Geometry and Visibility of Satellite Navigation Systems in Restricted Area

Jacek Januszewski

Abstract:	In open area the accuracy of the observer’s position obtained from the satellite navigation systems depends on a number of satellites (ls) visible above masking elevation angle (Hmin) and the geometry of systems – Geometric Ditution of Precision (GDOP) coefficient. The detailed distributions of satellite azimuths Az (8 intervals, each 45O wide) and GDOP coefficient (8 intervals) for different angles Hmin and different observer’s latitudes ? (9 zones, each 10O wide) calculated for GPS system and the future system Galileo are presented in this paper. The same number of satellites fully operational (27) have been considered for both systems. In restricted area (urban area, maritime area) system accuracy depends on the parameters mentioned for open area and the dimensions & location of the obstacles. In urban area the calculations were made for the observer situated in the middle of the street for different widths of the street and obstacles heights. Other street parameters were: the angle between the North and street’s axis and latitude. In maritime area the calculations (masking angle, the number of satellites visible above the obstacles, dilution of precision coefficients values etc.) were made for coastal and channel navigation. The additional calculations were made for in restricted area like: ship sailing along the high coast, sailing in the strait or channel with high coast on both sides, sailing in the channel below the bridge, entering to the port situated at the foot of the mountain, in harbour area with high buildings and harbour cranes. All calculations, based on reference ellipsoid WGS–84, were made by using author's simulating program.
Published in:	Proceedings of the 2005 National Technical Meeting of The Institute of Navigation January 24 - 26, 2005 The Catamaran Resort Hotel San Diego, CA
Pages:	827 - 839
Cite this article:	Januszewski, Jacek, "Geometry and Visibility of Satellite Navigation Systems in Restricted Area," Proceedings of the 2005 National Technical Meeting of The Institute of Navigation, San Diego, CA, January 2005, pp. 827-839.
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