| 摘要 |
PURPOSE:To facilitate a noise-countermeasure in the processing of a video signal by counting horizontal synchronizing signals or signals synchronized with them, comparing the counting value of said counting with a prescribed value to detect the noise, and thereby providing an accurate detecting of the noise. CONSTITUTION:The horizontal synchronizing signal 1 and a vertical synchronizing signal 2 are inputted to a counter 6, and the counter 6 counts the number of the horizontal synchronizing signals during the period of the vertical synchronizing signal 2. The output of the counter 6 is inputted to a memory 7 and a comparator 8. Since the result of the counter 6 preceding one-field is stored in the memory 7, the comparator 8 detects the coincidence between the output of the counter 6 preceding one-field and the current output of the counter 6. In case the detection result is in dissidence, the comparator 8 outputs an error output 9 indicating that there is an influence of noise. In this way, an accurage detection of the noise is made possible.
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