Video synchronous detector apparatus

摘要

A video synchronous detector apparatus for discriminating a video intermediate frequency signal, in which the video intermediate frequency signal is divided into two parts, one of which is applied to one terminal of a multiplier circuit, and the other of which is applied to the other terminal of the multiplier circuit through a picture-carrier intermediate frequency extraction circuit having a frequency selection circuit and a limiter circuit. The frequency selection circuit is provided with a trap circuit. The trap circuit has a center resonance frequency equal to a differential frequency between a picture-carrier intermediate frequency (fp) and a differential frequency between a color subcarrier intermediate frequency (fc) and a sound-carrier intermediate frequency (fs) so that a so-called sound-cross-color disturbance caused by a beat between the intermediate frequency sound signal and the intermediate frequency picture signal may be reduced.