| 摘要 |
PROBLEM TO BE SOLVED: To decrease the number of stand-by transponders by providing a function for detecting the abnormality of a transmitting transponder and a function for switching the stand-by transponder. SOLUTION: A transmission stand-by system control part 4 compares information monitored by a transponder input monitoring part 3 and an output monitoring part 5, detects the output abnormality of a transponder 2-1, drives a stand-by transponder 2-r, and controls an optical switch 7, and allows the optical signal of a terminal station device 1-1 to be inputted to the stand-by transponder 2-r. At the same time, the information of switching from the transponder 2-1 to the stand-by transponder 2-r is transmitted to a writing reception system side by a monitor signal. A reception preliminary system control part 12 on the reception system operates the stop of a receiving transponder 13-1, the driving of a reception stand-by transponder 13-r, and the control of (n+1)×n optical switch 19, and switches a signal inputted to a terminal station terminal 16-1 from the output signal of a transponder 13-1 to the output signal of a stand-by transponder 13-r. |
