| 摘要 |
PURPOSE:To make countermeasures for a power failure or the trouble and damage of a terminal station unnecessary and to improve transmission efficiency by constituting an optical loop of first and second optical fiber lines, dividing the optical loop into plural sections and causing the total number of the terminal stations, which are respectively coupled to each section, to be <= the number of the sections. CONSTITUTION:A control station 21 and respective repeating stations 22 and 23 are respectively connected in the shape of the loop by first and second optical fibers a1-a3 and b1-b3. Namely, the optical loop, which defines the control station 21 as a starting point and an ending point, is divided into sections A-C by the respective repeating stations 22 and 23. Terminal stations 24-26, 27-29 and 30-32 to be <= the number of all the sections are coupled to the respective sections A-C. The optical transmission of a requesting signal is executed to the terminal stations 24-32 by the first optical fibers a1-a3 of the optical loop and the optical transmission of a responding signal, which is sent from the terminal stations 24-32, is executed by the second optical fibers b1-b3. Further, an optical signal to be sent from the second optical fibers b1-b3 is received by the repeating stations 22 and 23 and loop control station 21. Then, since the optical signal is sent to the optical loop of the optical fibers a1-a3 with loading the responding signal which is edited during an erasing period to erase the requesting signal, the transmission efficiency can be made extremely high. |
