System and/or method for determining sufficiency of pseudorange measurements

• US 7,978,131 B2
• Filed: 12/15/2009
• Issued: 07/12/2011
• Est. Priority Date: 05/19/2006
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Ahmed, Rizwan E., Rowitch, Douglas Neal
• Primary Examiner(s): Tarcza; Thomas H
• Assistant Examiner(s): LIU, HARRY K
• Application Number:
  US12/638,900
• Publication Number:
  US 20100328149A1
• Time in Patent Office: 574 Days
• Field of Search: 342/357.58
• US Class Current: 342/357.58
• CPC Class Codes: G01S 19/24 Acquisition or tracking or demodulation of signals transmitted by the system synchronisation aspects of direct sequence spread spectrum modulation H04B1/7073

Abstract

The subject matter disclosed herein relates to a system and method for determining a sufficiency of measurements for locating positions. In one example, although claimed subject matter is not so limited, a process to improve accuracy of pseudorange measurements may be conducted using multiple dwells.

Claims

1. A method comprising:

determining a plurality of pseudorange measurements to space vehicles (SVs) at a location based, at least in part, on information received during a first dwell;

determining quantitative assessments of accuracy associated with said plurality of pseudorange measurements; and

selectively employing at least one additional dwell to improve accuracy of said pseudorange measurements in response to a weighting of at least some of said quantitative assessments according to geometries associated with said SVs.

2. The method of claim 1, further comprising determining the quantitative assessments of the accuracy associated with the plurality of the pseudorange measurements based, at least in part, on root mean square error estimates associated with the pseudorange measurements.

3. The method of claim 1, further comprising determining the weighting of at least some of the quantitative measurements based, at least in part, on elevation angles associated with locations of the SVs.

4. The method of claim 1, further comprising determining the weighting of at least some of the quantitative measurements based, at least in part, on azimuth angles associated with locations of the SVs.

5. The method of claim 1, wherein the weighting of at least some of the quantitative assessments comprises a weighted horizontal dilution of precision.

6. The method of claim 1, further comprising processing signals received from at least some of the SVs over the first dwell and the at last one additional dwell.

7. The method of claim 1, further comprising:

combining the weighted quantitative assessments to provide a metric; and

selectively initiating the at least one additional dwell in response to a comparison of the metric with a threshold value.

8. An apparatus comprising:

a computing platform to;

determine a plurality of pseudorange measurements to space vehicles (SVs) at a location based, at least in part, on information received during a first dwell;

determine quantitative assessments of accuracy associated with said plurality of pseudorange measurements; and

selectively initiate at least one additional dwell to improve accuracy of said pseudorange measurements in response to a weighting of at least some of said quantitative assessments according to geometries associated with said SVs.

9. The apparatus of claim 8, wherein the computing apparatus is further capable of determining the quantitative assessments of the accuracy associated with the plurality of the pseudorange measurements based, at least in part, on root mean square error estimates associated with the pseudorange measurements.

10. The apparatus of claim 8, wherein the computing platform is further adapted to determine the weighting of at least some of the quantitative measurements based, at least in part, on elevation angles associated with locations of the SVs.

11. The apparatus of claim 8, wherein the computing platform is further adapted to determine the weighting of at least some of the quantitative measurements based, at least in part, on azimuth angles associated with locations of the SVs.

12. The apparatus of claim 8, wherein the weighting of at least some of the quantitative assessments comprises a weighted horizontal dilution of precision.

13. The apparatus of claim 8, wherein the computing platform is further adapted to process signals received from at least some of the SVs over the first dwell and the at last one additional dwell.

14. The apparatus of claim 8, wherein the computing platform is further adapted to:

combine the weighted quantitative assessments to provide a metric; and

selective initiating the at least one additional dwell in response to a comparison of the metric with a threshold value.

15. An article comprising:

a storage medium having stored thereon instructions executable by a processor to;

determine a plurality of pseudorange measurements to space vehicles (SVs) at a location based, at least in part, on information received during a first dwell;

determine quantitative assessments of accuracy associated with said plurality of pseudorange measurements; and

selectively initiate at least one additional dwell to improve accuracy of said pseudorange measurements in response to a weighting of at least some of said quantitative assessments according to geometries associated with said SVs.

16. The article of claim 15, wherein the instructions are further executable by the processor to determine the quantitative assessments of the accuracy associated with the plurality of the pseudorange measurements based, at least in part, on root mean square error estimates associated with the pseudorange measurements.

