| 摘要 |
PURPOSE:To provide the satellite broadcast receiving device which excellently mutes an image and an audio when a television broadcast signal other than a channel which is permitted as a CS broadcast is received. CONSTITUTION:The base band signal SBS outputted from an FM demodulating circuit (not shown in figure) is supplied to a QPSK demodulating circuit 3 through a BPF 2 and the I/Q signal which is demodulated by the demodulating circuit 3 is supplied to a PCM decoder 4. The PCM decoder 4 detects the state of the C7 bit ('1' at the time of the CS broadcast) in the PCM audio data and supplies the detection signal SD1 to an OR circuit 8. Further, the SBS is supplied to a detecting circuit 6 through a BPF 5, and the signal extracted by the BPF 5 is converted into a DC value, which is supplied to a voltage comparator 7 and compared with a reference level. The detection signal SD2 of the carrier of the PCM audio signal is obtained by the voltage comparator 7 and then supplied to an OR circuit 8. The image and audio are muted according to the output of the OR circuit 8.
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