Method and apparatus for providing a clock signal with high frequency accuracy

Abstract From the Canadian patent

A circuit for providing a sufficiently accurate clock signal for reconstruction of an image from a video signal can function with or without receiving an incoming video signal containing clock data. In this way a clock , signal for supporting an on-screen display can be created in the absence of an incoming video signal. Control data used to control a voltage controlled oscillator generating a clock signal is recorded when the control logic of the oscillator is locked to the timing data in an incoming video signal. In the absence of an incoming video signal, the recorded control data is retrieved and resubmitted to the control logic so that the oscillator can be made to output an …