Subcarrier regenerator and pal identifier system

Claim 2

In a color television receiver adapted to receive a composite video signal including a color information signal and a synchronizing signal both of which are characterized by predetermined, periodic changes in phase, means for demodulating the color information signal comprising: first and second demodulator means; gating means for abstracting the synchronizing signal from the composite signal; means for receiving the abstracted synchronizing signal and for deriving a continuous, constant-phase subcarrier therefrom; means for simultaneously applying said subcarrier to said first and said second demodulator means at different phase angles; means for receivinG said color information signal and for imparting a delay thereto substantially equal to the period of said changes in phase; first summing means for receiving the delayed and undelayed color information signals and outputting a color information signal having a predetermined phase relationship to said subcarrier during first, alternate time periods; second summing means for receiving the delayed and undelayed color information signals and outputting a color information signal having said predetermined phase relationship to said subcarrier during second time periods occurring between said first, alternate time periods; third summing means for receiving the delayed and undelayed color information signals and outputting to said second demodulator means a color information signal characterized by an absence of the predetermined, periodic changes in phase; switch means operable to alternately couple said first demodulator means to said first and said second summing means; identifier means for operating said switch means in synchronism with changes in the phase relationship of signals suppled thereto; means for applying two of the differently-phased subcarriers to said identifier means; and means for coupling said synchronizing signal from said gating means to said identifier means.

Claim 3

The invention defined in claim 1, wherein said identifier means is responsive to said synchronizing signal and said two differently phased subcarriers to develop a control signal to control said switch means in synchronization with the relative phase changes between said synchronizing signal and two differently phased subcarriers.

Claim 4

The invention defined in claim 2, wherein said means for applying said subcarrier to said first and said second demodulator means includes coupling means to apply said subcarrier at a first phase angle and at a second phase angle to said first demodulator means and to apply said subcarrier at a third phase angle and at a fourth phase angle to said second demodulator means, wherein said third and fourth phase angles are in quadrature with respect to said first and second phase angles respectively, and said second phase angle is 180* displaced from said first phase angle, and wherein said subcarrier at said first and second phase angles is applied to said identifier means.

Claim 5

In a color television receiver adapted to receive a composite video signal including first and second chroma signals and burst signals, said first chroma signal and said burst signal alternating in phase for consecutive horizontal scansion periods, means for demodulating said chroma signals comprising: identifier means having first, second and third input terminals and an output terminal and operable to produce a voltage at said output terminal representative of the phase relationship of signals applied to said first, second and third input terminals; regenerator means response to said burst signals for producing a continuous, constant-phase subcarrier; means for applying said burst signal to said regenerator means and to said first input terminal of said identifier means; first and second demodulators; transformer means for receiving the constant-phase subcarrier from said regenerator means and for applying a first pair of signals displaced in phase by 180* and occurring at the subcarrier frequency to said first demodulator and to the second and third input terminals of said identifier, and for applying two other signals displaced in phase by 180* and occurring at the subcarrier frequency to said second demodulator, said two other signals being displaced in phase by 90* relative to corresponding ones of said first pair of signals; first means for outputting said first chroma signal at a given phase angle relative to said subcarrier during alternate horizontal scansion periods; second means for outputting said first chroma signal at said given phase angle during the other horizontal scansion periods; third means for outputting said second chroma signal at a relatively constant phase angle during consecutive horizontal scansion periods; switch means responsive to said voltage for alternately coupling said first demodulator to said first means or said second means; means coupling said output terminal of said identifier to said switch means; and means coupling said second demodulator to said third means.

Claim 6

In a color television receiver adapted to receive a composite video signal including first and second chroma signals and burst signals, said first chroma signal and said burst signal alternating in phase for consecutive horizontal scansion periods, means for demodulating said chroma signals comprising: identifier means having first, second and third input terminals and an output terminal and operable to produce a voltage at said output terminal representative of the phase relationship of signals applied to said first, second and third input terminals; regenerator means response to said burst signals for producing a continuous, constant-phase subcarrier; means for applying said burst signal to said regenerator means and to said first input terminal of said identifier means; first and second demodulators; transformer means for receiving the constant-phase subcarrier from said regenerator means and for applying a first pair of signals displaced in phase by 180* and occurring at the subcarrier frequency to said first demodulator and to the second and third input terminals of said identifier, and for applying two other signals displaced in phase by 180* and occurring at the subcarrier frequency to said second demodulator, said two other signals being displaced in phase by 90* relative to corresponding ones of said first pair of signals; first means for outputting said first chroma signal at a given phase angle relative to said subcarrier during alternate horizontal scansion periods; second means for outputting said first chroma signal at said given phase angle during the other horizontal scansion periods; third means for outputting said second chroma signal at a relatively constant phase angle during consecutive horizontal scansion periods; switch means responsive to said voltage for alternately coupling said first demodulator to said first means or said second means; means coupling said output terminal of said identifier to said switch means; and means coupling said second demodulator to said third means.

Claim 7

The invention defined in claim 4, wherein said means coupling said output terminal of said identifier means to said switch means comprises bistable circuit means for attaining a first state upon application of a voltage of a first polarity, and a second state upon application of a voltage of a second polarity.

Claim 8

The invention defined in claim 5, further including delay line means coupling said first chroma signal to said first and said second means and operative to impart a delay of substantially one horizontal scansion period to said first chroma signal; and means coupling said first chroma signal directly to said first and second means.