| 摘要 |
PURPOSE:To discriminate whether a fault is generated in a transmission line fault or an O/E (photoelectric conversion) section in a node by branching and connecting an input signal to the photoelectric conversion section detecting a signal normally to the input of the photoelectric conversion section having no signal branchingly so as to supervise its output. CONSTITUTION:When a signal on a transmission line inputted via optical switches 201, 202 is not detected by the O/E section 21 and the node applies loopback control, an optical switch 101 branches a signal from an input terminal 100 to the optical switches 101, 202 into two according to the command of a test control section 14. Moreover, the optical switch 202 connects the input from the optical switch 101 to the O/E section 21 according to the command of the section 14. The test control section 14 compares outputs of the two O/E sections 11, 21 and when they are identical, it is regarded that a fault takes place in the transmission line connected to the input terminal 200. If the O/E section 21 does not detect a signal and only the O/E section 11 detects the signal, the test control section 14 regards it as a fault occurred in the O/E section 21. |
