Position Determination Based on Hybrid Pseudorange Solution Data

• US 20100176990A1
• Filed: 01/14/2009
• Published: 07/15/2010
• Est. Priority Date: 01/14/2009
• Status: Active Grant

• Current Assignee: Trimble Navigation Limited (Trimble Inc.)
• Original Assignee: Trimble Navigation Limited (Trimble Inc.)
• Inventors: WEISENBURGER, Shawn, GREEN, Jim
• Granted Patent: US 8,044,852 B2
• Time in Patent Office: Days
• US Class Current: 342/357.620
• CPC Class Codes: G01S 19/22 Multipath-related issues
• 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 19/423 by combining or switching between position solutions derived from different satellite radio beacon positioning systems
• 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
• CPC Class Codes: G01S 19/428 using multipath or indirect path propagation signals in position determination

Abstract

Embodiments provided herein recite methods and systems for position determination based on hybrid pseudorange solution data. In one embodiment, navigation satellite system (NSS) pseudorange data is received for high yield pseudoranges. In addition, NSS pseudorange data is received for high accuracy pseudoranges. The high accuracy pseudoranges and selected ones of the high yield pseudoranges utilized by a hybrid PVT processor to determine a hybrid NSS-based location solution.

Claims

1. A method for hybrid position determination, comprising:

receiving navigation satellite system (NSS) pseudorange data from a first GNSS receiver configured to provide high yield pseudoranges;

receiving NSS pseudorange data from a second GNSS receiver configured to provide high accuracy pseudoranges; and

utilizing the high accuracy pseudoranges and selected ones of the high yield pseudoranges at a hybrid PVT processor to determine a hybrid NSS-based location solution.

2. The method of claim 1, wherein the step of combining includes:

using only the high accuracy pseudoranges for determining the NSS-based location when a sufficient number of the high accuracy pseudoranges are currently available; and

using one or more high yield pseudoranges with the high accuracy pseudoranges for determining the NSS-based location when an insufficient number of the high accuracy pseudoranges are currently available.

3. The method of claim 1, wherein the hybrid NSS-based location solution comprises:

estimating a basic location accuracy using a high accuracy pseudorange set of the high accuracy pseudoranges;

estimating an augmented location accuracy using an augmented pseudorange set of the high accuracy pseudoranges augmented with at least one of the high yield pseudoranges; and

using the basic or augmented pseudorange set for determining the hybrid NSS-based location solution according to the better of the basic or augmented location accuracy.

4. The method of claim 1, wherein the hybrid NSS-based location solution comprises:

estimating a first location accuracy using a first pseudorange set having the high accuracy pseudoranges and a first of the high yield pseudoranges;

estimating a second location accuracy using a second pseudorange set having the high accuracy pseudoranges and a second of the high yield pseudoranges; and

using the first or second pseudorange set for determining the hybrid NSS-based location solution according to the better of the first or second location accuracy.

5. The method of claim 4, wherein the step of estimating the first location accuracy includes:

estimating basic pseudorange accuracies of the high accuracy pseudoranges, respective;

estimating a first pseudorange accuracy of the first high yield pseudorange; and

determining the first location accuracy based on the accuracy estimates for the first pseudorange set.

6. The method of claim 5, wherein the step of estimating the first location accuracy includes:

calculating a dilution of precision (DOP) for NSS satellites corresponding to the first pseudorange set; and

estimating the first location accuracy based on the DOP and the estimated pseudorange accuracies for the first pseudorange set.

7. The method of claim 5, wherein the step of estimating the first pseudorange accuracy comprises:

estimating the first pseudorange accuracy based at least in part on a signal-to-noise ratio for a NSS signal corresponding to the first high yield pseudorange.

8. The method of claim 5, wherein the step of estimating the first pseudorange accuracy comprises:

estimating the first pseudorange accuracy based at least in part on an elevation angle for a NSS satellite corresponding to the first high yield pseudorange.

9. The method of claim 5, wherein the step of estimating the first pseudorange accuracy comprises:

estimating the first pseudorange accuracy based at least in part on a length of time tracking a NSS signal corresponding to the first high yield pseudorange.

