JPS6316951B2 - - Google Patents
Info
- Publication number
- JPS6316951B2 JPS6316951B2 JP54118512A JP11851279A JPS6316951B2 JP S6316951 B2 JPS6316951 B2 JP S6316951B2 JP 54118512 A JP54118512 A JP 54118512A JP 11851279 A JP11851279 A JP 11851279A JP S6316951 B2 JPS6316951 B2 JP S6316951B2
- Authority
- JP
- Japan
- Prior art keywords
- intermediate frequency
- video
- amplifier
- output
- audio
- 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
- 230000005684 electric field Effects 0.000 claims description 8
- 238000001514 detection method Methods 0.000 claims 3
- 238000010586 diagram Methods 0.000 description 3
- 230000006866 deterioration Effects 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 230000005236 sound signal Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03G—CONTROL OF AMPLIFICATION
- H03G3/00—Gain control in amplifiers or frequency changers
- H03G3/20—Automatic control
- H03G3/30—Automatic control in amplifiers having semiconductor devices
- H03G3/3052—Automatic control in amplifiers having semiconductor devices in bandpass amplifiers (H.F. or I.F.) or in frequency-changers used in a (super)heterodyne receiver
- H03G3/3068—Circuits generating control signals for both R.F. and I.F. stages
Landscapes
- Picture Signal Circuits (AREA)
- Television Receiver Circuits (AREA)
- Control Of Amplification And Gain Control (AREA)
Description
【発明の詳細な説明】
本発明はテレビジヨン受像機の音声中間周波回
路に関するものであり、弱入力電界時の音声感度
劣下の防止および中・強入力電界時にバズレベル
を低くすることを目的とするものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an audio intermediate frequency circuit for a television receiver, and its purpose is to prevent deterioration of audio sensitivity in the case of a weak input electric field and to lower the buzz level in the case of a medium or strong input electric field. It is something to do.
第１図は本発明の一実施例における音声中間周
波回路であり、従来の装置とともに説明する。 FIG. 1 shows an audio intermediate frequency circuit in one embodiment of the present invention, which will be explained together with a conventional device.
第１図において１はアンテナ、２はこのアンテ
ナ１の入力を受けるチユーナ、３はチユーナ２の
出力を増幅する映像中間周波増幅器、４はこの増
幅器３の出力を検波する映像検波器、５はこの検
波器４の出力を増幅する映像増幅器、６，７は映
像増幅器５の出力よりAGC電圧を作りチユーナ
２、映像中間周波増幅器３にAGC電圧を加える
高周波AGC回路６および映像中間周波AGC回路
７，８は映像中間周波増幅器３の出力を増幅し、
AGC回路７のAGC電圧でゲインコントロールさ
れる音声中間周波増幅器、９は音声中間周波検波
器である。 In FIG. 1, 1 is an antenna, 2 is a tuner that receives the input of this antenna 1, 3 is a video intermediate frequency amplifier that amplifies the output of the tuner 2, 4 is a video detector that detects the output of this amplifier 3, and 5 is this video detector. A video amplifier 6 and 7 amplify the output of the detector 4, a high frequency AGC circuit 6 and a video intermediate frequency AGC circuit 7, which generate AGC voltage from the output of the video amplifier 5 and apply the AGC voltage to the tuner 2 and the video intermediate frequency amplifier 3. 8 amplifies the output of the video intermediate frequency amplifier 3;
An audio intermediate frequency amplifier whose gain is controlled by the AGC voltage of the AGC circuit 7, and 9 an audio intermediate frequency detector.
従来の装置は増幅器８を設けずに、増幅器３の
出力を直接音声検波器９に加えたものである。 In the conventional device, the output of the amplifier 3 is directly applied to the audio detector 9 without providing the amplifier 8.
まず、従来の回路について説明する。映像中間
周波増幅器３にAGC電圧がかけられているので、
中・強電界強度の場合であつても増幅器３から出
る出力は一定であり、これを直接音声検波する
と、比較的バズが出ることになる。そこで、この
バズが出るのを少なくするために映像中間周波増
幅器３の出力を音声中間周波増幅器８で増幅す
る。このようにすると映像キヤリヤＰと音声キヤ
リヤＳのレベルが高いほどバズのレベルを改善す
ることができる。特にＰ／Ｓが大きい場合、
10dB程度の改善ができる。またＰ／Ｓが小さい
ときでもバズの絶対値レベルは改善される。これ
はＰ及びＳのレベルが大きいと、音声中間周波検
波器９の出力が大きく、歪みの少ない4.5MHz成
分が得られるからである。 First, a conventional circuit will be explained. Since the AGC voltage is applied to the video intermediate frequency amplifier 3,
Even in the case of medium or strong electric field strength, the output from the amplifier 3 is constant, and if this is directly detected by audio, a relatively buzz will be produced. Therefore, in order to reduce the occurrence of this buzz, the output of the video intermediate frequency amplifier 3 is amplified by the audio intermediate frequency amplifier 8. In this way, the higher the levels of the video carrier P and the audio carrier S are, the more the buzz level can be improved. Especially when P/S is large,
It can be improved by about 10dB. Furthermore, even when P/S is small, the absolute value level of buzz is improved. This is because when the levels of P and S are large, the output of the audio intermediate frequency detector 9 is large, and a 4.5 MHz component with less distortion can be obtained.
