AAS 98-195

LEO ORBIT DETERMINATION WITH DIFFERENTIAL GPS

P. J. Melvin - Naval Research Laboratory

Abstract

The purpose of this paper is to describe the use of GPS double differences for low Earth orbit determination in a Kalman filter. This filter is first described in AAS 96-145 which is available for download from http://tid.nrl.navy.mil/MELVIN/index.html or http://ssdd.nrl.navy.mil/melvin/. The chief advantage of combining ground station pseudoranges with those measured on-board a low Earth orbit (LEO) satellite is that clock errors are eliminated assuming synchronization to USNO. This prototype orbit determination software is for a new global network of seven GPS ground stations using Ashtech Z-12 continuous geodetic remote station (CGRS) receivers. Routines from the prototype will eventually migrate into the batch least squares orbit determination program OCEAN. The orbital accuracy is proven by use of data gathered on TOPEX with comparison to the precise orbit.

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