Methods, apparatuses, systems and computer readable mediums for determining location of assets

• US 9,107,057 B2
• Filed: 03/15/2013
• Issued: 08/11/2015
• Est. Priority Date: 03/15/2013
• Status: Active Grant

• Current Assignee: Cornerturn LLC
• Original Assignee: Cornerturn LLC
• Inventors: Borrell, Ronald A., Gilbert, Harold C., Cox, Michael W.
• Primary Examiner(s): Figueroa, Marisol
• Application Number:
  US13/839,620
• Publication Number:
  US 20140273918A1
• Time in Patent Office: 879 Days
• Field of Search: 4554561-457
• US Class Current: 1/1
• CPC Class Codes: G01S 5/0018 Transmission from mobile station to base station
• CPC Class Codes: G01S 5/0036 of measured values, i.e. measurement on mobile and position calculation on base station
• CPC Class Codes: H04W 4/02 Services making use of location information
• CPC Class Codes: H04W 4/029 Location-based management or tracking services
• CPC Class Codes: H04W 4/90 Services for handling of emergency or hazardous situations, e.g. earthquake and tsunami warning systems [ETWS]

Abstract

In locating a transmitter, a central processor calculates a matched filter detector output for each of one or more candidate transmitter locations by applying a linear filter to low frequency magnetic field measurements obtained at a plurality of receiver locations. The central processor then determines the location of the transmitter based on the one or more calculated matched filter detector outputs. The linear filter is derived for the one or more candidate transmitter locations.

Claims

1. A method for locating a transmitter, the method comprising:

calculating a matched filter detector output for each of one or more candidate transmitter locations by applying a linear filter to low frequency magnetic field measurements obtained at a plurality of receiver locations, the linear filter being derived for the one or more candidate transmitter locations, and the matched filter detector output being a polynomial function representing the one or more candidate transmitter locations;

generating a plurality of contour values associated with the one or more candidate transmitter locations based on the one or more calculated matched filter detector outputs; and

determining the location of the transmitter based on the plurality of contour values for the one or more calculated matched filter detector outputs.

2. The method of claim 1, further comprising:

hypothesizing a search domain including the one or more candidate transmitter locations.

3. The method of claim 1, wherein the determining the location of the transmitter comprises:

identifying the location of the transmitter as the candidate location associated with a maximum matched filter detector output among the one or more calculated matched filter detector outputs.

4. The method of claim 3, wherein the determining the location of the transmitter further comprises:

comparing the one or more calculated matched filter detector outputs to determine the maximum matched filter detector output among the one or more calculated matched filter detector outputs.

5. The method of claim 1, wherein the plurality of contour values form a localization contour associated with the one or more candidate transmitter locations, and wherein the location of the transmitter is determined based on the localization contour.

6. The method of claim 1, wherein the transmitter is determined to be located at the candidate location having a maximum contour value among the plurality of contour values.

7. The method of claim 1, wherein

the polynomial function represents a plurality of candidate transmitter locations for the transmitter;

the generating includes evaluating the polynomial function for each of the plurality of candidate transmitter locations to generate the plurality of contour values, each of the plurality of contour values being associated with a candidate location among the plurality of candidate transmitter locations; and

the determining includes identifying the location of the transmitter based on the plurality of contour values.

8. The method of claim 7, wherein the location of the transmitter is identified as the candidate location among the plurality of candidate transmitter locations having a maximum contour value among the plurality of contour values.

9. The method of claim 1, further comprising:

at least one of displaying and storing the location of the transmitter.

10. The method of claim 1, wherein the low frequency magnetic field measurements are generated based on magnetic field signals having frequencies between about 30 kHz and about 130 kHz.

11. The method of claim 1, wherein the linear filter is determined based on a propagation model associated with the one or more candidate transmitter locations, and wherein the propagation model does not include a complex image component.

12. The method of claim 1, wherein the linear filter is determined based on a propagation model associated with the one or more candidate transmitter locations, and wherein the propagation model does not account for effects defined by complex image theory.

