AUTONOMOUS ORBIT PROPAGATION SYSTEM AND METHOD

• US 20090237302A1
• Filed: 01/28/2009
• Published: 09/24/2009
• 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: Cayer, Dave, Derbez, Eric, Roy-Machabee, Guylain
• Granted Patent: US 8,125,382 B2
• Time in Patent Office: Days
• US Class Current: 342/357.420
• 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 of predicting a location of a satellite is provided wherein the GPS device, based on previously received information about the position of a satellite, such as an ephemeris, generates a correction acceleration of the satellite that can be used to predict the position of the satellite outside of the time frame in which the previously received information was valid. The calculations can be performed entirely on the GPS device, and do not require assistance from a server. However, if assistance from a server is available to the GPS device, the assistance information can be used to increase the accuracy of the predicted position.

Claims

1. A method of predicting a location of a satellite, comprising the steps of:

(a) providing a GPS device, said GPS device having an a RF antenna configured to receive a plurality of positions and a velocity associated with a satellite, said plurality of positions and velocity valid for an effective time period;

(b) said GPS device calculating, from said plurality of positions and said velocity, a correction acceleration of said satellite;

(c) said GPS device propagating an orbit of said satellite within a predicted time period using said plurality of positions, said velocity and said correction acceleration, at least a portion of said predicted time period occurring after said effective time period;

(d) said GPS device determining the location of said satellite using said orbit.

2. The method of claim 1, wherein said plurality of positions and said velocity are received within an ephemeris.

3. The method of claim 2, wherein said ephemeris is a broadcast ephemeris.

4. The method of claim 2, wherein a software module on said GPS device generates force model coefficients and Orbit State Vectors using said ephemeris.

5. The method of claim 4, wherein a propagation software module on said GPS device calculates said orbit.

6. The method of claim 5, wherein after said orbit is propagated, said orbit is stored as a polynomial within a memory of said GPS device.

7. The method of claim 6, wherein said orbit is converted into a synthetic ephemeris for use by said GPS device to determine said location of said satellite after said effective time period.

8. The method of claim 6, wherein said GPS device has a network interface, and if said network interface is in communication with an AGPS server, said AGPS server providing assistance to said GPS device in determining said location of said satellite.

9. The method of claim 8, wherein said AGPS server communicates seed data to said propagation module.

10. The method of claim 2, wherein said GPS device has a network interface, and if said network interface is in communication with an AGPS server, said AGPS server provides a synthetic ephemeris to said GPS device.

11. A GPS device, comprising:

a) an RF receiver configured to receive a communication of a plurality of positions and a velocity associated with a satellite, said plurality of positions and velocity valid for an effective time period;

b) a digital signal processor configured to demodulate said communications;

c) a seed generator configured to calculate, from said plurality of positions and said velocity, a correction acceleration of said satellite; and

d) a propagator configured to propagate an orbit of said satellite within a predicted time period using said plurality of positions, said velocity and said correction acceleration, at least a portion of said predicted time period occurring after said effective time period.

12. The GPS device of claim 11, wherein said plurality of positions and said velocity are received within an ephemeris.

13. The GPS device of claim 12, wherein said ephemeris is a broadcast ephemeris.

14. The GPS device of claim 12, wherein said seed generator is further configured to generate force model coefficients and Orbit State Vectors using said ephemeris.

15. The GPS device of claim 14, wherein said GPS device further comprises a memory, said memory configured to store said orbit, after said orbit is propagated.

16. The GPS device of claim 15, further comprising an AGPS interface module configured to convert said orbit into a synthetic ephemeris to determine said location of said satellite after said effective time period.

17. The GPS device of claim 11, wherein said GPS device further comprises a network interface configured to communicate with an AGPS server, and to receive assistance from said AGPS server.

18. The GPS device of claim 17, wherein said propagation module is configured to receive seed data from said AGPS server.

19. The GPS of claim 12 wherein said GPS device further comprises a network interface configured to receive a synthetic ephemeris.

20. A method of predicting a location of a satellite, comprising the steps of:

(a) providing a device with GNSS capability, having an a RF antenna configured to receive a plurality of positions and a velocity associated with a satellite, said plurality of positions and velocity valid for an effective time period;

(b) said device calculating, from said plurality of positions and said velocity, a correction acceleration of said satellite;

(c) said device propagating an orbit of said satellite within a predicted time period using said plurality of positions, said velocity and said correction acceleration, at least a portion of said predicted time period occurring after said effective time period;

(d) said device determining the location of said satellite using said orbit.