Distributed orbit modeling and propagation method for a predicted and real-time assisted GPS system

• US 8,004,462 B2
• Filed: 08/05/2009
• Issued: 08/23/2011
• Est. Priority Date: 04/25/2006
• Status: Active Grant

• Current Assignee: Rx Networks Inc. (Beijing BDStar Navigation Co., Ltd.)
• Original Assignee: Rx Networks Inc. (Beijing BDStar Navigation Co., Ltd.)
• Inventors: Roy-MacHabee, Guylian, Eagen, Maria, LaMance, James W.
• Primary Examiner(s): Tarcza; Thomas H
• Assistant Examiner(s): Mull; Fred H
• Application Number:
  US12/536,348
• Publication Number:
  US 20100090896A1
• Time in Patent Office: 748 Days
• Field of Search: 342/357.1, 342/357.09, 342/357.15, 342/357.66, 342/357.64
• US Class Current: 342/357.66
• CPC Class Codes: G01C 21/20 Instruments for performing navigational calculations G01C21/24, G01C21/26 take precedence
• 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
• CPC Class Codes: H04W 4/02 Services making use of location information

Abstract

A distributed orbit and propagation method for use in a predicted GPS or GNSS system, which includes a predicted GPS server (PGPS Server), a source of high accuracy orbit predictions (Orbit Server), a global reference network (GRN Server) providing real-time GPS or GNSS assistance data to the PGPS Server, a predicted GPS client (PGPS Client) running on a device equipped with a GPS or AGPS chipset. In response to requests from the PGPS Client, the PGPS Server produces and disseminates an initial seed dataset consisting of current satellite orbit state vectors and orbit propagation model coefficients. This seed dataset enables the PGPS Client to locally predict and propagate satellite orbits to a desired future time. This predictive assistance in turn helps accelerate Time To First Fix (TTFF), optimize position solution calculations and improve the sensitivity of the GPS chip present on, or coupled with, the device. In contrast with other conventional predicted GPS systems that forward large volumes of predicted orbits, synthetic ephemeris or synthetic almanac data, this method optimally reduces data transfer requirements to the client, and enables the client to locally synthesize its own predicted assistance data as needed. This method also supports seamless notification of real-time satellite integrity events and seamless integration of predicted assistance data with industry standard real-time assistance data.

Claims

1. A distributed GPS or GNSS method of orbit modeling and propagation, comprising:

(a) computing satellite force model parameters;

(b) providing said satellite force model parameters and an initial satellite position and velocity,

(c) generating a predicted Orbital State Vector comprising a satellite position and velocity, by propagating the initial satellite position and velocity to a different time than the time of said initial satellite position and velocity, using said satellite force model parameters; and

(d) providing a local GPS or AGPS device with assistance data derived from said predicted Orbital State Vector without requiring a network connection;

wherein said assistance data is derived by converting said predicted Orbital State Vector into a satellite navigation data model format at a time and in a format required by said GPS or AGPS device.

2. The method of claim 1, wherein the initial satellite position and velocity is provided to a Predicted GPS Client as a change to a previously delivered satellite position and velocity.

3. The method of claim 1, wherein the initial satellite position and velocity is provided to a Predicted GPS Client as a change from a propagated predicted Orbital State Vector based on a previously delivered satellite position and velocity.

4. The method of claim 1, wherein the satellite force model parameters are provided to a Predicted GPS Client as a change to previously delivered GNSS satellite force model parameters.

5. The method of claim 1, wherein the initial satellite position and velocity and the satellite force model parameters are provided to a Predicted GPS Client as a change to previously delivered initial satellite position and velocity and to previously delivered GNSS satellite force model parameters.

6. The method of claim 1, wherein the satellite position and velocity and GNSS satellite force model parameters are provided to a Predicted GPS Client in a compressed format.

7. A distributed GPS or GNSS method of orbit modeling and propagation, comprising:

(a) computing satellite force model parameters;

(b) providing a plurality of satellite positions and velocities;

(c) generating a predicted Orbital State Vector comprising a satellite position and velocity, by propagating an initial satellite position and velocity to a different time than the time of said initial satellite position and velocity, using said satellite force model parameters, said initial satellite position and velocity taken from said plurality of satellite positions and velocities; and

(d) providing a local GPS or AGPS device with assistance data derived from said predicted Orbital State Vector without requiring a real-time network connection;

wherein said assistance data is derived by converting said predicted Orbital State Vector into a satellite navigation data model format and provided to said GPS or AGPS device at a time and in a format required by said GPS or AGPS device.

