METHOD AND APPARATUS FOR POSITION DETERMINATION WITH EXTENDED SPS ORBIT INFORMATION

• US 20090295630A1
• Filed: 08/03/2007
• Published: 12/03/2009
• Est. Priority Date: 11/10/2006
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Moeglein, Mark Leo, Sheynblat, Leonid, Gum, Arnold Jason, Biacs, Zoltan, Wengler, Michael James
• Granted Patent: US 8,493,267 B2
• Time in Patent Office: Days
• US Class Current: 342/357.29
• CPC Class Codes: G01S 19/05 providing aiding data
• CPC Class Codes: G01S 19/258 relating to the satellite constellation, e.g. almanac, ephemeris data, lists of satellites in view
• CPC Class Codes: G01S 19/27 creating, predicting or correcting ephemeris or almanac data within the receiver

Abstract

A method and system for assisting mobile stations to locate a satellite use an efficient messaging format. A server computes a correction between coarse orbit data of a satellite and precise orbit data of the satellite. A coordinate system is chosen such that variation of the correction is substantially smooth over time. The server further approximates the correction with mathematical functions to reduce the number of bits necessary for transmission to a mobile station. The mobile station, upon receiving the coefficients, evaluates the mathematical functions using the coefficients and a time of applicability (e.g., the current time), converts the evaluated result to a standard coordinate system, and applies the conversion result to the coarse orbit data to obtain the precise orbit data.

Claims

1. A method of assisting a mobile station to obtain orbital information of a satellite, the method comprising:

computing a correction between coarse orbit data of the satellite and precise orbit data of the satellite; and

representing transforming spatial components of the correction from a first coordinate system using to a second coordinate system such that the correction in the second coordinate system is has chosen to substantially smooth variation of the correction over in time.

2. The method of claim 1 further comprising:

approximating the correction in the second coordinate system to reduce the number of bits necessary for transmission to the mobile station.

3. The method of claim 1 wherein approximating the correction comprises:

representing the correction by one or more series of mathematical functions; and

using coefficients of the mathematical functions as the approximated correction.

4. The method of claim 3 wherein the series of mathematical functions comprises one of the following functions:

harmonics, Hermite polynomials, Legendre polynomials, cosine and sine functions, or Keplerian orbital functions.

5. The method of claim 1 wherein the second coordinate system has axes that move with the satellite.

6. The method of claim 5 wherein the second coordinate system includes a radial axis, the radial axis being parallel to or coinciding with a line that connects a reference location to an estimated position of the satellite.

7. The method of claim 6 wherein the second coordinate system further includes a cross-track axis perpendicular to the radial axis and a direction of a satellite motion.

8. The method of claim 1 wherein approximating the correction comprises:

using a location of the mobile station as a reference location for the second coordinate system; and

transmitting the approximated correction as one-dimension data, the correction including a spatial dimension combined with a clock correction.

9. The method of claim 1 wherein approximating the correction comprises:

using a center of the earth as a reference location for the second coordinate system; and

transmitting the approximated correction as four-dimensional data, the correction including three spatial dimensions of the second coordinate system and a time dimension for a clock correction.

10. The method of claim 1 wherein the correction in one spatial dimension is substantially more accurate than in other spatial dimensions.

11. The method of claim 1 further comprising:

obtaining a reference time from a time server; and

transmitting the reference time with a coarse estimate of satellite positions to the mobile station.

12. The method of claim 11 further comprising:

improving accuracy of the reference time obtained from the time server; and

appending the reference time to the coarse estimate of satellite positions to form a message for transmission to the mobile station.

13. The method of claim 1 further comprising:

approximating the correction to satellite timing; and

transmitting the approximated correction to the mobile station for determination of a clock bias of the satellite.

14. The method of claim 1 further comprising:

transmitting the approximated correction to storage for access by the mobile station.

28. The method of claim 11 wherein the correction is represented by coefficients of a series of mathematical functions for each of the spatial dimensions.

15. A method comprising:

transforming a correction to satellite orbit data from a first coordinate system to a second coordinate system; and

applying the transformed satellite orbit data to coarse orbit data for determination of orbital information of the satellite.

16. The method of claim 15 wherein the correction in the first coordinate system has substantially smooth variation in time.

