| 摘要 |
PURPOSE:To transmit signals in both directions between neighboring stations with a spare system for the disconnection of a transmission line only by two loop-shaped transmission lines in a right turn and a left turn, by providing the transmission lines which transmit third signals in which first and second signals are multiplexed in turns oppositely with each other in loop shapes. CONSTITUTION:A separate multiplex circuit 11 performs the time divisional multiplex of a data signal D1 inputted from an input terminal 101 and a data signal D2 inputted from a switch 13, and outputs it to the transmission line L1. A separate multiplex circuit 12 performs the time divisional multiplex of the signal D2 inputted from an input terminal 102 and the data signal D1 inputted from a switch 14, and outputs it to the transmission line L2. When the disconnection of the transmission line L1 is generated between stations 1 and 2, the switch 16 of the station 2, and the switches 14 of stations 3 and 4 are switched. The data signal D1 to be transmitted to the station 2 in the right turn by the station 1 is transmitted also to the station 4 via the transmission line L2, and the data signal D1 is relayed at the switches 14 of the stations 4 and 3 by the switching of the above switch, then inputted from the transmission line L2 to the station 2.
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