| 摘要 |
PURPOSE:To simplify circuit constitution by orientating upward and downward repeater where a fault is occurring by separately transmitting a transmitted signal and fault-search signal and then by sending the transmitted signal at a repeating point by using the fault- search signal. CONSTITUTION:Via transmitted-signal cable 26 and fault-search signal cable 17 of transmission line cable 18, a transmitted signal and fault-search signal are separately transmitted and to each repeating point between cables 18, BPF9 connected to cable 17 and photo switch control circuit 22 controlling photo switches 23 and 24 by the output of BPF9 are connected. Further, cables 26 are provided with repeaters 8 and 10, photo switch circuits 23 and 24, and photo attenuating field 25. Then, when a fault of cable 26 is detected by the search signal of cable 17, circuit 22 is controlled by the output of BPF9 to change switches 23 and 24 over to the attenuator-25 side, and the transmitted signal is sent back at the repeating point to orientate repeates 8 and 10 getting out of order. |
