LEO-based positioning system for indoor and stand-alone navigation

• US 20050156782A1
• Filed: 06/29/2004
• Published: 07/21/2005
• Est. Priority Date: 01/15/2004
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Gutt, Greg M, Ferrell, Barton G., Cohen, Clark E., Whelan, David A.
• Granted Patent: US 7,489,926 B2
• Time in Patent Office: Days
• US Class Current: 342/357.480
• CPC Class Codes: G01S 19/26 involving a sensor measurement for aiding acquisition or tracking
• CPC Class Codes: G01S 19/423 by combining or switching between position solutions derived from different satellite radio beacon positioning systems

Abstract

A method for estimating a precise position of a user device from signals from a low earth orbit (LEO) satellite includes receiving at least one carrier signal at a user device, each carrier signal being transmitted a distinct LEO satellite. The user device processes the carrier signals to obtain a first carrier phase information. The user device recalls an inertial position fix derived at an inertial reference unit. The user device derives a position of the user device based on the inertial position fix and the first carrier phase information.

Claims

1. A method for estimating a precise position of a user device from signals from a low earth orbit (LEO) satellite, the method comprising:

receiving at least one carrier signal at a user device, each carrier signal being transmitted a distinct LEO satellite;

processing the carrier signals to obtain a first carrier phase information;

recalling an inertial position fix derived at an inertial reference unit; and

deriving a position of the user device based on the inertial position fix and the first carrier phase information.

2. The method of claim 1, wherein deriving a position of the user device further includes refining first carrier phase information to resolve integer cycle ambiguities based upon the inertial position.

3. The method of claim 1, wherein deriving a position of the user device further includes:

processing the carrier signals received at a reference station to obtain a second reference carrier phase information.

4. The method of claim 3, wherein deriving a position of the user device further includes:

refining the position of the user device is further based upon the second reference carrier phase information.

5. The method of claim 1, further comprising:

estimating an approximate user position and clock offset using code phase signals received from a set of navigational satellites.

6. The method of claim 5, wherein the inertial position fix is refined based upon the user position.

7. The method of claim 1, wherein the inertial reference unit is a MEMS inertial reference unit.

8. The method of claim 1, wherein the inertial position fix is refined upon the position of the user device.

9. A user device for estimating a precise position of the user device from signals from a low earth orbit (LEO) satellite, the method comprising:

a receiver configured to receive at least one carrier signal at the user device, each carrier signal being transmitted a distinct LEO satellite;

a signal processor configured for processing the carrier signals to obtain a first carrier phase information;

an inertial reference unit configured for recalling an inertial position fix derived at an inertial reference unit; and

a processor configured to derive a position of the user device based on the inertial position fix and the first carrier phase information.

10. The user device of claim 9, wherein the processor is further configured to resolve integer cycle ambiguities based upon the inertial position.

11. The user device of claim 9, wherein the receiver is further configured to process the carrier signals received at a reference station to obtain a second reference carrier phase information.

12. The user device of claim 11, wherein the processor is further configured to refine the position of the user device based upon the second reference carrier phase information.

13. The user device of claim 9, wherein the processor is further configured for estimating an approximate user position and clock offset using code phase signals received from a set of navigational satellites.

14. The user device of claim 13, wherein the inertial reference unit is further configured to refine the inertial position fix based upon the user position.

15. The user device of claim 9, wherein the inertial reference unit is a MEMS inertial reference unit.

16. The user device of claim 9, wherein the inertial reference unit is further configured to refine the inertial position fix based upon the position of the user device.

17. A computer software program stored on a computer readable medium, the computer program configured to estimate a precise position of a user device based on signals from a low earth orbit (LEO) satellite, the method comprising:

a first software component configured to receive at least one carrier signal, each carrier signal being transmitted a distinct LEO satellite;

a second software component configured to process the carrier signals to obtain a first carrier phase information;

a third software component configured to recall an inertial position fix derived at an inertial reference unit; and

a fourth software component configured to derive a position of the user device based on the inertial position fix and the first carrier phase information.

18. The software program of claim 17, wherein the fourth software component is further configured to refine the first carrier phase information to resolve integer cycle ambiguities based upon the inertial position.

19. The software program of claim 17, wherein the fourth software component is further configured to:

process the carrier signals received at a reference station to obtain a second reference carrier phase information.

20. The software program of claim 19, wherein deriving a position of the user device further includes:

refining the position of the user device is further based upon the second reference carrier phase information.

21. The software program of claim 17, further comprising:

a fifth software component configured for estimating an approximate user position and clock offset using code phase signals received from a set of navigational satellites.

22. The software program of claim 21, wherein the third software component is further configured to refine the inertial position fix based upon the approximate user position.

23. The software program of claim 17, wherein the inertial reference unit is a MEMS inertial reference unit.

24. The software program of claim 17, wherein the third software component is further configured to refine the inertial position fix based upon the position of the user device.

25. An apparatus for estimating a precise position of a user device from signals from a low earth orbit (LEO) satellite, the method comprising:

means for receiving at least one carrier signal at a user device, each carrier signal being transmitted a distinct LEO satellite;

means for processing the carrier signals to obtain a first carrier phase information;

means for recalling an inertial position fix derived at an inertial reference unit; and

means for deriving a position of the user device based on the inertial position fix and the first carrier phase information.

26. The apparatus of claim 25, wherein the means for deriving a position of the user device further includes means for refining first carrier phase information to resolve integer cycle ambiguities based upon the inertial position.

27. The apparatus of claim 25, wherein the means for deriving a position of the user device further includes:

means for processing the carrier signals received at a reference station to obtain a second reference carrier phase information.

28. The apparatus of claim 27, wherein the means for deriving a position of the user device further includes:

means for refining the position of the user device is further based upon the second reference carrier phase information.

29. The apparatus of claim 25, further comprising:

means for estimating an approximate user position and clock offset using code phase signals received from a set of navigational satellites.

30. The apparatus of claim 29, wherein the inertial position fix is refined based upon the user position.

31. The apparatus of claim 25, wherein the inertial reference unit is a MEMS inertial reference unit.

32. The apparatus of claim 25, wherein the inertial position fix is refined upon the position of the user device.