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Method and apparatus for geolocating a wireless communications device

  • US 7,057,556 B2
  • Filed: 04/18/2005
  • Issued: 06/06/2006
  • Est. Priority Date: 03/18/2002
  • Status: Active Grant
First Claim
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1. A method for determining a time difference of arrival of a single signal transmitted from a transmitting unit and received at two or more receiving sites, the method comprising:

  • (a) transforming the signal received at a first site to a frequency domain representation comprising first component signals each first component signal having a frequency and a phase angle parameter and transforming the signal received at a second site to a frequency domain representation comprising second component signals each second component signal having a frequency and a phase angle parameter;

    (b) operating in the frequency domain, determining a Hermitian product of first and second component signals having a same frequency parameter, wherein a frequency parameter of the Hermitian product comprises the same frequency parameter;

    (c) operating in the frequency domain, determining a phase angle parameter of each Hermitian product determined at the step (b);

    (d) determining a relationship between the phase angles parameter and the frequency parameter for a plurality of Hermitian products; and

    (e) determining the time difference of arrival from the relationship.

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