Long distance optical fiber sensing system and method

• US 8,610,886 B2
• Filed: 11/27/2012
• Issued: 12/17/2013
• 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:
  US13/686,329
• Publication Number:
  US 20130081472A1
• Time in Patent Office: 385 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 of determining locations of acoustic disturbances of an optical fiber, the method comprising:

injecting, at a remote sensing unit of a monitoring system, optical energy having a first wavelength into a first optical fiber deployed in a multi-dimensional layout, the multi-dimensional layout comprising a plurality of optical fibers, wherein the plurality of optical fibers has an overlapping point;

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

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

transmitting, by the remote sensing unit, to an analysis engine of the monitoring system the representative signal as an encoded signal; and

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

2. The method of claim 1, further comprising:

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

3. The method of claim 1, wherein the remote sensing unit is water-cooled.

4. The method of claim 1, wherein the transmitting, by the remote sensing unit, to an analysis engine of the monitoring system the representative signal as an encoded signal comprises:

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

5. The method of claim 1, wherein the transmitting, by the remote sensing unit, to an analysis engine of the monitoring system the representative signal as an encoded signal comprises:

transmitting the representative signal as an encoded signal having a second wavelength, wherein the second wavelength differs from the first wavelength.

6. An apparatus 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, at a remote sensing unit of a monitoring system, optical energy having a first wavelength into a first optical fiber deployed in a multi-dimensional layout, the multi-dimensional layout comprising a plurality of optical fibers, wherein the plurality of optical fibers has an overlapping point;

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

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

transmitting, by the remote sensing unit, to an analysis engine of the monitoring system the representative signal as an encoded signal; and

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

7. The apparatus of claim 6, the operations further comprising:

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

8. The apparatus of claim 6, wherein the transmitting, by the remote sensing unit, to an analysis engine of the monitoring system the representative signal as an encoded signal comprises:

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

9. The apparatus of claim 6, wherein the remote sensing unit is water-cooled.

10. The apparatus of claim 6, wherein:

one of the plurality of optical fibers is associated with a first set of instrumentation;

one other of the plurality of optical fibers is associated with a second set of instrumentation; and

the first set of instrumentation differs from the second set of instrumentation.

11. The apparatus of claim 10, wherein each of the first set of instrumentation and the second set of instrumentation comprises:

a splitter-combiner;

an optical energy source;

a detector comprising a first antenna; and

a wireless receiver comprising a second antenna, wherein the detector communicates with the wireless receiver via the first antenna and the second antenna.

12. A tangible non-transitory computer readable medium storing computer program instructions, which, when executed on a processor, cause the processor to perform operations comprising:

injecting, at a remote sensing unit of a monitoring system, optical energy having a first wavelength into a first optical fiber deployed in a multi-dimensional layout, the multi-dimensional layout comprising a plurality of optical fibers, wherein the plurality of optical fibers has an overlapping point;

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

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

transmitting, by the remote sensing unit, to an analysis engine of the monitoring system the representative signal as an encoded signal; and

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

13. The tangible non-transitory computer readable medium of claim 12, the operations further comprising:

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