13. A method for locating a transmitter, the method comprising:

maximizing a localization statistic by applying a linear filter to low frequency magnetic field measurements obtained at a plurality of receiver locations, the linear filter being determined based on a propagation model associated with one or more candidate transmitter locations, and the localization statistic being a polynomial function representing the one or more candidate transmitter locations;

generating a plurality of contour values associated with the one or more candidate transmitter locations based on the maximized location statistic; and

locating the transmitter based on the plurality of contour values associated with the one or more candidate transmitter locations.

14. The method of claim 13, wherein the plurality of contour values form a localization contour associated with the one or more candidate transmitter locations, and wherein the location of the transmitter is determined based on the localization contour.

15. The method of claim 13, wherein the transmitter is determined to be located at the candidate location having a maximum contour value among the plurality of contour values.

16. An apparatus for locating a transmitter, the apparatus comprising:

a central processor configured to

calculate a matched filter detector output for each of one or more candidate transmitter locations by applying a linear filter to low frequency magnetic field measurements obtained at a plurality of receiver locations, the linear filter being derived for the one or more candidate transmitter locations, and the matched filter detector output being a polynomial function representing the one or more candidate transmitter locations;

generate a plurality of contour values associated with the one or more candidate transmitter locations based on the one or more calculated matched filter detector outputs; and

determine the location of the transmitter based on the plurality of contour values for the one or more calculated matched filter detector outputs.

17. The apparatus of claim 16, wherein the central processor is further configured to hypothesize a search domain including the one or more candidate transmitter locations.

18. The apparatus of claim 16, wherein the central processor is configured to identify the location of the transmitter as the candidate location associated with a maximum matched filter detector output among the one or more calculated matched filter detector outputs.

19. The apparatus of claim 18, wherein the central processor is configured to compare the one or more calculated matched filter detector outputs to determine the maximum matched filter detector output among the one or more calculated matched filter detector outputs.

20. The apparatus of claim 16, wherein the plurality of contour values form a localization contour associated with the one or more candidate transmitter locations, and wherein the central processor is configured to determine the location of the transmitter based on the localization contour.

21. The apparatus of claim 16, wherein the transmitter is located at the candidate location having a maximum contour value among the plurality of contour values.

22. The apparatus of claim 16, wherein

the polynomial function represents a plurality of candidate transmitter locations for the transmitter;

and

the central processor is configured to,

evaluate the polynomial function for each of the plurality of candidate transmitter locations to generate the plurality of contour values, each of the plurality of contour values being associated with a candidate location among the plurality of candidate transmitter locations, and

identify the location of the transmitter based on the plurality of contour values.

23. The apparatus of claim 16, further comprising:

a display configured to display the location of the transmitter.

24. The apparatus of claim 16, further comprising:

a data storage configured to store the location of the transmitter.

25. The apparatus of claim 16, wherein the low frequency magnetic field measurements are generated based on magnetic field signals having frequencies between about 30 kHz and about 130 kHz.

26. The apparatus of claim 16, wherein the linear filter is determined based on a propagation model associated with the one or more candidate transmitter locations, and wherein the propagation model does not include a complex image component.

27. The apparatus of claim 16, wherein the linear filter is determined based on a propagation model associated with the one or more candidate transmitter locations, and wherein the propagation model does not account for effects defined by complex image theory.

28. An apparatus for locating a transmitter, the apparatus comprising:

a central processor configured to

maximize a localization statistic by applying a linear filter to low frequency magnetic field measurements obtained at a plurality of receiver locations, the linear filter being determined based on a propagation model associated with one or more candidate transmitter locations, and the localization statistic being a polynomial function representing the one or more candidate transmitter locations;

generate a plurality of contour values associated with the one or more candidate transmitter locations based on the maximized location statistic; and

locate the transmitter based on the plurality of contour values associated with the one or more candidate transmitter locations.

