| 摘要 |
PURPOSE:To reduce circuits and to improve reliability by inserting and transmitting one service slot to the other service slot in a returning state. CONSTITUTION:Concerning a two-fiber optical duplexing transmission system, plural ADM devices 31, 32, 33... and duplex lines composed of two optical transmission lines 11, 12, 13... and 21, 22, 23... are alternately connected in the shape of a ring, the signals of plural channels are transmitted, and the respective ADM devices 31, 32, 33... performs the repetition/transmission of passed signals and the insertion/separation of tributory signals corresponding to the passed signals. In this case, one optical transmission line normally assigns one channel and the other channel, for which all the channels are bisected, to a service slot and a protection slot respectively and transmits the protection slot in the empty state. At the ADM device for performing return in the returning state, the service slot of one and/or the other optical transmission line is transmitted while being inserted to the protection slot of the other and/or one optical transmission line. |
