JPS6430390A - Chrominance signal processor for video tape recorder - Google Patents

Abstract

PURPOSE:To execute stable phase control even when the level of a burst signal goes to low by controlling the phase of a carrier chrominance signal at the time of low-frequency conversion processing by using an output from a comparator that phase-compares a burst signal and a reference signal in chrominance subcarrier wave frequency. CONSTITUTION:In a third pulse generation circuit 27 and in a fourth pulse generation circuit 28, the level-variation of a burst signal is quickly detected, according to the result of said detection, either a first pulse generated in a first pulse generator 13 by using a horizontal synchronizing signal for reference or second pulse generated in a second pulse generation circuit 26 by amplitude- detecting a burst signal and shaping it, is selected by a switch 29, and the selected pulse is made a fifth pulse. During the duration of this fifth pulse, burst signals and reference signals are phase-compared. As a result, a burst signal can securely be captured even when the timing of a horizontal synchronizing signal shifts from the of a carrier chrominance signal, furthermore, the automatic phase control loop is not interrupted even when the level of the burst signal goes to low. Thus the phase control is made stable.