| 摘要 |
PURPOSE:To automatically and quickly detect the trouble of an optical transmission line by branching an optical signal at a remote edge from the transmitting source of the optical signal and returning it to the transmitting source directly. CONSTITUTION:At a transmitting side optical fiber cable 33 in a site unit 20 at a remote terminal for an intermediate operation unit 10 which goes to a transmitting source, at a receiving side optical fiber cable 36, an optical branching device 26 is provided, then optical coupler 25 is provided to an optical fiber cable at the receiving side, and short-circuited by an optical fiber cable 37. In the intermediate operation unit 10, it is always supervised by an on-line whether or not the same data as the transmitting data are returned. By a comparing deciding part 115, regardless of the fact that the abnormality is not detected, it is judged that an arithmetic processing unit 21 at the site unit 20 is trouble, when the data are not returned from the site unit 20. Consequently, it is not necessary to detect the trouble through a help and a labor. |
