Position determination based on corroborated signal processing of PRN codes

• US 8,085,191 B2
• Filed: 08/18/2008
• Issued: 12/27/2011
• Est. Priority Date: 08/18/2008
• Status: Active Grant

• Current Assignee: Trimble Navigation Limited (Trimble Inc.)
• Original Assignee: Trimble Navigation Limited (Trimble Inc.)
• Inventors: Green, James C.
• Primary Examiner(s): Tarcza, Thomas
• Assistant Examiner(s): GALT, CASSI J
• Application Number:
  US12/193,142
• Publication Number:
  US 20100315285A1
• Time in Patent Office: 1,226 Days
• Field of Search: 342/357.31
• US Class Current: 342/357.31
• CPC Class Codes: G01S 19/32 Multimode operation in a single same satellite system, e.g. GPS L1/L2
• CPC Class Codes: G01S 19/33 Multimode operation in different systems which transmit time stamped messages, e.g. GPS/GLONASS
• CPC Class Codes: G01S 19/426 by combining or switching between position solutions or signals derived from different modes of operation in a single system

Abstract

Embodiments provided herein recite methods and systems for corroborating position system code from Navigation Satellite System (NSS) signals. In one embodiment, a NSS high yield module attempts to determine a high yield location solution based on a first set of PRN codes. In addition, a NSS high accuracy module attempts to determine a high accuracy location solution based on signal processing of the same first set of PRN codes. A location solution corroborator module receives input from both the NSS high yield module and the NSS high accuracy module and generates a corroborated location solution. In one embodiment, a position provider outputs the corroborated location solution.

Claims

1. A navigation satellite system (NSS) method for position determination based on signal processing of PRN codes, the method comprising:

using a NSS high yield signal processing technique wherein a first high yield location solution is determined using a first set of PRN codes associated with a first NSS and a second high yield location solution is determined using a second set of PRN codes associated with a second NSS;

using a NSS high accuracy technique for attempting a first high accuracy location solution based on signal processing of said first set of PRN codes and for attempting a second high accuracy location solution based on signal processing of said second set of PRN codes;

selecting one of the first and second high accuracy location solutions as a NSS-based location when either or both of the first and second high accuracy location solutions is available, wherein when both the first and second high accuracy location solutions are available the first high accuracy location solution is selected when a first location difference between the first high accuracy and high yield location solutions is smaller than a second location difference between the second high accuracy and high yield location solutions, and the second high accuracy location solution is selected when the second location difference is smaller than the first location difference; and

selecting one of the first and second high yield location solutions for the NSS-based location when no high accuracy location solution is available and one or both of the high yield solutions is available.

2. The method of claim 1, further comprising:

selecting the PRN codes from the group of local and global NSS signals consisting of;

a global positioning system (GPS) signal, a Galileo signal, a Globalnaya Navigatsionnay Sputnikovaya Sistema (GLONASS) signal, and a Compass signal.

3. The method of claim 1, further comprising:

selecting the PRN codes from a group of satellite navigation signals consisting of;

L1 signals, E1 signals, E2 signals, L2 signals, L3 signals, E6 signals, B3 signals, LEX signals, L5 signals, E5 signals, and AltBOC signals.

4. The method of claim 1, further comprising:

determining a correction vector between the first high accuracy location solution and the first high yield location solution when the first high accuracy location solution is available; and

applying the correction vector to the first high yield location solution for determining the NSS-based location when the first high accuracy location solution subsequently is not available.

5. The method of claim 1, further comprising:

determining said first location difference between the first high accuracy location solution and the first high yield location solution when the first high accuracy location solution is available; and

issuing a location error notification when the first location difference is greater than a selected threshold.

6. The method of claim 1, wherein using the high yield technique further comprises:

calculating a first dilution of precision (DOP) and a second DOP for the first NSS and the second NSS, respectively; and

using the first DOP and the second DOP for determining a first location accuracy and a second location accuracy, respectively.

7. The method of claim 1, further comprising:

using the high yield technique for determining signal acquisition data for acquiring a NSS signal for a particular NSS satellite; and

using the signal acquisition data for assisting the high accuracy technique for acquiring a NSS signal from the particular NSS satellite.

