| 摘要 |
PURPOSE:To detect a faulty position and the cause of the fault in the center, by making the monitor signal from the relay amplifier different in oscillation frequency according to the fault mode of the relay amplifier. CONSTITUTION:Main line amplifying circuit 1 which compensates the attenuation quantity of the cable is so controlled automatically that the output level becomes constant by AGC circuit 2. Presence or absence of the detection output of the pilot signal, which is taken out by AGC circuit 2, and the output, which is obtained by detecting a part of the output of branch amplifying circuit 3 by detector 8, is detected by control circuit 7, and thus, fault modes of the amplifier such as pilot signal break and a fault of branch amplifying circuit 3 are discriminated. A signal corresponding to the discrimination result is applied from control circuit 7 to monitor signal generating circuit 6, and the monitor signal of a frequency corresponding to the fault mode is generated from circuit 6. In the center, this signal is branched to detect the fault mode of the relay amplifier. |
