STEREO AND TWO-TONE DEMODULATOR

摘要

PROBLEM TO BE SOLVED: To completely integrate a stereo/two-tone demodulator and to decrease the number of elements which are required for the integration of the demodulator. SOLUTION: The narrow band phase-locked loops 1 and 2 are synchronized by the frequency of a 1st voice carrier. First and 2nd amplifier stages 4 and 5 precede the loops 1 and 2 respectively and control the input signals of both loops 1 and 2 respectively. A carrier suppression circuit 3 puts the output signal, having a O-degree or 180-degree phase of an oscillator 20 of the loop 1 on the input signal of the loop 1. Then the circuit 3 outputs an output signal whose 1st voice carrier is suppressed and then connects the output signal to the stage 5.