Importance

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Abstract

Circuits are disclosed for processing color encoded video signals, encoded per a format wherein a chrominance signal in the form of a modulated subcarrier is buried in spectrum 'troughs' in the midband of a wider band luminance signal, an illustrative use of the encoding format being in video disc recording. The processing circuits serve, in use with composite signals developed during video disc playback, to convert an input composite signal of buried subcarrier format to an output composite signal of NTSC format. Comb filtering is employed to separate buried subcarrier chrominance signal from midband luminance signal components. A heterodyning step preceding comb filtering is performed in a manner substantially precluding 'jitter' of played back signals from disturbing accuracy of comb filter separating action, enabling use of a single 1H delay line form for the comb filter and enabling use of a relatively inexpensive, narrowband structure for the single delay line. The comb filter output provides a chrominance signal in a band suitable for output composite signal use. The output chrominance signal is also used in a subtractive process to effect comb filtering of the luminance signal to remove therefrom midband chrominance signals.

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First Claim