Method for determining vertical and horizontal GPS position using altitude information

• US 6,552,681 B1
• Filed: 10/02/2001
• Issued: 04/22/2003
• Est. Priority Date: 10/02/2000
• Status: Expired due to Term

• Current Assignee: NVIDIA Corporation
• Original Assignee: Skynetix LLC
• Inventors: Hayward, Roger, Fuller, Richard
• Primary Examiner(s): Blum, Theodore M.
• Application Number:
  US09/969,891
• Time in Patent Office: 567 Days
• Field of Search: 342/357.06, 342/357.09, 342/357.1, 342/357.13, 701/213
• US Class Current: 342/357.52
• CPC Class Codes: G01S 19/50 whereby the position solution is constrained to lie upon a particular curve or surface, e.g. for locomotives on railway tracks
• CPC Class Codes: G01S 5/0036 of measured values, i.e. measurement on mobile and position calculation on base station

Abstract

A method of using altitude information to arrive at a more accurate GPS position. A 3D GPS position is used as an initial estimate. The latitude and longitude of the initial estimate are used to retrieve an altitude from a database. This altitude is used to calculate a 2D GPS position. The 2D GPS position is then used to retrieve another altitude from the database, and the calculate-retrieve process is continued until the calculation converges.

Claims

1. A method of determining a global positioning system (GPS) location, comprising the acts of:

receiving GPS measurements from a GPS device;

calculating, as a three-dimensional solution, an initial position of said GPS device from said GPS measurements;

determining, from an altitude database, an initial altitude corresponding to an initial latitude and an initial longitude of said initial position;

calculating, as a two-dimensional solution using said initial altitude, a revised position of said GPS device from said GPS measurements;

determining, from said altitude database, a revised altitude corresponding to a revised latitude and a revised longitude of said revised position; and

calculating, as another two-dimensional solution using said revised altitude, another revised position of said GPS device from said GPS measurements.

2. The method of claim 1, further comprising:

iteratively performing the acts of determining and calculating until a defined threshold is met.

3. The method of claim 1, wherein said GPS measurements comprise at least four GPS measurements.

4. The method of claim 1, wherein said GPS measurements comprise at least four GPS measurements in a defined epoch.

5. The method of claim 1, wherein said GPS measurements comprise at least four GPS measurements in a plurality of epochs.

6. The method of claim 1, wherein said three-dimensional solution comprises latitude data, longitude data, altitude data, and clock data.

7. The method of claim 1, wherein said two-dimensional solution comprises latitude data, longitude data, and clock data.

8. The method of claim 1, wherein said GPS measurements comprise codephase pseudorange measurements.

9. The method of claim 1, wherein said GPS measurements comprise times of satellite signal transmission.

10. The method of claim 1, wherein said GPS measurements comprise sub-integer millisecond codephase measurements.

11. The method of claim 1, wherein said GPS measurements comprise delta-pseudorange measurements.

12. The method of claim 1, wherein said GPS measurements comprise a GPS almanac-derived position.

13. The method of claim 1, wherein said altitude database includes data formed from uniform latitude and longitude grids.

14. The method of claim 1, wherein said altitude database includes data formed from non-uniform latitude and longitude grids.

15. The method of claim 1, wherein said altitude database includes data formed from previous complete latitude, longitude, altitude and clock solutions.

16. A system for determining a global positioning system (GPS) location, comprising:

a communications unit configured to receive GPS measurements from a GPS device;

a memory configured to store an altitude database; and

a processing unit, coupled to said communications unit and said memory, configured to execute processing including the acts of;

calculating, as a three-dimensional solution, an initial position of said GPS device from said GPS measurements;

determining, from said altitude database, an initial altitude corresponding to an initial latitude and an initial longitude of said initial position;

calculating, as a two-dimensional solution using said initial altitude, a revised position of said GPS device from said GPS measurements;

determining, from said altitude database, a revised altitude corresponding to a revised latitude and a revised longitude of said revised position; and

calculating, as another two-dimensional solution using said revised altitude, another revised position of said GPS device from said GPS measurements,

wherein said communications unit is further configured to transmit said another revised position to said GPS device.

17. The system of claim 16, wherein said processing unit is further configured to execute processing including:

iteratively performing the acts of determining and calculating until a defined threshold is met.

18. The system of claim 16, wherein said three-dimensional solution comprises latitude data, longitude data, altitude data, and clock data.

19. The system of claim 16, wherein said two-dimensional solution comprises latitude data, longitude data, and clock data.

20. The system of claim 16, wherein said GPS measurements comprise codephase pseudorange measurements.

21. The system of claim 16, wherein said GPS measurements comprise delta-pseudorange measurements.

22. The system of claim 16, wherein said altitude database includes data formed from uniform latitude and longitude grids.

