Method and apparatus for color subcarrier generation

Claim 3

The method of claim 1 wherein the burst envelope is detected from the demodulated output of the said one of said channels only as such burst envelope exceeds a predetermined magnitude and has a predetermined polarity.

Claim 6

The method according to claim 3 including sampling the said another synchronously demodulated output signal by D.C. restoring such signal at sampling times.

Claim 9

The method according to claim 5 further including gating the synchronously demodulated output waveform during the time period within which the color synchronizing burst can normally occur.

Claim 10

The method according to claim 5 wherein said color synchronizing burst envelope is detected by means of rectification and detection of the peak of the signal as rectified.

Claim 11

The method according to claim 7 wherein said rectification is accomplished in four quadrants corresponding to positive and negative polarities for both channels of quadrature related synchronous demodulation.

Claim 12

Apparatus for generating a local color subcarrier from a color television signal comprising: first means for synchronously demodulating the chroma information from said color television signal providing a synchronously demodulated output signal for the time period range during which the color synchronizing burst signal can occur, second means for receiving the signal from the first means and detecting a synchronously demodulated color synchronizing burst envelope by means of detecting the peak of such envelope, third means responsive to such detection for providing an output signal representative of the amplitude value of a color synchronizing burst envelope of one synchronously demodulated output signal, fourth means for generating a local r.f. signal, and fifth means for controlling the frequency of the local r.f. signal employing said output signal representative of said amplitude value for causing the frequency of the local r.f. signal to change until the output signal representative of the amplitude value attains a predetermined condition.

Claim 13

Apparatus for generating a local color subcarrier from a color television signal comprising: first means for synchronously demodulating the chroma information from said color television signal providing a synchronously demodulated output signal for the time period range during which the color synchronizing burst signal can occur, second means for receiving the signal from the first means and detecting a synchronously demodulated color synchronizing burst envelope by means of detecting the peak of such envelope, third means responsive to such detection for providing an output signal representative of the amplitude value of a color synchronizing burst envelope of one synchronously demodulated output signal, fourth means for generating a local r.f. signal, and fifth means for controlling the frequency of the local r.f. signal employing said output signal representative of said amplitude value for causing the frequency of the local r.f. signal to change until the output signal representative of the amplitude value attains a predetermined condition.

Claim 14

The apparatus according to claim 9 wherein the tHird means responsive to such detection for providing an output signal comprises means for gating a burst envelope at the time of such detection and means for holding the value thereof between detections.

Claim 15

The apparatus according to claim 9 wherein the third means responsive to such detection for providing an output signal comprises means for D.C. restoring a synchronously demodulated output at times of said detection.

Claim 16

Apparatus according to claim 9 wherein the second means for detecting include unilateral conducting means responsive to at least a given polarity of synchronously demodulated information.

Claim 17

Apparatus for control of color subcarrier generation comprising: a pair of synchronous demodulators for receiving a color television composite chroma signal and demodulating the same in quadrature relation by means of a color subcarrier reference signal, means for detecting a demodulated burst envelope from the output signal of one of said synchronous demodulators, means responsive to such detection for providing an output signal representative of the amplitude value of the demodulated burst envelope from the remaining synchronous demodulator. means for generating the color subcarrier reference signal, and means for controlling the frequency of said color subcarrier reference signal employing said output signal representative of the amplitude value of a demodulated burst envelope for causing the frequency of the color subcarrier reference signal to change until said output representative of the amplitude value attains a predetermined condition.

Claim 18

Apparatus for control of color subcarrier generation comprising: a pair of synchronous demodulators for receiving a color television composite chroma signal and demodulating the same in quadrature relation by means of a color subcarrier reference signal, means for detecting a demodulated burst envelope from the output signal of one of said synchronous demodulators, means responsive to such detection for providing an output signal representative of the amplitude value of the demodulated burst envelope from the remaining synchronous demodulator. means for generating the color subcarrier reference signal, and means for controlling the frequency of said color subcarrier reference signal employing said output signal representative of the amplitude value of a demodulated burst envelope for causing the frequency of the color subcarrier reference signal to change until said output representative of the amplitude value attains a predetermined condition.

