Ionospheric error prediction and correction in satellite positioning systems

• US 20050146461A1
• Filed: 02/13/2003
• Published: 07/07/2005
• Est. Priority Date: 02/13/2002
• Status: Active Grant

• Current Assignee: CSR Technology Incorporated (Qualcomm, Inc.)
• Original Assignee: CSR Technology Incorporated (Qualcomm, Inc.)
• Inventors: Suzuki, Junichi, Pande, Ashutosh
• Granted Patent: US 7,741,994 B2
• Time in Patent Office: Days
• US Class Current: 342/357.210
• CPC Class Codes: G01S 19/072 Ionosphere corrections

Abstract

A GPS server capable of receiving information for use in determining ionospheric errors using mathematical formulas and sending ionospheric error correction information to GPS receivers that are in a location capable of receiving the ionospheric error correction information.

Claims

1. A method for correcting ionospheric errors in an satellite positioning system (“

SPS”

) having a SPS server with known positional coordinates and a SPS receiver, the method comprising;

receiving a SPS signal at the SPS server;

determining ionospheric errors in response to receiving the SPS signal;

creating an ionospheric model of predicted ionospheric errors from the determined ionospheric errors, the ionospheric model having ionospheric model parameters; and

transmitting the ionospheric model parameters to the SPS receiver.

2. The method of claim 1, wherein determining ionospheric errors includes

determining the calculated positional coordinates of the SPS server from the received SPS signal;

comparing the calculated positional coordinates of the SPS server to the known positional coordinates; and

determining the ionospheric error in response to comparing the calculated positional coordinates to the known positional coordinates.

3. The method of claim 2, wherein creating an ionospheric model includes utilizing a half cosine curve.

4. The method of claim 2, wherein creating an ionospheric model includes utilizing a triangle shape curve.

5. The method of claim 2, wherein creating an ionospheric model includes utilizing a lookup table.

6. The method of claim 1, further including

receiving a new SPS signal at the SPS server;

determining new ionospheric errors in response to receiving the new SPS signal;

comparing the new determined ionospheric errors to the predicted ionospheric error from the ionospheric model;

adjusting the ionospheric model of predicted ionospheric errors in response to the comparison outside a predetermined threshold value, the adjusted ionospheric model having adjusted ionospheric model parameters; and

transmitting the adjusted ionospheric model parameters to the SPS receiver.

7. The method of claim 6, wherein the predetermined threshold value corresponds to the changing points of the ionospheric error model.

8. The method of claim 7, wherein creating an ionospheric model includes utilizing a half cosine curve.

9. The method of claim 7, wherein creating an ionospheric model includes utilizing a triangle shape curve.

10. The method of claim 7, wherein creating an ionospheric model includes utilizing a lookup table.

11. The method of claim 6, further including

receiving the new SPS signal at the SPS receiver;

receiving the transmitted ionospheric model parameters from the SPS server;

creating, at the SPS receiver, a SPS receiver ionospheric model of predicted ionospheric errors from the received ionospheric model parameters;

determining the calculated positional coordinates of the SPS receiver from the received new SPS signal; and

compensating the calculated positional coordinates with the SPS receiver ionospheric model.

12. The method of claim 11, wherein creating an ionospheric model includes utilizing a half cosine curve.

13. The method of claim 11, wherein creating an ionospheric model includes utilizing a triangle shape curve.

14. The method of claim 11, wherein creating an ionospheric model includes utilizing a lookup table.

15. A satellite positioning system (“

SPS”

) comprising;

a SPS server capable of detecting ionospheric errors in a received SPS signal from a SPS satellite and creating an ionospheric error model having ionospheric model parameters in response to detecting the ionospheric errors;

a mobile SPS receiver in signal communication with the SPS server via a communication link, the mobile SPS receiver capable of receiving both the received SPS signal from the SPS satellite and the ionospheric model parameters from the SPS server and, in response to receiving both the received SPS signal and ionospheric model parameters the mobile SPS receiver is capable of compensating for ionospheric errors in the received SPS signal.

16. The SPS of claim 15, wherein the SPS server further includes

a server position calculation module in the SPS server;

a server ionospheric error modeling module in signal communication with the server position calculation module;

a server communication module in signal communication with the SPS receiver, and

a server processor in signal communication with the server position calculation module, server ionospheric error modeling module and server communication module, the processor capable of creating the ionospheric error model.

