JPH0434078U

JPH0434078U -

Info

Publication number: JPH0434078U
Application number: JP7619590U
Authority: JP
Priority date: 1990-07-18
Filing date: 1990-07-18
Publication date: 1992-03-19

Description

[Brief explanation of drawings]

第１図は本考案の第１の実施例の周波数選択回
路付音声中間周波検波回路のブロツク図、第２図
は、第１図のマイクロコンピユータの動作を説明
するためのフローチヤート、第３図は第２の実施
例の周波数選択回路付音声中間周波検波回路のブ
ロツク図である。１……映像中間周波増幅回路、２〜５……バン
ドパスフイルタ、６……ＦＭ検波回路、７……コ
ンパレータ、８……マイクロコンピユータ、１０
……制御信号、Ｃ８０１〜Ｃ８０８……コンデン
サ、Ｓ１〜Ｓ８……スイツチ、Ｔ６０１，Ｔ６０
２……トランス。 FIG. 1 is a block diagram of an audio intermediate frequency detection circuit with a frequency selection circuit according to the first embodiment of the present invention, FIG. 2 is a flowchart for explaining the operation of the microcomputer shown in FIG. 1, and FIG. 1 is a block diagram of an audio intermediate frequency detection circuit with a frequency selection circuit according to a second embodiment; FIG. 1... Video intermediate frequency amplification circuit, 2-5... Band pass filter, 6... FM detection circuit, 7... Comparator, 8... Microcomputer, 10
...Control signal, C801-C808...Capacitor, S1-S8...Switch, T601, T60
2...Trance.

Claims

[Claims for Utility Model Registration] (1) In response to a video signal containing an audio intermediate frequency signal of any one of a plurality of different frequencies,
a resonant circuit having a plurality of different resonant frequencies, the resonant circuit having a selection circuit that selects and switches one of the plurality of different resonant frequencies in response to a control signal; and the resonant circuit. a level detection circuit that detects a level in response to the output of the level detection circuit; and a level detection circuit that generates the control signal to sequentially switch between the plurality of different resonance frequencies, and then responds to the output of the level detection circuit that changes accordingly. and a control circuit that outputs the control signal so as to maintain one of the plurality of different resonance frequencies of the resonance circuit. (2) in response to a video signal that includes an audio intermediate frequency signal at any one of a plurality of different frequencies;
a first resonant circuit having a plurality of different resonant frequencies, the first resonant circuit having a selection circuit that selects and switches one of the plurality of different resonant frequencies in response to a control signal; an FM detection circuit responsive to the output of the first resonant circuit; and a resonant circuit responsive to the output of the FM detection circuit and having resonance frequencies of the plurality of different frequencies, the resonant circuit responsive to the control signal a second resonant circuit having means for selecting and switching one of the frequencies; a level detection circuit for detecting a level in response to the output of the second resonant circuit; generating a control signal and then maintaining one of the plurality of different resonant frequencies of the first and second resonant circuits in response to the output of the level detection circuit varying thereby; and a control circuit for outputting the control signal.