| 摘要 |
PURPOSE:To demodulate an FM stereo signal and a TV sound multiplex signal with simple constitution by constituting the device that an oscillating frequency of an FM stereo signal demodulator having a PLL circuit is switched. CONSTITUTION:An FM stereo signal is inputted from an input terminal 13, and the oscillating frequency of the PLL circuit of an FM stereo demodulator 11 is adjusted by a PLL timing capacitor 3 so as to be synchronized with a pilot signal and when a TV sound multiplex signal is inputted from the input terminal 13, and capacitor is switched to a PLL timing capacitor 16 and the signal is set to be synchronized with a control signal of the TV sound multiplex signal. When a control signal is inputted, a stereo indicator 4 is lighted and when the output is used for the muting of a muting circuit 10 of the TV sub sound signal demodulator 9, the muting to the circuit 10 is applied when no control signal is given. The output of two system is controlled by the muting circuit 2 and an output appears output terminals 15a, 15b. |
