Securing an optical communications network path by suppression of learned ambient disturbances
First Claim
1. A method for use with a telecommunications optical cable having a plurality of optical fibers, the method comprising:
- transmitting into at least one of the optical fibers of the cable transmitted optical signals so as to generate received signals from light which has been transmitted along said at least one of the optical fibers in response to said transmitted optical signals;
causing a comparison of characteristics of at least some of the received signals relative to characteristics obtained from previously received ones of the received signals to detect changes in the characteristics of the received signals relative to the previously received signals;
filtering the received signals to filter background disturbances from the received optical signals by learning those signals which arise from background disturbances and filtering those signals out to generate filtered signals;
from the comparison of the filtered signals, determining any changes in the characteristics.
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Accused Products
Abstract
A telecommunications optical fiber is secured against intrusion by detecting manipulation of the optical fiber prior to an intrusion event. This can be used in a non-locating system where the detection end is opposite the transmit end or in a locating system which uses Fresnel reflections and Rayleigh backscattering to the transmit end to detect and then locate the motion. The Rayleigh backscattering time sliced data can be stored in a register until an intrusion event is detected. The detection is carried out by a polarization detection system which includes an optical splitter which is manufactured in simplified form for economic construction. This uses a non-calibrated splitter and less than all four of the Stokes parameters. It can use a polarimeter type function limited to linear and circular polarization or two linear polarizers at 90 degrees.
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Citations
12 Claims
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1. A method for use with a telecommunications optical cable having a plurality of optical fibers, the method comprising:
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transmitting into at least one of the optical fibers of the cable transmitted optical signals so as to generate received signals from light which has been transmitted along said at least one of the optical fibers in response to said transmitted optical signals; causing a comparison of characteristics of at least some of the received signals relative to characteristics obtained from previously received ones of the received signals to detect changes in the characteristics of the received signals relative to the previously received signals; filtering the received signals to filter background disturbances from the received optical signals by learning those signals which arise from background disturbances and filtering those signals out to generate filtered signals; from the comparison of the filtered signals, determining any changes in the characteristics. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification
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- Resources
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Current AssigneeNetwork Integrity Systems, Inc.
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Original AssigneeNetwork Integrity Systems, Inc.
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InventorsMurphy, Cary R., Vokey, David E., Bridges, Mark K.
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Primary Examiner(s)RAHLL, JERRY T
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Application NumberUS13/309,087Publication NumberTime in Patent Office243 DaysField of Search385/13, 356/364US Class Current385/13CPC Class CodesG02B 6/276 Removing selected polarisat...H04B 10/071 using a reflected signal, e...H04B 10/532 Polarisation modulationH04B 10/85 Protection from unauthorise...H04L 63/1416 Event detection, e.g. attac...
