Network Location and Synchronization of Peer Sensor Stations in a Wireless Geolocation Network

• US 20110285589A1
• Filed: 05/24/2010
• Published: 11/24/2011
• Est. Priority Date: 05/24/2010
• Status: Active Grant

• Current Assignee: Skyhook Holding, Inc. (Liberty Broadband Corp.)
• Original Assignee: TruePosition Incorporated
• Inventors: Bull, Jeffrey F.
• Granted Patent: US 8,810,452 B2
• Time in Patent Office: Days
• US Class Current: 342/387
• CPC Class Codes: G01S 19/11 wherein the cooperating elements are pseudolites or satellite radio beacon positioning system signal repeaters
• CPC Class Codes: G01S 19/48 by combining or switching between position solutions derived from the satellite radio beacon positioning system and position solutions derived from a further system
• 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 5/06 Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements G01S5/12 takes precedence

Abstract

Transmitters are located with a network of sensors by measuring signal characteristics at multiple known locations and processing these measurements at a central node. The sensors communicate their location to the central node along with measured characteristics of the transmitter'"'"'s signal, and may be required to synchronize with other sensors. Often, GNSS receivers are utilized to locate and synchronize the sensors. However, the GNSS signals may be attenuated by obstructions. In this case, the sensors determine their location by making ranging measurements with sensors that can receive the GNSS signals. The waveform for the wireless backhaul permits this ranging. Additionally, many sensors can determine their location and time synchronize with the geolocation network through reception of signals from other sensors even if they do not have a direct connection to sensors that know their location and are time synchronized.

Claims

1. A system for geo-locating transmitters of interest using a network of geographically dispersed sensor stations, said network of geographically dispersed sensor stations including reference sensor stations and one or more blind sensor stations, comprising:

a plurality of sensor stations, wherein at least three sensor stations are at a known location and are synchronized with a reference clock, said at least three sensor stations being useful as reference sensor stations;

a central node configured to control the sensor stations; and

a backhaul communications network configured to permit wireless communications among the sensor stations and central node;

wherein the system is configured to employ said backhaul communications network and reference sensor stations for synchronization and geo-location of one or more blind sensor stations.

2. A system as recited in claim 1, wherein the system is further configured such that at least three reference sensor stations transmit a wireless communications waveform that is received by a blind sensor station, and the blind sensor station is synchronized and geo-located based on its reception of the wireless communications waveform from the at least three reference sensor stations.

3. A system as recited in claim 2, wherein the blind sensor station is configured to receive and determine the time of arrival (TOA) of the wireless communications waveforms broadcast by the at least three sensor stations.

4. A system as recited in claim 3, further comprising a processor associated with the blind sensor station, wherein the processor is configured to use reference sensor station geo-location information and TOA information for geo-location and time synchronization of the blind sensor station.

5. A system as recited in claim 4, wherein the processor associated with the blind sensor station has access to a database of reference sensor station geo-location information.

6. A system as recited in claim 5, wherein the reference sensor station geo-location information is encoded in the wireless communications waveforms broadcast by the at least three sensor stations.

7. A system as recited in claim 2, wherein the at least three reference sensor stations are configured to broadcast a wireless communications waveform in which a time of transmission is encoded.

8. A system as recited in claim 1, wherein the system is further configured to permit a blocked sensor station to communicate with the central node via said backhaul communications network and at least one other sensor station.

9. A system as recited in claim 1, wherein the plurality of sensor stations includes portable and fixed sensor stations.

10. A system as recited in claim 1, wherein the central node comprises a display device and external interface.

11. A system as recited in claim 1, wherein the system is further configured to geo-locate transmitters of interest using power measurements made by sensor stations that have been geo-located.

12. A system as recited in claim 1, wherein the system is further configured to geo-locate transmitters of interest using time based measurements made by sensor stations that have been geo-located and synchronized.

13. A system as recited in claim 1, wherein the system is further configured to geo-locate blind sensor stations via reception of terrestrial broadcast signals.

14. A system as recited in claim 13, wherein the terrestrial broadcast signals comprise high definition television (HDTV) signals.

15. A system as recited in claim 1, wherein the system is further configured to permit any sensor station to trigger a location and to act as a central node.

16. A method for geo-locating transmitters of interest using a network of geographically dispersed sensor stations, said network of geographically dispersed sensor stations including reference sensor stations and one or more blind sensor station, comprising:

determining the locations of at least three sensor stations and synchronizing said at least three sensor stations with a reference clock, said at least three sensor stations being useful as reference sensor stations;

employing wireless communications via a backhaul wireless communications network to synchronize and geo-locate at least one blind sensor station, said wireless communications including broadcast by said reference sensor stations of a wireless communications waveform that is received by the at least one blind sensor station and used for synchronization and geo-location; and

geo-locating at least one transmitter of interest using the network of geographically dispersed sensor stations, including the at least one blind sensor station.

17. A method as recited in claim 16, wherein the at least one blind sensor station receives and determines the time of arrival (TOA) of the wireless communications waveforms broadcast by the at least three sensor stations.

18. A method as recited in claim 17, further comprising employing a location processor associated with the at least one blind sensor station to use reference sensor station geo-location information and TOA information for geo-location and time synchronization.

19. A method as recited in claim 18, wherein the location processor accesses a database of reference sensor station geo-location information.

20. A method as recited in claim 19, wherein the reference sensor station geo-location information is encoded in the wireless communications waveforms broadcast by the at least three sensor stations.

21. A method as recited in claim 16, wherein the at least three reference sensor stations broadcast a wireless communications waveform in which a time of transmission is encoded.

22. A method as recited in claim 16, wherein a deficient sensor station communicates and synchronizes with a central node via said backhaul communications network and at least one other sensor station.

23. A method as recited in claim 16, wherein the plurality of sensor stations includes portable and fixed sensor stations.

24. A method as recited in claim 16, wherein power measurements made by sensor stations that have been geo-located and synchronized are used to geo-locate transmitters of interest.

25. A method as recited in claim 16, wherein time based measurements made by sensor stations that have been geo-located and synchronized are used to geo-locate transmitters of interest.

26. A method as recited in claim 16, wherein terrestrial broadcast signals are used to geo-locate blind sensor stations.

27. A method as recited in claim 26, wherein the terrestrial broadcast signals comprise high definition television (HDTV) signals.

28. A method as recited in claim 16, wherein any sensor station is permitted to trigger a location and to act as a central node.

29. A method as recited in claim 16, wherein a location trigger is received from an external entity.

30. A method for geo-locating transmitters of interest using a network of geographically dispersed sensor stations, said network of geographically dispersed sensor stations including reference sensor stations and at least one deficient sensor station, wherein the deficient sensor station is at an unknown location, is not synchronized with the reference sensor stations, and does not have a radio connection to three or more reference sensor stations, comprising:

determining the locations of at least three sensor stations and synchronizing said at least three sensor stations with a reference clock, said at least three sensor stations being useful as reference sensor stations; and

employing wireless communications via a backhaul wireless communications network to synchronize and geo-locate a first deficient sensor station, said wireless communications including broadcast by said reference sensor stations of a wireless communications waveform that is received by the first deficient sensor station and used for synchronization and geo-location.

31. A method as recited in claim 30, wherein the first deficient sensor station makes a transmission time measurement for every sensor station to which it has a direct connection via the wireless backhaul communications network, including one or more reference sensor stations and at least one other deficient sensor station.

32. A method as recited in claim 31, wherein the at least one other deficient sensor station makes transmission time measurements for every sensor station to which the at least one other deficient sensor station is directly connected via the backhaul wireless communications network.