JPH071867Y2 - Noise processing circuit - Google Patents
Noise processing circuitInfo
- Publication number
- JPH071867Y2 JPH071867Y2 JP15878588U JP15878588U JPH071867Y2 JP H071867 Y2 JPH071867 Y2 JP H071867Y2 JP 15878588 U JP15878588 U JP 15878588U JP 15878588 U JP15878588 U JP 15878588U JP H071867 Y2 JPH071867 Y2 JP H071867Y2
- Authority
- JP
- Japan
- Prior art keywords
- noise
- detection
- signal
- detecting
- noise component
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
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- Noise Elimination (AREA)
Description
【考案の詳細な説明】 [産業上の利用分野] 本考案は雑音処理回路、特に車載用FM受信機に内蔵され
るノイズキャンセラ等に好適な雑音処理回路の改良に関
する。DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an improvement of a noise processing circuit, particularly a noise processing circuit suitable for a noise canceller incorporated in an in-vehicle FM receiver.
[考案の概要] FM受信機において、車両から発生される雑音の影響を受
けずらい電波状態を検出するため電界強度レベルが所定
値以上である時、出力信号を発生する第1の検出手段
と、広帯域AGCレベルが所定地以下である時、出力信号
を発生する第2の検出手段とを設け、何れか一方の検出
信号によって雑音検出感度を抑制し、過変調による不要
な雑音除去動作を防止する雑音処理回路である。[Summary of the Invention] In a FM receiver, a first detecting means for generating an output signal when an electric field strength level is a predetermined value or more in order to detect a radio wave state that is difficult to be influenced by noise generated from a vehicle. , A second detecting means for generating an output signal when the broadband AGC level is below a predetermined level is provided, and noise detection sensitivity is suppressed by either one of the detection signals to prevent unnecessary noise removal operation due to overmodulation. It is a noise processing circuit.
[従来の技術] 車載用FM受信機は、車両から発生する雑音を取り除くた
めに、通常ノイズキャンセラと呼ばれる雑音除去回路を
内蔵している。この雑音除去回路は検波出力中に含まれ
る高調波のレベルを検出して、検波出力をスイッチング
して雑音を除去する。[Prior Art] An on-vehicle FM receiver has a built-in noise canceling circuit usually called a noise canceller in order to remove noise generated from the vehicle. This noise removal circuit detects the level of the higher harmonic wave contained in the detection output and switches the detection output to remove noise.
第3図は雑音除去回路付近のラジオ受信機の構成を示す
ブロック図で、図中、破線で囲まれた部分が雑音除去回
路であり、1は中間周波増幅/検波回路、2はバッフ
ァ、3は高域通過フィルタ、4は雑音検出回路、5は単
安定マルチバイブレータ、6は遅延回路、7はゲート回
路、8はマルチプレクサを表わす。FIG. 3 is a block diagram showing the configuration of the radio receiver in the vicinity of the noise removal circuit. In the figure, the part surrounded by the broken line is the noise removal circuit, 1 is an intermediate frequency amplification / detection circuit, 2 is a buffer, and 3 is a buffer. Is a high-pass filter, 4 is a noise detection circuit, 5 is a monostable multivibrator, 6 is a delay circuit, 7 is a gate circuit, and 8 is a multiplexer.
第4図は雑音検出回路4の詳細な構成を示す回路図であ
り、この回路は次のように動作する。FIG. 4 is a circuit diagram showing a detailed configuration of the noise detection circuit 4, and this circuit operates as follows.
車両雑音が発生したり過変調が起こったりすると、高域
通過フィルタ3を通って電圧が発生する。トランジスタ
Q2の入力は、トランジスタQ1に較べRa,Rb及びCで分割
された分だけ低くなっており、トランジスタQ1とQ2で構
成される差動増幅器の出力が大きくなると、単安定マル
チバイブレータ5が発振し、ゲート回路7が開く。When vehicle noise occurs or overmodulation occurs, a voltage is generated through the high pass filter 3. Transistor
Input of Q 2 is, Ra compared to the transistor Q 1, which is lower by the amount divided by Rb and C, the output of the differential amplifier formed by the transistors Q 1, Q 2 increases, monostable multivibrator 5 oscillates and the gate circuit 7 opens.
