| 摘要 |
A sync signal reproducing circuit for a composite video signal, includes a channel selector for receiving a first composite video signal and a second composite video signal output from a composite video signal input stage, and also receiving a composite video signal selection signal output from a microcomputer, to thereby selectively output the first and second composite video signals; a D-COM filter for receiving the composite video signal selected by the channel selector, and separately outputting its chrominance signal and luminance signal; and a chroma circuit for receiving the chrominance signal and luminance signal of the composite video signal output from the D-COM filter, and thus reproducing the chrominance signal and separating horizontal and vertical sync signals from the luminance signal. The reproducing circuit stably separates the horizontal and vertical sync signals from the luminance of a composite video signal, and the separated sync signals enable the composite video signal and the VGA video signal to be discriminated.
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