System and Method for Verifying Consistent Measurements in Performing GPS Positioning

• US 20090195446A1
• Filed: 02/04/2008
• Published: 08/06/2009
• Est. Priority Date: 02/04/2008
• Status: Active Grant

• Current Assignee: CSR Technology Incorporated (Qualcomm, Inc.)
• Original Assignee: CSR Technology Incorporated (Qualcomm, Inc.)
• Inventors: Liao, Xiangqian, Chansarkar, Mangesh
• Granted Patent: US 8,144,053 B2
• Time in Patent Office: Days
• US Class Current: 342/357.25
• CPC Class Codes: G01S 19/252 Employing an initial estimate of location in generating assistance data
• CPC Class Codes: G01S 19/28 Satellite selection
• CPC Class Codes: G01S 19/42 Determining position

Abstract

Systems and methods are provided for verifying whether a set of satellite signals may be used to calculate an estimated position. Example systems and methods may include a GPS receiver for receiving the satellite signals and a measurement consistency verifier to analyze a geometric configuration of the satellites from which the satellite signals were acquired. The measurement consistency verifier may determine if the satellites are sufficiently close to one another to provide consistent measurements.

Claims

1. A method for verifying whether a set of satellite signals may be used to determine a suitable estimated position of a GPS receiver, the method comprising:

determining a geometric configuration formed by an approximate user position and GPS satellites'"'"' position, the geometric configuration being in terms of azimuth and elevation;

based on the geometric configuration, determining if the satellites are sufficiently close to one another to yield consistent measurements.

2. The method of claim 1 where the step of determining if the satellites are sufficiently close to one another comprises:

selecting a pair of satellites to test for consistent measurements, one satellite being a reference satellite and the other being a satellite under test;

determining the following parameters;

R=user position horizontal uncertainty,

Δ

H=user position vertical uncertainty,

Δ

T=user time uncertainty,

E_i, E_j,=elevation for the selected pair of satellites,

A_i, A_j=azimuth for the selected pair of satellites,

{right arrow over (v)}_j^LOS, {right arrow over (v)}_i^LOS=satellite velocities along the line-of-sight for the selected pair of satellites, and

λ

=wavelength=1 if any one of the satellite signals is not bit synchronized, or 20 if both of the satellite signals are bit synchronized;

using the parameters in the inequality below to determine if;

3. The method of claim 2 further comprising:

before beginning the consistency verification, creating a consistent identity list and an inconsistent identity list and moving the satellite having the highest elevation angle into the consistent identity list and all of the remaining satellites into the inconsistent identity list;

moving satellites from an inconsistent identity list into a consistent identity list when the satellites are verified to be consistent with any satellite in the consistent identity list.

4. The method of claim 3 where:

the step of selecting the pair of satellites comprises;

ordering the satellites in the inconsistent identity list in order of highest to lowest elevation angles.

5. The method of claim 3 further comprising:

leaving the inconsistent satellites in the inconsistent identity list as the satellites are verified to be inconsistent with all the satellites in the consistent identity list.

6. The method of claim 3 where the step of determining if a sufficient number of satellite signals are found to be consistent includes determining if the number of satellites in the consistent identity list is the sufficient number or greater for positioning.

7. The method of claim 2 where the step of determining the parameters includes:

retrieving aiding data from an aiding source; and

determining the parameters from the aiding data.

8. A system for verifying whether a set of satellite signals can be used to calculate an estimated position comprising:

a GPS receiver for receiving the satellite signals;

a measurement consistency verifier to analyze a geometric configuration of the satellites from which the satellite signals were acquired and to determine if the satellites are sufficiently close to one another to provide consistent measurements.

