Optical fiber surveillance topology

• US 8,121,442 B2
• Filed: 12/24/2008
• Issued: 02/21/2012
• Est. Priority Date: 12/24/2008
• Status: Active Grant

• Current Assignee: AT&T Intellectual Property I LP (AT&T, Inc.)
• Original Assignee: AT&T Intellectual Property I LP (AT&T, Inc.)
• Inventors: Huffman, John Sinclair, Kirkpatrick, James Francis, Laszakovits, Gerald F.
• Primary Examiner(s): Stahl, Mike
• Application Number:
  US12/343,880
• Publication Number:
  US 20100158431A1
• Time in Patent Office: 1,154 Days
• Field of Search: None
• US Class Current: 385/13
• CPC Class Codes: G01H 9/004 using fibre optic sensors light guides per se G02B6/00, acousto-optical devices specially adapted for gating or modulating in optical wave guides G02F1/125
• CPC Class Codes: G01V 1/001 Acoustic presence detection
• CPC Class Codes: G08B 13/186 using light guides, e.g. optical fibres

Abstract

In accordance with an aspect of the disclosed technology, a fiber surveillance system includes a single optical fiber, used, for example, in the detection of acoustic signals associated with vibrations or other activity. In one embodiment of the disclosed technology, the fiber is arranged in a two dimensional topology to improve the spatial resolution of the system. With such a topology the spatial monitoring resolution of the surveillance system is significantly improved over systems in which the fiber is deployed in an essentially straight line topology. In a further embodiment of the disclosed technology, two or more such oriented fibers are juxtaposed or overlapped to yield even greater resolution.

Claims

1. An optical fiber surveillance system, comprising:

a first optical fiber arranged in a two dimensional topology associated with a two dimensional surface;

a source of optical energy configured to inject the optical energy into the first optical fiber;

an optical detector configured to detect a return optical signal, the return optical signal associated with an acoustic signal impinging on the first optical fiber; and

an analyzer for determining based on characteristics of the return optical signal, a cause of the acoustic signal and a spatial location within the two dimensional surface of the acoustic signal, the analyzer comprising;

a computer readable database comprising backscattered optical signals associated with known sources of acoustic signals impinging on a fiber; and

a processor for comparing the return optical signal to the backscattered optical signals.

2. The system of claim 1 further comprising a second optical fiber arranged in a two dimensional topology and overlapping the first optical fiber.

3. The system of claim 2 wherein the first and second optical fibers are located on an underwater bed of a body of water.

4. The system of claim 3 wherein the first and second optical fibers are located in a coastal area.

5. The system of claim 4 wherein the body of water is a port.

6. The system of claim 5 wherein the first and second fibers are located adjacent to a permanent structure.

7. The system of claim 2 wherein the first and second fibers are in an underground cave.

8. The system of claim 2 wherein the first and second fibers are adjacent to a railroad track.

9. The system of claim 8 wherein the first and second fibers are adjacent to an intersection of the railroad track and another vehicular pathway.

10. The system of claim 8 wherein the first and second fibers are adjacent to an intersection of two railroad tracks.

11. The system of claim 1 wherein the first optical fiber is located within a security perimeter and a second optical fiber is located outside the security perimeter.

14. The system of claim 7 wherein the underground cave is a mine.

18. The system of claim 1 wherein the length of the first optical fiber oriented in a given two dimensional area is greater than a largest diagonal associated with the given two dimensional area.

12. A method for determining a cause and a spatial location of a source of acoustic energy comprising:

receiving, from a fiber arranged in a two dimensional topology, an optical signal associated with the acoustic energy, the two dimensional topology associated with a two dimensional surface; and

analyzing the optical signal received to determine the cause and the spatial location of an acoustic signal, wherein analyzing the optical signal comprises;

accessing a computer readable database comprising backscattered optical signals associated with known sources of acoustic signals impinging on a fiber; and

comparing the optical signal received to the backscattered optical signals.

16. The method of claim 12 wherein the length of the fiber oriented in a given two dimensional area is greater than a largest diagonal associated with the given two dimensional area.

13. A method for determining a cause and a spatial location of a source of acoustic energy comprising:

receiving, from each of a plurality of fibers arranged in a two dimensional topology, an optical signal associated with the acoustic energy, the two dimensional topology associated with a two dimensional surface; and

analyzing optical signals received to determine the spatial location of an acoustic signal, wherein analyzing the optical signal comprises;

accessing a computer readable database comprising backscattered optical signals associated with known sources of acoustic signals impinging on a fiber; and

comparing the optical signal received to the backscattered optical signals.

15. The method of claim 13 where at least two of the plurality of fibers are overlapping.

17. The method of claim 13 wherein the length of each of at least two of the plurality of fibers, when oriented in a given two dimensional area, is greater than a largest diagonal associated with the given two dimensional area.