| 摘要 |
PURPOSE:To prevent occurrence of the miscontrol when the control is given to the signal process system of the demodulator circuit by controlling the signal process system not only via the output of the control signal frequency deciding unit but via the logic product with the signal obtained from the subchannel signal. CONSTITUTION:The multiple signal sent from the IF amplifier circuit is applied to FM detector circuit 1 for the FM demodulation to deliver FM demodulation signal F. Signal F is applied to LPF2 and BPF3 to deliver main channel signal M, subchannel signal S and control channel signal C each. At the same time, signal M is applied to demodulator circuit 15 via amplifier 5, signal S is applied to FM demodulator 8 via amplifier 6, the output of amplifier 6 is applied to subchannel signal detector 9, and the output of demodulator 8 is applied to circuit 15 respectively. Furthermore, signal C is applied to control signal frequency deciding circuits 11 and 12 via AM detector circuit 10, and the logic product is secured through AND circuits 13 and 14 between the output signals of circuits 11 and 12 and the output of detector 9. Then the control is given to the demodulation process of circuit 15 via the output of circuits 13 and 14. |