9. The system of claim 8 where the measurement consistency verifier includes software to perform:

a selection of a pair of satellites from a set of satellite identities;

a determination of the following parameters;

R=user position horizontal uncertainty,

Δ

H=user position vertical uncertainty,

Δ

T=user time uncertainty,

E_i, E_j,=elevation for the selected pair of satellites,

A_i, A_j=azimuth for the selected pair of satellites,

{right arrow over (v)}_j^LOS, {right arrow over (v)}_i^LOS=satellite velocities along the line-of-sight for the selected pair of satellites, and

λ

=wavelength=1 if any one of the satellite signals is not bit synchronized, or 20 if both of the satellite signals are bit synchronized;

using the parameters a determination of whether;

10. The system of claim 8 where the satellite selection function moves satellites from an inconsistent identity list into a consistent identity list as they are verified consistent with any satellite in the consistent identity list.

11. The system of claim 8 where the satellite selection function further orders the satellites in the inconsistent identity list in order of highest to lowest elevation angles.

12. The system of claim 8 where the satellite selection function keeps inconsistent satellites in a inconsistent identity list as they are verified not consistent with all the satellites in the consistent identity list.

13. The system of claim 8 where measurement consistency verifier determines if the number of satellites in the consistent identity list is the sufficient number or greater for positioning.

14. The system of claim 8 further comprising a connection to an aiding source over which the aiding source communicates aiding data, including parameters used in the inequality.

15. The system of claim 14 where the aiding source includes a mobile communications network.

16. The system of claim 15 where the GPS receiver resides on a mobile handset operable to communicate with the mobile communications network.

17. A mobile communications device for communicating over a mobile communications network, the mobile handset comprising:

a mobile communications transceiver for transmitting and receiving to and from a mobile communications network station;

a Satellite Positioning System (SATPS) receiver for receiving satellite signals from SATPS satellites;

an aiding data function for receiving aiding data from the mobile communications network station;

an assisted acquisition function to use the aiding data and a minimum set of satellite signals to determine an estimated position;

a measurement consistency verifier to analyze a geometric configuration of the satellites from which the satellite signals were received and to determine if the satellites are sufficiently close to one another to provide consistent measurements.

18. The mobile communications device of claim 17 where the measurement consistency verifier includes software to perform:

a selection of a pair of satellites from a set of satellite identities;

a determination of the following parameters;

R=user position horizontal uncertainty,

Δ

H=user position vertical uncertainty,

Δ

T=user time uncertainty,

E_i, E_j,=elevation for the selected pair of satellites,

A_i, A_j=azimuth for the selected pair of satellites,

{right arrow over (v)}_j^LOS, {right arrow over (v)}_i^LOS=satellite velocities along the line-of-sight for the selected pair of satellites, and

λ

=wavelength=1 if any one of the satellite signals is not bit synchronized, or 20 if both of the satellite signals are bit synchronized;

using the parameters a determination of whether;

19. A Satellite Positioning System (SATPS) receiver for receiving satellite signals from SATPS satellites, the SATPS receiver comprising:

a mobile communications network interface for receiving aiding data from a mobile communications network;

an assisted acquisition function to use the aiding data and a minimum set of satellite signals to determine an estimated position; and

a measurement consistency verifier to analyze a geometric configuration of the satellites from which the satellite signals were received and to determine if the satellites are sufficiently close to one another to provide consistent measurements.

20. The SATPS receiver of claim 19 where the measurement consistency verifier includes software to perform:

a selection of a pair of satellites from a set of satellite identities;

a determination of the following parameters;

R=user position horizontal uncertainty,

Δ

H=user position vertical uncertainty,

Δ

T=user time uncertainty,

E_i, E_j,=elevation for the selected pair of satellites,

A_i, A_j=azimuth for the selected pair of satellites,

{right arrow over (v)}_j^LOS, {right arrow over (v)}_i^LOS=satellite velocities along the line-of-sight for the selected pair of satellites, and

λ

=wavelength=1 if any one of the satellite signals is not bit synchronized, or 20 if both of the satellite signals are bit synchronized;

using the parameters a determination of whether;