Methods and systems for locating buried fiber optic cables
First Claim
1. A method of assessing location, above ground, relative to a buried optical fiber cable, comprising the steps of:
- creating a seismic pulse on the ground at a first location;
detecting rotation of a polarization state of light transmitted through the optical fiber cable relative to the first location;
creating a seismic pulse on the ground at one or more additional locations;
detecting rotation of a polarization state of light transmitted through the optical fiber cable relative to the additional locations; and
determining a closest location to the buried cable based upon an amount of rotation in the polarization state.
1 Assignment
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Accused Products
Abstract
The invention provides for assessing location and/or proximity to a buried or submerged optical fiber cable. A seismic generator creates seismic pulses, at known frequencies, on the ground (or water) at a first location and the synchronous rotation of the polarization state of light transmitted through the optical fiber cable is detected. Other seismic pulses are generated at different locations and the polarization rotation is detected at each such location to locate a closest proximity to the cable, corresponding to a minimum or maximum of polarization rotation. A wireless synchronous signal is generated with the seismic pulses to differentially isolate the polarization rotation signal; and, if desired, to further determine distance between the cable and the source of the seismic pulse.
47 Citations
30 Claims
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1. A method of assessing location, above ground, relative to a buried optical fiber cable, comprising the steps of:
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creating a seismic pulse on the ground at a first location;
detecting rotation of a polarization state of light transmitted through the optical fiber cable relative to the first location;
creating a seismic pulse on the ground at one or more additional locations;
detecting rotation of a polarization state of light transmitted through the optical fiber cable relative to the additional locations; and
determining a closest location to the buried cable based upon an amount of rotation in the polarization state. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A method of assessing distance above a surface to an optical fiber cable below the surface, comprising the steps of:
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creating a seismic pulse on the surface and generating a telecommunications signal synchronously with the seismic pulse;
detecting, at a first time, rotation of a polarization state of light transmitted through the optical fiber cable;
detecting, at a second time, receipt of the telecommunications signal; and
comparing the first and second times to determine the distance. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23)
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24. A system for determining distance above a surface to an optical cable below the surface, comprising:
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a seismic noise generator for generating seismic pulses on the ground at a select frequency;
an optical tap connected with the cable; and
a polarization selective element and an optical detector for sensing a polarization state of light transmitted through the cable and the optical tap, wherein a maximum of the polarization state determines closest proximity of the generator above the ground to the cable. - View Dependent Claims (25, 26)
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27. A system for determining distance, above a surface, to an optical cable below the surface, comprising:
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a seismic noise generator for generating seismic pulses on the surface at a select frequency;
a telecommunications device for generating a telecommunications signal synchronously with the pulses;
an optical tap connected with the cable;
a polarization selective element and an optical detector for sensing a polarization state of light transmitted through the cable and the optical tap at a first time;
a detector for receiving the telecommunications signal at a second time; and
synchronization electronics to improve detection of polarization states with respect to external noise and to quantify a time difference between the first and second times to determine the distance. - View Dependent Claims (28, 29)
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30. A method of assessing location, above water, relative to a submerged optical fiber cable having at least one terminal, comprising the steps of:
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creating a seismic pulse on the water at a first location;
detecting rotation of a polarization state of light transmitted through the optical fiber cable relative to the first location;
generating a seismic pulse in the water at one or more additional locations; and
detecting rotation of a polarization state of light transmitted through the optical fiber cable relative to the additional locations; and
determining a closest location to the buried cable based upon an amount of rotation in the polarization state.
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Specification