Switching sequence detector for p.a.l. color television

Claim 3

A system in accordance with claim 1, further defined by the frequency doubling means including differentiator and rectifier means coupled to receive said burst phase representative signal and generate a train of unidirectional pulses having a repetition rate numerically equal to said color burst phase switching rate and conversion means coupled to said differentiator and rectifier means for converting said train of pulses to a continuous waveform at said color burst phase switching rate.

Claim 4

A system in accordance with claim 2, in which the conversion means includes a shaping network for generating a continuous square wave at said color burst phase switching rate.

Claim 5

A system in accordance with claim 3, further defined by a switching circuit receiving said continuous square wave and synchronizing signal, the conductive and nonconductive states of the switching circuit corresponding to the polarity relationship of the edges of the respective signals.

Claim 6

In a signal reproducing system providing a color television signal containing phase-related components of a subcarrier having a selected nominal frequency wherein a color burst signal phase-related component is included whose phase alternates in a known sequence between two selected phases at a rate of one-half the horizontal sync pulse frequency with its phase alternated each reproduced line, the combination comprising, means for extracting the phase alternating color burst signal from the reproduced color television signal, means providing a stable reference signal at the nominal subcarrier frequency, means responsive to the phase alternating color burst signal for providing a signal indicative of the known phase switching sequence and rate of the color burst signal included in each reproduced line of the reproduced color television signal, means coupling the phase switching indicative signal to change the phase of the stable reference signal to that of the selected phases, and means for comparing the phase of the stable reference signal to the actual reproduced phase of the reproduced phase alternating color burst signal to provide an error signal representative of a difference in the actual phases of the compared signals.

Claim 7

In a signal reproducing system providing a color television signal containing phase-related components of a subcarrier having a selected nominal frequency wherein a color burst signal phase-related component is included whose phase alternates in a known sequence between two selected phases at a rate of one-half the horizontal sync pulse frequency with its phase alternated each reproduced line, the combination comprising, means for extracting the phase alternating color burst signal from the reproduced color television signal, means providing a stable reference signal at the nominal subcarrier frequency, means responsive to the phase alternating color burst signal for providing a signal indicative of the known phase switching sequence and rate of the color burst signal included in each reproduced line of the reproduced color television signal, means coupling the phase switching indicative signal to change the phase of the stable reference signal to that of the selected phases, and means for comparing the phase of the stable reference signal to the actual reproduced phase of the reproduced phase alternating color burst signal to provide an error signal representative of a difference in the actual phases of the compared signals.

Claim 8

A system in accordance with claim 5 further comprising means for adjusting the phase of the reproduced color television signal in response to the error signal.