GNSS Signal Processing with Regional Augmentation Positioning

• US 20120286991A1
• Filed: 02/14/2011
• Published: 11/15/2012
• Est. Priority Date: 02/14/2010
• Status: Active Grant

• Current Assignee: Trimble Navigation Limited (Trimble Inc.)
• Original Assignee: Trimble Navigation Limited (Trimble Inc.)
• Inventors: Chen, Xiaoming, Vollath, Ulrich, Ferguson, Kendall
• Granted Patent: US 9,164,174 B2
• Time in Patent Office: Days
• US Class Current: 342/357.23
• CPC Class Codes: G01S 1/00 Beacons or beacon systems transmitting signals having a characteristic or characteristics capable of being detected by non-directional receivers and defining directions, positions, or position lines fixed relatively to the beacon transmitters; Receivers co-operating therewith position fixing by co-ordinating a plurality of determinations of direction or position lines G01S5/00
• CPC Class Codes: G01S 19/02 Details of the space or ground control segments
• CPC Class Codes: G01S 19/04 providing carrier phase data
• CPC Class Codes: G01S 19/073 involving a network of fixed stations
• CPC Class Codes: G01S 19/32 Multimode operation in a single same satellite system, e.g. GPS L1/L2
• CPC Class Codes: G01S 19/40 Correcting position, velocity or attitude
• CPC Class Codes: G01S 19/41 Differential correction, e.g. DGPS [differential GPS]
• 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 for processing of GNSS data derived from multi-frequency code and carrier observations are presented which make available correction data for use by a rover located within the region, the correction data comprising: the ionospheric delay over the region, the tropospherπc delay over the region, the phase-leveled geometric correction per satellite, and the at least one code bias per satellite. In some embodiments the correction data includes an ionospheric phase bias per satellite. Methods and apparatus for determining a precise position of a rover located within a region are presented in which a GNSS receiver is operated to obtain multi-frequency code and carrier observations and correction data, to create rover corrections from the correction data, and to determine a precise rover position using the rover observations and the rover corrections. The correction data comprises at least one code bias per satellite, a fixed-nature MW bias per satellite and/or values from which a fixed-nature MW bias per satellite is derivable, and an ionospheric delay per satellite for each of multiple regional network stations and/or non-ionospheric corrections. Methods and apparatus for encoding and decoding the correction messages containing correction data are also presented, in which network messages include network elements related to substantially all stations of the network and cluster messages include cluster elements related to subsets of the network.

Claims

1. A method of determining a precise position of a rover located within a region, comprising:

a. operating a receiver to obtain rover observations comprising code observations and carrier-phase observations of GNSS signals on at least two carrier frequencies,

b. receiving correction data comprising

1. at least one code bias per satellite,

2. at least one of;

(i) a fixed-nature MW bias per satellite and (ii) values from which a fixed-nature MW bias per satellite is derivable, and

3. at least one of;

(iii) an ionospheric delay per satellite for each of multiple regional network stations, and (iv) non-ionospheric corrections;

c. creating rover corrections from the correction data; and

d. operating a processor to determine a precise rover position using the rover observations and the rover corrections.

2. The method of claim 1, wherein the code bias per satellite comprises a code bias per satellite estimated by a global network processor.

3. The method of claim 1, wherein the ionospheric delay per satellite comprises an ionospheric delay estimated from observations of multiple regional network stations.

4. The method of claim 1, wherein the ionospheric delay per satellite is estimated from a model of ionospheric delay over the region.

5. The method of claim 1, wherein the correction data further comprises an ionospheric phase bias per satellite.

6. The method of claim 1, wherein the non-ionospheric corrections comprise a tropospheric delay for each of multiple regional network stations.

7. The method of claim 1, wherein the non-ionospheric corrections comprise a geometric correction per satellite.

8. The method of claim 1, wherein the non-ionospheric corrections comprise, for each satellite in view at the receiver, a geometric correction representing satellite position error and satellite clock error.

9. The method of claim 8, wherein creating rover corrections from the data set comprises identifying each geometric correction with a respective satellite observed at the rover.

10. The method of claim 8, wherein using the rover observations and the rover corrections to determine a precise rover position comprises:

determining a geometric range per satellite using at least one of (i) broadcast ephemeris and (ii) precise ephemeris and, for each satellite, applying the geometric correction to the geometric range to obtain a corrected geometric range per satellite.

11. The method of claim 1, wherein the non-ionospheric corrections comprise, for each satellite in view at the rover, a geometric correction for each of three locations in the regions, and wherein creating rover corrections from the correction data comprises, for each satellite in view at the rover, determining a geometric correction for an approximate rover location from the geometric corrections for the three locations.

12. The method of claim 1, wherein the correction data comprises an ionospheric delay per satellite at multiple regional network stations, and wherein creating rover corrections from the data set comprises interpolating an ionospheric delay for the rough position.

13. The method of claim 1, wherein the correction data comprises an ionospheric delay per satellite at multiple regional network stations and an ionospheric phase bias per satellite, and wherein creating rover corrections from the data set comprises, for each satellite, interpolating an absolute ionospheric delay for the rough position and combining with the ionospheric phase bias.

14. The method of claim 1, wherein the data set comprises a tropospheric delay per satellite at multiple regional network stations, and wherein creating rover corrections from the data set comprises interpolating a tropospheric delay for the rough position.

