Diversity Time and Frequency Location Receiver

• US 20120256789A1
• Filed: 07/24/2009
• Published: 10/11/2012
• Est. Priority Date: 12/30/2008
• Status: Active Grant

• Current Assignee: Skyhook Holding, Inc. (Liberty Broadband Corp.)
• Original Assignee: TruePosition Incorporated
• Inventors: Bull, Jeffrey F., Cohen, Benjamin H., Norgaard, Adam W.
• Granted Patent: US 8,436,768 B2
• Time in Patent Office: Days
• US Class Current: 342/357.25
• CPC Class Codes: G01S 19/215 issues related to spoofing
• CPC Class Codes: G01S 5/0215 Interference
• CPC Class Codes: G01S 5/0221 Receivers
• CPC Class Codes: G01S 5/02216 Timing or synchronisation of the receivers

Abstract

A Wide Area Sensor Network is disclosed that utilizes wideband software defined radios (SDRs) to provide a capability to monitor the airwaves over a wide frequency range, detect when critical frequencies are being jammed or otherwise interfered with, and locate the source of the interference so that the interference can be eliminated. In addition, a diversity receiver is disclosed. The diversity receiver generates position, time and frequency references for use in locating and synchronizing sensor platforms of a WLS. In an illustrative embodiment, the diversity receiver comprises a first receiver subsystem comprising a terrestrial broadcast receiver, and a common processor platform (CPP) coupled via first link means to the first receiver subsystem. The first receiver subsystem provides a stable time reference and position information to the CPP via the first link means. In addition, the diversity receiver includes second link means for coupling the diversity receiver to a sensor platform and providing time and frequency references and location data to the sensor platform.

Claims

1. A diversity receiver for generating position, time and frequency references for use in locating and synchronizing sensor platforms of a wireless location system (WLS), comprising:

a first receiver subsystem comprising a terrestrial broadcast receiver;

a common processor platform (CPP) coupled via first link means to the first receiver subsystem, wherein the first receiver subsystem provides a stable time reference and position information to the CPP via the first link means; and

second link means for coupling the diversity receiver to a sensor platform and providing time and frequency references and location data to said sensor platform.

2. A diversity receiver as recited in claim 1, wherein said terrestrial broadcast receiver comprises an HDTV receiver.

3. A diversity receiver as recited in claim 1, wherein said terrestrial broadcast receiver comprises an antenna for receiving an aiding signal communicating aiding information including broadcaster locations, channel assignments and timing characteristics and parameters.

4. A diversity receiver as recited in claim 1, wherein said terrestrial broadcast receiver comprises an aiding information interface for receiving aiding information including broadcaster locations, channel assignments and timing characteristics and parameters.

5. A diversity receiver as recited in claim 4, wherein the aiding information interface is configured to couple the terrestrial broadcast receiver to a landside aiding server or network.

6. A diversity receiver as recited in claim 1, further comprising a second receiver subsystem comprising a GNSS receiver operatively coupled via third link means to said CPP, wherein the second receiver subsystem provides a second stable time reference and position information to the CPP via the third link means.

7. A diversity receiver as recited in claim 6, wherein the GNSS receiver comprises an aiding information interface for reception of a GNSS aiding signal, said aiding signal communicating satellite constellation orbital information and other information used to correct for clock drift, atmosphere signal delay, and ionosphere delay, whereby the accuracy of a GNSS receiver'"'"'s location estimate and the time and frequency references can be enhanced.

8. A diversity receiver as recited in claim 6, wherein the GNSS receiver comprises an aiding information interface for receiving aiding information from a landside aiding server or network.

9. A diversity receiver as recited in claim 7 or claim 8, wherein the GNSS receiver is configured to operate in a static timing mode in which a time and frequency reference are provided when no GNSS signals are available.

10. A diversity receiver as recited in claim 6, wherein the CPP is configured to designate a primary and secondary receiver subsystem based on time-to-fix, signal quality, or operator preference.

