| 摘要 |
PURPOSE:To secure an automatic switching for the reception between the FM stereo signal and the TV multiple aural signal by detecting the pilot signal contained in the FM stereo composite signal, the subchannel signal in the TV multiple aural signal or the control signal. CONSTITUTION:When the FM stereo composite signal emerges at the detection output of the tuner, pilot signal B is detected with only switch 7 closed plus demodulation 4 given. Thus the right and left stereo composite signals are supplied to low frequency signal systems 9 and 10. When the TV multiple aural signals emerge at the output of the tuner, subchannel signal E or control signal F is detected 6 and with switch 8 only closed to be then supplied to systems 9 and 10 after demodulation 5. In such way, two different kinds of signals are switched automatically. As no signal is detected 3 and 6 when the broadcast features the monaural signal, either switch 7 or 8 is closed to regenerate the monaural signal. |