以上が基本動作であり、C及びRbが雑音検出感度を決定
するコンデンサと抵抗であり、Cを固定するとRbを大き
くする程雑音検出感度が低下する。The above is the basic operation, and C and Rb are the capacitor and the resistor that determine the noise detection sensitivity. When C is fixed, the noise detection sensitivity decreases as Rb increases.
[考案が解決しようとする課題] この回路では、雑音検出回路は一定であり、従って、音
楽等の過変調が原因で検波出力に高調波が増加しても、
回路は検波出力をスイッチングして、雑音除去動作を開
始し、かえって音を歪ませる結果になることがあった。
従来、この過変調による雑音除去動作に対しては、Rbを
大きくして雑音検出感度を低下させて対処してきた。[Problems to be solved by the invention] In this circuit, the noise detection circuit is constant, and therefore, even if harmonics increase in the detection output due to overmodulation of music or the like,
The circuit may switch the detection output and start the noise removal operation, which may distort the sound.
Conventionally, the noise removal operation due to this overmodulation has been dealt with by increasing Rb to reduce the noise detection sensitivity.
しかしながら、この方式の雑音除去回路では、本来の目
的である車両から発生する雑音を充分に除去することが
できない欠点があった。However, this type of noise removal circuit has a drawback in that it cannot sufficiently remove the noise generated from the vehicle, which is the original purpose.
[考案の目的] 本考案の目的は車両から発生する雑音の影響を受けずら
い電波状態を検出し、この時雑音検出感度を抑制させ、
過変調が原因による不要な雑音除去動作を防止すること
により、必要時の車両雑音除去性能向上と不要な除去動
作の防止を両立させることにある。[Purpose of the Invention] The purpose of the present invention is to detect the radio wave condition that is difficult to be affected by the noise generated from the vehicle and suppress the noise detection sensitivity at this time.
By preventing an unnecessary noise removing operation due to overmodulation, it is possible to improve the vehicle noise removing performance when necessary and prevent the unnecessary removing operation.
[課題を解決するための手段] 本考案は上記目的を達成するため、受信信号に含まれた
ノイズ成分を所定検出レベルで検出しノイズ成分検出信
号を得るノイズ成分検出手段と、前記ノイズ成分を、前
記ノイズ成分検出信号に基づいて除去し受信再生信号を
得るノイズ成分除去手段と、中間周波増幅回路の出力信
号より受信電界強度を検出し、得られた電界強度検出信
号が所定レベル以上の時、第1の検出信号を出力する第
1の検出手段と、高周波増幅回路の利得を検出し、得ら
れた利得検出信号が所定レベル以下の時、第2の検出信
号を出力する第2の検出手段と、前記第1,第2の検出信
号のうちいずれか一方が出力された時、第3の検出信号
を出力する第3の検出手段と、前記第3の検出信号に応
じて前記ノイズ成分の検出感度を低下させるように前記
ノイズ成分検出手段を制御する検出感度制御手段と、を
備えたことを要旨とする。[Means for Solving the Problems] In order to achieve the above object, the present invention provides a noise component detecting unit for detecting a noise component included in a received signal at a predetermined detection level to obtain a noise component detection signal, and the noise component. When the received electric field strength detection signal is above a predetermined level, the received electric field strength is detected from the output signal of the intermediate frequency amplifier circuit , A first detection means for outputting the first detection signal, and a second detection for detecting the gain of the high-frequency amplifier circuit and outputting the second detection signal when the gain detection signal obtained is below a predetermined level. Means, a third detection means for outputting a third detection signal when either one of the first and second detection signals is output, and the noise component according to the third detection signal. Detection sensitivity of A sensitivity control means for controlling the noise component detecting means as, and summarized in that with a.
[作用] 本考案の雑音処理回路において、電界強度検出信号が所
定レベル以上の時、又は高周波成分の利得検出信号が所
定レベル以下の時、第1又は第2の検出信号が出力さ
れ、これに応答して第3の検出信号が出力される。第3
の検出信号に応じてノイズ成分の検出感度が低下させら
れて、過変調による不要な雑音除去動作が防止される。[Operation] In the noise processing circuit of the present invention, the first or second detection signal is output when the electric field strength detection signal is above the predetermined level or when the gain detection signal of the high frequency component is below the predetermined level. In response, the third detection signal is output. Third
The detection sensitivity of the noise component is reduced according to the detection signal of, and unnecessary noise removal operation due to overmodulation is prevented.
