| 摘要 |
PURPOSE:To shorten a halt time of a signal transmission caused by abnormality of an optical fiber, by providing two or more optical fibers for transmitting a transmitting signal. CONSTITUTION:A digital transmitting signal 1 is converted to a series signal by a multiplex transmitting device 2, also converted to an optical signal, passes through an optical fiber line 5, and transmitted and restored to a photoelectric converting device 8 of a receiving side. With regard to the opposite direction, too, said processing is executed in the same way. On the other hand, by the multiplex transmitting devices 2, 9, a pilot signal 18 and 19 are transmitted and received, abnormality of a transmitting system is detected by whether said signal exists or not, also a faulty part is discriminated with a high accuracy by checking a receiving level of the signal. When a fault is detected, a spare optical fiber 20 or 23 provided in advance in a cable 4 to switched to a faulty fiber by connecting terminals 6, 7, 14 and 15, by which a restoration of the system is completed in a short time. |
