GNSS ATMOSPHERIC ESTIMATION WITH AMBIGUITY FIXING

• US 20120119944A1
• Filed: 05/26/2011
• Published: 05/17/2012
• Est. Priority Date: 05/30/2010
• Status: Abandoned Application

• Current Assignee: Trimble Navigation Limited (Trimble Inc.)
• Original Assignee: Trimble Navigation Limited (Trimble Inc.)
• Inventors: Chen, Xiaoming
• Application Number:
  US13/117,111
• Publication Number:
  US 20120119944A1
• Time in Patent Office: Days
• US Class Current: 342/26.A
• CPC Class Codes: G01S 19/32 Multimode operation in a single same satellite system, e.g. GPS L1/L2
• CPC Class Codes: G01S 19/44 Carrier phase ambiguity resolution; Floating ambiguity; LAMBDA [Least-squares AMBiguity Decorrelation Adjustment] method

Abstract

Methods and apparatus are presented for estimating environmental parameters from GNSS signals in real time. Some embodiments estimate a float solution using a federated ionospheric filter. Some embodiments fix ambiguities for improved estimates.

Claims

1. A method of processing GNSS signal data to estimate environmental parameter values, comprising

obtaining GNSS data collected at a plurality of stations distributed over a region from signals received from GNSS satellites over multiple epochs,

obtaining a satellite code bias per satellite,

estimating from the GNSS data and the satellite code biases a set of float ambiguities per station per satellite and values for atmospheric parameters comprising at least one of:

(i) a total electron content per station per satellite, (ii) a zenith total delay per station, (iii) a zenith total delay per station and a set of tropospheric gradients per station, and (iv) a slant total delay per station per satellite,

fixing the ambiguities, and

estimating from the GNSS data and the fixed ambiguities corrected values for the atmospheric parameters.

2. The method of claim 1, further comprising:

obtaining meteorological data for locations within the region, and

determining values over the region for at least one of integrated precipitable water vapor and tropospheric slant wet delay, from the corrected values for the atmospheric parameters and from the meteorological data.

3. The method of claim 1, wherein estimating the set of float ambiguities and values for atmospheric parameters comprises applying at least one iterative filter to the GNSS data and the satellite code biases.

4. The method of claim 1, wherein estimating the set of float ambiguities and values for atmospheric parameters comprises applying a set of factorized filters to the GNSS data and the satellite code biases.

5. The method of claim 1, wherein estimating the set of float ambiguities and values for atmospheric parameters comprises applying a federated ionospheric filter to the GNSS data and the satellite code biases.

6. The method of claim 1, wherein the value of total electron content per station per satellite comprises a value mapped to vertical.

7. The method of claim 1, wherein obtaining meteorological data comprises obtaining surface meteorological data for locations within the region.

8. The method of claim 1, wherein obtaining meteorological data comprises obtaining radiosonde temperature data for locations within the region.

9. The method of claim 1, wherein elapsed time between obtaining the GNSS data and determining the corrected values for the atmospheric parameters is no more than about 5 seconds.

10. The method of claim 1, wherein elapsed time between obtaining the GNSS data and determining values over the region for at least one of integrated precipitable water vapor and tropospheric slant wet delay is no more than about 5 seconds.

21. A computer program product comprising:

a 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.

11. Apparatus for processing GNSS signal data to estimate environmental parameter values, comprising

at least one recursive filter to estimate from satellite differential code biases and from the GNSS signal data a set of float ambiguities per station per satellite, and values for atmospheric parameters comprising at least one of :

(i) a total electron content per station per satellite, (ii) a zenith total delay per station, (iii) a zenith total delay per station and a set of tropospheric gradients per station, (iv) a slant tropospheric total delay per station per satellite, and (v) a total electron content per station per satellite.

an ambiguity-fixing module to prepare fixed ambiguities from the float ambiguities, and

a corrector module to prepare from the GNSS data and the fixed ambiguities corrected values for the atmospheric parameters.

12. The apparatus of claim 11, further comprising:

a meteorological watch module to determine values for at least one of integrated precipitable water vapor and tropospheric slant wet delay from the corrected values for the atmospheric parameters and from meteorological data.

13. The apparatus of claim 11, wherein the at least one recursive filter comprises a Kalman filter.

14. The apparatus of claim 11, wherein the at least one recursive filter comprises a set of factorized filters.

15. The apparatus of claim 11, wherein the at least one recursive filter comprises a federated ionospheric filter.

16. The apparatus of claim 11, wherein the value of total electron content per station per satellite comprises a value mapped to vertical.

17. The apparatus of claim 11, wherein the meteorological watch module is operative to process meteorological data comprising surface meteorological data for locations within the region.

18. The apparatus of claim 11, wherein the meteorological watch module is operative to process meteorological data comprising radiosonde sounding data for locations within the region.

19. The apparatus of claim 11, wherein elapsed time between obtaining the GNSS data and determining the corrected values over the region for the atmospheric parameters is no more than about 5 seconds.

20. The apparatus of claim 11, wherein elapsed time between obtaining the GNSS data and determining values over the region for integrated precipitable water vapor and ionospheric slant wet delay is no more than about 5 seconds.