| 摘要 |
PURPOSE:To prevent a closed circuit from being constituted in an optical loopback circuit by inhibiting the optical loopback operation of other optical repeater circuit while one optical repeater circuit applies the optical loopback operation. CONSTITUTION:When an optical loopback signal is inputted to a supervisory circuit of an outgoing optical repeater circuit 20, an optical loopback control signal S1 is supplied to a control input of an optical loopback circuit 4 from the circuit 20 and an output of the circuit 20 is fed to an input of an optical repeater circuit 30 via the circuit 40 to apply loopback operation. An optical loopback ON signal S2 is inputted to a supervisory circuit of the incoming optical repeater circuit 30 at the same time to inhibit the sending of an optical loopback control signal S4. When the optical loopback OFF signal S3 is inputted to the supervisory circuit of the circuit 30 from the supervisory circuit of the outgoing optical repeater circuit 20, the inhibition of the optical loopback operation is released. The incoming optical repeater circuit 30 is operated similarly. |
