Efficient Approach for International Space Station Global Positioning System Multipath Analysis

A simple approach is proposed for investigating the effects of dynamic solar panel and thermal radiator movements on the Space Station (SS) GPS carrier phase measurments. This proposed geometrical theory of diffraction (GTD) computer modeling approach is analyzed and compared with the conventional GTD modeling approach for accuracy and efficiency. The proposed new approach, at every time step, recomputes the multipath only from the dynamically changed solar panels and thermal radiators but not from the static elements. The total multipath at every time step from the SS structures is then the appropriate combination of multipath from both the changed dynamic structures and the unchanged static structures. This new modeling approach reduces the computing time considerably and only very slightly decreases the accuracy of the percent coverage of the GPS receiver antenna gain and phase shift patterns. (AIAA)