17. The SPS of claim 15, further including a server storage module in signal communication with the server position calculation module, server ionospheric error modeling module, server processor and server communication module.

18. The SPS of claim 17, wherein the SPS server is capable of receiving and processing both L1 and L2 carrier frequencies.

19. The SPS of claim 15, wherein the mobile SPS receiver further includes

a mobile position calculation module in the mobile SPS receiver;

a mobile ionospheric error modeling module in signal communication with the mobile position calculation module; and

a mobile processor in signal conmmunication with both the server position calculation module and server ionospheric error modeling module, the processor capable of compensating for ionospheric errors in the received SPS signal utilizing ionospheric model parameters.

20. The SPS of claim 19, further including a mobile storage module in signal communication with the mobile position calculation module, mobile ionospheric error modeling module, mobile processor and mobile communication module.

21. A satellite positioning system (“

SPS”

) comprising;

means for detecting ionospheric errors in a received SPS signal from a SPS satellite at a SPS server;

means for creating an ionospheric error model having ionospheric model parameters in response to detecting the ionospheric errors with the detecting means; and

a mobile SPS receiver in signal communication with the detecting means and creating means via a communication link, the mobile SPS receiver capable of receiving both the received SPS signal from the SPS satellite and the ionospheric model parameters from the detecting means and creating means and, in response to receiving both the received SPS signal and ionospheric model parameters the mobile SPS receiver is capable of compensating for ionospheric errors in the received SPS signal.

22. The SPS of claim 21, wherein the SPS server further includes

means for calculating the position of the SPS server from the received SPS signal;

means for modeling the ionospheric error from the received SPS signal;

means for communicating to the SPS receiver; and

means for controlling the calculating means, modeling means and communication means.

23. The SPS of claim 21, wherein the mobile SPS receiver further includes

means for calculating the position of the mobile SPS receiver;

means for communicating to the SPS server; and

means for modeling the ionospheric error from the received SPS signal at the SPS server.

24. A signal-bearing medium having software for for correcting ionospheric errors in an satellite positioning system (“

SPS”

) having a SPS server with known positional coordinates and a SPS receiver, the signal-bearing medium comprising;

logic configured for receiving a SPS signal at the SPS server;

logic configured for determining ionospheric errors in response to receiving the SPS signal;

logic configured for creating an ionospheric model of predicted ionospheric errors from the determined ionospheric errors, the ionospheric model having ionospheric model parameters; and

logic configured for transmitting the ionospheric model parameters to the SPS receiver.

25. The signal-bearing medium of claim 24, wherein the determining logic includes

logic configured for determining the calculated positional coordinates of the SPS server from the received SPS signal;

logic configured for comparing the calculated positional coordinates of the SPS server to the known positional coordinates; and

logic configured for determining the ionospheric error in response to comparing the calculated positional coordinates to the known positional coordinates.

26. The signal-bearing medium of claim 25, wherein the creating logic includes utilizing a half cosine curve.

27. The signal-bearing medium of claim 25, wherein the creating logic includes utilizing a triangle shape curve.

28. The signal-bearing medium of claim 25, wherein the creating logic includes utilizing a lookup table.

29. The signal-bearing medium of claim 24, further including

logic configured for receiving a new SPS signal at the SPS server;

logic configured for determining new ionospheric errors in response to receiving the new SPS signal;

logic configured for comparing the new determined ionospheric errors to the predicted ionospheric error from the ionospheric model;

logic configured for adjusting the ionospheric model of predicted ionospheric errors in response to the comparison outside a predetermined threshold value, the adjusted ionospheric model having adjusted ionospheric model parameters; and

logic configured for transmitting the adjusted ionospheric model parameters to the SPS receiver.

30. The signal-bearing medium of claim 29, further including

logic configured for receiving the new SPS signal at the SPS receiver;

logic configured for receiving the transmitted ionospheric model parameters from the SPS serve;

logic configured for creating, at the SPS receiver, a SPS receiver ionospheric model of predicted ionospheric errors from the received ionospheric model parameters;

logic configured for determining the calculated positional coordinates of the SPS receiver from the received new SPS signal; and

logic configured for compensating the calculated positional coordinates with the SPS receiver ionospheric model.