| 摘要 |
PURPOSE:To hold a synchronous phase with a simple circuit configuration, by applying a false input signal from an AC signal generating part to an automatic phase controlling part as an AC signal when an input signal is defective. CONSTITUTION:The output of a phase detecting part 1 is applied to an LPF2 and a signal detecting part 5. When a discriminated result is normal, the output of the detecting part 5 is applied to an AC signal controlling part 7 to inhibit an AC signal outputted from an AC signal generating part 8 from being applied to an adding part 6. When the output of the detecting part 1 is lower than a reference level, the detecting part 5 discriminates that the state is abnormal and the controlling part 7 applies the AC signal from the generating part 8 to the adding part 6 as a false input signal. Consequently, an output from the automatic phase controlling part 3 is applied to a voltage control oscillating part 4. The output of the controlling part is approximately proportional only to the DC component of the output signal from the generating part 8, so that the oscillating part 4 can oscillate at the frequency close to the central frequency of the input signal. |
