| 摘要 |
PURPOSE:To generate an excellent receiving output through the removal of unpleasant sound, by muting the detected output in response to the generation of one, at least, among a plurality of detected signals. CONSTITUTION:An unlock detector 3 discriminates unlock state of a PLL circuit to produce an unlock detecting signal. On the other hand, a frequency slip detector 5 detects the shift between the self-running frequency of a voltage controlled type oscillator 21 and an AM stereo signal frequency to output a detection signal. Further, a level detector 6 detects that an AM stereo signal is lowered, and outputs a detection signal. Further, a pilot signal level detector 7 detects the absence of a stereo pilot signal and outputs the detection signal. These detection signals are applied to a muting control circuit 4. Further, the control circuit 4 exercise on/off control for a muting circuit 8 according to the four detection signals. |
