Optical Fiber Surveillance Topology

• US 20100158431A1
• Filed: 12/24/2008
• Published: 06/24/2010
• 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: Kirkpatrick, James Francis, Laszakovits, Gerald F., Huffman, John Sinclair
• Granted Patent: US 8,121,442 B2
• Time in Patent Office: Days
• US Class Current: 385/12
• 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;

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

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

an analyzer for determining, based on the characteristics of the return signal, the location along the fiber of the acoustic signal.

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

3. The system of claim 2 wherein the fibers are located on the underwater bed of a body of water.

4. The system of claim 3 wherein the 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 fibers are located adjacent to a permanent structure.

7. They system of claim 2 wherein the fibers are in an underground cave.

8. They system of claim 2 wherein the fibers are adjacent to a railroad track.

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

10. The system of claim 8 wherein the fibers are in adjacent to the intersection of two railroad tracks.

11. The system of claim 2 further comprising a database of backscattered optical signals associated with known sources of acoustic signals impinging on a fiber.

12. They system of claim 11 further comprising a computer for comparing a signal in the database with a received backscattered signal

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

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

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

14. A method for determining the 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; and

analyzing the received signal to determine the geographic location of the acoustic signal.

18. The method of claim 14 wherein the length of the fiber oriented in a given two dimensional area is greater than the largest diagonal associated with the given two dimensional area.

15. A method for determining the 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; and

analyzing the received signals to determine the geographic location of the acoustic signal.

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

19. The method of claim 15 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 the largest diagonal associated with the given two dimensional area.