Claim 19

The apparatus according to claim 13 wherein said means for detecting includes peak detector means.

Claim 20

The apparatus according to claim 13 wherein said means responsive to said detection for providing an output signal, holds an output level to provide such output signal between demodulated burst envelopes from the said remaining synchronous demodulator.

Claim 21

The apparatus according to claim 13 wherein said means for detecting includes unilateral conductor means responsive to a given polarity of output signal from said one of said synchronous demodulators.

Claim 22

The apparatus according to claim 13 wherein said means responsive to the detection for providing an output signal comprises means for sampling the output signal from the remaining synchronous demodulator and means for holding said output signal between samplings.

Claim 23

The apparatus according to claim 13 wherein said means responsive to the detection comprises means for D.C. restoring the output signal of the remaining synchronous demodulator at times of said detection.

Claim 24

The apparatus according to claim 13 wherein the synchronous demodulators provide demodulated output signals at times substantially corresponding to the presence of the back porch of the color television signal.

Claim 25

Means for providing a reference signal corresponding to a color television synchronizing burst comprising: synchronous demodulator means, means for detecting the color synchronizing burst envelope of an output signal of the synchronous demodulator means, and means for providing a preset reference value for the waveform of one synchronizing burst envelope output signal of said synchronous demodulator means at times corresponding to said detection.

Claim 26

Means for providing a reference signal corresponding to a color television synchronizing burst comprising: synchronous demodulator means, means for detecting the color synchronizing burst envelope of an output signal of the synchronous demodulator means, and means for providing a preset reference value for the waveform of one synchronizing burst envelope output signal of said synchronous demodulator means at times corresponding to said detection.

Claim 27

The apparatus according to claim 20 wherein said detecting means comprises rectifier means and means for detecting the peak of the signal rectified.

Claim 28

The apparatus according to claim 20 wherein said synchronous demodulator means comprises quadrature related synchronous demodulators, and wherein said detecting means comprises four rectifiers for detecting both inverted and noninverted outputs of said synchronous demodulators.

Claim 29

The circuit according to claim 22 further including means for gating the synchronously demodulated outputs substantially at the time of the back porch of the said color television signal.

Claim 30

Apparatus for generating a local color subcarrier from a color television signal comprising: means for synchronously demodulating the chroma information from said color television signal providing a synchronously demodulated output signal for the time period range during which the color synchronizing burst signal can occur, means for detecting the color synchronizing burst envelope as synchronously demodulated, means for DC restoring the output signal of the synchronously demodulated means at times when said color synchronizing burst is detected by said means for detecting, a controlled oscillator for generating said local subcarrier for application as a reference signal to said synchronously demodulating means, and means coupling a DC restored output signal of the synchronously demodulating means to control said oscillator.

Claim 31

Apparatus for generating a local color subcarrier from a color television signal comprising: means for synchronously demodulating the chroma information from said color television signal providing a synchronously demodulated output signal for the time period range during which the color synchronizing burst signal can occur, means for detecting the color synchronizing burst envelope as synchronously demodulated, means for DC restoring the output signal of the synchronously demodulated means at times when said color synchronizing burst is detected by said means for detecting, a controlled oscillator for generating said local subcarrier for application as a reference signal to said synchronously demodulating means, and means coupling a DC restored output signal of the synchronously demodulating means to control said oscillator.

Claim 32

Apparatus according to claim 24, wherein said means for detecting comprises a rectifier

Claim 33

The apparatus according to claim 24 wherein said synchronously demodulating means comprises quadrature related synchronous demodulators, and wherein said detection means comprises four rectifier means coupled to receive both inverted and noninverted output signals of said synchronous demodulators.

Claim 34

The apparatus according to claim 26 wherein said means for detecting further comprises a peak detector receiving the output signal of said rectifier means for operating said DC restoring means at the time of peaks corresponding to said color synchronizing burst envelope.