11. A diversity receiver as recited in claim 6, further comprising a reference oscillator operatively coupled to the CPP, wherein the CPP is configured to communicate via said first and third link means with the first and second receiver subsystems, to receive stable time signals from the receiver subsystems, and to use at least one of the time signals to discipline the reference oscillator, and wherein said reference oscillator provides a stable frequency reference to the CPP.

12. A diversity receiver as recited in claim 11, wherein the CPP is further configured either to select one of the first and second receiver subsystems or to hybridize the information provided by the receiver subsystems to create an optimized time reference, frequency reference and timestamp to be provided to the sensor platform.

13. A first location sensor for use in a wireless location system (WLS) comprising a network of location sensors, said first location sensor comprising:

a first receiver subsystem comprising an HDTV receiver;

a common processor platform (CPP) coupled via first link means to the first receiver subsystem, wherein the first receiver subsystem provides a stable time reference and position information to the CPP via the first link means;

second link means for coupling the first location sensor to a sensor platform and providing time and frequency references and location data to said sensor platform;

a second receiver subsystem comprising a GNSS receiver operatively coupled via third link means to said CPP, wherein the second receiver subsystem provides a second stable time reference and position information to the CPP via the third link means; and

a reference oscillator operatively coupled to the CPP;

wherein the CPP is configured to communicate via said first and third link means with the first and second receiver subsystems, to receive stable time signals from the receiver subsystems, and to use at least one of the time signals to discipline the reference oscillator, and wherein said reference oscillator provides a stable frequency reference to the CPP.

14. A first location sensor as recited in claim 13, wherein said HDTV receiver comprises an antenna for receiving an aiding signal communicating aiding information including broadcaster locations, channel assignments and timing characteristics and parameters.

15. A first location sensor as recited in claim 13, wherein said HDTV receiver comprises an aiding information interface for receiving aiding information including broadcaster locations, channel assignments and timing characteristics and parameters.

16. A first location sensor as recited in claim 15, wherein the aiding information interface is configured to couple the HDTV receiver to a landside aiding server or network.

17. A first location sensor as recited in claim 13, wherein the GNSS receiver comprises an aiding information interface for reception of a GNSS aiding signal, said aiding signal communicating satellite constellation orbital information and other information used to correct for clock drift, atmosphere signal delay, and ionosphere delay, whereby the accuracy of a GNSS receiver'"'"'s location estimate and the time and frequency references can be enhanced.

18. A first location sensor as recited in claim 13, wherein the GNSS receiver comprises an aiding information interface for receiving aiding information from a landside aiding server or network.

19. A first location sensor as recited in claim 17 or claim 18, wherein the GNSS receiver is configured to operate in a static timing mode in which a time and frequency reference are provided when no GNSS signals are available.

20. A first location sensor as recited in claim 13, wherein the CPP is configured to designate a primary and secondary receiver subsystem based on time-to-fix, signal quality, or operator preference.

21. A first location sensor as recited in claim 13, wherein the CPP is further configured either to select one of the first and second receiver subsystems or to hybridize the information provided by the receiver subsystems to create an optimized time reference, frequency reference and timestamp to be provided to the sensor platform.

22. A system for determining the location of a location sensor of a wireless location system (WLS), comprising:

means for acquiring gross timing information;

means for acquiring correction factors for terrestrial signals;

means for acquiring terrestrial broadcast signals; and

means for computing a location of the sensor using the terrestrial signals and the correction factors, and for refining the computed location until it is within a defined tolerance;

wherein the computed location is available for use in subsequent operations of the WLS.

23. A system as recited in claim 22, wherein the gross timing information is accurate to within 10 ms of International Atomic Time (IAT).

24. A method for determining the location of a location sensor of a wireless location system (WLS), wherein the location sensor is unable to receive GNSS signals, comprising:

acquiring gross timing information;

acquiring correction factors for terrestrial signals;

acquiring terrestrial broadcast signals and computing a location of the sensor using the terrestrial signals and the correction factors;

refining the computed location until it is within a defined tolerance; and

storing the computed location for use in subsequent operations of the WLS.

25. A method as recited in claim 24, wherein the gross timing information is accurate to within 10 ms of International Atomic Time (IAT).