JP2995806B2 - Signal level detection circuit - Google Patents
Signal level detection circuitInfo
- Publication number
- JP2995806B2 JP2995806B2 JP2173724A JP17372490A JP2995806B2 JP 2995806 B2 JP2995806 B2 JP 2995806B2 JP 2173724 A JP2173724 A JP 2173724A JP 17372490 A JP17372490 A JP 17372490A JP 2995806 B2 JP2995806 B2 JP 2995806B2
- Authority
- JP
- Japan
- Prior art keywords
- signal
- signal level
- circuit
- detection circuit
- detection
- 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 - Fee Related
Links
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- Control Of Amplification And Gain Control (AREA)
Description
【発明の詳細な説明】 Ａ産業上の利用分野 本発明は信号レベル検出回路に関し、例えばビデオテ
ープレコーダに適用して好適なものである。Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal level detection circuit, and is suitably applied to, for example, a video tape recorder.
Ｂ発明の概要 本発明は、信号レベル検出回路において、AGC回路の
検波回路を兼用して入力信号の信号レベルを検出するこ
とにより、全体構成を簡易化することができる。B. Summary of the Invention The present invention can simplify the overall configuration by detecting the signal level of an input signal in a signal level detection circuit also as a detection circuit of an AGC circuit.
Ｃ従来の技術 従来、ビデオテープレコーダにおいては、AGC（autom
atic gain control）回路を用いて再生信号の信号レベ
ルを所定値に保持するようになされている。C Conventional technology Conventionally, in video tape recorders, AGC (automated
An atic gain control circuit is used to hold the signal level of the reproduced signal at a predetermined value.
さらにジヤストトラツキングの状態を簡易に検出し得
るように、AGC回路に入力する再生信号の信号レベルを
信号レベル検出回路で検出し得るようになされている。Further, the signal level of the reproduced signal input to the AGC circuit can be detected by a signal level detection circuit so that the state of the just tracking can be easily detected.
すなわち第３図に示すように、ビデオテープレコーダ
１においては、再生信号SRFを２乗検波回路２に与え、
ここで再生信号SRFの信号レベルを検出し、検出結果S
OUTをメータ駆動回路（図示せず）に出力する。That is, as shown in FIG. 3, in the video tape recorder 1, giving a reproduced signal S RF to the square detection circuit 2,
Here, the signal level of the reproduction signal SRF is detected, and the detection result S
OUT is output to a meter drive circuit (not shown).
これによりユーザにおいては、再生信号の信号レベル
に応じてトラツキング調整し得、簡易にジヤストトラツ
キングの状態に調整することができる。As a result, the user can adjust the tracking according to the signal level of the reproduced signal, and can easily adjust to the state of the just tracking.
さらにビデオテープレコーダ１においては、再生信号
SRFをAGC回路４の可変利得増幅回路６に与え、当該可変
利得増幅回路６の出力信号を続く信号処理回路に出力す
る。Further, in the video tape recorder 1, the reproduction signal
SRF is supplied to the variable gain amplifier circuit 6 of the AGC circuit 4, and the output signal of the variable gain amplifier circuit 6 is output to the subsequent signal processing circuit.
AGC回路４においては、２乗検波回路８で可変利得増
幅回路６の出力信号レベルを検出した後、当該検出結果
SKE及び基準電圧VREFの比較結果を誤差増幅回路10で
得、当該比較結果を可変利得増幅回路６に帰還する。In the AGC circuit 4, after the output signal level of the variable gain amplifier circuit 6 is detected by the square detection circuit 8, the detection result is obtained.
The result of comparison between SKE and the reference voltage VREF is obtained by the error amplifier circuit 10, and the result of comparison is fed back to the variable gain amplifier circuit 6.
これにより可変利得増幅回路６においては、２乗検波
回路８の検出結果が一定値になるように利得が制御さ
れ、かくして再生信号SRFの信号レベルを所定値に補正
して続く信号処理回路で処理するようになされている。Thus, in the variable gain amplifier circuit 6, the square detection result of the detection circuit 8 is controlled gain as a constant value, thus the signal processing circuit subsequent to correct the signal level of the reproduced signal S RF to a predetermined value It is made to handle.
