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Clock phase ranging methods and systems

  • US 7,986,270 B2
  • Filed: 01/02/2008
  • Issued: 07/26/2011
  • Est. Priority Date: 02/27/2006
  • Status: Active Grant
First Claim
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1. A method of determining a distance between first and second wireless communication devices, comprising the steps of:

  • conducting a first estimate of a time of flight of a signal between the first and second wireless communication devices;

    conducting subsequent estimates of time of flight of signals between the first and second wireless communication devices, wherein the subsequent estimates are each performed with a clock phase in one of the devices that is offset relative to its phase in a prior estimate;

    computing differences between the first time of flight estimate and the subsequent estimates;

    computing a refined estimate of the time of flight of a signal between the first and second wireless communication devices based on the differences between the subsequent and prior time-of-flight estimates; and

    computing a distance based on the refined time-of-flight estimate.

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