Method and apparatus for determining location using signals-of-opportunity

• US 8,018,383 B1
• Filed: 06/08/2010
• Issued: 09/13/2011
• Est. Priority Date: 06/08/2010
• Status: Expired due to Fees

• Current Assignee: GaN Corporation
• Original Assignee: Q-Track Corporation
• Inventors: Richards, Eric, Depierre, Robert Edward, Unden, Alfred Hans, Schantz, Hans Gregory
• Primary Examiner(s): Tarcza; Thomas H
• Assistant Examiner(s): McGue; Frank
• Application Number:
  US12/796,643
• Time in Patent Office: 462 Days
• Field of Search: 342/453
• US Class Current: 342/453
• CPC Class Codes: G01S 5/02213 Receivers arranged in a network for determining the position of a transmitter
• CPC Class Codes: G01S 5/02521 using a radio-map

Abstract

A signal-of-opportunity location device (SOLD) that may be situated in a complex radio propagation environment with multiple RF signal obstructions receives RF signals from a distant transmitter. The RF signals from the distant transmitter interact with obstructions in the propagation environment local to the SOLD. The local obstructions perturb the RF signals causing the RF signals to exhibit near field behavior in the complex radio propagation environment. The SOLD receives the locally perturbed signals. The SOLD detects signal characteristics of RF signal components of the received signals and compares these signal characteristics with reference data in a reference data store to determine the current location of the SOLD.

Claims

1. A method of determining location, comprising:

receiving, by a receiver, a radio frequency (RF) signal-of-opportunity that exhibits a signal component at the receiver, the RF signal-of-opportunity being perturbed by a perturber within the propagation environment of the receiver, the receiver being configured to receive the RF signal-of-opportunity within near field range of the perturber;

detecting, by the receiver, a signal characteristic of the signal component to provide signal characteristic information; and

comparing the signal characteristic information with reference data to determine the current location of the receiver.

2. The method of claim 1, wherein the signal component is one of a horizontal polarization, a vertical polarization and a radial polarization of the RF signal-of-opportunity.

3. The method of claim 1, wherein the signal characteristic is a characteristic of an electric field of the RF signal-of-opportunity.

4. The method of claim 1, wherein the signal characteristic is a characteristic of a magnetic field of the RF signal-of-opportunity.

5. The method of claim 1, wherein the signal characteristic is amplitude.

6. The method of claim 1, wherein the RF signal-of-opportunity exhibits first and second signal components at the receiver.

7. The method of claim 6, wherein the detecting step comprises detecting, by the receiver, a first signal characteristic of the first signal component and a second signal characteristic of the second signal component.

8. The method of claim 7, further comprising:

determining signal characteristic comparison information from the first and second signal characteristics; and

comparing the signal characteristic comparison information with reference data to determine the current location of the receiver.

9. The method of claim 8, wherein the determining step further comprises comparing the respective amplitudes of the first signal characteristic and the second signal characteristic to generate the signal characteristic comparison information.

10. The method of claim 8, wherein the determining step further comprises comparing the respective phases of the first signal characteristic and the second signal characteristic to generate the signal characteristic comparison information.

11. The method of claim 8, wherein the determining step further comprises taking the difference between the first signal characteristic and the second signal characteristic to generate signal characteristic comparison information.

12. The method of claim 1, wherein the reference data includes signal characteristic information for each of a plurality of different frequencies in a frequency band of interest at a particular location within the propagation environment.

13. The method of claim 12, wherein the reference data further includes different signal characteristic information and corresponding location information for each of a plurality of different locations within the propagation environment.

14. The method of claim 12, wherein the reference data varies according to the time of day.

15. A method of calibrating a location detector, comprising:

receiving, by a receiver, a first radio frequency (RF) signal-of-opportunity that exhibits a signal component at the receiver, the first RF signal-of-opportunity being perturbed by a perturber within the propagation environment of the receiver, the receiver being configured to receive the RF signal-of-opportunity at a current location within near field range of the perturber;

detecting, by the receiver, a signal characteristic of the signal component to provide signal characteristic information; and

storing, by a reference data store, the signal characteristic information and corresponding location information designating the current location of the receiver, thus providing reference data to the reference data store.

16. The method of claim 15, wherein the first RF signal-of-opportunity is one of a plurality of RF signals-of-opportunity, each RF signal-of-opportunity exhibiting a different frequency within a band of interest and being perturbed by the propagation environment.

17. The method of claim 16, the method further comprising:

repeating the receiving, detecting and storing steps for each RF signal-of-opportunity at their respective different frequencies, thus providing reference data including respective signal characteristic information for each of the RF signals-of-opportunity at their respective different frequencies at the current location of the receiver.