[実施例] 以下図面による実施例を参照して本考案を説明すると、
第1図は本考案によるFM受信機の雑音処理回路を示し、
第3図と同一符号は同一又は類似の回路をあらわす。第
1図において、9は第1の検出手段、10は第2の検出手
段、11はレベル設定手段で、該手段11は、例えばNOR回
路12及びレベル設定回路13で構成される。[Embodiment] The present invention will be described below with reference to an embodiment with reference to the drawings.
FIG. 1 shows a noise processing circuit of an FM receiver according to the present invention,
The same reference numerals as those in FIG. 3 represent the same or similar circuits. In FIG. 1, 9 is a first detecting means, 10 is a second detecting means, 11 is a level setting means, and the means 11 is composed of, for example, a NOR circuit 12 and a level setting circuit 13.
第1の検出手段9は中間周波増幅/検波回路1から入力
される受信局の電界強度に比例したシグナルメータ駆動
電圧S1が所定値E1以上である時、出力信号O1を発生す
る。The first detecting means 9 generates an output signal O 1 when the signal meter driving voltage S 1 input from the intermediate frequency amplification / detection circuit 1 and proportional to the electric field strength of the receiving station is a predetermined value E 1 or more.
また、第2の検出手段10は高周波増幅回路14から入力さ
れる広帯域AGC電圧S2のレベルが所定値E2以下である
と、出力信号O2を発生する。Further, the second detecting means 10 generates an output signal O 2 when the level of the wide band AGC voltage S 2 input from the high frequency amplifier circuit 14 is a predetermined value E 2 or less.
更にレベル設定手段11において、NOR回路12は上記第1
及び第2の検出手段9,10の出力が接続されており、少な
くとも一方の出力信号O1又はO2が入力されると、これを
検出して、その検出出力O3がレベル設定回路13に与えら
れ、該回路により雑音検出回路4の雑音検出感度を低下
させる。Further, in the level setting means 11, the NOR circuit 12 has the first
And the outputs of the second detecting means 9 and 10 are connected, and when at least one of the output signals O 1 or O 2 is input, this is detected, and the detection output O 3 thereof is sent to the level setting circuit 13. The noise detection sensitivity of the noise detection circuit 4 is lowered by this circuit.
なお、上記広帯域AGC電圧は高周波増幅回路に現れる電
圧を、増幅,検波,整流,反転させて得られる直流電圧
で、通常、受信電界強度に反比例している。この直流電
圧を使用して高周波増幅回路の利得を制御する手段を広
帯域AGCと呼んでいるが、高周波増幅回路の出力を検出
しているため、受信局以外の局でも動作する特徴があ
り、通常、受信周波数±2MHzの広い帯域で動作する。The broadband AGC voltage is a DC voltage obtained by amplifying, detecting, rectifying and inverting the voltage appearing in the high frequency amplifier circuit, and is usually inversely proportional to the received electric field strength. The means for controlling the gain of the high-frequency amplifier circuit using this DC voltage is called wideband AGC, but since it detects the output of the high-frequency amplifier circuit, it has the characteristic of operating in stations other than the receiving station. Operates in a wide band of reception frequency ± 2MHz.
第2図は第1及び第2の手段及びレベル設定手段の具体
的構成例で、第1及び第2の設定手段9,10としては、そ
れぞれ比較器15,16が用いられている。FIG. 2 shows a concrete configuration example of the first and second means and the level setting means, and comparators 15 and 16 are used as the first and second setting means 9 and 10, respectively.
比較器15の入力端子は中間周波増幅/検波回路1のシ
グナルメータ駆動電圧出力端子1aに接続され、その入
力端子には前記所定値E1に相当する基準電圧源17が接続
され、比較器15の出力はNOR回路12の一方の入力端子に
接続されている。The input terminal of the comparator 15 is connected to the signal meter driving voltage output terminal 1a of the intermediate frequency amplification / detection circuit 1, and the reference voltage source 17 corresponding to the predetermined value E 1 is connected to the input terminal of the comparator 15. The output of is connected to one input terminal of the NOR circuit 12.
