| 摘要 |
PURPOSE:To detect the disconnection of an optical communication line without confusing a signal subject to photoelectric conversion whether or not coming from other station or its own station by assigning information representing the direction of the optical signal to one bit in a service data. CONSTITUTION:First 4-bits of each service data signal in a service data signal string are used for synchronization bits and an information bit representing the direction of the optical signal is assigned to the 8-th bit in the remaining bits. When a data is sent from a station A to a station B, a low level is set to the bit and when the data is sent from the station B to the station A, a high level is set to the bit. When a fault of a loosened optical connector or the like takes place, an optical signal (main signal) from the station B is reflected in the end face of the optical connector 17. On the other hand, the optical signal from the station A is not inputted to the station B. As a result, the information bit in the service data signal received by an alarm control unit 16 goes to a high level and the alarm control unit 16 judges it to be the disconnection of the line. |
