GNSS signal processing with ionosphere model for synthetic reference data

• US 9,170,335 B2
• Filed: 02/13/2012
• Issued: 10/27/2015
• Est. Priority Date: 02/14/2011
• Status: Active Grant

• Current Assignee: Trimble Inc.
• Original Assignee: Trimble Navigation Limited (Trimble Inc.)
• Inventors: Chen, Xiaoming, Drescher, Ralf, Leandro, Rodrigo
• Primary Examiner(s): Phan, Dao
• Application Number:
  US13/372,488
• Publication Number:
  US 20130044026A1
• Time in Patent Office: 1,352 Days
• Field of Search: 342/357.23, 342/357.25, 342/357.27, 342/357.44, 701/469, 701/470
• US Class Current: 1/1
• CPC Class Codes: G01S 19/072 Ionosphere corrections
• 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
• CPC Class Codes: G01S 19/45 by combining measurements of signals from the satellite radio beacon positioning system with a supplementary measurement

Abstract

Some embodiments of the present invention derive an ionospheric phase bias and an ionospheric differential code bias (DCB) using an absolute ionosphere model, which can be estimated from data obtained from a network of reference stations or obtained from an external source such as WAAS, GAIM, IONEX or other. Fully synthetic reference station data is generated using the ionospheric phase bias and/or the differential code bias together with the phase leveled clock and ionospheric-free code bias and/or MW bias.

Claims

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

a. obtaining rover data derived from code observations and carrier phase observations of global navigation satellite system (GNSS) signals of multiple satellites over multiple epochs,

b. obtaining correction data comprising (i) an ionospheric phase bias per satellite, (ii) information from which a code leveled clock error per satellite and a phase leveled clock error per satellite is derivable, (iii) a Melbourne-Wü

bbena (MW) bias per satellite, and (iv) an ionospheric differential code bias per satellite, and

c. using the rover data and the correction data and an ionospheric model to determine at least rover antenna positions.

2. The method of claim 1, wherein using the rover data and the correction data and an ionospheric model to determine at least rover antenna positions comprises using the ionospheric model to determine an ionospheric delay per satellite applicable to a region in which the rover antenna is located.

3. The method of claim 1, wherein using the rover data and the correction data and an ionospheric model to determine at least rover antenna positions comprises:

determining a virtual base station location, and using the correction data to generate epochs of synthesized base station data.

4. The method of claim 3, wherein using the correction data to generate epochs of synthesized base station data comprises using a code leveled clock and a phase leveled clock and precise satellite orbit information to determine ionospheric-free code and phase observations for the virtual base station location, and combining the ionospheric-free code and phase observations for the virtual base station location with the ionospheric phase bias and an ionospheric delay derived from the ionospheric model to generate L1 &

L2 phase observations.

5. The method of claim 4, further comprising combining a differential code bias and the ionospheric delay and the ionospheric-free code combination to generate L1 and L2 code observations.

6. The method of claim 4, further comprising combining a MW bias, the ionospheric delay, a difference between a code leveled clock error and phase leveled clock error, and the ionospheric-free code combination to generate L1 &

L2 code observations.

7. A computer-readable medium disposed at a rover associated with the rover antenna, on which is embodied a computer program product comprising instructions configured, when executed on a computer processing unit, to carry out the method of claim 1.

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

a. obtaining rover data derived from code observations and carrier phase observations of global navigation satellite system (GNSS) signals of multiple satellites over multiple epochs,

b. obtaining correction data comprising a Melbourne-Wü

bbena(MW) bias per satellite, information from which a code leveled clock error per satellite and a phase leveled clock error per satellite is derivable, an ionospheric differential code bias per satellite, and information defining an ionospheric model, and

c. using the rover data and the correction data and the ionospheric model to determine at least rover antenna positions.

9. The method of claim 8, wherein using the rover data and the correction data and the ionospheric model to determine at least rover antenna positions comprises using the ionospheric model to determine an ionospheric delay per satellite applicable to a region in which the rover antenna is located.

10. The method of claim 8, wherein using the rover data and the correction data and the ionospheric model to determine at least rover antenna positions comprises:

determining a virtual base station location, and using the correction data to generate epochs of synthesized base station data.

