| 摘要 |
PROBLEM TO BE SOLVED: To improve the S/N of a demodulated stereo signal by reducing the influence of noise increasing in a high-frequency range due to triangular noise distribution generated when an FM stereo signal of a conventional system is demodulated. SOLUTION: An IF output M(t) is inputted, an FM stereo signal M1(t) is obtained by a PLL demodulator 5, etc., and an FM stereo signal M-1(t) having the opposite polarity is generated with the M1(t) and the output of a fixed oscillator 7 of frequency 2ωX. Then M1(t) and M-1(t) are applied to an electronic switcher 11, which is switched with pulses generated from a subcarrier cos2ωpt; and its output has its phase detected by a phase detector 13 with a carrier of M1(t) to obtain a stereo signal.
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