Performance Assessment of Almanac Navigation

Timo Jokitalo, Heidi Kuusniemi, Stefan Söderholm, Swarna Kakarlapudi

Abstract:	This paper presents the results of a study whose aim was to characterize the errors that typically happen if old orbit data are used in the absence of more recent information of satellite orbits. First, the position accuracy resulting from using almanacs in navigation computation is presented with real-life and simulated test data. Using current almanacs does usually not result in the horizontal position error exceeding one kilometer. Up to 40 days old almanacs were analyzed and they result in approximately 20 kilometer of horizontal position error. Then, the behavior of using almanacs in the position computation is analyzed in the long-term, with up to 200 days old almanac information being analyzed. The consequential position errors are compared to errors resulting from the usage of old ephemeris information. In addition, errors are analyzed also in the measurement domain, and alongtrack, radial, and cross-track orbital errors are presented when almanacs and old ephemerides are used.
Published in:	Proceedings of the 20th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2007) September 25 - 28, 2007 Fort Worth Convention Center Fort Worth, TX
Pages:	1351 - 1358
Cite this article:	Jokitalo, Timo, Kuusniemi, Heidi, Söderholm, Stefan, Kakarlapudi, Swarna, "Performance Assessment of Almanac Navigation," Proceedings of the 20th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2007), Fort Worth, TX, September 2007, pp. 1351-1358.
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