Heterodyne color signal recognition.

摘要

A heterodyne color signal recognition circuit generates an error signal for each horizontal line of an input video signal for which the phase relationship of the horizontal sync pulse and color subcarrier burst exceeds a given phase relationship by a predetermined tolerance. The error signals are summed over a video field to produce a preliminary non-direct color signal for the video field. Preliminary non-direct color signals for successive video fields are digitally filtered to generate a non-direct color signal indicative of a heterodyne color signal source, the non-direct color signal being used to automatically switch in a time base corrector between the input video signal and further video processing.