18. The method of claim 17, further comprising:

moving the receiver to a plurality of locations and repeating the receiving, detecting and storing steps at each location to build the reference data store to include signal characteristic information with corresponding location information for each location of the plurality of locations.

19. The method of claim 15, further comprising querying a user to determine if the user desires to perform calibration of the location detector for a propagation environment for which calibration was not previously conducted.

20. A method of determining location comprising:

retrieving, by a mobile receiver from a server, reference data that correlates a plurality of locations with a respective plurality of signal characteristics;

receiving, by the mobile receiver, a radio frequency (RF) signal from a fixed transmitter, the RF signal exhibiting a signal component at the mobile receiver;

detecting, by the mobile receiver, a signal characteristic of the signal component, thus providing signal characteristic information;

comparing the signal characteristic information with the reference data to determine the current location of the mobile receiver;

wherein the receiving, by the mobile receiver, a radio frequency (RF) signal further comprises receiving, by the mobile receiver, a radio frequency (RF) signal-of-opportunity that exhibits a signal component at the mobile receiver, the RF signal-of-opportunity being perturbed by a perturber within the propagation environment of the mobile receiver, the mobile receiver being adapted to receive the RF signal-of-opportunity within near field range of the perturber.

21. The method of claim 20, wherein the signal component is one of a horizontal polarization, a vertical polarization and a radial polarization of the RF signal-of-opportunity.

22. The method of claim 20, wherein the signal characteristic is a characteristic of an electric field of the RF signal-of-opportunity.

23. The method of claim 20, wherein the signal characteristic is a characteristic of a magnetic field of the RF signal-of-opportunity.

24. A method of determining location comprising:

receiving, by a mobile receiver, a radio frequency (RF) signal that exhibits a signal component at the mobile receiver;

detecting, by the mobile receiver, a signal characteristic of the signal component;

transmitting, by the mobile receiver to a server, the signal characteristic;

comparing, by the server, the signal characteristic to reference data, the reference data correlating a plurality of locations with a respective plurality of signal characteristics; and

determining, by the server, the location of the mobile receiver from the comparing step, thus providing a determined location of the mobile receiver

wherein the receiving, by the mobile receiver, a radio frequency (RF) signal further comprises receiving, by the mobile receiver, a radio frequency (RF) signal-of-opportunity that exhibits a signal component at the mobile receiver, the RF signal-of-opportunity being perturbed by a perturber within the propagation environment of the mobile receiver, the mobile receiver being adapted to receive the RF signal-of-opportunity within near field range of the perturber.

25. A method of determining location comprising:

determining a coarse location;

selecting, from a reference data store, particular reference data corresponding to the coarse location, the reference data store including reference data that correlates a plurality of locations with a respective plurality of signal characteristics,

receiving, by a mobile receiver, a radio frequency (RF) signal from a fixed transmitter, the RF signal exhibiting a signal component at the mobile receiver,

detecting, by the mobile receiver, a signal characteristic of the signal component,

comparing the signal characteristic to the reference data, the reference data correlating a plurality of locations with a respective plurality of signal characteristics, and

determining the current location of the mobile receiver employing the comparison;

wherein the receiving, by the mobile receiver, a radio frequency (RF) signal further comprises receiving, by the mobile receiver, a radio frequency (RF) signal-of-opportunity that exhibits a signal component at the mobile receiver, the RF signal-of-opportunity being perturbed by a perturber within the propagation environment of the mobile receiver, the mobile receiver being adapted to receive the RF signal-of-opportunity within near field range of the perturber.

26. The method of claim 25, wherein the signal component is one of a horizontal polarization, a vertical polarization and a radial polarization of the RF signal-of-opportunity.

27. The method of claim 25, wherein the signal characteristic is a characteristic of an electric field of the RF signal-of-opportunity.

28. The method of claim 25, wherein the signal characteristic is a characteristic of a magnetic field of the RF signal-of-opportunity.

29. A method of calibrating a location detector comprising:

determining a coarse location;

querying a server to determine if reference data corresponding to a coarse location are available, the reference data correlating a plurality of locations with a respective plurality of signal characteristics;

querying a user, if reference data corresponding to a coarse location are not available, to determine if a user desires to calibrate the location detector, and if the user does desire to calibrate the location detector, continuing the process with the steps of;

receiving, by a mobile receiver, a first radio frequency (RF) signal-of-opportunity from a fixed transmitter, the first RF signal-of-opportunity exhibiting a signal component at the mobile receiver;

detecting, by the mobile receiver, a signal characteristic of the signal component;

storing, by a reference data store, the signal characteristic information along with respective location information designating the current location of the location detector to provide reference data to the reference data store

wherein the receiving, by the mobile receiver, a first radio frequency (RF) signal-of-opportunity comprises receiving, by the mobile receiver, the first radio frequency (RF) signal-of-opportunity that exhibits a signal component at the mobile receiver, the first RF signal-of-opportunity being perturbed by a perturber within the propagation environment of the mobile receiver, the mobile receiver being adapted to receive the first RF signal-of-opportunity within near field range of the perturber.

