| 摘要 |
PURPOSE:To simplify the constitution through disusing the system control peculiar to the loop back constitution from the center, by performing only the duplex system control as the system control from the center and by controlling system switcing for loop back constitution by the loop back state of the terminal station equipment. CONSTITUTION:One center equipment 13 and plural terminal station equipments 23 are connected into a loop-form to constitute the loop-shaped network. By the fault of the transmission line in the part marked with X, equipment 13 and equipment 23#4 are looped back to set the single loop, and the ''1'' system side becomes the current system except equipment 23#4, and common circuit 22 is connected to terminal station equipment control circuit 20 of the ''0'' system side. As a result, only the duplex system control is performed as the system control from the center, and system switching for loop back constitution is controlled by the loop back state of the terminal station equipment, thereby making the system control peculiar to the loop back constitution from the center needless. |