17. The method of claim 15 wherein the correction in the first coordinate system has a higher accuracy in one spatial dimension than in other spatial dimensions.

18. The method of claim 15 wherein axes of the first coordinate system rotate with movement of the satellite.

19. The method of claim 15 wherein axes of the first coordinate system are defined by position and motion of the satellite.

20. The method of claim 15 wherein operations of the transforming and the applying are performed by a mobile station.

21. The method of claim 15 further comprising:

computing the correction to the satellite orbit data at a server; and

transforming the correct from the second coordinate system to the first coordinate system at the server.

22. A method of a mobile station comprising:

receiving correction to coarse orbit data of a satellite;

transforming the correction from a first coordinate system to a second coordinate system, the correction represented in the first coordinate system having a higher accuracy in one spatial dimension than in other spatial dimensions; and

applying the correction to the coarse orbit data for determination of orbital information of the satellite.

23. The method of claim 22 wherein the first coordinate system includes three orthogonal axes.

24. The method of claim 22 wherein the first coordinate system includes non-orthogonal axes.

25. The method of claim 22 wherein the first coordinate system includes a radial axis, the radial axis being parallel to or coinciding with a line that connects a reference location to an estimated position of the satellite.

26. The method of claim 25 wherein the reference location is a center of the earth.

27. The method of claim 25 wherein the reference location is an estimated location of the mobile station.

29. A method of a mobile station comprising:

receiving coarse orbit data of a satellite;

receiving correction data to the coarse orbit data of the satellite;

converting the correction data from a first coordinate system to a second coordinate system, the first coordinate system is chosen to smooth variation of the correction over time; and

applying the correction data to the coarse orbit data for determination of orbital information of the satellite.

30. The method of claim 29 further comprising:

determining a position and timing of the satellite based on the correction data.

31. The method of claim 29 wherein receiving the correction data comprises:

receiving a coefficient sequence of a series of mathematical functions for at least one axes of the coordinate system; and

evaluating the mathematical functions using the coefficient sequence and a time of applicability to obtain the correction data.

32. The method of claim 31 wherein the coefficient sequence comprises coefficients for one of the following functions:

harmonics, Hermite polynomials, Legendre polynomials, cosine and sine functions, or Keplerian orbital functions.

33. The method of claim 29 wherein the first coordinate system has axes that move with the satellite.

34. The method of claim 33 wherein the first coordinate system includes a radial axis, the radial axis being parallel to or coinciding with a line that connects a reference location to an estimated position of the satellite.

35. The method of claim 29 wherein the first coordinate system further includes a cross-track axis perpendicular to the radial axis and a direction of a satellite motion.

36. The method of claim 29 further comprising:

using a location of the mobile station as a reference location for the first coordinate system; and

receiving coefficients of a series of mathematical functions, the coefficients representing one-dimension data that includes a spatial dimension combined with a clock correction.

37. The method of claim 29 further comprising:

using a center of the earth as a reference location for the first coordinate system; and

receiving coefficients of four series of mathematical functions, the coefficients representing four-dimension data that includes three spatial dimensions of the first coordinate system and a time dimension for a clock correction.

38. The method of claim 29 wherein the correction data is represented in the first coordinate system with a higher accuracy in one spatial dimension than in other spatial dimensions.

39. The method of claim 29 further comprising:

receiving a reference time from one of following;

a network time server, a location assistance server, a packet switched data network, or GPS data received from a reference receiver.

40. A server system for assisting a mobile station to obtain orbital information of a satellite, the server system comprising:

a correction unit to compute a correction between coarse orbit data of the satellite and precise orbit data of the satellite and to represent spatial components of the correction using a coordinate system having axes that move with the satellite; and

41. The server system of claim 40 further comprising:

an approximation unit to approximate the correction in the coordinate system to reduce the number of bits necessary for transmission to the mobile station.

42. The server system of claim 41 wherein the approximation unit represents the correction by one or more series of mathematical functions and uses coefficients of the mathematical functions to approximate the correction.

43. The server system of claim 40 wherein the server system is coupled to data storage to store the approximated correction for use by the mobile station.

44. The server system of claim 40 further comprising:

a transmission unit to transmit the approximated correction to the mobile station via a network.

