Long distance optical fiber sensing system and method

• US 8,937,713 B2
• Filed: 11/14/2013
• Issued: 01/20/2015
• Est. Priority Date: 09/28/2009
• 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
• Primary Examiner(s): Stock, Jr., Gordon J
• Application Number:
  US14/080,011
• Publication Number:
  US 20140090474A1
• Time in Patent Office: 432 Days
• Field of Search: None
• US Class Current: 356/73.1
• CPC Class Codes: G01D 5/35358 using backscattering to detect the measured quantity
• CPC Class Codes: G01D 5/35374 Particular layout of the fiber
• 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: G01M 11/3109 Reflectometers detecting the back-scattered light in the time-domain, e.g. OTDR
• CPC Class Codes: G01M 11/3136 for testing of multiple fibers
• CPC Class Codes: G01S 17/04 Systems determining the presence of a target
• CPC Class Codes: G01S 17/26 wherein the transmitted pulses use a frequency-modulated or phase-modulated carrier wave, e.g. for pulse compression of received signals
• CPC Class Codes: G01S 17/88 Lidar systems specially adapted for specific applications
• CPC Class Codes: G01V 1/001 Acoustic presence detection
• CPC Class Codes: G08B 13/124 with the breaking or disturbance being optically detected, e.g. optical fibers in the perimeter fence

Abstract

A long-distance fiber optic monitoring system having a sensing unit and an analyzer that is remotely located from the sensing unit is provided. The sensing unit comprises a source of optical energy for injecting optical energy into the fiber optical cable and an optical detector configured to detect an optical return signal from the optical fiber. The detected optical return signal is associated with an acoustic signal impinging on the optical fiber. The analyzer receives a signal from the remote sensing unit via the optical fiber that is representative of the optical return signal, and determines a location of a disturbance based at least on the received signal. The representative signal can be transmitted from the remote sensing unit to the analyzer as an optical signal or via a metallic wired included with the optical fiber.

Claims

1. A method for determining a location of acoustic disturbances of a first optical fiber comprising:

injecting, by a remote sensing unit of a monitoring system, optical energy into the first optical fiber of a plurality of optical fibers having an overlapping point;

receiving, by the remote sensing unit, an optical return signal via the first optical fiber;

generating, by the remote sensing unit, a representative signal comprising a plurality of features of the optical return signal, the plurality of features associated with acoustic disturbances impinging on the first optical fiber; and

transmitting, by the remote sensing unit, the representative signal to an analysis engine of the monitoring system.

2. The method of claim 1, further comprising:

determining locations of the acoustic disturbances based on an analysis of the representative signal.

3. The method of claim 2, further comprising:

determining one of a path of travel and a velocity of motion based on the locations of the acoustic disturbances.

4. The method of claim 1, further comprising:

water-cooling the remote sensing unit.

5. The method of claim 1, wherein the transmitting the representative signal comprises:

transmitting the representative signal over a metallic wire of the first optical fiber.

6. The method of claim 1, wherein the transmitting the representative signal, comprises:

transmitting the representative signal as an encoded signal.

7. An apparatus for determining a location of acoustic disturbances of a first optical fiber comprising:

a processor; and

a memory to store computer program instructions, the computer program instructions when executed on the processor cause the processor to perform operations comprising;

injecting optical energy into the first optical fiber of a plurality of optical fibers having an overlapping point;

receiving an optical return signal via the first optical fiber;

generating a representative signal comprising a plurality of features of the optical return signal, the plurality of features associated with acoustic disturbances impinging on the first optical fiber; and

transmitting the representative signal to an analysis engine.

8. The apparatus of claim 7, wherein the analysis engine determines locations of the acoustic disturbances based on an analysis of the representative signal.

9. The apparatus of claim 7, wherein the plurality of optical fibers is deployed in a multi-dimensional layout.

10. The apparatus of claim 8, wherein the analysis engine further determines one of a path of travel and a velocity of motion based on the locations of the acoustic disturbances.

11. The apparatus of claim 7, wherein the transmitting the representative signal comprises:

transmitting the representative signal over a metallic wire of the first optical fiber.

12. The apparatus of claim 7, wherein the transmitting the representative signal, comprises:

transmitting the representative signal as an encoded signal.

13. A system for determining a location of acoustic disturbances of a first optical fiber, the system coupled to a plurality of optical fibers having an overlapping point, the system comprising:

an underwater housing;

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

a detector to detect an optical return signal received via the first optical fiber;

a processor; and

a memory to store computer program instructions, the computer program instructions when executed on the processor cause the processor to perform operations comprising;

generating a representative signal comprising a plurality of features of the optical return signal, the plurality of features associated with acoustic disturbances impinging on the first optical fiber; and

transmitting the representative signal.

14. The system of claim 13, further comprising a cooling system.

15. The system of claim 14, wherein the cooling system comprises a plurality of intake ports and a plurality of exhaust ports.

16. The system of claim 15, wherein the plurality of intake ports filters water for impurities.

17. The system of claim 13, wherein the underwater housing is a pressure-resistant housing.

18. The system of claim 13, wherein the representative signal is transmitted over a metallic wire of the first optical fiber.

19. The system of claim 13, wherein the representative signal is transmitted as an encoded signal.