JPS6218982Y2 - - Google Patents
Info
- Publication number
- JPS6218982Y2 JPS6218982Y2 JP7508980U JP7508980U JPS6218982Y2 JP S6218982 Y2 JPS6218982 Y2 JP S6218982Y2 JP 7508980 U JP7508980 U JP 7508980U JP 7508980 U JP7508980 U JP 7508980U JP S6218982 Y2 JPS6218982 Y2 JP S6218982Y2
- Authority
- JP
- Japan
- Prior art keywords
- circuit
- signal
- agc
- detection
- time constant
- 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
Links
- 238000001514 detection method Methods 0.000 claims description 30
- 230000003321 amplification Effects 0.000 claims description 6
- 230000007274 generation of a signal involved in cell-cell signaling Effects 0.000 claims description 6
- 238000003199 nucleic acid amplification method Methods 0.000 claims description 6
- 239000003990 capacitor Substances 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 2
- 230000035939 shock Effects 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 230000010355 oscillation Effects 0.000 description 1
Landscapes
- Control Of Amplification And Gain Control (AREA)
- Circuits Of Receivers In General (AREA)
Description
【考案の詳細な説明】
本考案はAGC回路の改良に係り、特に同調操
作時におけるAGC回路の応答特性を改善せんと
するものである。[Detailed Description of the Invention] The present invention relates to the improvement of an AGC circuit, and particularly aims to improve the response characteristics of the AGC circuit during tuning operation.
従来、ラジオ受信機の検波回路の出力端に積分
回路を介してAGC信号発生回路を接続し、該
AGC信号発生回路から発生するAGC信号によつ
てRF（ラジオ周波）増幅回路及びIF（中間周
波）増幅回路の利得制御を行うAGC回路が公知
である。しかして、この様な従来のAGC回路
は、歪特性を改善する為に前記積分回路の時定数
を大にしなければならない。特にAMステレオ受
信機においては、AM成分（メイン信号）と位相
成分（サブ信号）とのレベルを等しくしなければ
ならないので、出力の対入力変動を小にする必要
があり、その為、前記積分回路の時定数を小とす
ることは出来ない。しかしながら、前記積分回路
の時定数を大とすると、離調状態から同調状態に
急激に変化する同調操作時にAGC回路が追従せ
ず、シヨツク音が発生する。 Conventionally, an AGC signal generation circuit was connected to the output end of the detection circuit of a radio receiver via an integrating circuit, and the
2. Description of the Related Art An AGC circuit is known that controls the gain of an RF (radio frequency) amplification circuit and an IF (intermediate frequency) amplification circuit using an AGC signal generated from an AGC signal generation circuit. However, in such a conventional AGC circuit, the time constant of the integrating circuit must be increased in order to improve distortion characteristics. Particularly in AM stereo receivers, the levels of the AM component (main signal) and phase component (sub signal) must be made equal, so it is necessary to minimize the fluctuation of the output relative to the input. The time constant of the circuit cannot be made small. However, if the time constant of the integrating circuit is made large, the AGC circuit will not follow the tuning operation that rapidly changes from the detuned state to the tuned state, and a shock noise will occur.
本考案は、上述の点に鑑み成されたもので、正
常受信時には、積分回路の時定数を大として歪特
性の改善を計り、かつ同調操作時には積分回路の
時定数を小として応答特性の改善を計らんとする
ものである。 The present invention was developed in view of the above-mentioned points. During normal reception, the time constant of the integrating circuit is increased to improve distortion characteristics, and during tuning operation, the time constant of the integrating circuit is decreased to improve response characteristics. This is what we are trying to measure.
以下本考案の一実施例に基き、図面を参照しな
がら説明する。図において、１はアンテナ、２は
RF増幅回路、３は局部発振回路４を備える周波
数変換回路、５はIF増幅回路、６はAM検波回
路、７は第１抵抗８とコンデンサ９とから成る積
分回路、１０は該積分回路７からの出力信号が印
加されるAGC信号発生回路、１１は前記IF増幅
回路５から出力されるIF信号をFM検波するFM
検波回路、１２は該FM検波回路１１の出力信号
中の特定周波数成分のみを通過させるバンドパス
フイルター、１３は該バンドパスフイルター１２
の出力信号のレベルを検知する検知回路、１４は
前記積分回路７の第１抵抗８と並列接続された
NPNトランジスタ１５及び第２抵抗１６から成
る可変抵抗手段、１７は該可変抵抗手段１４を駆
動する駆動回路である。 An embodiment of the present invention will be described below with reference to the drawings. In the figure, 1 is the antenna, 2 is the antenna
RF amplifier circuit; 3 is a frequency conversion circuit including a local oscillation circuit 4; 5 is an IF amplifier circuit; 6 is an AM detection circuit; 7 is an integrating circuit consisting of a first resistor 8 and a capacitor 9 ; 11 is an FM circuit that performs FM detection of the IF signal output from the IF amplifier circuit 5;
a detection circuit; 12 is a bandpass filter that passes only a specific frequency component in the output signal of the FM detection circuit 11; 13 is the bandpass filter 12;
A detection circuit 14 is connected in parallel with the first resistor 8 of the integrating circuit 7 .
