Timing error compensator
First Claim
1. A circuit for time displacing a color television signal which includes a color burst synchronizing component of known frequency in the synchronizing interval at the beginning of each of its lines, said color burst containing the intra line time base of the signal, said signal being passed through an analog to digital converter for converting each line to a digital form and thereafter through a digital to analog converter responsive to a clock signal for reconverting the digital form of the signal to an analog form, said time displacement circuit comprising means responsive to the color burst component of each television line passing through said analog to digital converter to provide a representation of said color burst component continuously during at least a portion of the succeeding line when the succeeding color burst occurs, means coupled to receive a representation of a color burst component of the next succeeding line and said continuously provided color burst representation and compare the contained intra line time bases, and means responsive to said comparing means for generating a clock signal with its time base adjusted in accordance with the differences in the compared time bases, said clock signal generating means coupled to said digital to analog converter for controlling the reconversion of the digitized line of television information occurring between said compared color burst representations to produce an analog form of said digitized signal having its time base in accordance with the clock signal time base.
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Accused Products
Abstract
A time displacement adjustment device compensates time base errors that progressively cumulate in a time varying signal having a synchronizing information component from which the signal time base can be determined. Periodically, the synchronizing component is sampled and a representation thereof continuously generated with the component'"'"'s timing relationship to the signal retained. Each continuously generated representation and the succeeding sample of the synchronizing component are compared to determine the time base error that progressively occurs in the signal between the successive samples of the synchronizing component. That signal is expanded or compressed accordingly to correct the erroneous timing.
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Citations
31 Claims
- 1. A circuit for time displacing a color television signal which includes a color burst synchronizing component of known frequency in the synchronizing interval at the beginning of each of its lines, said color burst containing the intra line time base of the signal, said signal being passed through an analog to digital converter for converting each line to a digital form and thereafter through a digital to analog converter responsive to a clock signal for reconverting the digital form of the signal to an analog form, said time displacement circuit comprising means responsive to the color burst component of each television line passing through said analog to digital converter to provide a representation of said color burst component continuously during at least a portion of the succeeding line when the succeeding color burst occurs, means coupled to receive a representation of a color burst component of the next succeeding line and said continuously provided color burst representation and compare the contained intra line time bases, and means responsive to said comparing means for generating a clock signal with its time base adjusted in accordance with the differences in the compared time bases, said clock signal generating means coupled to said digital to analog converter for controlling the reconversion of the digitized line of television information occurring between said compared color burst representations to produce an analog form of said digitized signal having its time base in accordance with the clock signal time base.
- 11. A signal time displacement adjuster for information signals which include a periodically occurring synchronizing component indicative of the signal time base comprising means coupled to periodically receive and continuously generate a representation of each synchronizing component until the period of a successive synchronizing component is received including means for comparing the time base indicated by the synchronizing component representation and that of a time base reference signal to adjust the time base of the reference signal to that indicated by the synchronizing component representation and form said continuously generated representation of the synchronizing component, means for comparing the time base indicated by the continuously generated representation of the synchronizing component representation next received to provide a signal representative of time base differences therebetween, and storage means coupled to receive said information signal responsive to said comparison to adjust the duration of storage of each period of said signal between successive synchronizing component representations in accordance with the time base difference signal provided by said comparing means.
- 22. A video recorder for reproducing a television signal having a pilot tone synchronizing component and a video information component, said video recorder including a circuit to compensate for erroneous head to tape velocity comprising an analog to digital converter for converting a reproduced line of the video information to digital form, an adjustable clock generator for providing a clock signal, a digital to analog converter coupled to convert the digitized video information to analog form in response to said clock generator, means coupled to receive and continuously provide a first pilot tone synchronizing component representation beyond the end of a first line of said television signal in which it appears, means to compare the time base of said first pilot tone synchronizing component representation with the time base of a pilot tone synchronizing component representation of a succeeding line to produce a time base difference signal representative of the time base difference between said pilot tone synchronizing component representations, and means to adjust the time base of the clock provided by said clock generator to convert said first line to analog form in accordance with the time base difference signal.
- 25. Apparatus for time displacing a signal while it is being converted from a digital form to an analog form comprising a digital to analog converter responsive to clock signals to receive and convert a series of digital signals to an analog representation, an adjustable time base clock signal generator for generating a clock signal having a time base dependent on the time base of a time base control signal, said clock signal coupled to said digital to analog converter to command it to convert said series of digital signals to an analog representation, and means for generating said time base control signal.
- 27. A velocity error compensator for adjusting the time base of an input color television signal having pilot tone synchronizing component indicative of the intra line time base of the television signal comprising means coupled to receive and continuously generate a representation of the pilot tone synchronizing component of a first line of said television signal for a duration extending beyond the end of the line in which the represented pilot tone synchronizing component appeared, means for comparing the phase of the continuously generated representation of the pilot tone synchronizing component with that of a pilot tone synchronizing component of a succeeding line of said television signal, and means responsive to the phase comparing means for progressively varying the time base of said first line of said television signal in accordance with the phase difference between the components compared by the phase comparing means.
Specification