| 摘要 |
PURPOSE:To actuate normally a phase lock characteristic of a phase locked loop at all times by providing a frequency control means having an ON/OFF control function to the phase locked loop formed in response to the burst signal input. CONSTITUTION:Phase detection outputs e1, e2 are inputted to terminals 107, 108 and the output of addition 17 and subtraction 18 is multiplied (19). On the other hand, the outputs e1, e2 are multiplied (20) as it is, the output of the multipliers 19, 20 is multiplied (21) to obtain a phase error voltage E. The error voltage E is compared (22) with a reference value Vr from a reference voltage generating circuit 23, a slicer 24 outputs H level for E>Vr and L for E<=Vr and the output is inputted to a one-shot trigger circuit 25. The one-shot trigger circuit 25 transmits a binary signal by using a binary level, and a clock fc from an oscillator 27 is subjected to up- or down-count at a reversible counter 26. The output of the counter 26 is subjected to D/A conversion 28 to output (109) the phase control signal. Then the phase locking characteristic is kept normal independently of the burst time.
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