JPS6224979Y2 - - Google Patents
Info
- Publication number
- JPS6224979Y2 JPS6224979Y2 JP1979110668U JP11066879U JPS6224979Y2 JP S6224979 Y2 JPS6224979 Y2 JP S6224979Y2 JP 1979110668 U JP1979110668 U JP 1979110668U JP 11066879 U JP11066879 U JP 11066879U JP S6224979 Y2 JPS6224979 Y2 JP S6224979Y2
- Authority
- JP
- Japan
- Prior art keywords
- high frequency
- frequency amplifier
- amplifier
- output
- voltage
- 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
- 230000001360 synchronised effect Effects 0.000 claims description 5
- 238000001514 detection method Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
Description
【考案の詳細な説明】
本考案は入力信号がなくなつた場合に検波出力
に雑音が多く出るのをなくすようにした自動利得
制御装置を提供しようとするものである。[Detailed Description of the Invention] The present invention aims to provide an automatic gain control device that eliminates the occurrence of a lot of noise in the detection output when there is no input signal.
第１図に従来の自動利得制御装置の一例を挙げ
て、これを説明する。入力端子ａから入るテレビ
ジヨン高周波信号は入力波器１で帯域制限を受
け、次に高周波増幅器で増幅される。この高周波
増幅器はホワードAGCあるいはリバースAGCの
いずれかの手段にて利得制御出来、受信信号に対
しては比較的広帯域に設計されている。次に多く
の場合差動増幅器を用いた高周波増幅器３が設け
られている。これはICで作られる場合が多いた
めである。この高周波増幅器３もリバースAGC
がかかるようになつていて、かなり広帯域であ
る。増幅されたテレビジヨン高周波信号は同期検
波器４等で検波されビデオ信号となる。このビデ
オ信号は増幅器５で増幅され通常1Vp−ｐで出力
端子ｂに出力される。出力の一部を取り、検波器
６で再度検波し、同期信号成分を抜き出す。その
検波信号に含まれる雑音成分を雑音除去回路７に
て取り除き、直流成分のみとし、直流増幅器８で
増幅し、その出力を高周波増幅器３の制御電圧と
して利用する。さらに直流増幅器８の微小電圧変
化分をさらに直流増幅器９で増幅し、その出力に
より高周波増幅器２の利得を制御する。この時の
制御電圧の変化を第２図に示す。 An example of a conventional automatic gain control device will be explained with reference to FIG. A television high-frequency signal input from input terminal a is band-limited by an input transducer 1, and then amplified by a high-frequency amplifier. This high frequency amplifier can control the gain using either forward AGC or reverse AGC, and is designed to have a relatively wide band for received signals. Next, a high frequency amplifier 3, which in most cases uses a differential amplifier, is provided. This is because they are often made with ICs. This high frequency amplifier 3 is also reverse AGC
, and has a fairly wide band. The amplified television high frequency signal is detected by a synchronous detector 4 or the like and becomes a video signal. This video signal is amplified by an amplifier 5 and outputted to an output terminal b, usually at 1 Vp-p. A part of the output is taken and detected again by the detector 6, and the synchronization signal component is extracted. A noise removal circuit 7 removes the noise component contained in the detected signal, leaving only a DC component, which is amplified by a DC amplifier 8, and its output is used as a control voltage for the high-frequency amplifier 3. Further, the minute voltage change of the DC amplifier 8 is further amplified by the DC amplifier 9, and the gain of the high frequency amplifier 2 is controlled by the output thereof. FIG. 2 shows the change in control voltage at this time.
