| 摘要 |
PURPOSE:To use a line required for polling the same as that for a main signal by assigning a polling signal bit transmitted/received between both terminal stations to a prescribed bit with different subinformation frame generated based on the violation of the code rule attended with the CMI coding. CONSTITUTION:In the method by a polling used for the optical communication system where main information subjected to the CMI coding is transmitted and received between terminal stations A, B and connected to the terminal stations B, A via repeaters 55, 56, when a transmission line 50 is sound, both the terminal stations A, B apply supervision to the relay stations by using the polling. In this case, the polling signal bit is assigned corresponding to the terminal station to a prescribed bit of subinformation frame generated based on the violation of the CMI coding rule of the main information. Thus, no collision of the polling signal bits takes place. Since the subinformation is superimposed on the main information, the transmission line 50 is used, where the main information is sent. Even if the transmission line 50 connected to one terminal station A is opened, it is supervised by the other terminal station B.
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