| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for making an optical transmission system safe by using the principle of LOS while eliminating a defect related to an interference due to noise. SOLUTION: In the method for making optical transmission system safe, provided with a means 11 for transmitting a wanted optical signal Su, a means, which is equipped with a transmission optical fiber 12, for transmitting the wanted optical signal Su and an optical signal containing optical noise, a means for sampling and extracting one part of an optical signal called monitoring optical signal, and a means for analyzing the output of the monitoring optical signal to deduce that the transmission optical fiber 12 is broken corresponding to the output of the monitoring optical signal, in the monitoring optical signal, a first signal containing only noise and a second signal containing both the noise and a wanted signal are isolated and when the ratio of the output of the second signal to the output of the first signal is substantially equal to '1', in order to deduce that the transmission optical fiber 12 is broken, the output of these two signals is compared. |