29. The apparatus of claim 28, wherein the plurality of contour values form a localization contour associated with the one or more candidate transmitter locations, and wherein the central processor is configured to determine the location of the transmitter based on the localization contour.

30. A non-transitory computer readable storage medium storing instructions that, when executed, cause a processor to perform a method for locating a transmitter, the method comprising:

calculating a matched filter detector output for each of one or more candidate transmitter locations by applying a linear filter to low frequency magnetic field measurements obtained at a plurality of receiver locations, the linear filter being derived for the one or more candidate transmitter locations, and the matched filter detector output being a polynomial function representing the one or more candidate transmitter locations;

generating a plurality of contour values associated with the one or more candidate transmitter locations based on the one or more calculated matched filter detector outputs; and

determining the location of the transmitter based on the plurality of contour values for the one or more calculated matched filter detector outputs.

31. The computer readable storage medium of claim 30, wherein the method further comprises:

hypothesizing a search domain including the one or more candidate transmitter locations.

32. The computer readable storage medium of claim 30, wherein the determining the location of the transmitter comprises:

identifying the location of the transmitter as the candidate location associated with a maximum matched filter detector output among the one or more calculated matched filter detector outputs.

33. The computer readable storage medium of claim 32, wherein the determining the location of the transmitter further comprises:

comparing the one or more calculated matched filter detector outputs to determine the maximum matched filter detector output among the one or more calculated matched filter detector outputs.

34. The computer readable storage medium of claim 30, wherein the plurality of contour values form a localization contour associated with the one or more candidate transmitter locations, and wherein the location of the transmitter is determined based on the localization contour.

35. The computer readable storage medium of claim 30, wherein the transmitter is determined to be located at the candidate location having a maximum contour value among the plurality of contour values.

36. The computer readable storage medium of claim 30, wherein

the polynomial function represents a plurality of candidate transmitter locations for the transmitter;

the generating includes evaluating the polynomial function for each of the plurality of candidate transmitter locations to generate the plurality of contour values, each of the plurality of contour values being associated with a candidate location among the plurality of candidate transmitter locations; and

the determining includes identifying the location of the transmitter based on the plurality of contour values.

37. The computer readable storage medium of claim 36, wherein the location of the transmitter is identified as the candidate location among the plurality of candidate transmitter locations having a maximum contour value among the plurality of contour values.

38. The computer readable storage medium of claim 30, wherein the method further comprises:

at least one of displaying and storing the location of the transmitter.

39. The computer readable storage medium of claim 30, wherein the low frequency magnetic field measurements are generated based on magnetic field signals having frequencies between about 30 kHz and about 130 kHz.

40. The computer readable storage medium of claim 30, wherein the linear filter is determined based on a propagation model associated with the one or more candidate transmitter locations, and wherein the propagation model does not include a complex image component.

41. The computer readable storage medium of claim 30, wherein the linear filter is determined based on a propagation model associated with the one or more candidate transmitter locations, and wherein the propagation model does not account for effects defined by complex image theory.

42. A non-transitory computer readable storage medium storing instructions that, when executed, cause a processor to perform a method for locating a transmitter, the method comprising:

maximizing a localization statistic by applying a linear filter to low frequency magnetic field measurements obtained at a plurality of receiver locations, the linear filter being determined based on a propagation model associated with one or more candidate transmitter locations, and the localization statistic being a polynomial function representing the one or more candidate transmitter locations;

generating a plurality of contour values associated with the one or more candidate transmitter locations based on the maximized location statistic; and

locating the transmitter based on the plurality of contour values associated with the one or more candidate transmitter locations.

43. The computer readable medium of claim 42, wherein the plurality of contour values form a localization contour associated with the one or more candidate transmitter locations, and wherein the location of the transmitter is determined based on the localization contour.

44. The computer readable medium of claim 42, wherein the transmitter is determined to be located at the candidate location having a maximum contour value among the plurality of contour values.