| 摘要 |
PURPOSE:To ensure the supply of a stable clock for the communication system of a terminal side by letting a phase synchronizing oscillating means run by itself at a preset frequency, even if a fault occurs in the communication system of a master station side. CONSTITUTION:While a gate circuit 23 outputs a clock signal 26, the phase synchronizing oscillator 24 converts the clock signal 26 into a frequency, necessitated for a communicating means 22 for a terminal as synchronizing with the clock signal 26, and outputs it to the communicating means 22 for the terminal. However, when the gate circuit 23 does not output the clock signal 26, it runs by itself at the preset frequency. The said self running frequency is adjusted beforehand to the frequency, necessitated for the communicating means 22 for the terminal. Thus, even if the fault occurs in the communication system between the master station, and the first clock signal comes abnormal, the phase synchronizing oscillator 24 oscillates at the self-running frequency, and supplies the second clock signal to the communicating means for the terminal.
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