An Extended Propagation Ephemeris for GNSS

James L. Garrison and Brenda E. Eichel

Peer Reviewed

Abstract:	A Global Navigation Satellite Systems (GNSS) ephemeris is defined, providing satellite positions accurate to 7.7 and 48.7 meters, over 24 and 72 hours, respectively. An empirical model is created, based upon the Fourier analysis of one year of precision orbit data, using argument of latitude as the independent variable. This model was then fit to smaller batches of orbit data. Dominant frequencies in the residuals, using time as the independent variable, defined a second empirical model for corrections in an orbit-based reference frame. The ephemeris was tested using one month of data, fitting segments between 24 and 168 hours. Random error was then simulated, using standard deviations between 0.1 and 5 m, to study the sensitivity to orbit propagation accuracy. Propagation errors of 5 meters increased the 24-hour ephemeris error to 12.2 meters, but had an insignificant effect on the longer ephemerides.
Published in:	NAVIGATION: Journal of the Institute of Navigation, Volume 53, Number 3
Pages:	167 - 179
Cite this article:	Garrison, James L., Eichel, Brenda E., "An Extended Propagation Ephemeris for GNSS", NAVIGATION: Journal of The Institute of Navigation, Vol. 53, No. 3, Fall 2006, pp. 167-179.
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