Ｄ発明が解決しようとする課題 ところで、この種の信号レベル検出回路の構成を簡略
化することができれば、その分ビデオテープレコーダの
全体構成を簡略化し得、便利であると考えられる。The problem to be solved by the invention D By the way, if the structure of this kind of signal level detection circuit can be simplified, the whole structure of the video tape recorder can be simplified accordingly, which is considered to be convenient.
本発明は以上の点を考慮してなされたもので、従来に
比して簡易な構成の信号レベル検出回路を提案しようと
するものである。The present invention has been made in view of the above points, and an object of the present invention is to propose a signal level detection circuit having a simpler configuration than the conventional one.
Ｅ課題を解決するための手段 かかる課題を解決するため本発明においては、制御信
号SCOMの信号レベルに応じた利得で、入力信号SRFを増
幅して出力する可変利得増幅回路６と、可変利得増幅回
路６から出力される出力信号の信号レベルを検出する検
波回路８と、検波回路８の検出結果SKEと所定の基準値V
REFとの比較結果に基づいて、制御信号SCOMを出力する
誤差増幅回路10と、制御信号SCOM及び検出結果SKEの減
算信号SOUT1を得、入力信号SRFの信号レベルに応じて信
号レベルが変化する信号レベル検出信号SOUTを出力する
減算回路22とを備えるようにする。In the present invention for solving means according challenge to solve E problem, a gain corresponding to the signal level of the control signal S COM, a variable gain amplifier 6 for amplifying and outputting an input signal S RF, variable A detection circuit 8 for detecting a signal level of an output signal output from the gain amplification circuit 6, a detection result S KE of the detection circuit 8 and a predetermined reference value V
Based on the comparison result between the REF, the control signal and the error amplification circuit 10 for outputting S COM, to obtain a subtraction signal S OUT1 of the control signal S COM and detection result S KE, signal according to the signal level of the input signal S RF A subtraction circuit 22 that outputs a signal level detection signal SOUT whose level changes is provided.
Ｆ作用 検波回路８の検出結果SKEと誤差増幅回路10の制御信
号SCOMを減算し、入力信号SRFの信号レベルに応じて信
号レベルが変化する信号レベル検出信号SOUT1を得るよ
うにすれば、AGC回路の検波回路８を兼用して、入力信
号SRFの信号レベルを検出することができ、その分全体
構成を簡略化することができる。Detection results of the F acting detection circuit 8 subtracts the control signal S COM of S KE and the error amplifier circuit 10, by to obtain a signal level detection signal S OUT1 whose signal level varies according to the signal level of the input signal S RF For example, the signal level of the input signal SRF can be detected by also using the detection circuit 8 of the AGC circuit, and the overall configuration can be simplified accordingly.
Ｇ実施例 以下図面について、本発明の一実施例を詳述する。G Example Hereinafter, an example of the present invention will be described in detail with reference to the drawings.
第３図との対応部分に同一符号を付して示す第１図に
おいて、20は全体としてビデオテープレコーダを示し、
減算回路22において、２乗検波回路８の検出結果SKEか
ら誤差増幅回路10の出力信号SCOMを減算してメータ駆動
回路に出力する。In FIG. 1 in which parts corresponding to those in FIG. 3 are assigned the same reference numerals, reference numeral 20 denotes a video tape recorder as a whole,
In the subtraction circuit 22, the square detection result of the detection circuit 8 subtracts the output signal S COM of the error amplifier circuit 10 from the S KE outputs to the meter drive circuit.
すなわち第２図に示すように、２乗検波回路８の検出
結果SKEにおいては、AGC回路の制御範囲内においては、
所定の信号レベルに保持されるのに対し、AGC回路の制
御範囲以下においては、再生信号SRFの信号レベルに比
例して信号レベルが増加する。That is, as shown in FIG. 2, in the detection result S KE of the square detection circuit 8, within the control range of the AGC circuit,
While being held at a predetermined signal level, in the following control range of the AGC circuit, the signal level increases in proportion to the signal level of the reproduced signal S RF.
