Abstract: The filter first looks in the composite sync signal for a pulse enduring at least 6 microseconds. In response to such a detection, it reconfigures to look for pulses which endure at least 12 microseconds and illustratively requires two 12-microsecond pulses in 4 horizontal lines of time which comprise a window which opens after the 6 microsecond detection. This window provides good noise immunity. If these conditions are met, it emits a drive signal for a counted duration and then reconfigures to prepare for the next field.

Abstract: The present invention discloses a device and method for compensating for the time lag associated with circuitry within the television receiver when recognizing vertical sync. Accordingly, one aspect of the present invention introduces a static phase correction into the vertical drive sequence for a standard signal so that the television picture is more nearly vertically centered on the screen. Additional aspects of the invention provide for compatibility with other circuits in the television receiver. Specifically, a delay generator coordinates with the phase correcter and other phase and frequency monitoring circuits so that the receiver is not needlessly triggered into nonstandard operation.