23. The system of claim 16, wherein said altitude database includes data formed from previous complete latitude, longitude, altitude and clock solutions.

24. A system for determining a global positioning system (GPS) location, comprising:

a GPS device configured to provide GPS measurements; and

a server configured to communicate with said GPS device, wherein said server includes a processor configured to execute processing including the acts of;

calculating, as a three-dimensional solution, an initial position of said GPS device from said GPS measurements;

determining, from an altitude database, an initial altitude corresponding to an initial latitude and an initial longitude of said initial position;

calculating, as a two-dimensional solution using said initial altitude, a revised position of said GPS device from said GPS measurements;

determining, from said altitude database, a revised altitude corresponding to a revised latitude and a revised longitude of said revised position; and

calculating, as another two-dimensional solution using said revised altitude, another revised position of said GPS device from said GPS measurements.

25. The system of claim 24, wherein said processor is further configured to execute processing including:

iteratively performing the acts of determining and calculating until a defined threshold is met.

26. The system of claim 24, wherein said three-dimensional solution comprises latitude data, longitude data, altitude data, and clock data.

27. The system of claim 24, wherein said two-dimensional solution comprises latitude data, longitude data, and clock data.

28. The system of claim 24, wherein said GPS measurements comprise codephase pseudorange measurements.

29. The system of claim 24, wherein said GPS measurements comprise delta-pseudorange measurements.

30. The system of claim 24, wherein said altitude database includes data formed from uniform latitude and longitude grids.

31. The system of claim 24, wherein said altitude database includes data formed from previous complete latitude, longitude, altitude and clock solutions.

32. A computer program for determining a global positioning system (GPS) location, said computer program embodied on a computer-readable medium and configured to control a computing device to execute processing comprising the acts of:

receiving GPS measurements from a GPS device;

calculating, as a three-dimensional solution, an initial position of said GPS device from said GPS measurements;

determining, from an altitude database, an initial altitude corresponding to an initial latitude and an initial longitude of said initial position;

calculating, as a two-dimensional solution using said initial altitude, a revised position of said GPS device from said GPS measurements;

determining, from said altitude database, a revised altitude corresponding to a revised latitude and a revised longitude of said revised position; and

calculating, as another two-dimensional solution using said revised altitude, another revised position of said GPS device from said GPS measurements.

33. The computer program of claim 32, wherein said computer program further controls said computing device to execute processing comprising:

iteratively performing the acts of determining and calculating until a defined threshold is met.

34. The computer program of claim 32, wherein said three-dimensional solution comprises latitude data, longitude data, altitude data, and clock data.

35. The computer program of claim 32, wherein said two-dimensional solution comprises latitude data, longitude data, and clock data.

36. The computer program of claim 32, wherein said GPS measurements comprise codephase pseudorange measurements.

37. The computer program of claim 32, wherein said GPS measurements comprise delta-pseudorange measurements.

38. The computer program of claim 32, wherein said altitude database includes data formed from uniform latitude and longitude grids.

39. The computer program of claim 32, wherein said altitude database includes data formed from previous complete latitude, longitude, altitude and clock solutions.

40. A global positioning system (GPS) device, comprising:

a GPS receiver configured to make GPS measurements;

a memory configured to store an altitude database; and

a processing unit, coupled to said GPS receiver and said memory, configured to execute processing including the acts of;

calculating, as a three-dimensional solution, an initial position of said GPS device from said GPS measurements;

determining, from said altitude database, an initial altitude corresponding to an initial latitude and an initial longitude of said initial position;

calculating, as a two-dimensional solution using said initial altitude, a revised position of said GPS device from said GPS measurements;

determining, from said altitude database, a revised altitude corresponding to a revised latitude and a revised longitude of said revised position; and

calculating, as another two-dimensional solution using said revised altitude, another revised position of said GPS device from said GPS measurements.

41. The GPS device of claim 40, wherein said processing unit is further configured to execute processing including:

iteratively performing the acts of determining and calculating until a defined threshold is met.

42. The GPS device of claim 40, wherein said three-dimensional solution comprises latitude data, longitude data, altitude data, and clock data.

43. The GPS device of claim 40, wherein said two-dimensional solution comprises latitude data, longitude data, and clock data.

44. The GPS device of claim 40, wherein said GPS measurements comprise codephase pseudorange measurements.

45. The GPS device of claim 40, wherein said GPS measurements comprise delta-pseudorange measurements.

46. The GPS device of claim 40, wherein said altitude database includes data formed from uniform latitude and longitude grids.

47. The GPS device of claim 40, wherein said altitude database includes data formed from previous complete latitude, longitude, altitude and clock solutions.