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Networked wireless communications device programmed to identify and eliminate probable multipath errors to enhance accuracy in correcting sleep clock for thermally induced errors

  • US 20050221847A1
  • Filed: 04/01/2004
  • Published: 10/06/2005
  • Est. Priority Date: 04/01/2004
  • Status: Active Grant
First Claim
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1. A method for correcting a sleep clock of a wireless communications device to account for temperature induced errors by identifying and limiting probable multipath errors, the method comprising operations of:

  • responsive to wakeup following a sleep state, measuring a difference between time reference output by a sleep clock and a network time reference and utilizing the difference to compute a current error in the sleep clock'"'"'s frequency;

    determining whether predetermined criteria are satisfied by aspects of a current error including (1) magnitude and (2) character in relation to errors from previous sleep states;

    bounding a current error unless the criteria is met, the bounding operation comprising;

    utilizing a predetermined relationship between sleep state duration and predetermined sleep clock error maxima to identify an appropriate maximum error, and limiting magnitude of the current error to the identified maximum error;

    estimating a sleep clock'"'"'s frequency utilizing inputs including the limited current error;

    utilizing a most recent estimate of the sleep clock'"'"'s frequency whenever planning a wakeup time.

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