VIDEO INFORMATION UNIT AND SAMPLING POINT OPTIMIZING CIRCUIT

摘要

PROBLEM TO BE SOLVED: To obtain an optimum sampling point of a video signal automatically. SOLUTION: A switch 4 of this unit is thrown to the position of a memory 3 with a delay of one frame and a delay in a delay circuit 10 is changed by dt each within a range of a dot clock period of an input video signal and an A/D converter 2 applies A/D conversion to the input video signal based on a sampling clock from the delay circuit 10. Every time the delay of the delay circuit 10 is varied by dt each, a comparator 6 of a correlation device 5 compares input digital video signal with an output digital video signal of the memory 3 and a counter 7 counts an output of the comparator 6 being the number of times of coincidence between both the video signals. The count indicates autocorrelation value and a microcomputer 11 detects a change point from a string of the autocorrelation for each delay of the delay circuit 10 and uses a sampling clock at a delay of the delay circuit 10 with respect to a median of the two change points as a sampling clock with an optimum sampling point.