| 摘要 |
PURPOSE: To detect faults in an optical transmission line in a short time by adding prescribed information to the preamble part of an optical signal and monitoring the received prescribed information only so as to detect abnormality in the optical transmission line. CONSTITUTION: A host station 20 and plural slave stations 30 are connected to two optical transmission lines 10, 11 being a duplex loop of the multi-drop system. The host station 20 is provided with two each of optical transmitters T1, T2, optical receivers R1, R2 and a control section 21. The control section 21 adds information according to a prescribed code rule required to recognize whether or not the optical transmission lines 10, 11 are abnormal to the preamble part of the optical signal being a burst signal and outputs the resulting signal to the optical transmision lines 10, 11. Furthermore, the control section 21 controls the optical transmitters T1, T2 to make transmission and allows the optical receivers R1, R2 in pairs with the optical transmitters T1, T2 to receive the optical signal circulated through the optical transmission lines 10, 11. Then the control section 21 detects whether or not the prescribed information in the preamble part violates the CMI code rule. |
