| 摘要 |
PURPOSE:To prevent the production of a waveform distortion in a loopback signal by eliminating a waveform distortion caused in a logic gate in a loopback path at an identification reproduction section of other repeater section and sending the result to an optical transmission line. CONSTITUTION:When the loopback is commanded to a terminal 11 of a repeater section 10 in an incoming line, an AND gate is conducted and an incoming signal after reproduction outputted from an identification reproduction circuit 14 is fed to a timing extraction circuit 23 and an identification reproduction circuit 24 in a repeater section 20 in an outgoing line via the AND gate 19 and OR gates 27, 28. The incoming signal supplied to the identification reproducing circuit 24 is subject to identification reproduction in the timing extracted by a timing extraction circuit 23 to eliminate waveform distortion caused in the transmission through the AND gate 19 and the OR gate 28, the result is converted into an optical signal and reflected in the optical fiber cable of the outgoing line. Thus, the loopback of the signal without waveform distortion is attained and the location of a fault occurrence is ensured. |
