Portable, iterative geolocation of RF emitters

• US 20080158059A1
• Filed: 12/27/2006
• Published: 07/03/2008
• Est. Priority Date: 12/27/2006
• Status: Active Grant

• Current Assignee: Skyhook Holding, Inc. (Liberty Broadband Corp.)
• Original Assignee: TruePosition Incorporated
• Inventors: Anderson, Robert J., Bull, Jeffrey F., Lefever, Ronald S.
• Granted Patent: US 7,616,155 B2
• Time in Patent Office: Days
• US Class Current: 342/387
• CPC Class Codes: G01S 5/0072 Transmission between mobile stations, e.g. anti-collision systems
• CPC Class Codes: G01S 5/06 Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements G01S5/12 takes precedence

Abstract

Iterative geolocation of a stationary RF emitter through the use of TDOA may include the use of a single portable geolocation (e.g., TDOA) sensor, a pair of portable geolocation sensors and three of more portable geolocation sensors. Adding portable geolocation sensors to the iterative process reduces the constraints on the signals to be located as well as providing a reduction in the number of iterations required to obtain improved location accuracy.

Claims

1. A portable geolocation sensor, comprising:

a timing signal receiver for receiving timing signals;

a tunable wideband receiver, operatively coupled to said timing signal receiver, for receiving and processing signals from an emitter of interest (EOI);

a signal processor, operatively coupled to said tunable wideband receiver, for time stamping transmissions from the EOI; and

a portable housing enclosing said timing signal receiver, tunable wideband receiver and signal processor.

2. A portable geolocation sensor as recited in claim 1, wherein said timing signal receiver is coupled to said tunable wideband receiver by a digital communications link.

3. A portable geolocation sensor as recited in claim 1, wherein said tunable wideband receiver comprises a wideband digital receiver.

4. A portable geolocation sensor as recited in claim 1, wherein said tunable wideband receiver is configured to receive transmissions from an EOI that comprises a base transceiver station (BTS) of a wireless communications system.

5. A portable geolocation sensor as recited in claim 1, wherein said timing signal receiver is configured to receive GNSS signals from a satellite-based navigation system, and to provide an accurate sampling clock signal.

6. A portable geolocation sensor as recited in claim 1, wherein said timing signal receiver is configured to provide a stable frequency reference to said signal processor, and wherein said signal processor is configured to use said frequency reference to characterize the timing and frequency stability of the EOI transmissions.

7. A portable geolocation sensor as recited in claim 1, wherein said tunable wideband receiver and signal processor are configured to receive, time stamp, store and process received transmissions from the EOI.

8. A portable geolocation sensor as recited in claim 1, further comprising a communications link (207) for communicating with a controller and display device (203).

9. A portable geolocation sensor as recited in claim 8, wherein said controller and display device is configured to provide a means by which a user can control the portable geolocation sensor, to display the location of the EOI, and to provide guidance on the direction and distance the user can move to enhance the location accuracy on a subsequent data acquisition cycle.

10. A portable geolocation sensor as recited in claim 1, further comprising a communications transceiver configured to permit communications with a second portable geolocation sensor.

11. A portable geolocation sensor as recited in claim 1, wherein said timing signal receiver is further configured to serve as an Assisted-GPS/GNSS server and to send GPS/GNSS aiding data to assist a second portable geolocation sensor in acquiring GPS/GNSS signals.

12. A portable geolocation sensor as recited in claim 10, wherein said communications transceiver comprises a mesh communications transceiver.

13. A portable geolocation sensor as recited in claim 1, wherein said portable geolocation sensor is configured to determine its location by using said timing signal receiver to receive signals from a Global Positioning System (GPS) or Global Navigation Satellite System (GNSS).

