| 摘要 |
PURPOSE: To detect the abnormality of an optical transmission line in a short time by adding specific information to the information body part of a light signal to be sent to a subordinate station, monitoring only the specific information which is received, and detecting the abnormality of the optical transmission line. CONSTITUTION: A master station 20 is equipped with two optical transmitters T1 and T2, optical receivers R1 and R2, and a control part 21. The control part 21 appends the information on a specific code rule, required to recognize whether or not the optical transmission lines 10 and 11 are in an abnormal state, to the information body part of the light signal consisting of a burst signal and outputs the resulting signal to the optical transmitters T1 and T2. Further, the control part 21 sends it from the optical transmitter T1 or T2 and also inputs the light signal, having made one round of the optical transmission line 10 or 11, by receiving it through the optical receiver R1 or R2 paired with the optical transmitter T1 or T2. Then the state of the optical transmission line 10 or 11 is judged by detecting whether or not the specific information of the bit synchronizing word head part in the information body part meets the CM1 code rule. |