8. The method of claim 7, wherein the signal acquisition data is selected from the group consisting of:

Doppler, code phase, NSS clock, clock drift, and PRN number.

9. The method of claim 1, further comprising:

determining an estimated location accuracy of the NSS-based location based at least in part on a dilution of precision; and

issuing a notification when the estimated location accuracy of the NSS-based location is less than a selected minimum accuracy.

10. The method of claim 9 further comprising:

selecting the selected minimum accuracy with user-accessible slider having accuracy settings.

11. The method of claim 1, further comprising:

issuing a notification when a currently available number of pseudoranges for either of the first and second high accuracy location solutions is less than a selected availability number; and

issuing a notification based on a dilution of precision (DOP) threshold.

12. The method of claim 11, further comprising:

selecting the availability number with user-accessible slider having integer settings.

13. The method of claim 12, wherein the availability number is selected from at least two of the numbers in the group consisting of:

zero, one, two, three, four, five, six, seven and eight.

14. The method of claim 1, further comprising:

using the high accuracy technique for a determining ionospheric parameters of an ionospheric model; and

using the ionospheric parameters for determining the high yield location solutions.

15. The method of claim 1, further comprising:

using a reference clock signal for processing NSS signals from NSS satellites in a high yield NSS receiver; and

using the same reference clock signal for processing the NSS signals from the NSS satellites in a high accuracy NSS receiver, the high accuracy NSS receiver being physically separate from the high yield NSS receiver.

16. The method of claim 1, further comprising:

de-weighting pseudoranges corresponding to NSS satellites having elevation angles below an elevation threshold for determining the first high accuracy location solution.

17. The method of claim 1, further comprising:

using NSS satellite signals having a lower signal-to-noise ratio for determining the first high yield location solution.

18. A navigation satellite system (NSS) position determination system comprising:

a NSS high yield module for determining a first high yield location solution based on first positioning signals associated with a first NSS and for determining a second high yield location solution based on second positioning signals associated with a second NSS;

a NSS high accuracy module for determining a first high accuracy location solution based on the first positioning signals and for determining a second high accuracy location solution based on the second positioning signals; and

a location solution corroborator module for receiving input from both the NSS high yield module and the NSS high accuracy module, the location solution corroborator module for providing a corroborated location solution; and

a position provider outputting the corroborated location solution, wherein the corroborated location solution which is output comprises;

one of the first and second high accuracy location solutions as a NSS-based location when either or both of the first and second high accuracy location solutions is available, wherein when both the first and second high accuracy location solutions are available the first high accuracy location solution is output as the corroborated solution when a first location difference between the first high accuracy and high yield location solutions is smaller than a second location difference between the second high accuracy and high yield location solutions, and the second high accuracy location solution is output when the second location difference is smaller than the first location difference; and

one of the first and second high yield location solutions for the NSS-based location is output when no high accuracy location solution is available and one or both of the high yield solutions is available.

19. The system of claim 18 wherein one of said first NSS and said second NSS is a global navigation satellite system (GNSS) position determination system.

20. The system of claim 18 wherein one of said first NSS and said second NSS is a local navigation satellite system (LNSS) position determination system.

21. The system of claim 18 further comprising:

a correction vector module for receiving input from both the NSS high yield module and the NSS high accuracy module and determining a correction vector applicable to the first high yield location solution; and

a correction vector application module for applying the correction vector to the first high yield location solution.

22. The system of claim 18 further comprising:

a warning module for providing a notification when the accuracy of the corroborated location solution is below an accuracy threshold.

23. The system of claim 18 wherein the positioning signals are provided by the group of NSS providers consisting of:

a global positioning system (GPS) signal, a Galileo signal, a Globalnaya Navigatsionnay Sputnikovaya Sistema (GLONASS) signal, and a Compass signal.

24. The system of claim 18 wherein the corroborated location solution has an accuracy greater than or equal to the least accurate of the first and second high yield location solutions and less than or equal to the least accurate of the first and second high accuracy location solutions.