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Position locating and communication system using multiple satellite constellations

  • US 5,619,211 A
  • Filed: 11/17/1994
  • Issued: 04/08/1997
  • Est. Priority Date: 11/17/1994
  • Status: Expired due to Term
First Claim
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1. A system for providing location information to users, comprising:

  • a first group of at least three geolocation information transmitting satellites in substantially geosynchronous independent elliptical first orbits around the Earth, wherein said first orbits are inclined to earth'"'"'s equatorial plane by at least ten degrees and with orbital parameters providing first closed ground tracks having longitudinal extent greater than zero and less than one hundred and eighty degrees, and each of said first closed ground tracks of said satellites of said first group being substantially common, and said first closed ground tracks defining a predetermined area of coverage wherein said user is located; and

    a second group of one or more geolocation transmitting satellites in substantially geosynchronous second orbits around the earth, wherein said second orbits provide ground tracks lying substantially outside the first ground tracks and wherein said user obtains non-indeterminate positional fixes from said first group of at least three geolocation information transmitting satellites and from said second group of one or more geolocation transmitting satellites.

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