14. A portable geolocation sensor as recited in claim 1:

wherein said timing signal receiver is coupled to said tunable wideband receiver by a digital communications link;

wherein said tunable wideband receiver comprises a wideband digital receiver and is configured to receive transmissions from an EOI that comprises a base transceiver station (BTS) of a wireless communications system;

wherein said timing signal receiver is configured to receive GPS signals from a satellite-based navigation system, and to provide an accurate sampling clock signal;

wherein said timing signal receiver is configured to provide a stable frequency reference to said signal processor, and wherein said signal processor is configured to use said frequency reference to characterize the timing and frequency stability of the EOI transmissions;

wherein said tunable wideband receiver and signal processor are configured to receive, time stamp, store and process received transmissions from the EOI;

further comprising a communications link for communicating with a controller and display device;

wherein said controller and display device is configured to provide a means by which a user can control the portable geolocation sensor, to display the location of the EOI, and to provide guidance on the direction and distance the user can move to enhance the location accuracy on a subsequent data acquisition cycle; and

further comprising a communications transceiver configured to permit communications with a second portable geolocation sensor.

15. A portable geolocation sensor as recited in claim 14, wherein said timing signal receiver is further configured to serve as an Assisted-GPS/GNSS server and to send GPS/GNSS aiding data to assist a second portable geolocation sensor in acquiring GPS/GNSS signals.

16. A portable geolocation sensor as recited in claim 14, wherein said communications transceiver comprises a mesh communications transceiver.

17. A portable geolocation sensor as recited in claim 14, wherein said portable geolocation sensor is configured to determine its location by using said timing signal receiver to receive signals from a Global Positioning System (GPS) or Global Navigation Satellite System (GNSS).

18. A method for locating an emitter of interest (EOI) using at least one portable geolocation sensor, comprising:

at a first location, using a first portable geolocation sensor to receive, time stamp and store EOI transmissions during a first period of time;

moving the first portable geolocation sensor to a second location;

at the second location, using the first portable geolocation sensor to receive, time stamp and store EOI transmissions during a second period of time; and

computing the location of the EOI using data representative of the EOI transmissions stored during said first and second periods of time.

19. A method as recited in claim 18, wherein the method is employed to locate an EOI that transmits for a sufficient period of time so that the single geolocation sensor can be moved and the EOI received, time stamped and stored at three or more locations.

20. A method as recited in claim 18, wherein the method is employed to locate an EOI that is stationary.

21. A method as recited in claim 18, wherein the method is employed to locate an EOI that includes timing information within its transmissions.

22. A method as recited in claim 18, wherein the first portable geolocation sensor comprises:

a timing signal receiver configured to receive timing signals;

a tunable wideband receiver configured to receive signals from an EOI; and

a signal processor configured to time stamp transmissions from the EOI.

23. A method as recited in claim 22, wherein said timing signal receiver is coupled to said tunable wideband receiver by a digital communications link.

24. A method as recited in claim 22, wherein said tunable wideband receiver comprises a wideband digital receiver.

25. A method as recited in claim 18, wherein the method is used to receive transmissions from, and to locate, a base transceiver station (BTS) of a wireless communications system.

26. A method as recited in claim 22, wherein said timing signal receiver is configured to receive GPS signals from a satellite-based navigation system, and to provide an accurate sampling clock signal.

27. A method as recited in claim 22, wherein said timing signal receiver is configured to provide a stable frequency reference to said signal processor, and wherein said signal processor is configured to use said frequency reference to characterize the timing and frequency stability of the EOI transmissions.

28. A method as recited in claim 22, wherein said tunable wideband receiver and signal processor are configured to receive, time stamp, store and process received transmissions from the EOI.

29. A method as recited in claim 22, further comprising using a controller and display device coupled to said portable geolocation sensor to control the portable geolocation sensor, to display the location of the EOI, and to provide guidance on the direction and distance to move the portable geolocation sensor to enhance the location accuracy on a subsequent data acquisition cycle.

30. A method as recited in claim 22, further comprising using a communications transceiver to conduct communications between the portable geolocation sensor and a second portable geolocation sensor.

31. A method as recited in claim 22, further comprising using said timing signal receiver to serve as an Assisted-GPS server and to send GPS aiding data to assist a second portable geolocation sensor in acquiring GPS signals.

32. A method as recited in claim 30, wherein said communications transceiver comprises a mesh communications transceiver.

33. A method as recited in claim 22, wherein said portable geolocation sensor is configured to determine its location by using said timing signal receiver to receive signals from a Global Positioning System (GPS) or Global Navigation Satellite System (GNSS).

