Television signal horizontal interval timing reconstruction system

摘要

A circuit for communicating both a video signal and a timing signal over a single information channel from a television camera head to a remote camera control unit. A horizontal interval timing signal is modified by delaying the beginning of each timing pulse so that each pulse is shortened in duration by a fixed amount. This modified timing signal is added to a video signal such that the portion of the sum signal which corresponds to the modified timing signal has a distinctive amplitude which is outside of the range of amplitudes established by the white and black levels of the video signal. At the camera control unit, a circuit separates the modified timing signal from the sum signal and synchronizes a multi-phase oscillator therewith through use of a phase locked loop. The original timing and video signals are reconstructed through logical operations which use selected phases of the oscillator.