Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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 or time-based algorithm to generate a plot of elements, applying a delta to each element of the plot of elements to adjust sensitivity thereof to provide a threshold and comparing a plurality of the elements of the stream with the threshold and triggering the alarm condition in the event that the threshold is exceeded; where the algorithm is changed in different time periods in response to ambient conditions of the environment determined for those time periods.

Abstract: 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.

Abstract: 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.

Abstract: An optical fiber is monitored for changes in a monitor signal caused when the fiber is subjected to vibration, motion, or handling typical of an intrusion attempt and for triggering an alarm condition in response by one or more sensors. The sensor emits data on each disturbance event including the existence of the disturbance event and a value associated with the disturbance event dependent on an intensity of the disturbance. The arrangement herein provides an algorithm to analyze the disturbance events which calculates for each event a score dependent on the presence of the event and the value associated with the event, generates a summation of the scores in a FIFO and when the summation of the scores exceeds a predetermined threshold within a predetermined time period, the processor emits a signal triggering the alarm condition.

Abstract: An optical fiber is monitored for changes in a monitor signal caused when the fiber is subjected to vibration, motion, or handling typical of an intrusion attempt and for triggering an alarm condition in response by one or more sensors. The sensor emits data on each disturbance event including the existence of the disturbance event and a value associated with the disturbance event dependent on an intensity of the disturbance. The arrangement herein provides an algorithm to analyze the disturbance events which calculates for each event a score dependent on the presence of the event and the value associated with the event, generates a summation of the scores in a FIFO and when the summation of the scores exceeds a predetermined threshold within a predetermined time period, the processor emits a signal triggering the alarm condition.

Abstract: Some or all of the optical fibers of a single-mode or multi-mode cable are monitored for intrusion by transmitting through the fibers a signal which can be analyzed for changes in its characteristics which are indicative of movement as a prelude to an intrusion event. To avoid independent monitors of all of the fibers, in some cases the same light signal is looped through a plurality of the fibers in series by passive jumpers. Switches can be used to disconnect out those fibers which are compromised. As an alternative a plurality of separate monitoring signals can be provided each associated with its own sensor where unique combinations of the signals are transmitted through separate fibers allowing a higher number of fibers to be monitored than the number of signals.

Abstract: A signal which varies over time is monitored to determine an alarm condition, where the sample stream of digital values from an A/D converter is divided in to equal length pieces and a Fourier Transform (FT) algorithm is used to transform each piece of the stream into a three dimensional dataset including frequency domain amplitude, frequency and time. A Frequency Envelope is calculated by taking the maxima over the time dimension for a period of time, leaving a two dimensional frequency domain amplitude vs frequency dataset which is compared with new data arriving to determine the alarm condition for each element of the Frequency Envelope either by applying a constant delta additively or multiplicatively or by using a “leaky bucket” algorithm.