| 摘要 |
PROBLEM TO BE SOLVED: To prevent faults in a block of an optical transmission line from affecting other blocks. SOLUTION: This optical input interruption detector is provided with an optical reception amplifier circuit 2, a clock recovery circuit 5 that extracts clock component, an identification circuit 4 that takes up again a timing on the basis of the extracted clock, a digital processing section 16 that receives a data output from the identification circuit 4 and the extracted clock to process the signals, a frequency divider means 10 that frequency-divides a data output from the identification circuit 4, an interruption detection circuit 12 that outputs a 1st interruption detection signal denoting an interruption of an optical input on the basis of whether or not a change point took place through the monitor of a frequency-divided signal at a prescribed time interval, and an OR circuit 14 that generates a LOS signal denoting the interruption of the optical input, on the basis of the 1st interruption detection signal and a 2nd interruption detection signal detected in relation to one of the optical reception amplifier circuit 2, the clock recovery circuit 5 and a photodetector. |
