Test device for verifying operation of an optical fiber monitoring system utilizing direct optical injection

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.