HORIZONTAL LINE COUNTER STABILIZATION IN A VIDEO RECEIVER

摘要

In a system for identifying specific horizontal lines of video that are included in a video signal, a horizontal line counter (100) is cleared to indicate the beginning of a vertical interval by a reset signal (VERDEL) derived from a vertical sync signal (VER). The line counter is clocked by a signal (HOR) at the horizontal sync rate that is derived from a harmonic (N-FH) of the horizontal sync signal. The relative phase shift between the reset and clock signals for the horizontal line counter is measured (105, 120). The measured phase shift is used as an input to a variable phase shifter (110) to adjust the phasing between the horizontal line counter control signals and the original sync signals. The phase adjustment permits significantly decreasing the sensitivity of the horizontal line counter to jitter of vertical sync.