| 摘要 |
PURPOSE:To detect automatically the state of restoration in a failed section, by transmitting a monitor signal to a signal intermitting section by a loop back terminal station and receiving the monitor signal transmitted from the loop back terminal station of opposite party via a signal relay section. CONSTITUTION:When a signal interruption takes place on transmission lines 3d, 4d, a transmission controller 2c connects a signal on a transmission line 4c to a transmission line 3c and a transmission controller 2d connects a signal from a transmission line 3e to a transmission line 4e, respectively, and a monitor controller 1 connects a signal from a transmission line 3a to a transmission line 3h and connects a signal from a transmission line 4h to a transmission line 4a, respectively to constitute the loop back. Monitor signal generating circuits 24c, d keep to transmit the monitor signal to the signal interruption sections 3d, 4d from the controllers 2c, 2d. Further, detecting circuits 25c, 28d monitor whether the monitor signal transmitted from the opposite party is transmitted on the transmission lines 3d, 4d. When the transmission lines 3d, 4d are restored, the circuit 25c, 28d detect the transmission of the monitor signal and recognizes that the signal interruption section is restored. |
