US 4,291,330 AGranted

Video signal processing circuit for eliminating an interfering signal

AssigneeSony Corporation

InventorJun Hirai

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Abstract

A video signal processing circuit eliminates an interfering signal that is included in a video signal, and is especially effective for eliminating an intefering signal that results from reproducing a video signal that is recorded in successive slant tracks on a recording medium, such as magnetic tape. In the video signal processing circuit, a delay line delays at least the luminance component of the video signal by a predetermined number of horizontal line intervals, a first subtracting circuit combines the delayed luminance component with the undelayed luminance component to produce a first difference signal, a limter limits the first difference signal and presents the limited first difference signal to a second subtracting circuit, where the latter signal is subtractively combined with the delayed luminance signal to produce an output signal free of interfering signals. In order to improve the performance of the processing circuit, a high pass filter and an adder circuit can be included to pass the high frequency portion of the first difference signal around the limiter. Alternatively, a deemphasizing circuit and a preemphasizing circuit can be respectively included in advance of, and following, the limiter.

A video signal processing circuit for eliminating an interfering signal included in a video signal that is reproduced, from a recorded video signal recorded in successive parallel tracks on a record medium, by a transducer which scans one of said successive tracks, said interfering signal including crosstalk signals reproduced by said transducer from a track next adjacent the track being scanned, and said video signal comprising a frequency modulated luminance component whose carrier frequency varies by an amount 1/2(2 m+1)f.sub.H from the carrier frequency of the luminance component in the crosstalk signals reproduced from said track next adjacent the track being scanned, where m is an integer and f.sub.H is the horizontal line frequency, said circuit comprising:

first frequency demodulating means for frequency demodulating said luminance component and providing a demodulated luminance component;
delaying means for delaying said reproduced video signal for a predetermined number of horizontal line intervals to produce a delayed video signal;
second frequency demodulating means for frequency demodulating the luminance component in said delayed video signal and providing a demodulated delayed luminance component;
first combining means for combining said demodulated luminance component with said demodulated delayed luminance component, said first combining means producing a first difference signal representing the difference between said demodulated luminance component and said demodulated delayed luminance component;
means for limiting said first diffference signal to produce a limited difference signal;
high pass filter means coupled to said first combining means to pass a high frequency portion of said first difference signal;
second combining means for additively combining said high frequency portion with said limited difference signal to provide a combined signal;
and
third combining means for combining said demodulated luminance signal with said combined signal to produce an output signal representing the difference between said demodulated luminance signal and said combined signal, whereby said third combining means produces said output signal free of said interfering signal.

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Abstract

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