これに対して誤差増幅回路10の出力信号SCOMにおいて
は、AGC回路の制御範囲以下で一定値に保持されるのに
対し、AGC回路の制御範囲内においては、再生信号SRFの
信号レベルに反比例して信号レベルが減少する。In the output signal S COM of the error amplifier circuit 10 with respect thereto, while being held at a constant value in the following control range of the AGC circuit, within the control range of the AGC circuit, the signal level of the reproduced signal S RF The signal level decreases in inverse proportion.
従つて減算回路22を介して検出結果SKEから出力信号S
COMを減算することにより、再生信号SRFの信号レベルに
比例して信号レベルが増加する信号レベル検出信号S
OUT1を得ることができる。Accordingly, the output signal S is obtained from the detection result SKE through the subtraction circuit 22.
By subtracting COM , the signal level detection signal S whose signal level increases in proportion to the signal level of the reproduction signal SRF
OUT1 can be obtained.
これによりAGC回路の２乗検波回路８を兼用して、再
生信号SRFの信号レベルを検出することができる。As a result, the signal level of the reproduced signal SRF can be detected by also using the square detection circuit 8 of the AGC circuit.
従つて、２乗検波回路２に代えて減算回路22を設ける
だけの簡易な構成で、再生信号SRFの信号レベルを検出
することができる。Therefore, the signal level of the reproduced signal SRF can be detected with a simple configuration in which the subtraction circuit 22 is provided instead of the square detection circuit 2.
実際上、２乗検波回路においては、バランスドモジユ
レータ等を用いて構成することから、減算回路を用いる
場合に比して、信号レベル検出回路全体の構成が複雑に
なることを避け得ない。Actually, since the square-law detection circuit is configured using a balanced modulator or the like, it is unavoidable that the configuration of the entire signal level detection circuit becomes complicated as compared with the case where a subtraction circuit is used.
従つて、この実施例によれば、２乗検波回路２に代え
て減算回路22を設けて再生信号SRFの信号レベルを検出
することにより、その分ビデオテープレコーダ全体の構
成を簡略化することができる。Accordance connexion, according to this embodiment, by detecting the signal level of the reproduced signal S RF with the square-law detection circuit subtracting circuit 22 in place of the 2 provided, simplifying the structure of the whole amount videotape recorder Can be.
以上の構成において、再生信号SRFは可変利得制御回
路６を介して２乗検波回路８で信号レベルが検出され、
当該検出結果に基づいて所定の信号レベルに保持され
る。In the above configuration, the signal level of the reproduced signal SRF is detected by the square detection circuit 8 via the variable gain control circuit 6,
It is maintained at a predetermined signal level based on the detection result.
これに対して信号レベル検出回路においては、２乗検
波回路８の検出結果SKEから誤差増幅回路10の出力信号S
COMが減算され、これにより再生信号SRFの信号レベルに
比例して信号レベルが変化する信号レベル検出信号S
OUT1を得ることができる。On the other hand, in the signal level detection circuit, the output signal S of the error amplification circuit 10 is calculated based on the detection result S KE of the square detection circuit 8.
COM is subtracted, whereby the signal level detection signal S whose signal level changes in proportion to the signal level of the reproduction signal SRF
OUT1 can be obtained.
以上の構成によれば、AGC回路の２乗検波回路８を兼
用して再生信号SRFの信号レベルを検出することによ
り、全体として簡易な構成の信号レベル検出回路を得る
ことができる。According to the above configuration, by detecting a square signal level of the alternate to the reproduced signal S RF and detector circuit 8 of the AGC circuit, it is possible to obtain a signal level detection circuit of a simple configuration as a whole.
なお上述の実施例においては、２乗検波回路８の検出
結果SKEから誤差増幅回路10の出力信号SCOMを減算する
場合について述べたが、本発明はこれとは逆に、出力信
号SCOMから検出結果SKEを減算してもよい。Incidentally, in the aforementioned embodiment, it has dealt with the case where the detection result S KE squared detection circuit 8 subtracts the output signal S COM of the error amplifier circuit 10, the present invention is contrary to this, the output signal S COM May be subtracted from the detection result SKE .
