Satellite positioning system receiver time determination in minimum satellite coverage

• US 7,623,066 B2
• Filed: 11/12/2004
• Issued: 11/24/2009
• Est. Priority Date: 11/12/2004
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Stephen, James E., King, Thomas M., Geier, George J.
• Primary Examiner(s): Tarcza; Thomas H
• Assistant Examiner(s): Liu; Harry
• Application Number:
  US10/986,699
• Publication Number:
  US 20060103574A1
• Time in Patent Office: 1,838 Days
• Field of Search: 342/357, 34235701-35717
• US Class Current: 342/357.27
• CPC Class Codes: G01S 19/25 involving aiding data received from a cooperating element, e.g. assisted GPS
• CPC Class Codes: G01S 19/252 Employing an initial estimate of location in generating assistance data
• CPC Class Codes: G01S 19/42 Determining position
• CPC Class Codes: G01S 19/50 whereby the position solution is constrained to lie upon a particular curve or surface, e.g. for locomotives on railway tracks

Abstract

A method in a satellite positioning system receiver, including acquiring (210) a set of satellite positioning system satellites, determining (220) satellite subset time based on over-determined position solutions for at least two different subsets of the satellites acquired, determining (230) satellite time from at least two satellite subset times, computing (250) a position solution based on the satellite time or a refined (240) satellite time.

Claims

1. A satellite positioning system receiver, comprising:

a satellite signal receiver;

a controller coupled to the satellite signal receiver,

the controller configured to determine time from at least two satellite subset times,

the satellite subset times obtained based on over-determined position solutions for at least two different subsets of satellites acquired by the satellite signal receiver.

2. The receiver of claim 1,

the controller configured to determine a satellite subset time for at least two satellite subsets, each satellite subset comprising at least five of a set of six satellites acquired by the satellite signal receiver, and

the controller configured to determine time from at least two of the satellite subset times.

3. The receiver of claim 1,

the controller configured to determine a satellite subset time for at least two satellite subsets using corresponding satellite subset pseudorange information and using aiding information, each satellite subset comprising four of a set of at least five satellites acquired by the satellite signal receiver, and

the controller configured to determine time from at least two of the satellite subset times.

4. The receiver of claim 3, the controller configured to determine satellite subset time for at least two satellite subsets using corresponding satellite subset pseudorange information and using receiver altitude information.

5. The receiver of claim 1 the controller configured to determine time from at least two of the satellite subset times by combining the at least two satellite subset times.

6. The receiver of claim 1, the controller configured to determine a location of the satellite positioning system receiver using all acquired satellites after determining time.

7. The receiver of claim 1,

the controller configured to cause the satellite signal receiver to acquire a number of satellites from which a plurality of satellite subset times may be computed from corresponding subsets of the satellites acquired,

the controller configured to reduce a number of satellite subsets for which satellite subset time is obtained if the number of satellites acquired exceeds a threshold.

8. The receiver of claim 7, the controller configured to prioritize satellite subsets sharing fewer common satellites over prioritizing subsets sharing more common satellites when reducing the number of satellite subsets.

9. The receiver of claim 1, the controller configured to determine a refined time based on synchronizing the satellite positioning system receiver with periodic satellite data if an accuracy of the time determined from at least two satellite subset times is less than the period of the periodic satellite data.