| 摘要 |
PURPOSE:To enable reception which is never influenced by a noise when an electric field deteriorates in intensity, by controlling the supply of a subcarrier signal according to whether the phase comparison output of a pilot signal is greater or less than a reference potential. CONSTITUTION:A pilot signal arriving at terminal 17 is phase-compared 30 with a reference signal of 19kHz at terminal 18 and the comparison output is supplied via LPF40 to comparing amplifiers 1 and 2, where it is compared with reference voltage 24. This comparison output voltage sets bistable switch circuits 5-8 to supply out-of-phase subcarrier signals inputted to terminals 19 and 20 from switch circuit 50 to switching system stereo demodulator 60, and a stereo signal at terminal 28 is separated into left and right signals, which are outputted to terminals 26 and 27. On the other hand, when the phase comparison output is less than reference potential 24, circuits 5-8 are reset and the supply of the subcarrier signal from switch circuit 50 to demodulation circuit 60 is cut off, so that monoaural signals will appear at terminals 26 and 27. |
