Geolocation of wireless access points for wireless platforms

• US 9,568,588 B2
• Filed: 10/14/2011
• Issued: 02/14/2017
• Est. Priority Date: 10/14/2011
• Status: Active Grant

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Jones, Eric B., Good, Kenneth R., Roach, Kyle J.
• Primary Examiner(s): Keith, Jack W
• Assistant Examiner(s): Nguyen, Chuong P
• Application Number:
  US13/273,825
• Publication Number:
  US 20130093628A1
• Time in Patent Office: 1,950 Days
• Field of Search: 342/450, 342/451, 342/126, 342/145
• US Class Current: 1/1
• CPC Class Codes: G01S 11/06 using intensity measurements
• CPC Class Codes: G01S 2013/466 by Trilateration, i.e. two antennas or two sensors determine separately the distance to a target, whereby with the knowledge of the baseline length, i.e. the distance between the antennas or sensors, the position data of the target is determined
• CPC Class Codes: G01S 2013/468 by Triangulation, i.e. two antennas or two sensors determine separately the bearing, direction or angle to a target, whereby with the knowledge of the baseline length, the position data of the target is determined
• CPC Class Codes: G01S 5/04 Position of source determined by a plurality of spaced direction-finders
• 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
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location

Abstract

A system and method for using a receiving wireless device to passively detect target wireless devices or access points, quantify signal strengths of the target wireless devices or access points, and accurately identify a position for, or geolocate, the target wireless devices or access points. A position of the receiving wireless device is determined and correlated with a signal strength received from a target wireless device taken from multiple positions of the receiving wireless device. A trilateration algorithm is applied to the correlated date to obtain coarse geographic positions for the target wireless device, then a filtering algorithm is applied to obtain an accurate position for the target wireless device, which is in turn displayed to a user of the receiving wireless device.

Claims

1. A method for identifying a fixed location of at least one target wireless device, comprising:

determining a first location of a receiving wireless device operated by a user;

detecting passively, with the receiving wireless device, a signal from at least one target wireless device in a vicinity of the receiving wireless device;

assigning, by a processor in the receiving wireless device, a value to a signal strength of the detected signal, the value being calculated by applying a log-distance path loss model;

correlating the determined first location of the receiving wireless device with the value of the signal strength of the detected signal from the at least one target wireless device at the first location of the receiving wireless device to result in first correlated data;

repeating the determining, detecting, assigning and correlating for a second location of the receiving wireless device and at least one third location for the receiving wireless device when the receiving wireless device is moved to the second location and to the at least one third location to result in second correlated data and at least one third correlated data;

applying a trilateration algorithm, by the processor in the receiving wireless device, to the first correlated data, the second correlated data and the at least one third correlated data to determine a plurality of candidate fixed locations for the at least one target wireless device;

applying a filtering algorithm, by the processor in the receiving wireless device, to the plurality of candidate fixed locations for the at least one target wireless device to identify a fixed location of the at least one target wireless device; and

outputting the identified fixed location of the at least one target wireless device to the user of the receiving wireless device.

2. The method of claim 1, wherein all of the determining, detecting correlating, assigning, applying and outputting are accomplished autonomously by the receiving wireless device.

3. The method of claim 1, wherein the receiving wireless device receives a signal from a global positioning satellite system to determine the first location, the second location and the at least one third location.

4. The method of claim 1, wherein the receiving wireless device detects passively the signal from the at least one target wireless device via a Wi-Fi receiver in the receiving wireless device.

5. The method of claim 1, further comprising determining, by the processor in the receiving wireless device, whether sufficient correlated data is collected to apply the trilateration algorithm.

6. The method of claim 1, further comprising moving the receiving wireless device to at least another third location and repeating the determining, detecting, assigning and correlating steps for the at least the another third location to result in at least another third correlated data,

wherein the trilateration algorithm is applied additionally to the at least the another third correlated data.