上記のことは中・強電界の場合には都合がよい
が、弱電界になると、映像キヤリヤ、音声キヤリ
ヤにノイズ成分が混入されるので、このノイズ成
分が増幅され、4.5MHz成分の中に多くのノイズ
成分が含まれることになる。そこで、本発明では
弱電界時に音声中間周波増幅器８の利得を低下さ
せ、ノイズ成分が4.5MHz成分にあまり含まれな
いようにしている。 The above is convenient in the case of medium to strong electric fields, but when the electric field becomes weak, noise components are mixed into the video carrier and audio carrier, so this noise component is amplified and becomes large in the 4.5MHz component. This will include noise components. Therefore, in the present invention, the gain of the audio intermediate frequency amplifier 8 is lowered when the electric field is weak, so that the noise component is not included in the 4.5 MHz component.
第２図は上記の様子を特性的に示したものであ
る。また、第３図は音声中間周波増幅器８の具体
回路例であり、端子１０より映像中間周波信号
が、端子１１よりAGC電圧が加えられる。１２
は出力端子である。 FIG. 2 characteristically shows the above situation. FIG. 3 shows a specific circuit example of the audio intermediate frequency amplifier 8, to which a video intermediate frequency signal is applied from a terminal 10 and an AGC voltage is applied from a terminal 11. 12
is the output terminal.
以上のように本発明によれば、入力電界強度に
応じて良好な音声信号を得ることができる。 As described above, according to the present invention, a good audio signal can be obtained depending on the input electric field strength.
第１図は本発明の一実施例における音声中間周
波回路のブロツク線図、第２図は同回路の特性
図、第３図は同回路の要部の具体回路図である。
３……映像中間周波増幅器、４……映像検波
器、５……映像増幅器、７……映像中間周波
AGC回路、８……音声中間周波増幅器、９……
音声中間周波検波器。
FIG. 1 is a block diagram of an audio intermediate frequency circuit according to an embodiment of the present invention, FIG. 2 is a characteristic diagram of the circuit, and FIG. 3 is a specific circuit diagram of the main parts of the circuit. 3...Video intermediate frequency amplifier, 4...Video detector, 5...Video amplifier, 7...Video intermediate frequency
AGC circuit, 8...Audio intermediate frequency amplifier, 9...
Audio intermediate frequency detector.
Claims (1)
音声中間周波増幅器に加え、上記映像検波回路の
出力を映像信号増幅器に加え、この映像信号増幅
器の出力を映像中間周波AGC回路に加え、この
映像中間周波AGC回路の出力を映像中間周波増
幅器と音声中間周波増幅器にAGC電圧として加
え、弱電界時に上記音声中間周波増幅器の利得を
低下させ、上記音声中間周波増幅器の出力を音声
中間周波検波回路に加ええたことを特徴とする音
声中間周波回路。1 Add the output of the video intermediate frequency amplifier to the video detection circuit and the audio intermediate frequency amplifier, add the output of the video detection circuit to the video signal amplifier, add the output of this video signal amplifier to the video intermediate frequency AGC circuit, and add the output of the video intermediate frequency amplifier to the video intermediate frequency AGC circuit. The output of the frequency AGC circuit is applied as an AGC voltage to the video intermediate frequency amplifier and the audio intermediate frequency amplifier, the gain of the audio intermediate frequency amplifier is reduced in the case of a weak electric field, and the output of the audio intermediate frequency amplifier is added to the audio intermediate frequency detection circuit. An audio intermediate frequency circuit characterized by:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11851279A JPS5642411A (en) | 1979-09-13 | 1979-09-13 | Audio intermediate frequency circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11851279A JPS5642411A (en) | 1979-09-13 | 1979-09-13 | Audio intermediate frequency circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5642411A JPS5642411A (en) | 1981-04-20 |
| JPS6316951B2 true JPS6316951B2 (en) | 1988-04-12 |
Family
ID=14738462
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP11851279A Granted JPS5642411A (en) | 1979-09-13 | 1979-09-13 | Audio intermediate frequency circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5642411A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS59182681A (en) * | 1983-04-01 | 1984-10-17 | Hitachi Micro Comput Eng Ltd | Television receiver |
| JPS618232A (en) * | 1984-06-20 | 1986-01-14 | Daido Kogyo Co Ltd | Manufacture of sprocket for bicycles and motor-cycles |
| US4718086A (en) * | 1986-03-27 | 1988-01-05 | Rca Corporation | AGC in sound channel of system for processing a scrambled video signal |
-
1979
- 1979-09-13 JP JP11851279A patent/JPS5642411A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5642411A (en) | 1981-04-20 |
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