Variable resistance means consisting of an NPN transistor 15 and a second resistor 16; reference numeral 17 is a drive circuit for driving the variable resistance means 14 .
アンテナ１に受信されたAM放送電波は、RF
増幅回路２で増幅され、周波数変換回路３でIF
信号に変換された後IF増幅回路５で増幅され、
AM検波回路６でAM検波される。該AM検波回路
６の出力信号は、出力端子１８から後段に伝送さ
れるとともに、積分回路７で積分された後AGC
信号発生回路１０に印加され、該AGC信号発生
回路１０から発生するAGC信号がRF増幅回路２
及びIF増幅回路５に印加されて利得制御が行な
われる。 AM broadcast radio waves received by antenna 1 are RF
Amplified by amplifier circuit 2 and converted to IF by frequency conversion circuit 3
After being converted into a signal, it is amplified by the IF amplification circuit 5,
AM detection circuit 6 performs AM detection. The output signal of the AM detection circuit 6 is transmitted from the output terminal 18 to the subsequent stage, and after being integrated by the integrating circuit 7 , the AGC
The AGC signal applied to the signal generation circuit 10 and generated from the AGC signal generation circuit 10 is applied to the RF amplifier circuit 2.
and is applied to the IF amplifier circuit 5 to perform gain control.
しかして、前記アンテナ１に受信される電波が
通常のAMモノラル放送の場合は、IF増幅回路５
に接続されたFM検波回路１１の検波出力は、直
流分のみであり、該直流分はバンドパスフイルタ
ー１２で遮断されるから、検知回路１３の入力信
号が零となり、駆動回路１７から出力が発生せ
ず、NPNトランジスタ１５はオフとなつてお
り、積分回路７は第１抵抗８とコンデンサ９とで
決まる大なる時定数を有する。前記アンテナ１に
受信される電波がAMステレオ放送の場合は、
FM検波回路１１の出力信号中には、直流分と、
５Hzステレオ表示信号（ID信号）と、AMステレ
オ差信号とが含まれる。その時、バンドパスフイ
ルター１２が５Hzを含む所定帯域の信号を通過す
る様に設定されていれば、前記直流分とAMステ
レオ差信号とが遮断され、検知回路１３の入力端
には、ID信号のみが印加される。AMステレオ放
送におけるID信号は、5mV程度の比較的小さな
レベルである。その為、検知回路１３の検知レベ
ルを、所定値（例えば10mV）に設定しておけ
ば、５Hzステレオ表示信号は、前記検知回路１３
で検知されず、AMステレオ放送の場合も、AM
モノラル放送の場合と同様、駆動回路１７の出力
信号は零となり、可変抵抗手段１４は積分回路に
何ら影響を与えない。 However, if the radio waves received by the antenna 1 are normal AM monaural broadcasting, the IF amplifier circuit 5
The detection output of the FM detection circuit 11 connected to the FM detection circuit 11 is only a DC component, and this DC component is blocked by the bandpass filter 12, so the input signal of the detection circuit 13 becomes zero, and an output is generated from the drive circuit 17. Therefore, the NPN transistor 15 is off, and the integrating circuit 7 has a large time constant determined by the first resistor 8 and the capacitor 9. If the radio waves received by antenna 1 are AM stereo broadcasts,
The output signal of the FM detection circuit 11 contains a DC component and
A 5Hz stereo display signal (ID signal) and an AM stereo difference signal are included. At that time, if the bandpass filter 12 is set to pass signals in a predetermined band including 5Hz, the DC component and the AM stereo difference signal are blocked, and only the ID signal is sent to the input terminal of the detection circuit 13. is applied. The ID signal in AM stereo broadcasting has a relatively low level of about 5mV. Therefore, if the detection level of the detection circuit 13 is set to a predetermined value (for example, 10 mV), the 5Hz stereo display signal will be detected by the detection circuit 13.
Even in the case of AM stereo broadcasting, AM
As in the case of monaural broadcasting, the output signal of the drive circuit 17 becomes zero, and the variable resistance means 14 has no effect on the integrating circuit.
従つて、AMモノラル放送であれ、AMステレ
オ放送であれ、正常に受信されている時は、積分
回路７の時定数が大となつており、歪率の改善が
達成される。 Therefore, whether it is an AM monaural broadcast or an AM stereo broadcast, when the broadcast is being received normally, the time constant of the integrating circuit 7 is large, and the distortion rate can be improved.
