| 摘要 |
<p>A video intermediate frequency signal and an audio intermediate frequency signal are separated from an intermediate frequency signal, and provided to a demodulator (14). The demodulator (14) demodulates the video intermediate frequency signal and an analog audio intermediate frequency signal of the audio intermediate frequency signal into a video baseband signal and an analog audio baseband signal, respectively, and outputs the resultant signals to an RF modulator (16). Further, the demodulator (14) provides the audio intermediate frequency signal to a NICAM filter (18). The NICAM filter (18) separates only a digital audio intermediate frequency signal including a digital audio carrier from the audio intermediate frequency signal. A muting circuit (20) is interposed between the NICAM filter (18) and the RF modulator (16), and has a function of interrupting passage of the digital audio intermediate frequency signal from the NICAM filter (18) to the RF modulator (16) based on a detection signal from a NICAM signal detecting circuit (19), which detects presence or absence of the digital audio intermediate frequency signal in the audio intermediate frequency signal. <IMAGE></p> |
