensity of the interference wave,
A detection unit for demodulating the output signal from the intermediate frequency filter unit,
The interference detection unit,
In a plurality of frequency regions and a plurality of methods in the peripheral frequency region of the frequency of the desired wave, in a plurality of methods, a plurality of detection units that respectively filter the intermediate frequency signal and detect the output level of the interference wave,
According to the output level of the interference wave, a frequency determination unit that determines a frequency region to correspond to the interference wave,
An intensity determining unit that selects one output level of the plurality of detection units according to a frequency domain and an output level that should correspond to the interference wave, and determines an intensity ratio between the desired wave and the interference wave; A receiving device comprising:

The plurality of detection units in the receiving device according to claim 7,
A first detection unit that outputs a first addition value of a signal output that has passed through two band filters each having a center frequency of a frequency higher and lower than the frequency of the desired wave by the first frequency,
A second detection unit that outputs a second addition value of signal outputs that have passed through two band filters each having a center frequency of a frequency higher and lower by the second frequency than the frequency of the desired wave,
A first difference value of a signal output passing through two band filters having frequencies higher and lower than the frequency of the desired wave by the first frequency as center frequencies, respectively, or the second difference centering on the frequency of the desired wave. The third detection unit that outputs a second difference value of a signal output that has passed through a band filter whose frequency is a pass band and a band filter that does not have the second frequency as a pass band,
The frequency determination unit determines, from the first addition value and the second addition value, a frequency region that should correspond to the interference wave,
The intensity determination unit selects one of the first addition value or a plurality of output levels including the first difference value, or the second addition value or the second difference value, according to the determined frequency region. The receiving apparatus according to claim 7, wherein any one of a plurality of output levels including the following is selected.