34. A method as recited in claim 22, further comprising:

moving the first portable geolocation sensor to a third location; and

at the third location, using the first portable geolocation sensor to receive, time stamp and store EOI transmissions during a third period of time;

wherein the step of computing the location of the EOI comprises using data representative of the EOI transmissions stored during said first, second and third periods of time.

35. A method as recited in claim 18, further comprising using the first geolocation sensor and a second geolocation sensor to receive, time stamp and store EOI transmissions during the first period of time;

wherein said second geolocation sensor is at a location which is different from the first and second locations, and wherein the step of computing the location of the EOI comprises the use of data from said first and second geolocation sensors representative of the EOI transmissions stored during said first and second periods of time.

36. A method as recited in claim 35, wherein said second geolocation sensor is time synchronized to said first geolocation sensor during at least said first period of time.

37. A method as recited in claim 35, wherein said first and second geolocation sensors employ a communications transceiver in each sensor to coordinate reception of the EOI transmission at the same times.

38. A method as recited in claim 18, wherein a time difference of arrival (TDOA) measurement is obtained by aligning a received frame timing of a wireless communications signal with a GNSS based frame clock at an initial data acquisition time at the first location, and then a data acquisition is performed at the second location, and the received frame timing at the second location is compared to the GNSS based frame clock to derive the TDOA between the first and second locations.

39. A system for locating an emitter of interest (EOI), comprising:

portable means, including at one receiver, to receive, time stamp and store EOI transmissions during a first period of time at a first location, and to receive, time stamp and store EOI transmissions during a second period of time at a second location; and

computing means, including a processor, for computing the location of the EOI using data representative of the EOI transmissions stored during said first and second periods of time.

40. A system as recited in claim 39, comprising means to locate an EOI that transmits for a sufficient period of time so that the portable means can be moved and the EOI received, time stamped and stored at three or more locations.

41. A system as recited in claim 39, wherein the portable means includes means for receiving timing information within EOI transmissions.

42. A system as recited in claim 39, wherein the portable means further comprises:

a timing signal receiver configured to receive timing signals;

a tunable wideband receiver configured to receive signals from an EOI; and

a signal processor configured to time stamp transmissions from the EOI.

43. A system as recited in claim 39, wherein the system comprises means to receive transmissions from, and to locate, a base transceiver station (BTS) of a wireless communications system.

44. A system as recited in claim 39, wherein the portable means further comprises means to receive GNSS signals from a satellite-based navigation system, and to provide an accurate sampling clock signal.

45. A system as recited in claim 39, wherein the portable means further comprises means for providing a stable frequency reference and for using said frequency reference to characterize the timing and frequency stability of the EOI transmissions.

46. A system as recited in claim 39, comprising means for receiving, time stamping, storing and processing received transmissions from the EOI.

47. A system as recited in claim 39, further comprising means for interfacing with a controller and display device to permit user control of the portable means, to display the location of the EOI, and to provide guidance to the user on the direction and distance to move the portable means to enhance the location accuracy on a subsequent data acquisition cycle.

48. A system as recited in claim 39, further comprising a communications transceiver to conduct communications between the portable means and a second portable means.

49. A system as recited in claim 39, further comprising means for providing GPS aiding data to assist a second portable means.

50. A system as recited in claim 48, wherein said communications transceiver comprises a mesh communications transceiver.

51. A system as recited in claim 39, wherein said portable means comprises means for determining its location by using signals from a Global Positioning System (GPS) or Global Navigation Satellite System (GNSS).

52. A system as recited in claim 39, comprising means for time synchronizing said portable means to a second portable means.

53. A system as recited in claim 39, comprising means for coordinating simultaneous reception of an EOI transmission by the portable means and a second portable means.

54. A system as recited in claim 39, comprising means for making a time difference of arrival (TDOA) measurement by aligning a received frame timing of a wireless communications signal with a GNSS based frame clock at an initial data acquisition time at the first location, and then performing data acquisition at a second location, and comparing the received frame timing at the second location to the GNSS based frame clock to derive the TDOA.