The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 13, 1989
Filed:
Aug. 16, 1984
Gerard K O'Neill, Princeton, NJ (US);
Leslie O Snively, Centreville, VA (US);
Geostar Corporation, Washington, DC (US);
Abstract
A radio position determination and message transfer system is implemented using a pair of satellites in geostationary orbit for relaying interrogation and reply signals between a ground station and a user-carried transceiver. The user position is calculated based on the arrival times of reply signals received at the ground station via the two satellites, the known transmission time of the interrogation signal from the ground station, and the user's elevation on the surface of the earth. The elevation is derived from a stored terrain map providing local terrain elevations at a plurality of points on the earth's surface. The stored terrain map allows accurate position fixes to be obtained for surface users regardless of the deviation of the local terrain from the spherical or ellipsoidal model of the earth's surface.