Television synchronizing signal reproducing apparatus

摘要

An apparatus for reproducing television synchronizing signals receives an input composite television video signal, separates synchronizing signals therefrom, and utilizes a separated horizontal synchronizing signal to separate a burst signal from the input. The burst signal is then provided through a phase-locked loop including a voltage controlled oscillator (VCO) and frequency divider. The separated horizontal sync signal is also provided through a phase-locked loop including a VCO and frequency divider. During reception of a color TV signal, a synchronizing signal generator receives the output of the first VCO as its clock and receives a horizontal reset pulse derived from the reproduced subcarrier output of the first phase-locked loop and the output of the second phase-locked loop, with the output of the frequency divider in the second phase-locked loop being provided back to its phase detector. When a black-and-white input signal is detected, the output of the VCO in the second phase-locked loop is provided as the clock input to the synchronizing signal generator and a horizontal driving signal output from the synchronizing signal generator is fed back as an input to the phase detector of the second loop.