FAULT PROCESSING SYSTEM FOR COMMUNICATION CHANNEL

PURPOSE:To exclude the frequency switching for active/standby systems and disabled synchronization of a post-stage connector by executing a proper fault processing in response to the classification of a line fault for an intermediate repeater. CONSTITUTION:A fault informing means 24 of an intermediate repeater 20 identifies a fault increasing the error rate of a reception pulse to a terminal station 30 and gives a notice. A switching instruction means 36 of the terminal station 30 receiving the notice instructs the switching to a standby communication system, an oscillator switching means 35 selects a VCO 32 and in the case of other fault not increasing the error rate, a fixed oscillator 33 is selected. A fault signal generating means 34 sends an abnormal signal to a post-stage connector according to the oscillator selection by the switching means 35. After the fault detection means 23 of the intermediate repeater 20 detects that the reception pulse error rate is sufficiently decreased, the informing means 24 informs the recovery to a terminal station repeater 30 and the instruction means 36 of the repeater 30 gives the instruction of returning the communication system from the standby system to the active system. Through the constitution above, the frequent switching between the active and standby systems is avoided and the disabled synchronization of the post-stage connector is avoided.