| 摘要 |
PURPOSE:To provide an information collection system which can increase its scale and also can back up a communication circuit against its fault. CONSTITUTION:An information collection system includes the tree-shaped communication circuits between a center station 1 and plural terminal stations respectively, the main optical transmission lines 4 forming the branches of each three- shaped communication circuit, the cross terminals 5 which are provided on each junction of the communication circuits, and the stand-by optical transmission lines 6 set among the terminals 5. The terminals 5 detect the disconnections of the lines 4 of the upstream side in response to the optical signals received from the lines 4. Then the terminals 5 connect the lines 6 to the optical transmission lines of the downstream side by bypassing the disconnected trunk optical transmission lines of the upstream side and then reproduce the optical signals on the lines 4 and 6 connected together. |
