| 摘要 |
PURPOSE:To locate easily a faulty point by providing a control means changing over a device case part to a feeding return path in response to a received light output and controlling the feeding from a terminal station, and transmitting means detecting the light reception quantity of the backward scattered light and sending a signal in response to to the received light quantity to the terminal station. CONSTITUTION:Repeaters 13a, 13b at the left side of fault location 12 are fed from a terminal station 14 and repeaters 13c, 13d at the right side are fed from a terminal station 15. Thus, in sending respectively prescribed fault retrieval signal from terminal stations 14, 15, a supervisory circuit of each repeater is operated and the fault retrieval signal is returned to the terminal station 14 via the repeaters 13a, 13b and further back through the repeaters 13b, 13a. Further, the fault retrieval signal is returned to the terminal station 15 via the repeaters 13a, 13c and further back through the repeaters 13c, 13d. Then a faulty point location circuit incorporated in the repeater is operated to locate the faulty point easily and accurately. |
