CPC G08B 13/186 (2013.01) [G02B 6/4469 (2013.01); H04B 10/071 (2013.01)] | 18 Claims |
1. A method for monitoring an optical fiber for disturbance events caused by physical vibration and/or physical displacement of the optical fiber comprising:
introducing a series of monitoring optical signals into the optical fiber;
receiving optical signals from the optical fiber which are modified by disturbance events on the optical fiber;
in a detection system:
analyzing received signals from the optical fiber after transmission along the optical fiber using OTDR to measure backscattered light to detect the disturbance events to be monitored;
and generating alarms in response to signals which are indicative of the disturbance events to be monitored;
under control of a control system, repeatedly applying to the optical fiber a generated signal which is not caused by an event to be monitored;
the generated signal being applied to the optical fiber by an actuator at a predetermined location on the optical fiber which generates a disturbance event caused by physical vibration and/or physical displacement of the optical fiber;
arranging the generated signal so as to be detected by the detection system when received;
wherein the generated signal contains a recognizable signature for detection by said detection system so as to distinguish at said detection system the generated signal from said disturbance events to be monitored;
in the detection system analyzing the received signals from the optical fiber after transmission along the optical fiber to detect the generated signal;
when the generated signal is detected, reporting detection of the detected generated signal to the control system;
and when said generated signal is not detected, the control system actuating a warning that the detection system is not properly operating.
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