Television synchronizing system operable from nonstandard signals

Claim 1

An improved television synchronizing apparatus adapted for generating internal vertical and horizontal synchronizing signals from a source of external composite vertical and horizontal synchronizing signals which may be nonstandard comprising: phase detection means including a first input coupled to the source of external signals for comparing the phase of said external signals with signals applied to a second input for producing control signal indicative of their relative phase; filter means coupled to said phase detector for filtering said control signal to form a second control signal; controllable oscillator means coupled to said filter means for producing oscillations at a frequency under the control of said second control signal, first counting means coupled to said oscillator and to said phase detection means for forming a phase-lock loop, said first counting means counting said oscillations to produce internal horizontal-rate synchronizing signals phase-locked to said external horizontal synchronizing signals; resettable second counting means coupled to said first counting means for producing internal vertical synchronizing signals in synchronism with said external vertical synchronizing signals wherein the improvement comprises inhibiting means coupled to said phase detection means and to said resettable counting means for inhibiting operation of said phase detection means during at least the equalizing and vertical synchronizing portions of said external synchronizing signals.