10. The method of claim 1, further comprising:

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

11. The method of claim 10 wherein:

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

12. The method of claim 1, further comprising:

issuing a notification when a currently available number of the high accuracy pseudoranges is less than a selected availability number; and

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

13. The method of claim 12, wherein:

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

14. The method of claim 12, wherein:

the availability number is selectable for at least two of the following numbers;

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

15. The method of claim 1, further comprising:

determining pseudorange differences comprising;

subtracting a high accuracy pseudorange from a high yield pseudorange for the same NSS satellite, in the same bit time period to generate a pseudorange difference;

repeating the subtracting for each additional in-view NSS satellite, to create a set of pseudorange differences;

utilizing the absolute value of each the pseudorange difference in the set of pseudorange differences to generate a set of pseudorange deltas ordered from smallest to largest;

inputting the high yield pseudorange with the smallest pseudorange delta to a hybrid NSS-based solution;

evaluating a position dilution of precision threshold for the hybrid NSS-based solution; and

repeating the inputting and evaluating for each high yield pseudorange in the order defined by the set of pseudorange deltas until a position dilution of precision threshold for the hybrid NSS-based solution is met.

16. The method of claim 1, further comprising:

receiving NSS signal acquisition data from a high yield NSS receiver for a first NSS satellite corresponding to a first of the high yield pseudoranges; and

using the signal acquisition data in a high accuracy NSS receiver for acquiring a NSS signal from the first NSS satellite for determining a first of the high accuracy pseudoranges.

17. The method of claim 16, wherein the signal acquisition data includes signal acquisition data that HY can pass to HA for acquisition or re-acquisition of HA pseudoranges selected from the group consisting of:

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

18. The method of claim 16, wherein:

the positioning data includes signal acquisition data that HY can pass to HA for acquire or re-acquire selected from the group consisting essentially of;

Doppler, velocity, time and code phase.

19. The method of claim 1, further comprising:

using a high accuracy technique for determining the high accuracy pseudoranges and using a high yield technique for determining the high yield pseudoranges;

wherein;

the high accuracy technique differs from the high yield technique for determining pseudoranges selected from the group of techniques consisting of;

a de-weighting pseudoranges corresponding to NSS satellites having elevation angles below an elevation threshold, a tracking state and a loop bandwidth.

20. The method of claim 1, further comprising:

using a high accuracy technique for determining the high accuracy pseudoranges and using a high yield technique for determining the high yield pseudoranges;

wherein;

the high yield technique differs from the high accuracy technique by using NSS satellite signals having a lower signal-to-noise ratio for determining the high yield pseudoranges.

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

a NSS high accuracy module for determining a high accuracy pseudorange solution based on a portion of a positioning signal;

a NSS high yield module for determining a high yield pseudorange solution based on the same positioning system code;

a hybrid solution module for receiving pseudorange input from both the NSS high accuracy module and the NSS high yield module, the hybrid solution module providing a hybrid pseudorange solution; and

a position provider outputting the hybrid pseudorange solution to said NSS high accuracy module and said NSS high yield module.

22. The system of claim 21 wherein said NSS is a global navigation satellite system (GNSS) position determination system.

23. The system of claim 21 wherein said NSS is a local navigation satellite system (LNSS) position determination system.

24. The system of claim 21 wherein said hybrid pseudorange solution further comprises an estimated pseudorange accuracy based at least in part on a signal-to-noise ratio for a NSS signal corresponding to the first high yield pseudorange.

25. The system of claim 21 wherein said hybrid pseudorange solution further comprises an estimated pseudorange accuracy corresponding to the first high yield pseudorange based at least in part on the group of NSS signal factors consisting of:

a length of time tracking a NSS signal, a tracking state and a loop bandwidth.

26. The system of claim 21 wherein said hybrid pseudorange solution further comprises an estimated pseudorange accuracy based at least in part on an elevation angle for a NSS satellite corresponding to the first high yield pseudorange.

27. The system of claim 21 further comprising:

a multipath discriminator module for receiving and comparing a pseudorange input from both the NSS high yield module and the NSS high accuracy module; and

a multipath discriminator module for removing the pseudorange input from the NSS high yield module with the pseudorange input from the NSS high accuracy module at the hybrid solution module when the comparing results are below a correlation percentage threshold.

28. The system of claim 21 wherein the positioning signal is selected from the group of NSS providers comprising:

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

29. A method for providing a bias adjustment when generating a hybrid navigation satellite system (NSS) position fix, said method comprising:

calculating a compensating bias by subtracting a high yield pseudorange from a high accuracy pseudorange for a same satellite for each of an NSS bit timing epoch;

forming an adjusted high yield pseudorange by adding the compensation bias to each high yield pseudorange;

calculating an NSS-hybrid position fix using said adjusted high yield pseudoranges and available high accuracy pseudoranges.

30. The method of claim 29, further comprising:

applying an aging/reduction factor to reduce the magnitude of the compensating bias for each of said adjusted high yield pseudorange, in a subsequent NSS bit timing epoch for which a corresponding high accuracy pseudorange is not available.