Stereo audio mute circuit

Details Stereo audio mute circuit Stereo audio mute circuit

1990-03-16

1992-04-07

Groody, James J.

Facsimile and static presentation processing

Facsimile

Specific signal processing circuitry

3581911, 3581921, 4551941, H04N 550, H04N 560

Patent

active

051033151

ABSTRACT:
A stereo television receiver includes a microprocessor for developing logic level control signals for controlling tuning, video processing and a LED stereo indicator. A sync separator circuit supplies a horizontal signal to a peak detector which supplies a logic level output signal to the microprocessor. An audio mute circuit includes a pair of transistor switches, one each coupled to the left and right audio channels. The switch base electrodes are coupled together and supplied through LEDs from two delay circuits. One delay circuit is activated by the LED stereo indicator logic level control signal and the other by a logic level output signal developed when a television signal is tuned. The period of the delay circuit activated by the tuning of a television signal is sufficiently long to permit a determination of whether a stereo or a monaural audio signal is present. The mute circuit eliminates annoying pops and clicks developed during monaural/stereo signal transitions and between the tuning of television signals.

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