また比較器16の入力端子は高周波増幅回路14の広帯域
AGC電圧出力端子14aに接続され、その入力端子には前
記所定値E2に相当する基準電圧源18が接続され、比較器
16の出力はNOR回路12の他方の入力端子に接続されてい
る。Further, the input terminal of the comparator 16 is a wide band of the high frequency amplifier circuit 14.
It is connected to the AGC voltage output terminal 14a, the reference voltage source 18 corresponding to the predetermined value E 2 is connected to the input terminal,
The output of 16 is connected to the other input terminal of the NOR circuit 12.
NOR回路12の出力は、レベル設定用トランジスタ19のベ
ースに接続され、そのコレクタは雑音検出回路4の雑音
検出感度設定用抵抗Rb,Rcの接続点に接続されている。The output of the NOR circuit 12 is connected to the base of the level setting transistor 19, and its collector is connected to the connection point of the noise detection sensitivity setting resistors Rb and Rc of the noise detection circuit 4.
次に上記実施例の動作を説明する。Next, the operation of the above embodiment will be described.
車両から発生される雑音の影響を受けずらい電波状態と
は(1)受信局の電界が設定レベル以上の場合及び
(2)受信局の近くに強電界の局が存在する場合であ
る。The radio wave condition that is not easily affected by the noise generated from the vehicle includes (1) the electric field of the receiving station is equal to or higher than a set level, and (2) the case where a strong electric field exists near the receiving station.
(1)の場合はFM放送波の弱肉強食現象及びリミッティ
ングによる振幅成分の制限効果によるもので、この場合
にはシグナルメータ駆動電圧S1は所定値E1以上となるの
で、この時だけ比較器15の出力は高レベルとなる。In the case of (1), it is due to the effect of limiting the amplitude component due to the weak and strong corrosion phenomenon of FM broadcast wave and limiting. In this case, the signal meter drive voltage S 1 becomes the predetermined value E 1 or more, so only at this time the comparator The output of 15 becomes high level.
これに対し(2)の場合は前記広帯域AGCが動作し、高
周波増幅回路14の利得を低下させるため、アンテナ入力
に混入する車両雑音をその利得低下分だけ減衰すること
によるもので、この場合には広帯域AGC電圧S2は所定値E
2以下となるので、この時だけ比較器16は高レベルとな
る。On the other hand, in the case of (2), the wide band AGC operates to reduce the gain of the high frequency amplifier circuit 14, and therefore vehicle noise mixed in the antenna input is attenuated by the gain reduction amount. Is the broadband AGC voltage S 2 is the predetermined value E
Since it becomes 2 or less, the comparator 16 becomes high level only at this time.
従って比較器15,16のNOR出力は車両から発生される雑音
の影響を受けずらい電波状態に該当しない時だけ、高レ
ベルとなって、トランジスタ19をオンにし、雑音検出感
度設定用抵抗はRbだけが選択され高感度となり、雑音除
去性能が向上する。Therefore, the NOR outputs of the comparators 15 and 16 become high level only when the radio wave condition is not affected by the noise generated from the vehicle and the transistor 19 is turned on, and the noise detection sensitivity setting resistor is Rb. Only the selected one will have high sensitivity and the noise reduction performance will be improved.
これに対し前記(1)および(2)に該当する場合はNO
R出力は低レベルとなり、トランジスタ19はオフされる
ので、雑音検出感度設定用抵抗はRb+Rcとなって、雑音
検出感度は低下する。従って過変調が主たる原因である
不要な雑音除去動作による雑音劣化を防止できる。勿
論、この時は車両から発生される雑音の影響は受けな
い。On the other hand, if the above (1) and (2) are applicable, NO
Since the R output becomes a low level and the transistor 19 is turned off, the noise detection sensitivity setting resistance becomes Rb + Rc, and the noise detection sensitivity decreases. Therefore, it is possible to prevent noise deterioration due to an unnecessary noise removal operation, which is mainly caused by overmodulation. Of course, at this time, it is not affected by the noise generated from the vehicle.
