Video signal processing unit

Abstract

A processing circuit for a composite color television signal formed of a chrominance component and a luminance component includes a comb filter of the type including a 1H delay line. In order to process the chrominance component, the comb filter is followed by an operational circuit providing a difference signal representing vertical correlation of the input chrominance component for consecutive line intervals, and a feedback loop circuit for combining the input chrominance component with the feedback difference signal before application to the comb filter. A detecting circuit detects correlation of video information in the luminance component in vertically aligned portions of successive horizontal line intervals, and provides a detecting signal which is used to adjust the feedback loop gain on the feedback loop circuit in accordance with the detecting signal. The processing circuit can further comprise a luminance comb filter including the delay line and an additive combining circuit, which is followed by a subtractive combining circuit and a band pass filter having an input connected to an output of the subtractive combining circuit and an output connected to an input of the latter. This circuit gives the luminance comb filter a flat frequency transfer characteristic. In the detecting circuit, a delay circuit is provided formed of a pre-emphasis circuit, an AM modulator, a delay line, an AGC circuit, an AM detecter, a de-emphasis circuit, and a low pass filter.