Reacquiring Satellite Signals Quickly

• US 20110316740A1
• Filed: 09/07/2011
• Published: 12/29/2011
• Est. Priority Date: 09/24/2008
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Waters, Deric W., Roh, June Chul, Rao, Sandeep
• Granted Patent: US 8,289,205 B2
• Time in Patent Office: Days
• US Class Current: 342/357.63
• CPC Class Codes: G01S 19/05 providing aiding data
• CPC Class Codes: G01S 19/235 Calibration of receiver components
• CPC Class Codes: G01S 19/246 involving long acquisition integration times, extended snapshots of signals or methods specifically directed towards weak signal acquisition
• CPC Class Codes: G01S 19/254 relating to Doppler shift of satellite signals
• CPC Class Codes: G01S 19/26 involving a sensor measurement for aiding acquisition or tracking

Abstract

Embodiments of the invention provide a method of reacquiring satellite signals quickly. A pseudorange of at least one satellite is estimated. A user'"'"'s position is also estimated. Then a signal from at one or more satellites may be received. By detecting when the user is stationary, the Doppler frequency estimation can be corrected or the SNR can be boosted more both of which lead to improved performance. The embodiments allow a GNSS receiver to process signals in when the signal level would otherwise be too low—for example indoors. The embodiments can improve performance when one or more satellites are temporarily blocked but one or more satellites are still being tracked.

Claims

1-18. -18. (canceled)

19. A method for reacquiring satellite signals quickly, said method comprising:

estimating a pseudorange of at least one satellite;

estimating a user position; and

receiving a signal from at least one satellite.

20. The method of claim 19, wherein estimating a user position comprising using a last known position of said user.

21. The method of claim 19, wherein estimating a user position comprising using a last known position if a maximum displacement as calculated from a plurality of sensor measurements is below a threshold.

22. The method of claim 19, wherein estimating a pseudorange of said at least one satellite comprising using coarse position estimate from an aiding source.

23. The method of claim 19, wherein estimating a pseudorange of said at least one satellite comprising using the position estimate from a co-located position estimator using non-Global Navigation Satellite System (GNSS) signals.

24. The method of claim 23, wherein said non-Global Navigation Satellite System (GNSS) signals is selected from the list comprising:

cellular signals from a plurality of base stations;

digital TV broadcast signals; and

ultra wideband (UWB) signals.

25-38. -38. (canceled)