| 摘要 |
PURPOSE:To suppress effectively the dot interference without degrading the resolution by detecting an average value of C signals leaked into separated Y signals and reducing C signal components in output Y signals on the basis of this value. CONSTITUTION:A comb line filter 10 uses correlation characteristics of three horizontal scanning lines to separate Y and C signals from each other. A separated Y signal 17a is applied to a band-pass filter 20 whose center frequency is 3.58MHz, and C signal components mixed in the Y signal are taken out. C signal components are converted to a positive value signal by an absolute value circuit 21 and passes an LPF22 to take out the average value, and this value is applied to a comparing circuit 23. The comparing circuit 23 compares the input signal 22a with a reference value; and if the signal 22a is larger than the reference value, a certain control signal 23a is outputted to operate coefficient circuits 25 and 26. As the result, a signal 27a synthesized by a synthesizing circuit 27 is the Y signal where C signal components are eliminated completely, and the dot interference is suppressed in this signal.
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