| 摘要 |
PURPOSE:To stop the operation of a main office time device freely by monitoring the time signal generated by a slave office time device and determining time which may be accurate, and setting the time signal of the main office time device in synchronism with the time signal of the slave office time device. CONSTITUTION:The time signal generated by the time generating device 1 of the main office time device A is modulated by a modem 2 and transmitted to slave office time devices B1-Bn through a changeover switch 4 and a transmission line 9. The device 1 or Bn compares a time signal demodulated by a modem 6 with the time signal generated by a time generating device 5 by a comparator 7 and drives the device 5 in synchronism with the device 1. Further, the device A calls the device B1-Bn upon occasion to receive the time signal generated by the device 5, compares the time signal with the time signal generated by the device 1 by a comparator 3, and monitor the accuracy of the time generated by the device B1-Bn. When the operation of the device A is stopped for maintenance inspection, the switch 4 is placed on its reception side to evade the transmission of a wrong time signal to the device B1-Bn. |
