An alarm screen comprises a frame comprising a laser sensor, a processing unit, and a wireless transmitter embedded in a hollow interior. The frame comprises an opening for the laser sensor to project a laser beam outside of the alarm screen. The laser sensor projects the beam through the opening, makes a set of one or more measurements of a distance between the laser sensor and an object in a path of the laser beam, and sends the set of measurements to the processing unit. The processing unit is configured to compare the distance measurements received from the laser sensor with a threshold distance detect, and send one or more signals to the wireless transmitter when at least one of the distance measurements received from the laser sensor exceeds the threshold. The wireless transmitter is configured to receive signals from the processing unit and wirelessly transmit the signals.

A method of monitoring a fence or other containments barrier for climbing events by an intruder comprises providing a first and second sensors at different heights on the fence, detecting from each of the sensors signals which are indicative of vibration of the fence, and comparing the signals from the first and second sensors to determine vibration events which change in relation to a height of the intruder on the fence indicative of climbing so as to distinguish climbing events from incidental events and to provide a signal in response thereto.

A long-distance optical cable physical safety monitoring system, including a light source module, a light interference module, a sensing module, a reflection module, a photovoltaic conversion module, and a data processing module. The light interference module is use for dividing a light beam into multiple light beams; the sensing module is use for transmitting the multiple light beams; the reflection module is used for reflecting the multiple light beams to make the light interference module to output an interference signal; the photovoltaic conversion module is used for converting the interference signal to obtain a data signal; the data processing module is used for processing the data signal. The long-distance optical cable physical safety monitoring system is passive, low in energy consumption, anti-jamming, low in false positive rate, simple in construction, and convenient in maintenance.

An alarm screen comprises a frame comprising a laser sensor, a processing unit, and a wireless transmitter embedded in a hollow interior. The frame comprises an opening for the laser sensor to project a laser beam outside of the alarm screen. The laser sensor projects the beam through the opening, makes a set of one or more measurements of a distance between the laser sensor and an object in a path of the laser beam, and sends the set of measurements to the processing unit. The processing unit is configured to compare the distance measurements received from the laser sensor with a threshold distance detect, and send one or more signals to the wireless transmitter when at least one of the distance measurements received from the laser sensor exceeds the threshold. The wireless transmitter is configured to receive signals from the processing unit and wirelessly transmit the signals.

An optical fiber is monitored for an intrusion event where reflected optical signals are divided into streams each associated with a respective location on the optical fiber. Blocks of the streams are selected each containing a plurality of streams and the streams are collated, for example by averaging, to create a single stream to which an algorithm is applied to create coefficients which are compared with a threshold value to generate an output indicative of disturbance of the fiber by an intrusion event. Each block representative of a length of the fiber is thus treated as a zone and the detection algorithm is applied to each. This creates a DAS system that does not require unique tuning as each zone is independently monitored. Applying the above zone principles and algorithms to the DAS system also provides a high level of nuisance alarm and false alarm rejection

A method is provided for analyzing a monitoring signal from a sensing system to determine an alarm condition, where the monitoring signal is provided as a stream of digital values which are analyzed using a frequency-based transform to generate a set of transform coefficients which are compared to a set of envelope coefficients. The sensitivity of the analysis is automatically controlled to accommodate environmental noise on the fiber by increasing the envelope coefficients to make the analysis less sensitive at each cycle by adopting the larger value from the comparison and by decaying the envelope coefficients at each cycle over time to a smaller value down to a floor value.

A method is provided for monitoring optical cable for disturbance events by providing dual monitoring systems where optical signals are received from at least one optical fiber of the cable which are modified by disturbance events. Two separate and distinct algorithms are applied to the received optical signals to generate first and second outputs related to the disturbance event where in a control system information from the first and second outputs is used to determine if an alarm should be issued. The monitoring systems can use a single DAS system and operate on the same data independently preferably using one algorithm which uses ZONE processes to obtain data about different zones in the fiber. Alternatively two DAS systems can be used, one DAS system and one ZONE system or two ZONE systems. In all cases weather data can be used to assist the two algorithms in determining the presence of false alarms.

A detection system for measuring one or more conditions within a predetermined area includes a fiber harness having at least one fiber optic cable for transmitting light. The at least one fiber optic cable defines a node arranged to measure the one or more conditions. A control system is operably coupled to the fiber harness such that scattered light associated with the node is transmitted to the control system. The control system analyzes the scattered light to determine at least one of a presence and magnitude of the one or more conditions at the node.

A detection system for measuring one or more condition within a predetermined area includes a fiber harness having at least one fiber optic cable for transmitting light. The at least one fiber optic cable defines a node arranged to measure the one or more conditions. A light source is coupled to the at least one fiber optic cable for emitting a modulated light to the node. The modulated light is transmitted into the predetermined area. A light sensitive device is coupled to the at least one fiber optic cable for receiving scattered light associated with the node. A control unit is operably coupled to the light source and to the light sensitive device to determine at least one of a presence and magnitude of the one or more conditions within the predetermined area.

A monitoring system using an optical line is disclosed. The monitoring system using an optical line according to the present invention comprises: a laser diode for generating an input optical signal; an optical element for receiving the input optical signal through a first port and outputting same through a second port, and for receiving a reflected optical signal through the second port and outputting same through a third port; an optical switch unit for receiving the input optical signal through an input port connected to the second port of the optical element, and for distributing same through at least two output ports; at least one optical monitoring line connected to the output ports of the optical switch unit; a photodiode connected to the third port of the optical element, for detecting the reflected optical signal; and a signal processing unit for processing the signal detected by the photodiode.