System and Method for Three-Dimensional Geolocation of Emitters Based on Energy Measurements

• US 20120235864A1
• Filed: 03/16/2011
• Published: 09/20/2012
• Est. Priority Date: 03/16/2011
• Status: Active Grant

• Current Assignee: Harris Global Communications, Inc. (L3Harris Technologies, Inc.)
• Original Assignee: ITT Manufacturing Enterprises, Inc. (ITT, Inc.)
• Inventors: Lu, Ning Hsing
• Granted Patent: US 8,878,726 B2
• Time in Patent Office: Days
• US Class Current: 342/451
• CPC Class Codes: G01S 11/06 using intensity measurements
• CPC Class Codes: G01S 5/0249 Determining position using measurements made by a non-stationary device other than the device whose position is being determined
• CPC Class Codes: G01S 5/0289 of multiple transceivers, e.g. in ad hoc networks

Abstract

According to an embodiment of the present invention, a three-dimensional (3-D) energy-based emitter geolocation technique determines the geolocation of a radio frequency (RF) emitter based on energy or received signal strength (RSS) of transmitted signals. The technique may be employed with small unmanned air vehicles (UAV), and obtains reliable geolocation estimates of radio frequency (RF) emitters of interest.

Claims

1. A system for locating an emitter within an area comprising:

a receiver to receive signals transmitted by said emitter and obtain measurements of signal strength for said received signals at a plurality of different locations within said area; and

a processor to process said signal strength measurements to locate said emitter within said area, wherein said processor includes;

a location module to process said signal strength measurements and determine a three-dimensional location of said emitter within said area based on relationships of distances between said emitter and each of said plurality of locations, wherein said distances are unknown, said signal strength measurements are proportional to said unknown distances, and said location module includes;

a variable module to determine said three-dimensional location by solving a set of simultaneous equations relating to said distances, wherein said set of simultaneous equations includes a first set of variables including values for coordinates of said plurality of locations, a second set of variables including values for distances between a reference origin in said area and said plurality of locations, a third set of variables representing said unknown distances between said emitter and said plurality of locations, and unknown variables representing coordinates of said three-dimensional location of said emitter within said area, and wherein said third set of variables representing said unknown distances within said set of simultaneous equations includes values that are approximated by corresponding signal strength measurements to solve for said unknown variables and determine said three-dimensional location.

3. The system of claim 1, wherein said variable module solves said set of simultaneous equations using a Least Mean Square technique.

6. The system of claim 1, wherein said location module includes:

a parameter module to determine a parameter for said set of simultaneous equations based on said signal strength measurements.

7. The system of claim 6, wherein said parameter is based on a ratio of said signal strength measurements.

8. The system of claim 1, wherein said set of simultaneous equations includes:

9. The system of claim 1, wherein said signals transmitted by said emitter include radio frequency signals.

10. The system of claim 1, wherein said receiver is mounted on a mobile platform that traverses a pre-planned path through said area to obtain said signal strength measurements at said plurality of locations.

11. The system of claim 10, wherein said mobile platform includes an unmanned air vehicle.

12. The system of claim 1, further including a plurality of receivers each mounted on a stationary platform at a corresponding one of said plurality of locations to obtain said signal strength measurements.

2. (canceled)

4-5. -5. (canceled)

13. A method for locating an emitter within an area comprising:

(a) receiving signals transmitted by said emitter via a receiver and obtaining measurements of signal strength for said received signals at a plurality of different locations within said area; and

(b) processing said signal strength measurements, via a processor, and determining a three-dimensional location of said emitter within said area based on relationships of distances between said emitter and each of said plurality of locations, wherein said distances are unknown, said measurements are proportional to said unknown distances, and step (b) further includes;

(b.1) determining said three-dimensional location by solving a set of simultaneous equations relating to said distances, wherein said set of simultaneous equations includes a first set of variables including values for coordinates of said plurality of locations, a second set of variables including values for distances between a reference origin in said area and said plurality of locations, a third set of variables representing said unknown distances between said emitter and said plurality of locations, and unknown variables representing coordinates of said three-dimensional location of said emitter within said area, and wherein said third set of variables representing said unknown distances within said set of simultaneous equations includes values that are approximated by corresponding signal strength measurements to solve for said unknown variables and determine said three-dimensional location.

15. The method of claim 13, wherein step (b.1) further includes:

(b.1.1) solving said set of simultaneous equations using a Least Mean Square technique.

18. The method of claim 13, wherein step (b) further includes:

determining a parameter for said set of simultaneous equations based on said signal strength measurements.

19. The method of claim 18, wherein said parameter is based on a ratio of said signal strength measurements.

20. The method of claim 13, wherein said set of simultaneous equations includes:

21. The method of claim 13, wherein said signals transmitted by said emitter include radio frequency signals.

22. The method of claim 13, wherein said receiver is mounted on a mobile platform, and step (a) further includes:

(a.1) traversing a pre-planned path through said area with said mobile platform to obtain said signal strength measurements at said plurality of locations.

23. The method of claim 22, wherein said mobile platform includes an unmanned air vehicle.

24. The method of claim 13, further including a plurality of receivers each mounted on a stationary platform at a corresponding one of said plurality of locations, and step (a) further includes:

(a.1) obtaining said signal strength measurements via said receivers on said stationary platforms at said corresponding ones of said plurality of locations.

14. (canceled)

16-17. -17. (canceled)

25. A program product apparatus comprising a computer readable medium with computer program logic recorded thereon for locating an emitter within an area, said program product apparatus further comprising:

a location module to process signal strength measurements of signals transmitted by said emitter and obtained at a plurality of different locations within said area and to determine a three-dimensional location of said emitter within said area based on relationships of distances between said emitter and each of said plurality of locations, wherein said distances are unknown, said measurements are proportional to said unknown distances, and said location module includes;

a variable module to determine said three-dimensional location by solving a set of simultaneous equations relating to said distances, wherein said set of simultaneous equations includes a first set of variables including values for coordinates of said plurality of locations, a second set of variables including values for distances between a reference origin in said area and said plurality of locations, a third set of variables representing said unknown distances between said emitter and said plurality of locations, and unknown variables representing coordinates of said three-dimensional location of said emitter within said area, and wherein said third set of variables representing said unknown distances within said set of simultaneous equations includes values that are approximated by corresponding signal strength measurements to solve for said unknown variables and determine said three-dimensional location.

27. The apparatus of claim 25, wherein said variable module solves said set of simultaneous equations using a Least Mean Square technique.

30. The apparatus of claim 25, wherein said location module includes:

a parameter module to determine a parameter for said set of simultaneous equations based on said signal strength measurements.

31. The apparatus of claim 30, wherein said parameter is based on a ratio of said signal strength measurements.

32. The apparatus of claim 25, wherein said set of simultaneous equations includes:

33. The apparatus of claim 25, wherein said signals transmitted by said emitter include radio frequency signals.

26. (canceled)

28-29. -29. (canceled)