| 摘要 |
PURPOSE:To secure the priority communication in a faulty mode without lowering the transmitting efficiency, by usually connecting the superior signal group to the 1st drop inserter and the inferior signal group to the 2nd drop inserter respectively and reversing said connections when the 1st transmission line has a fault. CONSTITUTION:For an end office device main body TDSB, the signals which are transferred to terminals are previously divided into superior and inferior groups. The superior and inferior groups are delivered through terminals A and B respectively. A changeover switch SW usually connects the terminal A to the 1st drop inserter DI1 and the terminal B to the 2nd drop inserter DI2 respectively. Therefore both the 1st and 2nd transmission lines R1 and R2 are usually used. When the line R1 has a fault, the terminal A is connected to the inserter DI2 and the terminal B to the inserter DI1 by the switch SW. As a result, the superior group is connected to a time slot on the line R2 to continue the communication. The signal phase is controlled between both transmission lines by a delay device D. Thus it is possible to treat the signals given through both transmission lines with the same phase. |