11. The method of claim 10, wherein using the correction data to generate epochs of synthesized base station data comprises using a code leveled clock and a phase leveled clock and precise satellite orbit information to determine ionospheric-free code and phase observations for the virtual base station location, and combining the ionospheric-free code and phase observations for the virtual base station location with the MW bias per satellite and the differential code bias per satellite and an ionospheric delay derived from the ionospheric model to generate L1 &

L2 phase observations.

12. The method of claim 11, further comprising combining the ionospheric differential code bias per satellite, MW bias per satellite and the ionospheric delay and the ionospheric-free code combination to generate L1 and L2 code observations.

13. A computer-readable medium disposed at a rover associated with the rover antenna, on which is embodied a computer program product comprising instructions configured, when executed on a computer processing unit, to carry out the method of claim 8.

14. Apparatus for determining position of a rover antenna, comprising a processor and a set of instructions enabling the processor to:

a. obtain rover data derived from code observations and carrier phase observations of global navigation satellite system (GNSS) signals of multiple satellites over multiple epochs,

b. obtain correction data comprising (i) an ionospheric phase bias per satellite, (ii) information from which a code leveled clock error per satellite and a phase leveled clock error per satellite is derivable, (iii) a Melbourne-Wü

bbena (MW) bias per satellite, and (iv) an ionospheric differential code bias per satellite, and

c. use the rover data and the correction data and an ionospheric model to determine at least rover antenna positions.

15. The apparatus of claim 14, wherein the instructions enable the processor to the rover data and the correction data and an ionospheric model to determine at least rover antenna positions by using the ionospheric model to determine an ionospheric delay per satellite applicable to a region in which the rover antenna is located.

16. The apparatus of claim 14, wherein the instructions enable the processor to use the rover data and the correction data and an ionospheric model to determine at least rover antenna positions by determining a virtual base station location, and using the correction data to generate epochs of synthesized base station data.

17. The apparatus of claim 14, wherein the instructions enable the processor to use the correction data to generate epochs of synthesized base station data using a code leveled clock and a phase leveled clock and precise satellite orbit information to determine ionospheric-free code and phase observations for the virtual base station location, and combine the ionospheric-free code and phase observations for the virtual base station location with the ionospheric phase bias and an ionospheric delay derived from the ionospheric model to generate L1 &

L2 phase observations.

18. The apparatus of claim 17, wherein the instructions further enable the processor to combine a differential code bias and the ionospheric delay and the ionospheric-free code combination to generate L1 and L2 code observations.

19. The apparatus of claim 17, wherein the instructions further enable the processor to combine a MW bias, the ionospheric delay, a difference between a code leveled clock error and phase leveled clock error, and the ionospheric-free code combination to generate L1 &

L2 code observations.

20. Apparatus for determining position of a rover antenna, comprising a processor and a set of instructions enabling the processor to:

a. obtain rover data derived from code observations and carrier phase observations of global navigation satellite system (GNSS) signals of multiple satellites over multiple epochs,

b. obtain correction data comprising a Melbourne-Wü

bbena (MW) bias per satellite, information from which a code leveled clock error per satellite and a phase leveled clock error per satellite is derivable, an ionospheric differential code bias per satellite, and information defining an ionospheric model, and

c. use the rover data and the correction data and the ionospheric model to determine at least rover antenna positions.

21. The apparatus of claim 20, wherein the instructions enable the processor to use the rover data and the correction data and the ionospheric model to determine at least rover antenna positions using the ionospheric model to determine an ionospheric delay per satellite applicable to a region in which the rover antenna is located.

22. The apparatus of claim 20, wherein the instructions enable the processor to use the rover data and the correction data and the ionospheric model to determine at least rover antenna positions by:

determining a virtual base station location, and using the correction data to generate epochs of synthesized base station data.

23. The apparatus of claim 22, wherein the instructions enable the processor to use the correction data to generate epochs of synthesized base station data using a code leveled clock and a phase leveled clock and precise satellite orbit information to determine ionospheric-free code and phase observations for the virtual base station location, and combine the ionospheric-free code and phase observations for the virtual base station location with the MW bias per satellite and the differential code bias per satellite and an ionospheric delay derived from the ionospheric model to generate L1 &

L2 phase observations.

24. The apparatus of claim 23, wherein the instructions further enable the processor to combine the ionospheric differential code bias per satellite, MW bias per satellite and the ionospheric delay and the ionospheric-free code combination to generate L1 and L2 code observations.