| 摘要 |
PURPOSE:To accurately detect the input break of an optical signal by detecting the shift of a timing signal from its best phase and outputting a phase control signal, deciding whether or not its phase control signal varies exceeding a set range or whether or not the peak value of the variation exceeds a specific value, and detecting the input break of the light signal. CONSTITUTION:If the input of the optical signal has a break, a discrimination part 4 detects the shifts of a noise component and the timing signal from their best phases. It is therefore indicated that the phase control signal shifts greatly from the best phase owing to the noise component whose phase is indeterminate or that the shift from the best phase and its direction vary greatly. A detection part 5 detects the state of the phase control signal and judges the input break of the optical signal when the phase control signal exceeding the set range or the variation peak value due to repetitive short-time variation exceeds a specific value. |
