Color subcarrier frequency comparator

Details Color subcarrier frequency comparator Color subcarrier frequency comparator

1974-08-20

1976-05-18

Libman, George H.

Facsimile and static presentation processing

Static presentation processing

Attribute control

324 88, H04N 962

Patent

active

039582698

ABSTRACT:
Apparatus for measuring the frequency of a reference signal which utilizes he color subcarrier signal of a television receiver as a standard frequency signal. In a first embodiment, the reference signal controls a circuit to develop bursts of a synthesized color subcarrier signal, gated at the horizontal line rate of a color television receiver. The synthesized signal is superimposed on the broadcast television signal and applied to the receiver to produce a modulation bar on the screen. Any frequency/phase difference between synthesized and broadcast color subcarrier signals will cause the modulation bar to move laterally across the screen, and/or cause the sequence of colors within the modulation bar to vary. Movement of the modulation bar is a coarse indication of frequency difference and change of the color sequence within the bar is a precise indication of phase difference.
In a second embodiment, the locally synthesized color subcarrier signal and the color subcarrier signal of the television receiver are compared in a linear phase comparator to develop a signal having an instantaneous voltage proportional to the phase difference between the two signals. The phase signal controls a generator which develops a cursor line on the screen. Movement of the line across the screen provides a coarse indication of phase difference between the subcarrier signals. The phase signal is also applied to a digital counter which affords a precise readout of the phase difference between the signals.

REFERENCES:
patent: 2814775 (1957-11-01), Kummer
patent: 2904630 (1959-09-01), Bruch et al.
patent: 3292083 (1966-12-01), Presbrey
patent: 3526707 (1970-09-01), Skinner et al.
patent: 3591710 (1971-07-01), Uetake et al.
patent: 3850412 (1974-11-01), Olson

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