15. The method of claim 1, wherein using the rover observations and the rover corrections to determine a precise rover position comprises:

combining the rover corrections with the rover observations to obtain corrected rover observations, and determining the precise rover position from the corrected rover observations.

16. The method of claim 1, wherein using the rover observations and the rover corrections to determine a precise rover position comprises:

using the rover corrections to estimate simulated reference station observables for each of multiple satellites in view at a selected location; and

differentially processing the rover observations with the simulated reference station observables to obtain the precise rover position.

17. The method of claim 16, wherein using the rover corrections to estimate simulated reference station observables for each of multiple satellites in view at a selected location comprises using the rover corrections to estimate at least one simulated reference station carrier-phase observation for each of multiple satellites observable at a selected location.

18. The method of claim 16, wherein using the rover corrections to estimate simulated reference station observables for each of multiple satellites in view at a selected location comprises using the rover corrections to estimate at least one simulated reference station code observation for each of multiple satellites observable at the selected location.

19. The method of claim 16, wherein the selected location is one of (i) the rough position of the rover and (ii) a location within 100 m of the rough position of the rover.

20. The method of claim 16, wherein using the rover corrections to estimate simulated reference station observables for each of multiple satellites in view at a selected location is performed in a processor at a location remote from the rover.

21. The method of claim 16, wherein using the rover corrections to estimate simulated reference station observables for each of multiple satellites in view at a selected location is performed in a processor at the rover.

22. A computer program product comprising:

a non-transitory computer usable medium having computer readable instructions physically embodied therein, the computer readable instructions when executed by a processor enabling the processor to perform the method of claim 1.

23. (canceled)

24. Apparatus for determining a precise position of a rover located within a region, comprising:

a. a receiver operative to obtain rover observations comprising code observations and carrier-phase observations of GNSS signals on at least two carrier frequencies,

b. a correction data receiver operative to receive correction data comprising

1. at least one code bias per satellite,

2. at least one of;

(i) a fixed-nature MW bias per satellite and (ii) values from which a fixed-nature MW bias per satellite is derivable, and

3. at least one of;

(iii) an ionospheric delay per satellite for each of multiple regional network stations, and (iv) non-ionospheric corrections; and

c. at least one processor operative to create rover corrections from the correction data and operative to determine a precise rover position using the rover observations and the rover corrections.

25. The apparatus of claim 24, wherein the code bias per satellite comprises a code bias per satellite estimated by a global network processor.

26. The method of claim 24, wherein the ionospheric delay per satellite comprises an ionospheric delay estimated from observations of multiple regional network stations.

27. The method of claim 24, wherein the ionospheric delay per satellite is estimated from a model of ionospheric delay over the region.

28. The apparatus of claim 24, wherein the correction data further comprises an ionospheric phase bias per satellite.

29. The method of claim 24, wherein the non-ionospheric corrections comprise a tropospheric delay for each of multiple regional network stations.

30. The method of claim 24, wherein the non-ionospheric corrections comprise a geometric correction per satellite.

31. The method of claim 24, wherein the non-ionospheric corrections comprise, for each satellite in view at the receiver, a geometric correction representing satellite position error and satellite clock error.

32. The apparatus of claim 31, wherein said at least one processor is operative to identify each geometric correction with a respective satellite observed at the rover.

33. The method of claim 31, wherein said at least one processor is operative to determine a geometric range per satellite using at least one of (i) broadcast ephemeris and (ii) precise ephemeris and, for each satellite, and to apply the geometric correction to the geometric range to obtain a corrected geometric range per satellite.

34. The method of claim 24, wherein the non-ionospheric corrections comprise, for each satellite in view at the rover, a geometric correction for each of three locations in the regions, and wherein the at least one processor is operative to determine, for each satellite in view at the rover, a geometric correction for an approximate rover location from the geometric corrections for the three locations.

35. The method of claim 24, wherein the correction data comprises an ionospheric delay per satellite at multiple regional network stations, and wherein the at least one processor is operative to interpolate an ionospheric delay for the rough position.

36. The method of claim 24, wherein the correction data comprises an ionospheric delay per satellite at multiple regional network stations and an ionospheric phase bias per satellite, and wherein the at least one processor is operative to, for each satellite, interpolate an absolute ionospheric delay for the rough position and combine with the ionospheric phase bias.

37. The method of claim 24, wherein the data set comprises a tropospheric delay per satellite at multiple regional network stations, and wherein the at least one processor is operative to interpolate a tropospheric delay for the rough position.

38. The method of claim 24, wherein the at least one processor is operative to combine the rover corrections with the rover observations to obtain corrected rover observations, and to determine the precise rover position from the corrected rover observations.

39. The method of claim 24, wherein the at least one processor is operative to use the rover corrections to estimate simulated reference station observables for each of multiple satellites in view at a selected location, and to differentially process the rover observations with the simulated reference station observables to obtain the precise rover position.

40. The apparatus of claim 39, wherein the at least one processor is operative to use the rover corrections to estimate at least one simulated reference station carrier-phase observation for each of multiple satellites observable at a selected location.

41. The method of claim 39, wherein the at least one processor is operative to use the rover corrections to estimate at least one simulated reference station code observation for each of multiple satellites observable at the selected location.

42. The method of claim 39, wherein the selected location is one of (i) the rough position of the rover and (ii) a location within 100 m of the rough position of the rover.

43. The method of claim 39, wherein the at least one processor is remote from the rover.

44. The method of claim 39, wherein the at least one processor is at the rover.