直流増幅器９の出力である制御電圧１０は入力
端子レベルが60〜90dBμにて制御出来、第２図
のａのような曲線となり、直流増幅器８の出力で
ある制御電圧１１は入力端子レベルが60dBμ以
下で動作するように設計されている。一方制御電
圧１０は入力レベルが60dBμ以上で働らくよう
になる。入力端子ａに信号がなくなると、２つの
高周波増幅器２及び３は共に最大利得となる。そ
の合計の利得が約80dBを越える場合で、かつ、
検波器３が同期検波を行なう回路の場合、雑音レ
ベルが検波器３の検波レベルを越えることとな
り、出力端子ｂに雑音成分が発生することとな
る。この雑音成分は高周波増幅器２および３が比
較的広帯域である場合10MHz以上に及ぶことがあ
る。出力端子ｂから出てくる信号を再度高周波の
テレビ信号に変調し伝送する時に、そのテレビ変
調信号のチヤンネルに隣接する別のテレビ信号が
あつた場合、前述の雑音成分が隣接する別のテレ
ビ信号に妨害を与えることになる。 The control voltage 10, which is the output of the DC amplifier 9, can be controlled at an input terminal level of 60 to 90 dBμ, forming a curve as shown in Figure 2 a, and the control voltage 11, which is the output of the DC amplifier 8, can be controlled at an input terminal level of 60 to 90 dBμ. It is designed to work with: On the other hand, the control voltage 10 becomes effective when the input level is 60 dBμ or more. When there is no signal at input terminal a, both high frequency amplifiers 2 and 3 have maximum gain. If the total gain exceeds approximately 80 dB, and
If the detector 3 is a circuit that performs synchronous detection, the noise level will exceed the detection level of the detector 3, and a noise component will be generated at the output terminal b. This noise component may reach 10 MHz or more if the high frequency amplifiers 2 and 3 have a relatively wide band. When the signal coming out of output terminal b is modulated again into a high-frequency television signal and transmitted, if another television signal is adjacent to the channel of the modulated television signal, the above-mentioned noise component will be generated by another adjacent television signal. will cause interference.
本考案はこのような妨害が起らないようにしよ
うとするものである。その手段は２つある。１つ
は第１図の高周波増幅器２及び３の最大利得が
80dBを越えないようにし、雑音レベルが検波器
４にかからないようにすることである。もう１つ
は強制的に最大利得が80dBを越えないようにす
ることである。前者はすでに設計されたIC等を
使用する場合不可能であり、後者の方が設計の自
由度をもつ。本考案は後者の手段を利用したもの
であり、そのブロツク図を第３図に示す。第１図
と同じものについては同じ番号を付して説明を省
略する。本考案の特徴とするところは直流増幅器
８の制御電圧が第２図のｃ〜ｄ間のある電圧を越
えないようにツエーナダイオード１２を直流増幅
器８の出力とアース間に入れる。そのようにする
と第１の高周波増幅器２の自動利得制御には関係
なく、第２の高周波増幅器３の利得の最大値を下
げることが可能となり、２つの高周波増幅器２，
３の最大利得が制御電圧１１の電圧がｄで80dB
を越えなければ雑音成分は検波器４にはほとんど
かからず、出力端子ｂに発生することはない。但
し、制御電圧ｃ〜ｄ間の電圧範囲は約0.3V程度
しかなく、その範囲にツエーナ電圧のバラツキを
おさえる必要がある。 The present invention seeks to prevent such interference from occurring. There are two ways to do this. One is that the maximum gain of high frequency amplifiers 2 and 3 in Fig. 1 is
The noise level should not exceed 80 dB and should not be applied to the detector 4. The other is to force the maximum gain to not exceed 80dB. The former is not possible when using an already designed IC, and the latter has more freedom in design. The present invention utilizes the latter means, and a block diagram thereof is shown in FIG. Components that are the same as those in FIG. 1 are given the same numbers and their explanation will be omitted. The feature of the present invention is that a Zener diode 12 is inserted between the output of the DC amplifier 8 and the ground so that the control voltage of the DC amplifier 8 does not exceed a certain voltage between c and d in FIG. By doing so, it becomes possible to lower the maximum value of the gain of the second high frequency amplifier 3 regardless of the automatic gain control of the first high frequency amplifier 2, and the two high frequency amplifiers 2,
The maximum gain of 3 is 80dB when the voltage of control voltage 11 is d
If it does not exceed , the noise component will hardly be applied to the detector 4 and will not be generated at the output terminal b. However, the voltage range between control voltages c to d is only about 0.3V, and it is necessary to suppress variations in the Zener voltage within that range.
