| 摘要 |
<p>PURPOSE: To prevent the generation of sudden phase shift between a reference signal and a reproduced balanced modulated signal by broadcasting a 38kHz pilot carrier wave in addition to a 19kHz pilot carrier wave. CONSTITUTION: A 38kHz suppressed carrier wave from an FM tuner 10 is locked to a 76kHz phase lock loop 60. This loop 60 has a monostable having the half cycle of cycle of the 38kHz suppressed carrier wave. In this case, when the phase of a reference signal 42 is erroneously shifted by noise burst, phase difference is detected since a double pilot carrier wave 70 of the 19kHz pilot signal from a 19kHz band pass filter 64 is supplied to a phase comparator 72. Based on this phase difference, a window comparator 74 allows a frequency bisecting FF 56 to cause a special transition to enable proper demodulation on the left and right sides.</p> |
