A General Method for Accurate Assessment of GNSS FDE Holes

S. Feng, W.Y. Ochieng

Abstract:	This paper proposes a new way to determine and assess FD/FDE holes using bounded regions on the Earth surface. The area of the hole can therefore be calculated from a polygonal region. An accurate FD/FDE performance statistic can then be calculated based on the ratio of the total area of holes and the coverage area (regional or global area). The method proposed is based on the precise computation of satellite coverage boundaries, their intersection points, analysis of the topology of the regions of intersection, the formation of closed regions and area calculation of polygonal surfaces. This is significantly more accurate than the conventional approach based on grid points with essentially no risk of missing any small holes. Test results using GPS and Galileo constellations show that the proposed method is highly accurate and requires minimal computational load compared to the conventional approach. This method could be used to assess not only the current and future constellations in terms of FD/FDE holes, but also the Degree of Coverage (DOC) performance in general. This is an important first step towards an accurate area computation based GNSS performance assessment. This is required to replace existing grid based methods.
Published in:	Proceedings of the 19th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2006) September 26 - 29, 2006 Fort Worth Convention Center Fort Worth, TX
Pages:	2658 - 2665
Cite this article:	Feng, S., Ochieng, W.Y., "A General Method for Accurate Assessment of GNSS FDE Holes," Proceedings of the 19th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2006), Fort Worth, TX, September 2006, pp. 2658-2665.
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