7. The method of claim 1, further comprising testing a range of path loss components.

8. The method of claim 1, wherein the calculated distance is a radius of a sphere and a correlated location of the receiving wireless device is a center point for the sphere for use in the trilateration algorithm for each location of the receiving wireless device.

9. The method of claim 1, wherein the filtering algorithm selects the candidate location with a smallest predicted error as the identified location of the at least one target wireless device.

10. The method of claim 1, wherein the identified location of the at least one target wireless device is output to the user of the receiving wireless device by being displayed on a display screen of the receiving wireless device.

11. The method of claim 1, wherein the receiving wireless device is a hand-held device.

12. The method of claim 11, wherein:

the hand-held device is one of a smartphone, a tablet and a PDA, and

the hand-held device is a stand-alone device for performing all of the steps of the method.

13. A receiving wireless device for identifying a fixed location of at least one target wireless device, comprising:

a position reference device configured to determine a location of the receiving wireless device;

an external data communication interface configured to receive wireless signals passively from the at least one target wireless device in a vicinity of the receiving wireless device;

a storage device configured to store at least a trilateration algorithm and a filtering algorithm for execution;

a processor that is programmed to

assign a value to a signal strength of the signal received from the at least one target wireless device in a vicinity of the receiving wireless device, the value being calculated by applying a log-distance path loss model,

correlate the location of the receiving wireless device with the assigned value of the signal strength of the signal received from the at least one target wireless device at the location of the receiving wireless device at which the signal is received to result in correlated data,

apply the stored trilateration algorithm to a plurality of the correlated data to determine a plurality of candidate fixed locations for the at least one target wireless device, and

apply the stored filtering algorithm to the plurality of candidate fixed locations for the at least one target wireless device to identify a fixed location of the at least one target wireless device; and

an output device configured to output the identified fixed location of the at least one target wireless device to a user of the receiving wireless device,

wherein the receiving wireless device is a hand-held device.

14. The receiving wireless device of claim 13, wherein the hand-held device is one of a smartphone, a tablet or a PDA.

15. The receiving wireless device of claim 13, wherein the position reference device is a global positioning satellite system receiver.

16. The receiving wireless device of claim 13, wherein the wireless signals passively received by the receiving wireless device from the at least one target wireless device are Wi-Fi signals.

17. The receiving wireless device of claim 13, the processor being further programmed to apply the calculated distance as a radius of a sphere with a correlated location of the receiving wireless device as a center point for the sphere for use in the trilateration algorithm for each location of the receiving wireless device.

18. The receiving wireless device of claim 13, the processor being further programmed to apply the filtering algorithm to select the candidate fixed location with a smallest predicted error as the identified fixed location of the at least one target wireless device.

19. The receiving wireless device of claim 13, further comprising a display screen, wherein the identified fixed location of the at least one target wireless device is output to the user of the receiving wireless device by being displayed on the display screen.

20. A non-transitory computer-readable medium storing instructions which, when executed by a processor in a receiving wireless device, cause the processor to execute a method for identifying a fixed location of at least one target wireless device, the method comprising:

determining a first location of the receiving wireless device operated by a user;

detecting passively, with the receiving wireless device, a signal from at least one target wireless device in a vicinity of the receiving wireless device;

assigning a value to a signal strength of the detected signal, the value being calculated by applying a log-distance path loss model;

correlating the determined first location of the receiving wireless device with the value of the signal strength of the detected signal from the at least one target wireless device at the first location of the receiving wireless device to result in first correlated data;

repeating the determining, detecting, assigning and correlating steps for a second location of the receiving wireless device and at least one third location of the receiving wireless device when the receiving wireless device is moved to the second location and to the at least one third location to result in second correlated data and at least one third correlated data;

applying a trilateration algorithm to the first correlated data, the second correlated data and the at least one third correlated data to determine a plurality of candidate fixed locations for the at least one target wireless device;

applying a filtering algorithm to the plurality of candidate fixed locations for the at least one target wireless device to identify a fixed location of the at least one target wireless device; and

outputting the identified fixed location of the at least one target wireless device to a user of the receiving wireless device.