| 摘要 |
<p>PURPOSE:To accurately find out the frequency of a reproducing clock from an intermittent digital signal by providing the titled device with a condition deciding part for outputting a synchronization detecting flag and a synchronizing signal period measuring means for measuring an interval between synchronizing signals. CONSTITUTION:A synchronization detecting part 801 detects a synchronizing signal from a digital data (DATAIN), and only at the time of inputting the synchronizing signal with an equal interval, outputs a synchronization detecting flag (SYCNT). When the flag SYCNT is active and an error detecting part 804 detects no error continuously by two blocks, the condition deciding part 805 outputs a condition forming flag (PLLOK) to a counter 806. When the deciding part 805 outputs the flag PLLOK, the counter 806 measures the interval between the synchronizing signals correctly. An inverse number converting part 808 converts the period between the counted synchronizing signals into a shifted value from the center of the reproducing clock frequency. The PLL frequency data (PLLf) outputted from the converting part 808 are supplied to a tape speed control part so as to be used for the control of a tape speed.</p> |
