| 摘要 |
PURPOSE:To allow cope with the titled circuit to the bilingual mode of sound multiplex broadcast with a simple constitution, by extracting either one signal of main and sub-channels in response to a control signal, and demodulating its output signal with a tuning frequency in response to the control signal. CONSTITUTION:A switch circuit of a variable band filter 20 extracts a sound intercarrier signal of a main channel when the control signal is at a low level and that of a sub-channel when at high level and applies the signal to an amplifier 4. An output of the amplifier 4 is limited for the amplitude at a limiter 5 and after noise is eliminated, the output is applied to a variable frequency discriminating circuit 22. Further, the signal demodulated at the circuit 22 is extracted for the main or the sub-sound signal under the control of the control signal 21, and after de-emphasis 7, the signal is amplified 14 and outputted from a speaker 16. |