Claim 35

The apparatus according to claim 25 wherein said detector further includes peak detection means receiving the output signal of said rectifier for operating said DC restoring means at the time of peaks corresponding to said color synchronizing burst envelope.

Claim 36

The apparatus according to claim 24 wherein said means for synchronously demodulating the chroma information provides said demodulated output signal for a time substantially corresponding to the presence of the back porch of the color television signal.

Claim 37

Apparatus for color subcarrier generation comprising: a pair of synchronous demodulators for receiving a color television composite chroma signal and demodulating the same in quadrature relation to one another by means of a color subcarrier reference signal, means for gating the outputs of said synchronous demodulators at a time substantially corresponding to the back porch of the color television signal, four quadrant detection means for detecting a given polarity of color synchronizing burst signal envelope from inverted and noninverted outputs of each synchronous demodulator as gated, and including means for detecting the peak of the detected signal, a DC restoration circuit coupled to the gated output of each synchronous demodulator, said DC restoration circuits being controlled to DC restore such gated output at the time a color synchronizing burst signal enveloped is detected, a local signal generator for providing said color subcarrier reference signal, and means for coupling the output signal of one of said DC restoration circuits to control the frequency of said local signal generator.

Claim 38

Apparatus for color subcarrier generation comprising: a pair of synchronous demodulators for receiving a color television composite chroma signal and demodulating the same in quadrature relation to one another by means of a color subcarrier reference signal, means for gating the outputs of said synchronous demodulators at a time substantially corresponding to the back porch of the color television signal, four quadrant detection means for detecting a given polarity of color synchronizing burst signal envelope from inverted and noninverted outputs of each synchronous demodulator as gated, and including means for detecting the peak of the detected signal, a DC restoration circuit coupled to the gated output of each synchronous demodulator, said DC restoration circuits being controlled to DC restore such gated output at the time a color synchronizing burst signal enveloped is detected, a local signal generator for providing said color subcarrier reference signal, and means for coupling the output signal of one of said DC restoration circuits to control the frequency of said local signal generator.

Claim 39

Apparatus according to claim 30 including means for coupling the output signal of the other restoration circuit to control the frequency range of the output coupled from the first restoration circuit.

Claim 40

Apparatus for color subcarrier generation comprising: quadrature and phase control synchronous demodulators for receiving a color television composite chroma signal and demodulating the same in quadrature relation to one another by means of a color subcarrier reference signal, means for gating the outputs of said synchronous demodulators at a time substantially corresponding to the back porch of a color television signal, single quadrant detection means for detecting only peaks of a given polarity of the color synchronizing burst signal envelope from the quadrature synchronous demodulator as gated, a D.C. restoration circuit coupled to the gated output signal of the phase control synchronous demodulator, said D.C. restoration circuit being controlled to D.C. restore such gated output signal at the time said color synchronizing burst signal envelope peaks of a given polarity are detected by said detection means, a local signal generator for providing said color subcarrier reference signal, and means for coupling the output signal of said D.C. restoration circuit to control the frequency of said local signal generator.

Claim 41

Apparatus for color subcarrier generation comprising: quadrature and phase control synchronous demodulators for receiving a color television composite chroma signal and demodulating the same in quadrature relation to one another by means of a color subcarrier reference signal, means for gating the outputs of said synchronous demodulators at a time substantially corresponding to the back porch of a color television signal, single quadrant detection means for detecting only peaks of a given polarity of the color synchronizing burst signal envelope from the quadrature synchronous demodulator as gated, a D.C. restoration circuit coupled to the gated output signal of the phase control synchronous demodulator, said D.C. restoration circuit being controlled to D.C. restore such gated output signal at the time said color synchronizing burst signal envelope peaks of a given polarity are detected by said detection means, a local signal generator for providing said color subcarrier reference signal, and means for coupling the output signal of said D.C. restoration circuit to control the frequency of said local signal generator.

Claim 42

The apparatus according to claim 32 wherein said detection means includes capacitor means for substantially storing values in response to previously detected peaks.

Claim 43

The apparatus according to claim 32 wherein said detection means includes unilateral conducting means to render the same sensitive only to peaks of said given polarity.