GNSS signal processing with known position for reconvergence

Patent metadata

Field	Value
Publication number	US-9709683-B2
Application number	US-201214002716-A
Country	US
Kind code	B2
Filing date	Mar 11, 2012
Priority date	Jan 14, 2008
Publication date	Jul 18, 2017
Grant date	Jul 18, 2017

Abstract

Methods and apparatus provide for positioning of a rover antenna from GNSS data derived from multi-frequency signals and correction data derived from a network of reference stations. At each of a plurality of epochs, the GNSS data and correction data are used to estimate values defining a rover antenna position and a set of multi-frequency ambiguities. An ionospheric-free carrier-phase ambiguity per satellite is estimated based on a known rover antenna position. The estimated ionospheric-free carrier-phase ambiguity is combined with an estimated widelane ambiguity and with an estimated ionospheric-free ambiguity and with values defining the known rover antenna position to obtain values defining an aided rover antenna position and aided multi-frequency ambiguities.

First claim

The invention claimed is:

1. A method of estimating a position of a rover antenna using a computer processor, the method comprising:
obtaining GNSS data derived from multi-frequency signals received at the rover antenna;
obtaining correction data for the GNSS data from a network of reference stations;
at each of a plurality of epochs, estimating values defining a rover antenna position and a set of multi-frequency ambiguities using the GNSS data and the correction data;
estimating an ionospheric-free carrier-phase ambiguity per satellite based on a known rover antenna position; and
assisting determination of an aided rover antenna position using the estimated ionospheric-free carrier-phase ambiguities.

2. The method of claim 1 , wherein assisting the determination of the aided rover antenna position comprises combining the estimated ionospheric-free carrier-phase ambiguity with an estimated widelane ambiguity, an estimated ionospheric-free ambiguity, and values defining the known rover antenna position to obtain values defining the aided rover antenna position and aided multi-frequency ambiguities.

3. The method of claim 2 , wherein the widelane ambiguities are estimated in a set of code-carrier filters operated by the processor.

4. The method of claim 2 , wherein the ionospheric-free ambiguities are estimated in a geometry filter operated by the processor.

5. The method of claim 1 , further comprising monitoring precision of an unaided rover antenna position estimate to determine when substantially no further benefit is obtained from using the estimated ionospheric-free carrier-phase ambiguities in assisting determination of the aided rover antenna position.

6. The method of claim 1 , wherein the ionospheric-free carrier-phase ambiguity per satellite is computed using the known rover antenna position and observed carrier-phase measurements.

7. The method of claim 1 , further comprising improving the ionospheric-free carrier-phase ambiguity for at least one satellite based on the known rover antenna position using a prevailing tropospheric bias on the respective satellite.

8. The method of claim 1 , wherein assisting the determination of the aided rover antenna position comprises using the estimated ionospheric-free carrier-phase ambiguity estimates with estimates of other parameters from a set of factorized filters.

9. The method of claim 8 , further comprising substituting the ionospheric-free carrier-phase ambiguity estimates for estimates from a bank of auxiliary code-carrier filters.

10. The method of claim 9 , further comprising creating separate bank of auxiliary code carrier filter results for the known position results so that normal auxiliary code carrier filter results remain unaffected.

11. A computer program product comprising a non-transitory computer-readable medium embodying instructions for causing an apparatus to perform the method of claim 1 .

12. An apparatus comprising:
a receiver configured to:
receive GNSS data derived from multi-frequency signals received at a rover antenna; and
receive correction data for the GNSS data from a network of reference stations; and

a processor coupled to the receiver and configured to:
at each of a plurality of epochs, estimate values defining a rover antenna position and a set of multi-frequency ambiguities using the GNSS data and the correction data;
estimate an ionospheric-free carrier-phase ambiguity per satellite based on a known rover antenna position; and
assist determination of an aided rover antenna position using the estimated ionospheric-free carrier-phase ambiguities.

13. The apparatus of claim 12 , wherein assisting determination comprises combining the estimated ionospheric-free carrier-phase ambiguity with an estimated widelane ambiguity, an estimated ionospheric-free ambiguity, and values defining the known rover antenna position to obtain values defining the aided rover antenna position and aided multi-frequency ambiguities.

14. The apparatus of claim 13 , wherein the widelane ambiguities are estimated in a set of code-carrier filters operated by the processor.

15. The apparatus of claim 13 , wherein the ionospheric-free ambiguities are estimated in a geometry filter operated by the processor.

16. The apparatus of claim 13 , wherein the processor is configured to estimate the ionospheric-free carrier-phase ambiguity per satellite using the known rover antenna position and observed carrier-phase measurements.

17. The apparatus of claim 12 , wherein the processor is further configured to monitor precision of an unaided rover antenna position estimate to determine when substantially no further benefit is obtained from using the estimated ionospheric-free carrier-phase ambiguities in assisting determination of an aided rover antenna position.

18. The apparatus of claim 12 , wherein the processor is further configured to improve the ionospheric-free carrier-phase ambiguity for at least one satellite based on the known rover antenna position using a prevailing tropospheric bias on the respective satellite.

19. The apparatus of claim 12 , wherein assisting determination comprises using the estimated ionospheric-free carrier-phase ambiguity estimates with estimates of other parameters from a set of factorized filters operated by the processor.

20. The apparatus of claim 12 , wherein the processor is further configured to substitute the ionospheric-free carrier-phase ambiguity estimates for estimates from a bank of auxiliary code-carrier filters.

21. The apparatus of claim 20 , wherein the processor is further configured to create a separate bank of auxiliary code carrier filter results for the known position results so that normal auxiliary code carrier filter results remain unaffected.

Assignees

• Leandro Rodrigo
• Vollath Ulrich
• Talbot Nicholas Charles
• Trimble Inc

Inventors

• Leandro Rodrigo
• Vollath Ulrich
• Talbot Nicholas Charles

Classifications

• G01S19/32

  Multimode operation in a single same satellite system, e.g. GPS L1/L2 · CPC title

• G01S19/072

  Ionosphere corrections · CPC title

• G01S19/44 Primary

  Carrier phase ambiguity resolution; Floating ambiguity; LAMBDA [Least-squares AMBiguity Decorrelation Adjustment] method · CPC title

• G01S19/43

  using carrier phase measurements, e.g. kinematic positioning; using long or short baseline interferometry · CPC title

• G01S19/09

  providing processing capability normally carried out by the receiver · CPC title