| 摘要 |
PURPOSE:To perform the phase locking of a system clock with high accuracy by driving an A/D converter with a clock pule and digitizing the input picture signal applied with the dot interlace. CONSTITUTION:The digital signal obtained by applying an A/D conversion 1 to the input picture signal applied with the dot interlace is transmitted to a frame pulse detecting circuit 2 and a horizontal synchronizing gate 3 to detect the frame and a horizontal synchronizing pulse. An internal horizontal synchronizing pulse applied with the phase control by said detected synchronizing pulse is produced by a synchronizing pulse generator 5. Then a phase detector 6 detects the phase difference between the horizontal and internal horizontal synchronizing pulses. A voltage control oscillator 9 produces a clock pulse applied with the phase control in response to the phase difference detected by the detector 6. The A/D converter 1 is driven by the clock pulse of the oscillator 9. Thus the input picture signal whose clock pulse is locked in phase and applied with dot interlace is digitized. |
