GNSS Signal Processing with Synthesized Base Station Data

• US 20120154215A1
• Filed: 09/19/2010
• Published: 06/21/2012
• Est. Priority Date: 06/22/2007
• Status: Active Grant

• Current Assignee: Trimble Inc.
• Original Assignee: Trimble Navigation Limited (Trimble Inc.)
• Inventors: Chen, Xiaoming, Leandro, Rodrigo, Vollath, Ulrich
• Granted Patent: US 9,594,168 B2
• Time in Patent Office: Days
• US Class Current: 342/357.49
• CPC Class Codes: G01S 19/04 providing carrier phase data
• CPC Class Codes: G01S 19/20 Integrity monitoring, fault detection or fault isolation of space segment
• CPC Class Codes: G01S 19/258 relating to the satellite constellation, e.g. almanac, ephemeris data, lists of satellites in view
• CPC Class Codes: G01S 19/37 Hardware or software details of the signal processing chain
• CPC Class Codes: G01S 19/43 using carrier phase measurements, e.g. kinematic positioning; using long or short baseline interferometry
• CPC Class Codes: G01S 19/44 Carrier phase ambiguity resolution; Floating ambiguity; LAMBDA [Least-squares AMBiguity Decorrelation Adjustment] method

Abstract

Methods and apparatus are described for determining position of a rover antenna, comprising: obtaining rover GNSS data derived from code observations and carrier phase observations of GNSS signals of multiple satellites over multiple epochs, obtaining precise satellite data for the satellites, determining a virtual base station location, generating epochs of synthesized base station data using at least the precise satellite data and the virtual base station location, and applying a differential process to at least the rover GNSS data and the synthesized base station data to determine at least rover antenna positions.

Claims

1. A method of determining position of a rover antenna, comprising:

obtaining rover GNSS data derived from code observations and carrier phase observations of GNSS signals of multiple satellites over multiple epochs,

obtaining precise satellite data for the satellites,

determining a virtual base station location,

generating epochs of synthesized base station data using at least the precise satellite data and the virtual base station location, and

applying a differential process to at least the rover GNSS data and the synthesized base station data to determine at least rover antenna positions.

2. The method of claim 1, wherein generating epochs of synthesized base station data comprises generating an epoch of virtual base station data for each epoch of GNSS rover data.

3. The method of claim 1, wherein obtaining precise satellite data comprises obtaining precise satellite data in sets, wherein generating epochs of synthesized base station data comprises generating an epoch of synthesized base station data for each set of precise satellite data, and wherein applying a differential process comprises matching each set of GNSS rover data with an epoch of synthesized base station data.

4. The method of claim 1, wherein determining a virtual base station location comprises determining the virtual base station location from at least one of:

an autonomously determined position of the rover antenna, a previously determined one of said rover antenna positions, a synthesized base station data generating module, an inertial navigation system, a mobile telephone tower location, and information provided by a user.

5. The method of claim 1, further comprising updating the virtual base station location on the occurrence of at least one of:

never, for each epoch of rover data, when the distance between an approximate rover antenna position and the virtual base station location exceeds a predetermined threshold, and for each update of the rover antenna positions.

6. The method of claim 1, wherein each epoch of the synthesized base station data is generated for a corresponding virtual base station location.

7. The method of claim 1, wherein determining the virtual base station location comprises selecting a virtual base station location close to a current approximate rover antenna position.

8. The method of claim 1, wherein a new virtual base position is determined when one or more of the following criteria is met:

each rover epoch, each nth rover epoch, after a time interval, after exceeding a distance between a current approximate rover position and a current virtual base station location.

9. The method of claim 1, wherein the virtual base station location is generated for a specific GNSS time interval.

10. The method of claim 1, wherein applying a differential process to at least the rover GNSS data and the synthesized base station data to determine at least rover antenna positions comprises at least one of:

aided inertial navigation (integrated inertial navigation and GNSS) processing, real-time kinematic (RTK) processing, instant real-time kinematic (IRTK) processing;

differential GPS processing;

float processing;

triple differenced processing;

post-processing and real-time processing.

11. The method of claim 1, further comprising matching each epoch of the rover GNSS data with an epoch of synthesized base station data within a few milliseconds.

25. An article of manufacture comprising a tangible medium embodying instructions configured, when executed on a computer processing unit, to carry out a method according to claim 1.

12. The method of 1, wherein generating epochs of synthesized base station data comprises generating a set of synthesized base station observations for each of a plurality of discrete times, and wherein applying a differential process comprises processing each epoch of GNSS rover data with a set of synthesized base station observations for a discrete time which is within ten seconds of the epoch of the GNSS rover data being processed.

13. Apparatus for determining position of a rover antenna, comprising:

an element to obtain rover GNSS data derived from code observations and carrier phase observations of GNSS signals of multiple satellites over multiple epochs,

an element to obtain precise satellite data for the satellites,

an element to determine a virtual base station location,

an element to generate epochs of synthesized base station data using at least the precise satellite data and the virtual base station location, and

an element to apply a differential process to at least the rover GNSS data and the synthesized base station data to determine at least rover antenna positions.

14. The apparatus of claim 13, wherein the element to generate epochs of synthesized base station data is adapted to generate an epoch of virtual base station data for each epoch of GNSS rover data.

15. The apparatus of claim 13, wherein the element to obtain precise satellite data is adapted to obtain precise satellite data in sets, wherein the element to generate epochs of synthesized base station data is adapted to generate an epoch of synthesized base station data for each set of precise satellite data, and wherein the element to apply a differential process is adapted to match each set of GNSS rover data with an epoch of synthesized base station data.

16. The apparatus of claim 13, wherein the element to determine a virtual base station location is adapted to determine the virtual base station location from at least one of:

an autonomously determined position of the rover antenna, a previously determined one of said rover antenna positions, a synthesized base station data generating module, an inertial navigation system, a mobile telephone tower location, and information provided by a user.

17. The apparatus of claim 13, wherein the element to determine a virtual base station location is adapted to update the virtual base station location on the occurrence of at least one of:

never, for each epoch of rover data, when the distance between an approximate rover antenna position and the virtual base station location exceeds a predetermined threshold, and for each update of the rover antenna positions.

18. The apparatus of claim 13, wherein each epoch of the synthesized base station data is generated for a corresponding virtual base station location.

19. The apparatus of claim 13, wherein the element to determine a virtual base station location is adapted to select a virtual base station location close to a current approximate rover antenna position.

20. The apparatus of claim 13, wherein the element to determine a virtual base station location is adapted to determine a new virtual base position when one or more of the following criteria is met:

each rover epoch, each nth rover epoch, after a time interval, after exceeding a distance between a current approximate rover position and a current virtual base station location.

21. The apparatus of claim 13, wherein the virtual base station location is generated for a specific GNSS time interval.

22. The apparatus of claim 13, wherein the element to apply a differential process is adapted to perform at least one of:

aided inertial navigation (integrated inertial navigation and GNSS) processing, real-time kinematic (RTK) processing, instant real-time kinematic (IRTK) processing;

differential GPS processing;

float processing;

triple differenced processing;

post-processing and real-time processing.

23. The apparatus of claim 13, further comprising an element to match each epoch of the rover GNSS data with an epoch of synthesized base station data within a few milliseconds.

24. The apparatus of claim 13, wherein the element to generate epochs of synthesized base station data is adapted to generate a set of synthesized base station observations for each of a plurality of discrete times, and wherein the element to apply a differential process is adapted to process each epoch of GNSS rover data with a set of synthesized base station observations for a discrete time which is within ten seconds of the epoch of the GNSS rover data being processed.

26. (canceled)