17. The article of claim 15, wherein the instructions are further executable by the processor to determine the weighting of at least some of the quantitative measurements based, at least in part, on elevation angles associated with locations of the SVs.

18. The article of claim 15, wherein the instructions are further executable by the processor to determine the weighting of at least some of the quantitative measurements based, at least in part, on azimuth angles associated with locations of the SVs.

19. The article of claim 15, wherein the weighting of at least some of the quantitative assessments comprises a weighted horizontal dilution of precision.

20. The article of claim 15, wherein the instructions are further executable by the processor to process signals received from at least some of the SVs over the first dwell and the at last one additional dwell.

21. The article of claim 15, wherein the instructions are further executable by the processor to:

combine the weighted quantitative assessments to provide a metric; and

selectively initiate the at least one additional dwell in response to a comparison of the metric with a threshold value.

22. A position determination entity comprising:

a receiver to receive pseudorange measurements to space vehicles (SVs) from a subscriber station over a data link, said position determination entity being adapted to;

determine a plurality of pseudorange measurements to space vehicles (SVs) at a location based, at least in part, on information received during a first dwell;

determine quantitative assessments of accuracy associated with said plurality of pseudorange measurements; and

selectively initiate at least one additional dwell at said subscriber station to improve accuracy of said pseudorange measurements in response to a weighting of at least some of said quantitative assessments according to geometries associated with said SVs.

23. The position determination entity of claim 22, wherein the position determination entity is further adapted to determine the quantitative assessments of the accuracy associated with the plurality of the pseudorange measurements based, at least in part, on root mean square error estimates associated with the pseudorange measurements.

24. The position determination entity of claim 22, wherein the position determination entity is further adapted to process signals received from at least some of the SVs over the first dwell and the at last one additional dwell.

25. The position determination entity of claim 22, wherein the position determination entity is further adapted to:

combine the weighted quantitative assessments to provide a metric; and

selectively initiate the at least one additional dwell in response to a comparison of the metric with a threshold value.

26. A subscriber unit comprising:

receiver to receive an acquisition assistance (AA) message from a data link, said AA message comprising information indicative of geometries associated with space vehicles (SVs), said subscriber unit being adapted to;

determine a plurality of pseudorange measurements to space vehicles (SVs) at a location based, at least in part, on information received during a first dwell;

determine quantitative assessments of accuracy associated with said plurality of pseudorange measurements; and

selectively initiate at least one additional dwell to improve accuracy of said pseudorange measurements in response to a weighting of at least some of said quantitative assessments according to said information.

27. The subscriber unit of claim 26, wherein the subscriber unit is further capable of determining the quantitative assessments of the accuracy associated with the plurality of the pseudorange measurements based, at least in part, on root mean square error estimates associated with the pseudorange measurements.

28. The subscriber unit of claim 26, wherein the subscriber unit is further capable of determining the weighting of at least some of the quantitative measurements based, at least in part, on elevation angles associated with locations of the SVs.

29. The subscriber unit of claim 26, wherein the subscriber unit is further capable of determining the weighting of at least some of the quantitative measurements based, at least in part, on azimuth angles associated with locations of the SVs.

30. An apparatus comprising:

means for determining a plurality of pseudorange measurements to space vehicles (SVs) at a location based, at least in part, on information received during a first dwell;

means for determining quantitative assessments of accuracy associated with the plurality of pseudorange measurements; and

means for selectively initiating at least one additional dwell to improve accuracy of the pseudorange measurements in response to a weighting of at least some of the quantitative assessments according to geometries associated with the SVs.

31. The apparatus of claim 30, wherein the means for determining quantitative assessments is capable of determining the quantitative assessments of the accuracy associated with the plurality of the pseudorange measurements based, at least in part, on root mean square error estimates associated with the pseudorange measurements.

32. The apparatus of claim 30, further comprising means for determining the weighting of at least some of the quantitative measurements based, at least in part, on elevation angles associated with locations of the SVs.

33. The apparatus of claim 30, further comprising means for determining the weighting of at least some of the quantitative measurements based, at least in part, on azimuth angles associated with locations of the SVs.

34. The apparatus of claim 30, wherein the weighting of at least some of the quantitative assessments comprises a weighted horizontal dilution of precision.

35. The apparatus of claim 30, further comprising means for processing signals received from at least some of the SVs over the first dwell and the at last one additional dwell.

36. The apparatus of claim 30, further comprising:

means for combining the weighted quantitative assessments to provide a metric; and

means for selectively initiating the at least one additional dwell in response to a comparison of the metric with a threshold value.