[考案の効果] 以上説明したように本考案によれば、車両雑音の影響が
ある時は雑音検出感度が自動的に向上し効果的な雑音除
去が行われると共に車両雑音の影響が無い時は雑音検出
感度を自動的に低下させて過変調による不要な雑音除去
を未然に防止できる。[Advantage of the Invention] As described above, according to the present invention, when the influence of vehicle noise is exerted, the noise detection sensitivity is automatically improved to perform effective noise removal, and when the influence of vehicle noise is not exerted. The noise detection sensitivity is automatically lowered to prevent unnecessary noise removal due to overmodulation.
第1図は本考案の一実施例を示すブロック図、第2図は
該実施例における雑音処理部の具体的構成例を示す図、
第3図は従来の雑音除去回路を示すブロック図、第4図
は第3図における雑音検出回路の詳細な構成を示す回路
図である。 1……中間周波増幅/検波回路、4……雑音検出回路、
9……第1の検出手段、10……第2の検出手段、11……
レベル設定手段、14……高周波増幅回路、Ra,Rb……雑
音検出感度設定用抵抗。FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a diagram showing a concrete configuration example of a noise processing unit in the embodiment,
FIG. 3 is a block diagram showing a conventional noise removing circuit, and FIG. 4 is a circuit diagram showing a detailed configuration of the noise detecting circuit in FIG. 1 ... Intermediate frequency amplification / detection circuit, 4 ... Noise detection circuit,
9 ... First detecting means, 10 ... Second detecting means, 11 ...
Level setting means, 14 ... High frequency amplifier circuit, Ra, Rb ... Resistors for noise detection sensitivity setting.
Claims (1)
レベルで検出しノイズ成分検出信号を得るノイズ成分検
出手段と、 前記ノイズ成分を、前記ノイズ成分検出信号に基づいて
除去し受信再生信号を得るノイズ成分除去手段と、 中間周波増幅回路の出力信号より受信電界強度を検出
し、得られた電界強度検出信号が所定レベル以上の時、
第1の検出信号を出力する第1の検出手段と、 高周波増幅回路の利得を検出し、得られた利得検出信号
が所定レベル以下の時、第2の検出信号を出力する第2
の検出手段と、 前記第1、第2の検出信号のうちいずれか一方が出力さ
れた時、第3の検出信号を出力する第3の検出手段と、 前記第3の検出信号に応じて前記ノイズ成分の検出感度
を低下させるように前記ノイズ成分検出手段を制御する
検出感度制御手段と、 を備えたことを特徴とする雑音処理回路。1. A noise component detecting means for detecting a noise component contained in a reception signal at a predetermined detection level to obtain a noise component detection signal, and a reception reproduction signal for removing the noise component based on the noise component detection signal. Noise component removal means for obtaining the received electric field strength from the output signal of the intermediate frequency amplifier circuit, when the obtained electric field strength detection signal is above a predetermined level,
A first detecting means for outputting a first detection signal; and a second detecting means for detecting the gain of the high frequency amplifier circuit and outputting a second detection signal when the gain detection signal obtained is below a predetermined level.
Detecting means, third detecting means for outputting a third detecting signal when one of the first and second detecting signals is output, and the third detecting means for outputting the third detecting signal according to the third detecting signal. A noise processing circuit comprising: a detection sensitivity control unit that controls the noise component detection unit so as to reduce the detection sensitivity of a noise component.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP15878588U JPH071867Y2 (en) | 1988-12-06 | 1988-12-06 | Noise processing circuit |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP15878588U JPH071867Y2 (en) | 1988-12-06 | 1988-12-06 | Noise processing circuit |
Publications (2)
Publication Number | Publication Date |
---|---|
JPH0279636U JPH0279636U (en) | 1990-06-19 |
JPH071867Y2 true JPH071867Y2 (en) | 1995-01-18 |
Family
ID=31439428
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP15878588U Expired - Lifetime JPH071867Y2 (en) | 1988-12-06 | 1988-12-06 | Noise processing circuit |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH071867Y2 (en) |
-
1988
- 1988-12-06 JP JP15878588U patent/JPH071867Y2/en not_active Expired - Lifetime
Also Published As
Publication number | Publication date |
---|---|
JPH0279636U (en) | 1990-06-19 |
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Legal Events
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