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Rapid satellite signal acquisition in a satellite positioning system

  • US 5,418,538 A
  • Filed: 05/21/1993
  • Issued: 05/23/1995
  • Est. Priority Date: 05/21/1993
  • Status: Expired due to Term
First Claim
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1. A method for rapid acquisition of one or more Satellite Positioning System (SATPS) satellite signals by an SATPS station, referred to as a new SATPS station, that seeks to acquire or to reacquire such SATPS signals, the method comprising the steps of:

  • (1) providing a reference SATPS station, whose location coordinates are known with high accuracy, with a transmitter to broadcast differential SATPS information to other nearby SATPS stations, including the new SATPS station;

    (2) providing differential SATPS information from the reference station to the new station, including satellite number or equivalent satellite indicia, for each SATPS satellite that is visible from the reference station, referred to as an SATPS reference/visible satellite;

    (3) establishing a selected number of channels to acquire SATPS signals from each of the SATPS reference/visible satellites;

    (4) stepping through the frequency range and code-phase attributes for each of the SATPS reference/visible satellites to acquire and lock onto the SATPS signals;

    (5) after a first SATPS satellite signal is acquired, reducing the frequency tuning range to a smaller frequency range, based upon that satellite'"'"'s expected Doppler shift frequency range; and

    (6) using this smaller frequency range to search for and acquire an SATPS signal from at least one additional SATPS satellite.

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