45. The server system of claim 40 further comprising:

a transmission unit to broadcast the approximated correction to the mobile station.

46. The server system of claim 40 wherein the coordinate system includes a radial axis parallel to or coinciding with a line that connects a reference location to an estimated position of the satellite.

47. The server system of claim 40 wherein the approximation unit represents the correction by one or more series of mathematical functions and uses coefficients of the mathematical functions as the approximated correction.

48. The server system of claim 40 wherein the correction unit comprises logic to compute a clock correction for the satellite.

49. The server system of claim 48 wherein the clock correction is to be approximated by at least one coefficient of a series of mathematical functions.

50. The server system of claim 40 further comprising:

an interface unit to obtain a reference time from a time server; and

a transmission unit to transmit the reference time with a coarse estimate of satellite positions to the mobile station.

51. A computer-readable medium including instructions stored thereon, comprising:

instructions to compute a correction between coarse orbit data of the satellite and precise orbit data of the satellite; and

instructions to represent transform spatial components of the correction from a first coordinate system to a second coordinate system such that the correction in the second coordinate system has substantially smooth variation in time using a coordinate system that is chosen to smooth variation of the correction over time and

52. The computer-readable medium of claim 51, further comprising:

instructions to interpolate the correction in the second coordinate system using mathematical functions with truncated terms to reduce the number of bits necessary for transmission to the mobile station.

53. The computer-readable medium of claim 51, wherein the second coordinate system includes a radial axis parallel to or coinciding with a line that connects a reference location to an estimated position of the satellite, and a cross-track axis perpendicular to the radial axis and a direction of a satellite motion.

54. The computer-readable medium of claim 51, further comprising:

instructions to approximate the correction with more coefficients in at least one spatial dimension than other spatial dimensions.

55. The computer-readable medium of claim 51, further comprising:

instructions to compute a clock correction for the satellite.

56. The computer-readable medium of claim 51, further comprising:

instructions to obtain a reference time from a time server; and

instructions to transmit the reference time with a coarse estimate of satellite positions to the mobile station.

57. A system of a mobile station comprising:

a receiver interface to receive input;

an evaluation unit, based on the input, to compute correction data to coarse orbit data of a satellite;

a conversion unit to convert the correction data from a first coordinate system to a second coordinate system, the first coordinate system chosen to smooth variation of the correction data over time; and

a reconstruction unit to apply the correction data to the coarse orbit data for determination of orbital information of the satellite.

58. The system of claim 57 wherein the axes of the first coordinate system includes a radial axis, the radial axis being parallel to or coinciding with a line that connects a reference location to an estimated position of the satellite.

59. The system of claim 57 wherein the reconstruction unit generates corrected orbit data to determine a position and timing of the satellite.

60. The system of claim 57 wherein the input includes coefficients of mathematical functions for at least one axis of the coordinate system.

61. The system of claim 60 wherein the evaluation unit includes logic to evaluate the mathematical functions using the coefficients and a time of applicability to obtain the correction data.

62. The system of claim 57 wherein the receiver interface receives the input via file transfer from data storage.

63. The system of claim 57 wherein the receiver interface receives the input in a message transmitted from a server.

64. The system of claim 57 wherein the correction data is represented in the first coordinate system with higher accuracy in one spatial dimension than in other spatial dimensions.

65. A computer-readable medium including instructions stored thereon, comprising:

instructions to convert correction data from a first coordinate system to a second coordinate system, the first coordinate system chosen to smooth variation of the correction data over time; and

instructions to apply the correction data to coarse orbit data for determination of orbital information of the satellite.

66. The computer-readable medium of claim 65 further comprising:

instructions to determine a position and timing of the satellite based on the correction data.

67. The computer-readable medium of claim 65, wherein the first coordinate system includes a radial axis parallel to or coinciding with a line that connects a reference location to an estimated position of the satellite, and a cross-track axis perpendicular to the radial axis and a direction of a satellite motion.

68. The computer-readable medium of claim 65, wherein the correction data is represented in the first coordinate system with higher accuracy in one spatial dimension than in other spatial dimensions.

69. The computer-readable medium of claim 65 further comprising:

instructions to receive coefficients of mathematical functions for at least one axis of the coordinate system; and

instructions to evaluate the mathematical functions using the coefficients and a time of applicability.