Determining position without use of broadcast ephemeris information

• US 20060055598A1
• Filed: 09/14/2004
• Published: 03/16/2006
• Est. Priority Date: 09/14/2004
• Status: Active Grant

• Current Assignee: CSR Limited (Qualcomm, Inc.)
• Original Assignee: SIRF Technology Incorporated (Qualcomm, Inc.)
• Inventors: Garin, Lionel J., Phatak, Makarand S.
• Granted Patent: US 7,142,157 B2
• Time in Patent Office: Days
• US Class Current: 342/357.640
• CPC Class Codes: G01S 19/05 providing aiding data
• CPC Class Codes: G01S 19/20 Integrity monitoring, fault detection or fault isolation of space segment
• 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: G01S 19/51 Relative positioning

Abstract

Devices and methods are described for determining position information without broadcast ephemeris data for extended time periods. A server or client device receives or collects historical state data of satellites of a satellite-based positioning system and generates predictions of future satellite trajectories for future time periods. When a server generates the predictions, the predictions are subsequently transferred to a client device. The client device selects predictions appropriate to time of interest. The time can be any time during a period of at least seven calendar days. The client device reconstructs satellite states using information on the predictions and uses the reconstructed satellite states to acquire satellite signals as appropriate to the current location and time of the client device. The client device determines and/or tracks its position using information of the satellite states and timing information of the satellite signals.

Claims

1. A portable communications device, comprising:

a first communication system that receives data representative of predicted satellite states via a first communication link, wherein the predicted satellite states are continuously generated for future time periods using historical satellite state data for at least one satellite of a satellite-based positioning system;

a prediction generator that selectively reconstructs at least one reconstructed satellite state for at least one of the time periods using the received data; and

at least one signal processor that uses the at least one reconstructed satellite state to acquire a satellite signal.

2. A method for determining a position of a client device, comprising:

receiving historical state data for at least one satellite of a satellite-based positioning system;

continuously predicting satellite states for future time periods using the historical state data;

transferring data representative of the predicted satellite states to the client device via a first communication link;

selectively reconstructing at least one reconstructed satellite state in the client device using the transferred data; and

determining the position of the client device using the at least one reconstructed satellite state along with timing information of satellite data received on a second communication link.

3. The method of claim 2, wherein the historical state data includes at least one of satellite position state vectors, satellite velocity state vectors, satellite clock biases, and satellite clock rate errors.

4. The method of claim 2, wherein the historical state data is received via at least one coupling with a database, wherein the historical state data is delivered to at least one server.

5. The method of claim 4, wherein the coupling includes at least one of a wired coupling, a wireless coupling, and a wired/wireless coupling to a ground-based network.

6. The method of claim 2, wherein continuously predicting satellite states includes predicting at least one of satellite position state vectors and satellite velocity state vectors of future satellite trajectories and future satellite clock biases and satellite clock rate errors for the satellites.

7. The method of claim 2, wherein the future time periods include one or more consecutive sub-periods with each sub-period covering a pre-specified span of time.

8. The method of claim 2, wherein the future time periods collectively cover a span of time having a length of at least seven calendar days.

9. The method of claim 2, wherein the future time periods include a plurality of time periods each having a length of at least four hours.

10. The method of claim 2, wherein transferring data representative of the predicted satellite states includes:

generating the data by compressing the predicted satellite states into sets of compressed parameters; and

transferring the sets of compressed parameters to the client device using at least one of a single transmission and multiple transmissions.

11. The method of claim 10, wherein each set of compressed parameters corresponds to the predicted satellite states for one period of the future time periods.

12. The method of claim 11, wherein the period is approximately four hours in length.

13. The method of claim 10, wherein a first set of compressed parameters includes all parameters of the predicted satellite states for a first future time period, wherein a second set of compressed parameters includes difference information from which parameters of the predicted satellite states for a second future time period are calculated.

14. The method of claim 13, wherein the difference information is defined relative to the first set of compressed parameters.

15. The method of claim 2, wherein transferring data further comprises transferring data in response to a request signal received from the client device.

16. The method of claim 2, wherein transferring data further comprises transferring parameters using at least one broadcast message.

17. The method of claim 2, wherein the first communication link includes at least one of a wired coupling, a wireless coupling, and a wired/wireless coupling.

18. The method of claim 2, further comprising storing the received parameters in at least one memory area of the client device.

19. The method of claim 2, wherein the transferred data comprise Kepler parameters, and wherein selectively reconstructing the at least one reconstructed satellite state solving Kepler equations of motion using selected ones of the transferred Kepler parameters.

20. The method of claim 2, wherein the transferred data comprise a subset of the predicted satellite states, and wherein selectively reconstructing the at least one reconstructed satellite state further comprises:

retrieving the transferred predicted satellite states that correspond to at least one selected period of the future time periods from at least one memory area of the client device; and

numerically integrating satellite dynamical equations of motion using the retrieved transferred predicted satellite states to provide the at least one reconstructed satellite state.

21. The method of claim 2, further comprising detecting an absence of ephemeris data from the satellites.

22. The method of claim 2, further comprising performing integrity monitoring in the device.

23. A method for determining a position of a client device, comprising:

receiving historical state data for at least one satellite of a satellite-based positioning system;

continuously predicting satellite states for future time periods using the historical state data and transferring parameters representative of the predicted satellite states to the client device from a server;

selectively reconstructing at least one reconstructed satellite state for at least one of the future time periods using the transferred parameters; and

generating a future satellite state in the client device at a future time using the at least one reconstructed satellite state.

24. A method for determining a position of a client device, comprising:

receiving historical trajectory data corresponding to satellites of a satellite-based positioning system over a first communication channel;

generating predictions of future satellite trajectories for future time periods using the historical state data;

generating satellite states using the predictions;

acquiring satellite signals over a second communication channel using the generated satellite states; and

determining the position of the client device using the generated satellite states and timing data in the acquired satellite signals.

25. A communications system, comprising:

a first communication component that receives historical state data of satellites of a satellite-based positioning system;

a first signal processing component that continuously generates predictions of future satellite states for future time periods using the historical state data;

a second signal processing component that generates sets of parameters that represent the predicted satellite states, wherein each set of parameters includes information of predicted satellite states for at least one period of the future time periods; and

a second communication component that transfers the generated sets of parameters to portable electronic devices that use the transferred sets of parameters to selectively reconstruct at least one reconstructed satellite state.

26. The system of claim 25, wherein each portable electronic devices comprises:

a first communication system that receives the transferred sets of parameters via a first communication channel;

a second communication system that receives data from the satellites via a second communication channel;

a satellite state reconstructor that selectively reconstructs the at least one reconstructed satellite state in the portable device using at least one of the transferred sets of parameters; and

at least one signal processor configured to use the at least one reconstructed satellite state to acquires satellite signal.

27. Computer readable medium including executable instructions which, when executed in a processing system, determine a position of a device by:

receiving historical trajectory data corresponding to satellites of a satellite-based positioning system;

generating predictions of future satellite trajectories for future time periods using the historical state data;

reconstructing at least one reconstructed satellite state using the predicted future satellite trajectories;

acquiring satellite signals using the at least one reconstructed satellite state; and

determining the position using the at least one reconstructed satellite state and timing data from the acquired satellite signals.