以上のように、本考案によれば、テレビジヨン
入力信号を波器を介した後、第１の高周波増幅
器，第２の高周波増幅器に順次加え、第２の高周
波増幅器の出力を同期検波器で検波してビデオ信
号を得るようにするとともに、このビデオ信号を
検波した出力に基いて上記第１，第２の高周波増
幅器にAGCをかけるようにした装置において、
上記第２の高周波増幅器に印加するAGC電圧の
ラインにツエナーダイオードを１個接続すること
により、入力信号がなくなつた場合でも第１，第
２の高周波増幅器の合計のゲインを一定値以上に
ならないように制限することができ、雑音が検波
器の出力に出てくることを防止することができる
ものである。 As described above, according to the present invention, the television input signal is applied to the first high frequency amplifier and the second high frequency amplifier sequentially after passing through the wave detector, and the output of the second high frequency amplifier is processed by the synchronous detector. In the apparatus, the video signal is obtained by detection, and the first and second high-frequency amplifiers are subjected to AGC based on the output of the detected video signal.
By connecting one Zener diode to the AGC voltage line applied to the second high-frequency amplifier, the total gain of the first and second high-frequency amplifiers will not exceed a certain value even if there is no input signal. It is possible to prevent noise from appearing in the output of the detector.
第１図は従来例における自動利得制御装置のブ
ロツク線図、第２図は同装置の特性図、第３図は
本考案の一実施例における自動利得制御装置のブ
ロツク線図である。
１……入力波器、２，３……高周波増幅器、
４……同期検波器、６……検波器、８，９……直
流増幅器。
FIG. 1 is a block diagram of a conventional automatic gain control device, FIG. 2 is a characteristic diagram of the same device, and FIG. 3 is a block diagram of an automatic gain control device according to an embodiment of the present invention. 1...Input wave device, 2, 3...High frequency amplifier,
4... Synchronous detector, 6... Detector, 8, 9... DC amplifier.
Claims (1)
を介して第１の高周波増幅器に加え、この第１の
高周波増幅器の出力信号を第２の高周波増幅器に
加え、この第２の高周波増幅器の出力信号を同期
検波器に加えてその出力端よりビデオ信号を得る
ようにするとともに、このビデオ信号を検波器で
再度検波してAGC電圧を作成し、このAGC電圧
出力ラインとアース間にツエナーダイオードを挿
入し、かつ上記AGC電圧を直流増幅器に加え、
上記検波器より出力されるAGC電圧を入力レベ
ルがある所定のレベル以下で働らく第１のAGC
電圧としてツエナーダイオードを介して上記第２
の高周波増幅器に加え、上記直流増幅器の出力を
上記入力レベルが上記所定のレベル以上で働らく
第２のAGC電圧として上記第１の高周波増幅器
に印加するようにした自動利得制御装置。 Applying the received television input signal to a first high frequency amplifier via an input transducer, applying the output signal of the first high frequency amplifier to a second high frequency amplifier, and applying the output signal of the second high frequency amplifier to a first high frequency amplifier. In addition to the synchronous detector, a video signal is obtained from its output end, this video signal is detected again by the detector to create the AGC voltage, and a Zener diode is inserted between this AGC voltage output line and ground. , and add the above AGC voltage to the DC amplifier,
The first AGC operates when the AGC voltage output from the above detector is below a certain input level.
The above second voltage is passed through the Zener diode as a voltage.
In addition to the high frequency amplifier, the automatic gain control device is configured to apply the output of the DC amplifier to the first high frequency amplifier as a second AGC voltage that operates when the input level is equal to or higher than the predetermined level.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1979110668U JPS6224979Y2 (en) | 1979-08-10 | 1979-08-10 |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1979110668U JPS6224979Y2 (en) | 1979-08-10 | 1979-08-10 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5629520U JPS5629520U (en) | 1981-03-20 |
| JPS6224979Y2 true JPS6224979Y2 (en) | 1987-06-26 |
Family
ID=29343192
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1979110668U Expired JPS6224979Y2 (en) | 1979-08-10 | 1979-08-10 |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6224979Y2 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5685914A (en) * | 1979-12-14 | 1981-07-13 | Matsushita Electric Ind Co Ltd | Automatic gain control device of television receiver |
| JPS59141972U (en) * | 1983-03-11 | 1984-09-21 | 星崎電機株式会社 | Dishwasher door seal device |
| JPH0616067Y2 (en) * | 1984-12-26 | 1994-04-27 | ハ−ドグラス工業株式会社 | Door |
| JP2578591B2 (en) * | 1986-11-07 | 1997-02-05 | 三洋電機株式会社 | Automatic gain control circuit |
-
1979
- 1979-08-10 JP JP1979110668U patent/JPS6224979Y2/ja not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5629520U (en) | 1981-03-20 |
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