8. A distributed GPS or GNSS method of orbit modeling and propagation, comprising:

(a) computing satellite force model parameters;

(b) providing an initial satellite position and velocity to a Predicted GPS Client via a communications link;

(c) generating within said Predicted GPS Client a predicted Orbital State Vector comprising a satellite position and velocity, by propagating said initial satellite position and velocity to a different time than the time of said initial satellite position and velocity, using said satellite force model parameters provided to said Predicted GPS Client; and

(d) providing a local GPS or AGPS device with assistance data derived from said predicted Orbital State Vector without requiring a real-time network connection;

wherein said assistance data consists of the satellite position and velocity contained in said predicted Orbital State Vector without converting into the satellite navigation data model format and provided by said Predicted GPS Client to said GPS or AGPS device at a time and in a format required by said GPS or AGPS device.

9. The method of claim 8, wherein the Predicted GPS Client is integrated into a GPS or AGPS device.

10. The method of claim 8, wherein the initial satellite position and velocity is provided to the Predicted GPS Client as a change to a previously delivered satellite position and velocity.

11. The method of claim 10, wherein the changes in satellite position and velocity are provided to the Predicted GPS Client in a compressed format.

12. The method of claim 8, wherein the initial satellite position and velocity is provided to the Predicted GPS Client as a change from a propagated predicted Orbital State Vector based on a previously delivered satellite position and velocity.

13. The method of claim 12, wherein the satellite position and velocity are provided to the Predicted GPS Client in a compressed format.

14. The method of claim 8, wherein the satellite force model parameters are provided to the Predicted GPS Client as a change to previously delivered satellite force model parameters.

15. The method of claim 14, wherein the changes in satellite force model parameters are provided to the Predicted GPS Client in a compressed format.

16. The method of claim 8, wherein the initial satellite position and velocity and the GNSS satellite force model parameters are provided to the Predicted GPS Client as a change to the initial satellite position and velocity and to the satellite force model parameters from previously delivered initial satellite position and velocity and satellite force model parameters.

17. The method of claim 16, wherein the changes in satellite position and velocity and satellite force model parameters are provided to the Predicted GPS Client in a compressed format.

18. The method of claim 8, wherein the satellite position and velocity and satellite force model parameters are provided to the Predicted GPS Client in a compressed format.

19. The method of claim 8, wherein the Predicted GPS Client is hosted on a mobile device.

20. The method of claim 8, wherein the Predicted GPS Client is hosted on a common CPU with the GPS or AGPS device.

21. The method of claim 8, wherein the Predicted GPS Client is hosted on a device that does not have a local GPS or AGPS device.

22. The method of claim 8, wherein a Predicted GPS Server computes satellite force model parameters using a plurality of satellite force models, and wherein the Predicted GPS Client generates predicted Orbital State Vectors by propagating provided initial satellite position and velocity provided by said Predicted GPS Server using satellite force model parameters from one or more of available ones of said satellite force models provided by said Predicted GPS server.

23. A distributed GPS or GNSS method of orbit modeling and propagation, comprising:

(a) computing satellite force model parameters using a Predicted GPS Server;

(b) delivering said satellite force model parameters and a plurality of satellite positions and velocities via a communications link;

(c) generating within a Predicted GPS Client a predicted Orbital State Vector comprising a satellite position and velocity, by propagating an initial satellite position and velocity provided by said Predicted GPS Server to a different time than the time of an initial satellite position and velocity, using said satellite force model parameters provided by said Predicted GPS server to said Predicted GPS Client, said initial satellite position and velocity taken from said plurality of satellite positions and velocities; and

(d) providing a local GPS or AGPS device with assistance data derived from said predicted Orbital State Vector without requiring a real-time network connection;

wherein said assistance data consists of the satellite position and velocity contained in said predicted Orbital State Vector without converting into the satellite navigation data model format and provided by said Predicted GPS Client to said GPS or AGPS device at a time and in a format required by said GPS or AGPS device.