| 摘要 |
PURPOSE:To quickly attain resynchronization at the time of recovery of a synchronizing electric power supply, by maintaining the input voltage of a voltage frequency transducer so that output frequency of a frequency divider is not varied, even in the event of instantaneous disconnection of the synchronizing electric power supply. CONSTITUTION:The second filter circuit 7 which obtains an output of a voltage frequency transducer 6 and generates output voltage of time lag of primary order is provided with a time constant which has been selected to a much larger value as compared with an instantaneous disconnection time of an electric power supply. Accordingly, even in case when an output of a phase difference detector 4 has become ''0'' due to instantaneous disconnection of a synchronizing electric power supply 1, an output of an adder 8 is scarcely varied, as a result, not only output frequency of a voltage frequency transducer 2 but also output frequency of a frequency divider 8 are not varied either, therefore, when the synchronizing electric power supply 1 has been recovered, the resynchronization is completed quickly by requiring only the time when an output of the first filter circuit 5 is varied a little. |
