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Earth tiling system for providing regional based service in a mobile satellite communication network

  • US 6,389,289 B1
  • Filed: 04/12/1999
  • Issued: 05/14/2002
  • Est. Priority Date: 05/07/1998
  • Status: Expired due to Term
First Claim
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1. A method for determining a geographical region within which a target is located, the target being positioned at a target location, using a map of a plurality of geographical regions on the surface of the earth, wherein an estimate of the target location has been previously determined, and wherein the estimate of the target location comprises a region of error, the method comprising the steps of:

  • determining at least one target grid square, wherein at least a portion of the error region is intersected by the at least one target grid square;

    identifying a first set of tiles that intersect the at least one target grid square;

    identifying a first set of the geographical regions, the first set of geographical regions comprising the geographical regions that are associated with the tiles in the first set of tiles;

    wherein a south polar tile comprises a geographical region that is centered at the south pole and that is bounded by a first line of latitude and wherein a north polar tile comprises a geographical region that is centered at the north pole and that is bounded by a second line of latitude, and further wherein the error region is bounded by an upper boundary and a lower boundary;

    comparing the upper boundary of the error region to the second line of latitude; and

    comparing the lower boundary of the error region to the first line of latitude; and

    if the upper boundary is positioned at or above the second line of latitude, then adding the north polar tile to the first set of tiles; and

    if the lower boundary is positioned at or below the first line of latitude, then adding the south polar tile to the first set of tiles.

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