| 摘要 |
PURPOSE:To set a search voltage to an optimum point and to avoid ease of out of synchronism by fixing a search signal to a nearly midpoint of a synchro nizing area at the initial acquisition of synchronism. CONSTITUTION:After a CPU 25 applies initial setting of the internal state after application of power, a search voltage SRCV is increased by dV each and whether or not there is a large change in a control voltage VCV is checked via an A/D converter 31 and when a state of no change in the control voltage VCV consecutively twice is detected, it is discriminated that the entrance to the synchronizing state is attained. Similarly, the CPU 25 decrease the search voltage SRCV by dV each from the maximum value and when a state with very small change in the control voltage VCV is detected thrice consecutively as a rule, it is discriminated for the entrance to the synchronization state. Then control voltages VL1, VH1 are used to calculate the optimum value SRCVC of the search voltage SRCV and the search voltage SRCV is set to the SRCVC via a D/A converter 22. |
