Control apparatus for a color television receiver

Claim 1

In a color television receiver adapted to receive a television signal including a luminance component, a chrominance component modulated in both phase and amplitude, periodically recurring color synchronizing bursts occupying prescribed intervals during the horizontal retrace portions of said signal and a color reference signal occupying a prescribed interval during the vertical retrace portion of said television signal and being of substantially longer duration than said color synchronizing bursts, apparatus comprising: first means for providing an oscillatory signal to demodulate said chrominance component and produce color difference signals containing information proportional to the hue and saturation of the televised scene, said means being responsive to the television signal for recovering the color synchronizing bursts thereof and for utilizing said bursts to lock the frequency of the oscillatory signal to the frequency of such bursts and to lock the phase of the oscillatory signal to the phase of said bursts; second means, also responsive to said television signal, for recovering said longer duration color reference signal and for utilizing said signal in developing a control signal to adjust the phase of said oscillatory signal as a function of the phase of said reference signal; and third means responsive to said oscillatory signal and to said control signal for varying the phase of said oscillatory signal in a direction to correspond with the phase of said reference signal as represented by said control signal; whereby the degree of error in the hue of a reproduced color image attributable to such transmission characteristics as multipath, transmission line reflection and the like is correspondingly reduced.