Method and apparatus for fiber optic signature recognition
AssigneeAT&T Intellectual Property II, L.P.
InventorsJohn Huffman, Peter Cornell
Life of this patent
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Abstract
A method and apparatus is disclosed for use in fiber optic signature recognition to analyze buried optical fiber to identify a non-threat area along a fiber route and to discontinue monitoring for disturbances along that area of the cable route. The technique includes determining the location of the zone of non-threatening disturbances from comparing an optical signal to the representation of a prearranged optical signal identified as friendly. Once a zone of non-threatening disturbances is identified, all subsequent disturbances in that zone are considered friendly. Cable monitoring is discontinued in the identified zone of non-threatening disturbances so as to avoid monitoring fiber cable when permitted workers are in the area.
Claims17
A perimeter security device comprising:
- a buried optical fiber cable having a predetermined length wherein a path of the buried optical fiber cable defines a secured perimeter;
- a fiber threat analysis system comprising:
- a light source and detector configured to couple to the buried optical fiber cable and send a series of optical pulses into the buried optical fiber cable and receive returned optical signals from points within the length of the buried optical fiber cable;
- a memory configured to store prearranged optical signals;
- and
- a processor coupled to the light source and detector and to the memory configured to use an approximation algorithm to take into account soil packing conditions around the length of the buried optical fiber cable and to identify sections of the buried optical fiber cable as threatened or non threatened, wherein ground disturbances along the path of the buried optical fiber cable manifest low frequency ground vibrations which are impressed at sections of the buried optical fiber cable and affect the returned optical signals;
- the low frequency vibrations manifested by the ground disturbances being analyzed using the approximation algorithm.
A method for perimeter security comprising:
- burying an optical fiber cable having a predetermined length wherein a path of the buried optical fiber cable defines a secured perimeter;
- storing prearranged optical signals representing low frequency ground vibration patterns;
- sending a series of optical pulses into the buried optical fiber cable;
- receiving returned optical signals from points within the length of the buried optical fiber cable, wherein ground disturbances along the path of the buried optical fiber cable manifest low frequency ground vibrations which are impressed at sections of the buried optical fiber cable and affect the returned optical signals;
- analyzing the returned optical signals to detect the low frequency ground vibrations using an approximation algorithm taking into account soil packing conditions around the buried optical fiber cable;
- comparing the returned optical signals with the stored prearranged optical signals;
- and
- identifying sections of the buried optical fiber cable as threatened or non threatened.
Dependencies are inferred from the claim text.