Abstract: A video signal correction circuit of a signal processing system includes means for determining the chroma line type, for inserting the line type information in the video signal, and for extracting the line type information from the video signal downstream to allow selecting the phase of the chroma subcarrier to match the phase of the output station reference.

Abstract: A frequency measuring circuit measures the period between successive pulses of an input signal and converts the pulse count to a measured frequency value. The measured frequency signal is filtered to eliminate spurious noise and a variable threshold is generated by comparing the measured frequency and the filtered frequency. Only frequency signals qualified by the variable threshold are accepted as valid and provided as the output.

Abstract: An adaptive chrominance separator is provided which responds to horizontal high frequency luminance detail as well as to vertical chrominance detail. The luminance and chrominance levels are detected and an adaptive decision is made, depending upon the relative levels, of whether to use a bandpass filter, a comb filter or the averaged outputs of both filters, to provide more accurate separation of the chrominance.

Abstract: In a time base correction system, a composite color television analog signal derived from a prerecorded tape is converted by an analog-to-digital (A/D) converter to a digital signal having horizontal sync and color burst signal components. The digitized sync and burst signals are processed on a line-by-line basis to provide an error signal between input video and a sampling clock in the form of a binary control word. The error signal is applied to a digital frequency synthesizer which generates a clock at the subcarrier frequency to achieve precise adjustment of frequency and phase of the A/D sampling clock with respect to the video signal. An analog phase locked loop operating at four times the subcarrier frequency feeds back a 4.times. subcarrier sampling clock to the analog-to-digital converter with adjustable frequency and phase.

Abstract: An all-pass filter provides inversion of a chrominance component in a composite signal without separating the chrominance component from the composite signal, to provide for example, synthesizing composite video from a previous line of video. The filter includes an input for receiving the composite signal along a subsequent signal path, and the application of selected, preferably symmetrical weighting factors to selected locations along the signal path. The path includes selected delay means coupled to define a filter output via summing means. The latter provides the composite signal with inverted chrominance without an objectionable change in the relative phase and amplitude of the luminance components relative to the inverted chrominance.