Intrusion detection system for an undersea environment

• US 9,927,263 B2
• Filed: 10/06/2016
• Issued: 03/27/2018
• Est. Priority Date: 07/02/2013
• Status: Active Grant

• Current Assignee: Penn State Research Foundation (Pennsylvania State University)
• Original Assignee: Penn State Research Foundation (Pennsylvania State University)
• Inventors: Young, Randy
• Primary Examiner(s): Lu, Shirley
• Application Number:
  US15/287,013
• Publication Number:
  US 20170023384A1
• Time in Patent Office: 537 Days
• CPC Class Codes: G01D 5/268 using optical fibres G01D5/28 - G01D5/38 take precedence
• CPC Class Codes: G01V 1/001 Acoustic presence detection
• CPC Class Codes: G02B 6/4427 Pressure resistant cables, e.g. undersea cables
• CPC Class Codes: G02B 6/506 Underwater installation
• CPC Class Codes: H02G 1/10 in or under water
• CPC Class Codes: H02G 9/12 supported on or from floats, e.g. in water
• CPC Class Codes: Y10T 428/2933 Coated or with bond, impregnation or core

Abstract

An intrusion detection system includes a suspended optical fiber having a neutral buoyancy and an optical time-domain reflectometer connected to the suspended optical fiber at an origin location. The suspended optical fiber is connected to a mooring at a first end of the suspended optical fiber and further includes at least one terminal end. The optical time-domain reflectometer includes a light source operable to emit an optical pulse of light into the suspended optical fiber from the origin location toward the terminal end, and a processor operable to receive an optical return signal from the terminal end of the suspended optical fiber or from a deformation created by a disturbance to the suspended optical fiber and to determine a location and a type of the disturbance based on an analysis of at least a time to receive the optical return signal and a magnitude of the optical return signal.

Claims

1. An intrusion detection system for determining a location and type of a disturbance in an underwater environment, the intrusion detection system comprising:

a suspended optical fiber having a generally neutral or positive buoyancy and suspended in the underwater environment, the suspended optical fiber having a first end and at least one terminal end, the suspended optical fiber connected to a mooring at the first end of the suspended optical fiber, the optical fiber being free-floating at locations between the first end and the at least one terminal end, the optical fiber being a raw optical fiber including a core, a cladding and a coating or a core and a cladding; and

an optical time-domain reflectometer connected to the suspended optical fiber at an origin location, the optical time-domain reflectometer comprising;

a light source operable to emit an optical pulse of light into the suspended optical fiber from the origin location toward the at least one terminal end of the suspended optical fiber, and

a processor operable to receive an optical return signal from the at least one terminal end of the suspended optical fiber or from a deformation created by the disturbance to the suspended optical fiber, the processor further operable to determine a location and a type of the disturbance based on an analysis of a time to receive the optical return signal, a magnitude of the optical return signal and a waveform shape of the optical return signal;

whereby a continuous suspended sensor is formed and sensing is for detection of the intrusion or disturbance in the underwater environment and is continuous along the entire length of the optical fiber.

2. The intrusion detection system of claim 1, wherein the suspended optical fiber is a composite suspended optical fiber with a length between 1 and 120 miles.

3. The intrusion detection system of claim 1, wherein the mooring is a submersible buoy.

4. The intrusion detection system of claim 3, wherein the optical time-domain reflectometer is a component located on the submersible buoy.

5. The intrusion detection system of claim 1, wherein the mooring is an anchor mooring.

6. The intrusion detection system of claim 1, wherein the optical time-domain reflectometer is positioned at the first end of the suspended optical fiber.

7. The intrusion detection system of claim 1, wherein the optical time-domain reflectometer is positioned at an intermediate location along the suspended optical fiber.

8. The intrusion detection system of claim 1, wherein the suspended optical fiber is one of a plurality of suspended optical fibers.

9. The intrusion detection system of claim 1, wherein the terminal end of the suspended optical fiber is a free end.

10. The intrusion detection system of claim 1, wherein the suspended optical fiber is connected to a second mooring.

11. The intrusion detection system of claim 1, wherein the second mooring is connected to the terminal end.

12. The intrusion detection system of claim 1, wherein a plurality of reflection points are analyzed to determine the type of the disturbance.

20. The intrusion detection system of claim 1, further comprising buoyancy elements attached to the raw optical fiber such that the raw optical fiber is suspended in the underwater environment.

21. The intrusion detection system of claim 20, wherein the buoyance elements are micro particles, a micro particle defined as a particle having a maximum dimension of about 250 microns.

22. The intrusion detection system of claim 21, wherein the micro particles are microspheres.

23. The intrusion detection system of claim 21, wherein the micro particles are coated on an outer surface of the raw optical fiber by an adhesive, the micro particles being in direct contact with the adhesive.

24. The intrusion detection system of claim 21, wherein the adhesive is petroleum jelly.

13. A method of determining a location and a type of disturbance in an underwater environment, comprising the steps of:

providing a continuous sensor, the continuous sensor being a raw optical fiber including a core, a cladding and a coating or a core and a cladding, the optical fiber having a first end and a terminal end;

suspending the optical fiber in the underwater environment, such that the optical fiber is free-floating at locations between the first end and the terminal end; and

sensing a location and a type of the intrusion or disturbance in the underwater environment by;

emitting a pulse of light using a light source of an optical time-domain reflectometer into an origin location of the suspended optical fiber, wherein the optical time-domain reflectometer is connected to the suspended optical fiber at the origin location;

receiving, using the optical time-domain reflectometer, a reflected pulse of light as an optical return signal through the suspended optical fiber, wherein the optical return signal is caused by a deformation to the suspended optical fiber, with the deformation to the suspended optical fiber created by a disturbance; and

determining, with a processor of the optical time-domain reflectometer, the location and the type of the disturbance by analyzing a plurality of parameters of the optical return signal including at least a time to receive the reflected pulse of light and a magnitude of the reflected pulse of light,

whereby the sensing is along the entire length of the optical fiber.

14. The method of claim 13, wherein the disturbance is acoustic or mechanical.

15. The method of claim 13, further comprising the step of attaching buoyancy elements to the raw optical fiber such that the raw optical fiber is suspended in the underwater environment.

16. The method of claim 15, wherein the buoyance elements are micro particles, a micro particle defined as a particle having a maximum dimension of about 250 microns.

17. The method of claim 16, wherein the micro particles are microspheres.

18. The method of claim 16, wherein the micro particles are coated on an outer surface of the raw optical fiber by an adhesive, the micro particles being in direct contact with the adhesive.

19. The method of claim 18, wherein the adhesive is petroleum jelly.