| 摘要 |
PURPOSE:To obtain an automatic tracking controlling device having a small scale circuit small in wow deterioration by adding a new phase locking loop that phase-locks the reference signal of phase control and the clock of a counter that measures and sets the quantity of delay from the signal. CONSTITUTION:Phase locking is made so that the reference signal 180 from a crystal oscillator 20 and a frequency divider 21 and a frequency dividing signal 181 from a counter 173 have the same phase by a phase locking loop 174 consisting of a phase comparator 170, an LPF171 and a voltage control oscillator 172 and a frequency dividing counter 173. On the other hand, a coincidence circuit 18 sends a pulse signal 185 delayed from the signal 180 by specified amount when bit information of an up down counter 17 coincides with bit information of the counter 173. A CTLP signal 187 from a delay circuit 4 is phase- compared by a phase comparator 23. The signal 187 is phase-locked to the reference signal 180, and the deterioration of wow capacity of tracking operation is reduced.
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