30. The method of claim 29, wherein the first RF signal-of-opportunity is one of a plurality of RF signals-of-opportunity, each RF signal-of-opportunity exhibiting a different frequency within a band of interest and being perturbed by the propagation environment.

31. The method of claim 30, the method further comprising:

repeating the receiving, detecting and storing steps for each RF signal-of-opportunity at their respective different frequencies, thus providing reference data including respective signal characteristic information for each of the RF signals-of-opportunity at their respective different frequencies at the current location of the mobile receiver.

32. The method of claim 31, further comprising:

moving the mobile receiver to a plurality of locations and repeating the receiving, detecting and storing steps at each location to build the reference data to include signal characteristic information with corresponding location information for each location of the plurality of locations.

33. A location detector, comprising:

a receiver that receives a radio frequency (RF) signal-of-opportunity that exhibits a signal component at the receiver, the RF signal-of-opportunity being perturbed by a perturber within the propagation environment of the receiver, the receiver being adapted to receive the RF signal-of-opportunity within near field range of the perturber;

a signal characteristic detector that detects a signal characteristic of the signal component to provide signal characteristic information; and

a comparing apparatus, responsive to the signal characteristic information, that compares the signal characteristic information with reference data to determine the current location of the receiver.

34. The location detector of claim 33, wherein the signal component is one of a horizontal polarization, a vertical polarization and a radial polarization of the RF signal-of-opportunity.

35. The location detector of claim 33, wherein the signal characteristic is a characteristic of an electric field of the RF signal-of-opportunity.

36. The location detector of claim 33, wherein the signal characteristic is a characteristic of a magnetic field of the RF signal-of-opportunity.

37. The location detector of claim 33, wherein the signal characteristic is amplitude.

38. The location detector of claim 33, wherein the RF signal-of-opportunity exhibits first and second signal components at the receiver.

39. The location detector of claim 38, wherein the signal characteristic detector detects a first signal characteristic of the first signal component and a second signal characteristic of the second signal component.

40. The location detector of claim 39, wherein the signal characteristic detector determines signal characteristic comparison information from the first and second signal characteristics.

41. A location detector adapted for calibration, comprising:

a receiver that receives a first radio frequency (RF) signal-of-opportunity that exhibits a signal component at the receiver, the first RF signal-of-opportunity being perturbed by a perturber within the propagation environment of the receiver, the receiver being adapted to receive the RF signal-of-opportunity at a current location within near field range of the perturber;

a signal characteristic detector that detects a signal characteristic of the signal component to provide signal characteristic information; and

a reference data store that stores the signal characteristic information and corresponding location information designating the current location of the receiver, thus providing calibration reference data to the reference data store.

42. The location detector of claim 41, wherein the first RF signal-of-opportunity is one of a plurality of RF signals-of-opportunity, each RF signal-of-opportunity exhibiting a different frequency within a band of interest and being perturbed by the propagation environment.

43. The location detector of claim 42, wherein the location detector repeats the receiving, detecting and storing operations for each RF signal-of-opportunity at their respective different frequencies, thus providing calibration reference data including respective signal characteristic information for each of the RF signals-of-opportunity at their respective different frequencies at the current location of the receiver.

44. The location detector of claim 43, wherein the location detector moves to a plurality of locations and repeats the receiving, detecting and storing operations at each location to build the calibration reference data to include signal characteristic information with corresponding location information for each location of the plurality of locations.

45. The location detector of claim 44, wherein the location detector queries a user to determine if the user desires to perform calibration of the location detector for a propagation environment for which calibration was not previously conducted.

46. A computer program product, comprising:

a computer readable storage medium;

first program instructions that receive a radio frequency (RF) signal-of-opportunity that exhibits a signal component at a receiver, the RF signal-of-opportunity being perturbed by a perturber within the propagation environment of the receiver, the receiver being adapted to receive the RF signal-of-opportunity within near field range of the perturber;

second program instructions that detect a signal characteristic of the signal component to provide signal characteristic information; and

third program instructions that compare the signal characteristic information with reference data to determine the current location of the receiver;

wherein the first, second, and third program instructions are stored on the computer readable storage medium.