いま、同調を行う為、同調摘子（図示せず）を
操作したとすると、同調操作に応じて、IF信号
周波数が微小変化を生じ、該微小変化がFM検波
回路１１で検波され、特に５Hz近傍の周波数を有
する不要信号が発生する。この不要信号は、ID
信号と周波数的に近いものであるが、そのレベル
がID信号の数百倍に達する大きな信号である。
従つて、例えばAMステレオ放送受信の場合で
も、前記不要信号とID信号とは、バンドパスフ
イルター１２を通過しても、ID信号は検知され
ず、不要信号のみが検知回路で検知され、駆動回
路１７から前記不要信号に応じた駆動信号が発生
する。それ故、同調操作時のみ前記駆動信号が発
生することになり、その時可変抵抗手段１４の
NPNトランジスタ１５が導通し、積分回路７の
第１抵抗８と並列に、該第１抵抗８よりも小さな
値の第２抵抗１６が接続されることになるから、
積分回路７のコンデンサ９は小さな時定数で充電
され、応答特性の改善が達成される。 Now, if you operate the tuning knob (not shown) to perform tuning, the IF signal frequency will cause a minute change in response to the tuning operation, and this minute change will be detected by the FM detection circuit 11, especially at 5 Hz. Unwanted signals with nearby frequencies are generated. This unnecessary signal is
Although it is close in frequency to the ID signal, it is a large signal with a level several hundred times higher than the ID signal.
Therefore, even in the case of AM stereo broadcast reception, for example, even if the unnecessary signal and ID signal pass through the bandpass filter 12, the ID signal is not detected, only the unnecessary signal is detected by the detection circuit, and the drive circuit A drive signal corresponding to the unnecessary signal is generated from 17. Therefore, the drive signal is generated only during the tuning operation, and at that time the variable resistance means 14
Since the NPN transistor 15 becomes conductive and the second resistor 16 having a smaller value than the first resistor 8 is connected in parallel with the first resistor 8 of the integrating circuit 7 ,
Capacitor 9 of integrating circuit 7 is charged with a small time constant, achieving improved response characteristics.
同調操作が終了し、不要信号が発生しなくなる
と、可変抵抗手段１４のNPNトランジスタ１５
が直ちにオフし、積分回路７の時定数は再び大と
なつて歪特性の改善に役立つ。 When the tuning operation is completed and unnecessary signals are no longer generated, the NPN transistor 15 of the variable resistance means 14
is immediately turned off, and the time constant of the integrating circuit 7 becomes large again, which helps improve the distortion characteristics.
以上述べた如く、本考案に係るAGC回路は、
積分回路の時定数を変化させることにより同調操
作時の応答特性の改善を計ることが出来るもの
で、同調操作時に従来発生していたシヨツク音を
確実に防止出来るものである。 As mentioned above, the AGC circuit according to the present invention is
By changing the time constant of the integrating circuit, it is possible to improve the response characteristics during tuning operations, and it is possible to reliably prevent the shock noise that conventionally occurs during tuning operations.
図は本考案の一実施例を示す回路ブロツク図で
ある。
主な図番の説明、６……AM検波回路、７積分
回路、１１……FM検波回路、１４……可変抵抗
手段。
The figure is a circuit block diagram showing one embodiment of the present invention. Explanation of main drawing numbers, 6...AM detection circuit, 7 Integration circuit, 11...FM detection circuit, 14 ...Variable resistance means.
Claims (1)
生回路に印加し、該AGC信号発生回路から発生
するAGC信号をRF増幅回路もしくはIF増幅回路
に印加することによりAGCを行なうAGC回路に
おいて、前記IF増幅回路から得られるIF信号を
FM検波するFM検波回路と、該FM検波回路の出
力信号中に含まれる特定周波数の信号を検出する
周波数検出手段と、該周波数検出手段の出力信号
のレベルを検知する検知回路と、該検知回路の出
力信号に応じて動作し、前記積分回路の時定数を
小に切換える可変抵抗手段とを備え、正常動作時
の前記積分回路の時定数に比べ、同調操作時の前
記積分回路の時定数を小にしたことを特徴とする
AGC回路。 In an AGC circuit that performs AGC by applying a detection output signal to an AGC signal generation circuit via an integrating circuit and applying an AGC signal generated from the AGC signal generation circuit to an RF amplification circuit or an IF amplification circuit, the IF amplification circuit performs AGC. IF signal obtained from the circuit
An FM detection circuit that performs FM detection, a frequency detection means that detects a signal of a specific frequency included in the output signal of the FM detection circuit, a detection circuit that detects the level of the output signal of the frequency detection means, and the detection circuit. variable resistance means that operates in response to an output signal of the integrator circuit and switches the time constant of the integrator circuit to a small value, the time constant of the integrator circuit during tuning operation being smaller than the time constant of the integrator circuit in normal operation. It is characterized by being made small.
AGC circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7508980U JPS6218982Y2 (en) | 1980-05-29 | 1980-05-29 |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7508980U JPS6218982Y2 (en) | 1980-05-29 | 1980-05-29 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS56176522U JPS56176522U (en) | 1981-12-26 |
| JPS6218982Y2 true JPS6218982Y2 (en) | 1987-05-15 |
Family
ID=29437779
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP7508980U Expired JPS6218982Y2 (en) | 1980-05-29 | 1980-05-29 |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6218982Y2 (en) |
-
1980
- 1980-05-29 JP JP7508980U patent/JPS6218982Y2/ja not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| JPS56176522U (en) | 1981-12-26 |
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