Network Integrity Systems, Inc.

Daniel M Goertzen

Cary R Murphy

Mark K Bridges

David E Vokey

Joseph Giovannini

Dave Eric Cunningham

Joseph Giovanni

Darrell J Magee, Iii

Matthew R Friede

Andrew V Pasterczyk, Jr

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.

Monitoring optical fibers using two dissimilar algorithms on a single monitoring system

Monitoring optical fibers with false alarm suppression using dissimilar algorithms

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.

Intrusion detection algorithm with reduced tuning requirement

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.

Test device for verifying operation of an optical fiber monitoring system

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.

Monitoring a fiber optic cable for intrusion using a weighted algorithm

A method is provided for detecting intrusion into optical fibers of a Passive Optical Network (PON) of the type which includes a multiplexing system at the head end for separating a data signal output at the head end to the plurality of fibers for supply to user end terminals and a data transmission system at each of the user end terminals for entering onto the fiber data as an optical signal. The method includes providing a monitor system having a transmitter at the head end and a monitor signal analysis system for analyzing changes in the optical monitor signal after transmission along the fiber for detecting an intrusion event. A monitor signal analysis system is provided at one or more user end terminals for detection and conversion of data from the analysis into a digital signal which is then transmitted from the user end terminals back to the head end using the data transmission system through the PON system or separately from the PON system.

Alarm system for an optical network

A method is provided for detecting movement indicative of intrusion events on optical drop fibers of a network where the individual drop fiber can be identified to locate the event. The method uses a monitor system at the network end and multiplexing the monitor signal along the individual fibers to the respective terminals. At each of the terminals, the monitor signal is returned unchanged or in modified form along the same or different fibers to the network end. At the network end the received monitor signals is analyzed for changes in said monitor signals indicative of movement. Which one or more of the drop fibers has triggered the alarm is determined by modifying the monitor signal in wavelength or polarization, or by applying a modulation at the source and/or at multiplexing and/or at returning so that the monitor signal of one drop fiber has a difference from the monitor signal of another drop fiber.

Drop discriminating network alarm system utilizing a single sensing fiber

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.

Monitoring individual fibers of an optical cable for intrusion

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.

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Winnipeg, Canada

Daniel M Goertzen