×

Method and system for post-processing differential global positioning system satellite positional data

  • US 5,764,184 A
  • Filed: 03/10/1997
  • Issued: 06/09/1998
  • Est. Priority Date: 03/10/1997
  • Status: Expired due to Term
First Claim
Patent Images

1. For use with a differential global positioning system (GPS) that includes:

  • a plurality of GPS satellites that transmit to earth navigational signals including at least satellite orbital position data, GPS time data, and satellite identification data;

    at least one earth-based reference station that receives said navigational signals and computes at least pseudo-range correction data; and

    an earth-based user receiver, at a user location, able to receive said navigational signals and compute a user position;

    a method for recovering accurate post-processed information as to said user position even if said pseudo-range correction data are not received in real-time, the method comprising the following steps;

    (a) computing and storing stand-alone position of said user receiver at at least one time, using said navigational signals;

    (b) storing time at which said navigational signals were used to compute said stand-alone position;

    (c) storing identity of each of said GPS satellites whose navigational signals were used to compute said stand-alone position;

    (d) using pre-stored almanac data for each of said GPS satellites whose navigational signals were used in step (a) and using information stored at step (a), step (b) and step (c) to compute a direction cosine from said user receiver to each of said GPS satellites whose navigational signals were used to compute said stand-alone position (hereinafter, said used GPS satellites);

    wherein at least one said reference station computed and transmitted pseudo-range correction data for each of said used GPS satellites; and

    (e) using direction cosine data computed at step (d) to map each of said pseudo-range correction data corresponding to each of said used GPS satellites and for each time at which said stand-alone position was computed to obtain corrections to said user position.

View all claims
  • 2 Assignments
Timeline View
Assignment View
    ×
    ×