Videotape recorder and reproducer velocity compensator apparatus

Claim 2

In a video tape recorder adapted for reproducing a recorded composite color video signal, said recorder receiving a reference color subcarrier signal, said recorder reproducing an uncorrected composite color video signal having line-to-line velocity errors and time base errors, velocity error detector apparatus comprising: burst separator means receiving said uncorrected composite color video signal for separating the reproduced color subcarrier bursts from said video signal, means for generating a sample signal in response to a zero crossing in each of said reproduced color subcarrier bursts, means receiving said reference color subcarrier For generating a plurality of repetitive signals at the reference color subcarrier rate, and means receiving said sample signals for non-ambiguously sampling said repetitive signals as a four quadrant phase detector.

Claim 3

The combination of claim 1 wherein said means for non-ambiguously sampling said repetitive signals includes: means receiving said reference subcarrier for generating a plurality of window signals at the reference subcarrier rate, said window signals corresponding in number and relative phase to said repetitive signals and having a width and phased with respect to the non-retrace portions of corresponding repetitive signals to provide widths of said non-retrace portions outside said windows at least as large as the maximum line-to-line velocity error of the video tape recorder.

Claim 4

The combination of claim 2 wherein said means for non-ambiguously sampling said repetitive signals further includes: sampling means receiving said repetitive signals and said sample signals for sampling and storing the value of each repetitive signal at the time of a sample signal, subtraction means receiving said stored values for generating and storing each of the differences between said stored values in consecutive lines, and means for selecting as the error signal output the stored difference value generated from a repetitive signal of which the corresponding window signal is coincident with said sample signal.

Claim 5

The combination of claim 2 wherein said plurality of repetitive signals comprise two trains of ramp signals staggered in phase by 180* of the reference subcarrier cycle and said plurality of window signals comprise two trains of gating pulses staggered in phase by 180* of the reference subcarrier cycle.

Claim 6

The combination of claim 1 wherein said repetitive signals are ramp signals.

Claim 7

The combination of claim 1 wherein said error detecting means includes: means for generating a sample signal in response to a zero crossing in each of said reproduced color subcarrier bursts, means receiving the reference subcarrier signal for generating first and second ramp signals, having retrace portions, at the reference subcarrier rate, and staggered in phase by 180* of a subcarrier cycle, and means receiving the reference subcarrier signal for generating first and second window signals at the reference subcarrier rate and staggered in phase by 180* of a subcarrier cycle and having widths and phased relative to the non-retrace portions of the corresponding first and second ramp signals to provide widths of said non-retrace portions outside corresponding window signals at least as large as the maximum line-to-line velocity error of the video tape recorder.

Claim 8

The combination of claim 6 wherein said error detecting means further includes: sampling means receiving said ramp signals and said sample signals for sampling and storing the value of each ramp signal at the time of a sample signal, subtraction means receiving said stored values for generating and storing the differences between said stored values in consecutive lines, and means for selecting as the error signal output the stored difference value generated from a ramp signal of which the corresponding window signal is coincident with said sample signal.

Claim 9

In a video tape recorder adapted for reproducing a recorded composite color video signal, said recorder receiving a reference color subcarrier signal, said recorder reproducing an uncorrected composite color video signal having line-to-line velocity errors and time base errors, said recorder further including a time base error corrector system of a type including an electronically variable delay line adapted for insertion in the reproduced composite color video signal path for varying the phase of the video signal in accordance with an error signal applied to the control input, the combination comprising means for delaying by approximately one hoRizontal line the reproduced composite color video signal applied to said electronically variable delay line, error detecting means receiving said reference subcarrier signal and said uncorrected composite color video signal, each of said signals independent of said delaying means, for comparing the color subcarrier bursts of said composite color video signal to said reference color subcarrier signal to generate an error signal output corresponding to each incremental change in phase error between said reproduced color subcarrier bursts and said reference color subcarrier bursts in succeeding horizontal video lines, means receiving said error signal output for generating a ramp signal output proportional to said error signal, and means for applying said ramp signal output to the control input of said electronically variable delay line.

Claim 10

In a video tape recorder adapted for reproducing a recorded composite color video signal, said recorder receiving a reference color subcarrier signal, said recorder reproducing an uncorrected composite color video signal having line-to-line velocity errors and time base errors, said recorder further including a time base error corrector system of a type including an electronically variable delay line adapted for insertion in the reproduced composite color video signal path for varying the phase of the video signal in accordance with an error signal applied to the control input, the combination comprising means for delaying by approximately one hoRizontal line the reproduced composite color video signal applied to said electronically variable delay line, error detecting means receiving said reference subcarrier signal and said uncorrected composite color video signal, each of said signals independent of said delaying means, for comparing the color subcarrier bursts of said composite color video signal to said reference color subcarrier signal to generate an error signal output corresponding to each incremental change in phase error between said reproduced color subcarrier bursts and said reference color subcarrier bursts in succeeding horizontal video lines, means receiving said error signal output for generating a ramp signal output proportional to said error signal, and means for applying said ramp signal output to the control input of said electronically variable delay line.