さらに上述の実施例においては、２乗検波回路を用い
て可変利得増幅回路の出力信号を検波することにより、
当該出力信号の信号レベルを検出する場合について述べ
たが、検波回路はこれに限らず、ダイオードを用いた包
絡線検波回路等、種々の検波回路を広く適用することが
できる。Further, in the above-described embodiment, by detecting the output signal of the variable gain amplifying circuit using the square detection circuit,
Although the case where the signal level of the output signal is detected has been described, the detection circuit is not limited to this, and various detection circuits such as an envelope detection circuit using a diode can be widely applied.
さらに上述の実施例においては、本発明をビデオテー
プレコーダに適用した場合について述べたが、本発明は
これに限らず、入力信号を所定の信号レベルに補正して
出力する際、当該入力信号の信号レベルを検出する信号
レベル検出回路に広く適用することができる。Further, in the above-described embodiment, the case where the present invention is applied to a video tape recorder has been described. However, the present invention is not limited to this, and when the input signal is corrected to a predetermined signal level and output, the input signal is It can be widely applied to a signal level detection circuit for detecting a signal level.
Ｈ発明の効果 上述のように本発明によれば、AGC回路の検波回路を
兼用して入力信号の信号レベルを検出することにより、
全体として簡易な構成の信号レベル検出回路を得ること
ができる。H Effect of the Invention As described above, according to the present invention, by detecting the signal level of an input signal by also using the detection circuit of the AGC circuit,
As a whole, a signal level detection circuit having a simple configuration can be obtained.
【図面の簡単な説明】 第１図は本発明の一実施例によるビデオテープレコーダ
を示すブロツク図、第２図はその動作の説明に供する特
性曲線図、第３図は従来のビデオテープレコーダを示す
ブロツク図である。 １、20……ビデオテープレコーダ、２、８……２乗検波
回路、６……可変利得増幅回路、10……誤差増幅回路、
22……減算回路。BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a video tape recorder according to an embodiment of the present invention, FIG. 2 is a characteristic curve diagram for explaining its operation, and FIG. 3 is a diagram showing a conventional video tape recorder. It is a block diagram shown. 1, 20 video tape recorder, 2, 8 square detection circuit, 6 variable gain amplifier circuit, 10 error amplifier circuit
22 ... Subtraction circuit.
Claims (1)
力信号を増幅して出力する可変利得増幅回路と、 上記可変利得増幅回路から出力される出力信号の信号レ
ベルを検出する検波回路と、 上記検波回路の検出結果と所定の基準値との比較結果に
基づいて、上記制御信号を出力する誤差増幅回路と、 上記制御信号及び上記検出結果の減算信号を得、上記入
力信号の信号レベルに応じて信号レベルが変化する信号
レベル検出信号を出力する減算回路と を具えることを特徴とする信号レベル検出回路。A variable gain amplifier circuit for amplifying and outputting an input signal with a gain according to a signal level of a control signal; and a detection circuit for detecting a signal level of an output signal output from the variable gain amplifier circuit. An error amplifier circuit that outputs the control signal based on a comparison result between the detection result of the detection circuit and a predetermined reference value; and a subtraction signal of the control signal and the detection result, and a signal level of the input signal. And a subtraction circuit that outputs a signal level detection signal whose signal level changes according to the following.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2173724A JP2995806B2 (en) | 1990-06-29 | 1990-06-29 | Signal level detection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2173724A JP2995806B2 (en) | 1990-06-29 | 1990-06-29 | Signal level detection circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0463006A JPH0463006A (en) | 1992-02-28 |
| JP2995806B2 true JP2995806B2 (en) | 1999-12-27 |
Family
ID=15965969
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2173724A Expired - Fee Related JP2995806B2 (en) | 1990-06-29 | 1990-06-29 | Signal level detection circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2995806B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP6240010B2 (en) * | 2014-03-24 | 2017-11-29 | 日本電信電話株式会社 | amplifier |
-
1990
- 1990-06-29 JP JP2173724A patent/JP2995806B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0463006A (en) | 1992-02-28 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |