Control apparatus for a color television receiver

Abstract

A color reference signal is inserted during the vertical blanking interval of a transmitted television waveform, for utilization by the described apparatus in automatically setting the hue and saturation of the display of an NTSC or a PAL receiver. The apparatus responds to the transmitted burst signal to set the frequency and phase of the sub-carrier oscillator of the receiver and, further, to the transmitted reference signal to correct any such inaccurate setting of phase as is caused by adverse conditions of networking and transmission from the studio to the receiver.

What is claimed is: 
     
       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;   .Iadd.second means, including at least first and second chrominance demodulators responsive to said oscillatory signal, and also responsive to said television signal, for demodulating said chrominance component and producing color difference signal outputs representative of the hue and saturation of the televised scene;   .[.second.]. .Iadd.third .Iaddend.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.]. .Iadd.fourth .Iaddend.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.Iadd., said fourth means comprising a variable phase shifter, external to said first means, and interposed between an output of said first means and said demodulators.Iaddend.;   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   .Iadd.said apparatus also including fifth means for coupling the chrominance component of said television signal to said demodulators for demodulation with said phase-adjusted oscillatory signal to produce said color difference signals; and   sixth means responsive to said longer duration color reference signal and said color synchronizing bursts for varying the gain of said fifth means as a function of the amplitudes of said bursts and said reference signal.Iaddend.. .[.2. The apparatus of claim 1 wherein there is additionally included fourth means for coupling the chrominance component of said television signal for demodulation with said phase-adjusted oscillatory signal to produce said color difference signals, and wherein fifth means is also included to respond to corresponding coupling of said longer duration color reference signal to control the amplitude of said color difference signals and the saturation of the reproduced color image   
     
     
        as a function of the amplitude of said reference signal..].  3. .[.The apparatus of claim 1.]. .Iadd.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, 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, including at least first and second chrominance demodulators responsive to said oscillatory signal, and also responsive to said television signal, for demodulating said chrominance component and producing color difference signal outputs representative of the hue and saturation of the televised scene;   third 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;   fourth 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, said fourth means comprising a variable phase shifter, external to said first means, and interposed between an output of said first means and said demodulators;   and fifth means coupled to said third means for providing a DC correction signal to alter the control signal to which said fourth means responds, with said correction signal being controllable to adjust the hue of a reproduced color image in accordance with individual viewing preference;   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; .Iaddend.wherein there is additionally included .[.fourth.]. .Iadd.sixth .Iaddend.means for coupling the chrominance component of said television signal for demodulation with said phase-adjusted oscillatory signal to produce said color difference signals, and wherein .[.fifth.]. .Iadd.seventh .Iaddend.means is also included to respond to .[.corresponding coupling of.]. said longer duration color reference signal and said color synchronizing bursts .Iadd.to vary the gain of said sixth means .Iaddend.to control the amplitude of said color difference signals and the saturation of the reproduced color image as a function of   
     
     
        the amplitude of said reference signal. 4. The apparatus of claim 1 wherein said .[.second.]. .Iadd.third .Iaddend.means includes a phase comparator coupled to compare the phase of the oscillatory signal provided by said first means with the phase of said recovered longer duration color reference signals, and for providing said control signal as being representative of the degree to which the phase of said oscillatory signal 
     
     
        differs from the phase of said reference signal. 5. The apparatus of claim 1 wherein said third means includes an amplifier coupled to receive said color difference signals .Iadd.produced by one of said demodulators .Iaddend.and gated during the prescribed interval during the vertical retrace portion of the television signal in which said longer duration color reference signal is inserted, for developing said control signal for adjusting the phase of the oscillatory signal provided by said first means as being representative of the amplitude of said color difference signals 
     
     
        during said prescribed interval. 6. The apparatus of claim 1 wherein there is additionally included .[.fourth.]. .Iadd.seventh .Iaddend.means coupled to said .[.second.]. .Iadd.third .Iaddend.means for providing a .Iadd.direct current .Iaddend.correction signal to alter .[.the.]. .Iadd.said .Iaddend.control signal.Iadd., said seventh means comprising a source of direct current and a potentiometer coupled thereto, said potentiometer having an adjustable tap, with adjustment of said tap varying the magnitude of said direct current correction signal to control the alteration of said control voltage and thereby the phase shift imparted to said oscillatory signal by said interposed phase shifter .Iaddend..[.representative of the phase difference between said oscillatory signal and said longer duration reference signal, with said correction signal being controlable to adjust the hue of a reproduced 
     
     
        color image in accordance with individual viewing preference.].. 7. The apparatus of claim 1 for use in a color television receiver providing color difference signals along B-Y and R-Y demodulation axes and operative with a television signal including said longer duration color reference signal at --(B-Y) phase, wherein said .[.second.]. .Iadd.third .Iaddend.means includes means for monitoring the amplitude of the color difference signals provided along said R-Y demodulation axis and to develop said control signal for said .[.third.]. .Iadd.fourth .Iaddend.means to adjust the phase of said oscillatory signal to reduce the amplitude of said R-Y color difference signal .Iadd.during the occurrence of said longer duration color reference signal .Iaddend.in a direction to automatically compensate for transmission characteristic changes as would adversely affect the hue of the reproduced color image. 
     
     
           The apparatus of claim 1 for use in a color television receiver providing color difference signals along R-Y and B-Y demodulation axes and operative with a television signal including said longer duration color reference signal at --(R-Y) phase, wherein said .[.second.]. .Iadd.third .Iaddend.means includes means for monitoring the amplitude of the color difference signals provided along said B-Y demodulation axis and to develop said control signal for said .[.third.]. .Iadd.fourth .Iaddend.means to adjust the phase of said oscillatory signal to reduce the amplitude of said B-Y color difference signal .Iadd.during the occurrence of said longer duration color reference signal .Iaddend.in a direction to automatically compensate for transmission characteristic changes as would adversely affect the hue of the reproduced color image. .Iadd.9. 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, 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, including at least first and second chrominance component demodulators responsive to said oscillatory signal, and also responsive to said television signal, for demodulating said chrominance component and producing color difference signal outputs representative of the hue and saturation of the televised scene;   third 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;   fourth 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; and   fifth means for selectively altering the control signal to which said fourth means responds, said fifth means comprising means for utilizing a DC correction signal developed with independence of the phase of said reference signal to alter the control signal developed as a function of the phase of said reference signal, with said correction signal being controllable to adjust the hue of a reproduced color image,   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..Iaddend. .Iadd.10.  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, 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, said first means including a reference oscillator synchronized in frequency and phase by said bursts;   second means, including at least first and second chrominance component demodulators responsive to said oscillatory signal, and also responsive to said television signal, for demodulating said chrominance component and producing color difference signal outputs representative of the hue and saturation of the televised scene;   third 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;   said third means comprising means for sensing the output of one of said demodulators during the occurrence of said reference signal and deriving a control voltage therefrom;   fourth 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;   said fourth means comprising a variable phase shifter, external to said oscillator, and interposed between an output of said oscillator and said demodulators;   fifth means for coupling the chrominance component of said television signal to said demodulators for demodulation with said phase-adjusted oscillatory signal to produce color difference signals, said fifth means also effecting a coupling of said reference signal to said demodulators; and   sixth means responsive to said longer duration color reference signals and said color synchronizing bursts for varying the gain of said fifth means to control the amplitude of the color difference signals and the saturation of the reproduced image as a function of the amplitude of said   
     
     
        reference signals and said synchronizing bursts..Iaddend. .Iadd.11.  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, said reference signal 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 said bursts and to lock the phase of the oscillatory signal to the phase of said bursts;   said first means including a reference oscillator synchronized in frequency and phase by said bursts;   second means, including at least first and second chrominance component demodulators responsive to said oscillatory signal, and also responsive to said television signal, for demodulating said chrominance component and producing color-difference signal outputs representative of the hue and saturation of the televised scene;   third 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;   fourth 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;   said fourth means comprising a variable phase shifter, external to said oscillator, and interposed between an output of said oscillator and said demodulators;   fifth means for coupling the chrominance component of said television signal for demodulation with said phase-adjusted oscillatory signal to produce said color difference signals;   sixth means responsive to said longer duration color reference signal and said color synchronizing bursts for varying the gain of said fifth means to control the amplitude of said color difference signals and the saturation of the reproduced color image as a function of the amplitude of said reference signal; and   seventh means for selectively altering the control signal to which said fourth means responds, said seventh means comprising eighth means, including a source of direct current and a potentiometer coupled thereto, said potentiometer having an adjustable tap, for developing a DC correction voltage with independence of the phase of said reference signal; and   ninth means for utilizing said DC correction voltage to alter the control voltage developed by said third means, with the magnitude of said DC correction voltage varying in response to adjustment of said tap to adjust the hue of a reproduced color image in accordance with individual viewer preference;   
     
     
       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..Iaddend. .Iadd.12.  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, said reference signal 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 said 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;   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; and   fourth means coupled to said second means for providing a correction signal to alter the control signal representative of the phase difference between said oscillatory signal and said longer duration reference signal, with said correction signal being controllable to adjust the hue of a reproduced color image in accordance with individual viewing preference;   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..Iaddend.