| 摘要 |
PURPOSE:To prevent the noise generation of an audio signal system in AFT operation, by muting an audio signal from a channel switching point in time to the detection point of the zero-cross point of an AFT voltage. CONSTITUTION:A signal from a channel selection switch 13 which shows that channels are changed, and a decision signal from a decision circuit 10 which shows the completion of AFT operation are supplied to a generating circuit 14 for a muting signal, thereby generating the muting signal from the point in time when channels are change to the point in time when the AFT operation starts. This muting signal is supplied to an audio IF circuit 15 supplied with a signal from a video IF circuit 2. Therefore, an audio signal is muted during the leading-in period of AFT. After the leading-in period, the muting is reset to prevent the absence of the audio signal caused by resetting the audio signal unnecessarily. |
