In an optical fiber monitoring system which detects physical disturbance or other parameters such as temperature or strain of a fiber where a monitor signal is transmitted along the optical fiber and analyzed to detect changes which are indicative of an event, a method is provided for periodically checking proper operation of the optical fiber monitoring system. A fiber disturbance actuator periodically causes a pattern of disturbances of a portion of the fiber at a predetermined location thereon where the disturbance is characteristic of the event to be monitored. The monitor signal is analyzed to detect the pattern of changes and in the event that expected changes are not detected, a warning is issued that the intrusion detection system is not properly operating.

In an optical fiber monitoring system which detects physical disturbance or other parameters such as temperature or strain of a fiber where a monitor signal is transmitted along the optical fiber and analyzed to detect changes which are indicative of an event, a method is provided for periodically checking proper operation of the optical fiber monitoring system. A fiber disturbance actuator periodically causes a pattern of disturbances of a portion of the fiber at a predetermined location thereon where the disturbance is characteristic of the event to be monitored. The monitor signal is analyzed to detect the pattern of changes and in the event that expected changes are not detected, a warning is issued that the intrusion detection system is not properly operating.

A computer-implemented event statistic generation method for intrusion detection comprises processing a plurality of return signals from a coherent optical time domain reflectometer into time domain signals for each of a plurality of sensor bins, the plurality of return signals corresponding to a plurality of stimulation pulses injected into an optical sensor fiber during a time period. For each sensor bin, the method comprises transforming the respective time-domain signal into a corresponding frequency-domain signal, calculating, from the respective frequency-domain signal, a first signal power area of a first frequency band expected to contain system noise, calculating, from the respective frequency-domain signal, a second signal power area of a second frequency band expected to contain any energy related to at least a first event; and generating an event statistic proportional to the ratio of the second signal power area to the first signal power area at least in part by dividing the second signal power area by the first signal power area.

The optical fiber sensing method according to the present disclosure includes: sensing optical fibers being redundantly laid (10A1, 10A2); an execution unit (22) that executes sensing with the sensing optical fibers (10A1, 10A2); a detection unit (23) that detects occurrence of a fault in the sensing optical fiber (10A1) of an active system among the sensing optical fibers (10A1, 10A2); and a switching unit (21) that performs switching in such a way that the execution unit (22) executes sensing with the sensing optical fiber (10A2) of a standby system among the sensing optical fibers (10A1, 10A2) when the detection unit (23) detects occurrence of a fault.

The optical fiber sensing method according to the present disclosure includes: sensing optical fibers being redundantly laid (10A1, 10A2); an execution unit (22) that executes sensing with the sensing optical fibers (10A1, 10A2); a detection unit (23) that detects occurrence of a fault in the sensing optical fiber (10A1) of an active system among the sensing optical fibers (10A1, 10A2); and a switching unit (21) that performs switching in such a way that the execution unit (22) executes sensing with the sensing optical fiber (10A2) of a standby system among the sensing optical fibers (10A1, 10A2) when the detection unit (23) detects occurrence of a fault.

A system for detecting an intrusion of at least one of a monitoring fiber and a detector comprises a sensor having a closure monitor and an intrusion monitor, the closure monitor including a signal generator and at least one detector attached to the monitoring fiber. The signal generator transmits signal light such that the monitoring fiber receives the transmitted signal light and reflects a portion of the signal light via the at least one detector to the closure monitor and transmits a non-reflected portion of the signal light. The intrusion monitor receives the transmitted non-reflected portion of the signal light, and monitors the non-reflected portion of the signal light to detect transient changes in the non-reflected portion of the signal light indicative of at least one of a vibration, a motion and a handling of at least one of the monitoring fiber and the at least one detector.

Aspects of the present disclosure describe distributed fiber optic sensing (DFOS) systems, methods, and structures that advantageously extend DFOS techniques to anomaly detection using optical magnetism switches (OMC) that are integrated into the DFOS system.

A system 1 for remote sensing of information to be transmitted, said system 1 comprising; an optical time-domain reflectometer, OTDR, 2 adapted to transmit an optical probe signal OPS into an optical fiber 3 and to measure a backscattered signal power; and at least one electro-optical signaling unit 4 connected to said optical fiber 3, wherein the electro-optical signaling unit 4 is configured to change an attenuation and/or a reflection of the optical probe signal OPS depending on at least one signal provided by one or more signal sources 5 in response to the information to be transmitted.

A system 1 for remote sensing of information to be transmitted, said system 1 comprising; an optical time-domain reflectometer, OTDR, 2 adapted to transmit an optical probe signal OPS into an optical fiber 3 and to measure a backscattered signal power; and at least one electro-optical signaling unit 4 connected to said optical fiber 3, wherein the electro-optical signaling unit 4 is configured to change an attenuation and/or a reflection of the optical probe signal OPS depending on at least one signal provided by one or more signal sources 5 in response to the information to be transmitted.

An image processing apparatus (40) according to the present disclosure includes a display unit (42) and a control unit (41) configured to control the display unit (42) to display a sensing data image indicating sensing data of an optical fiber and a camera image of a camera (50) which photographs an area in which a predetermined event is detected by the sensing data.