| 摘要 |
<p>PURPOSE:To prevent malfunction due to environmental conditions by generating a clock having frequency of (n) times of synchronizing clock of a decoder, and generating a latch pulse which can be latched at an optimum point of a PCM voice data signal by frequency division from this clock. CONSTITUTION:A clock 30 having the frequency of (n) times of a synchronizing clock of a decoder 17 is generated by the use of a color burst 20 in a composite signal, and it is supplied to a 1/n frequency dividing circuit 29, a mark latching circuit 23, a start counter 27 and a 1/2 frequency dividing circuit 25. The mark latching circuit 23 latches a mark signal part 12 only in the period of a mark gate signal 36. A latched mark latch gate signal 31 becomes an enable signal of a preset counter 28, and counts an n/2 time clock 32. The output signal of the preset counter 28 becomes the preset signal 33 of the start counter 27, presets the count of the start counter 27, and outputs a reset pulse 34. The 1/n frequency dividing circuit 29 is reset by reset pulse 34, and a synchronizing clock 21 for latching a PCM voice data at optimum point is obtained.</p> |
