Visibility of non-GSO satellites from a terrestrial station and applications to inter-system interference

It is complex to visualize trajectories of non-geostationary orbiting satellites (NGSOs) from a fixed terrestrial station (TS) point of view, due to the Earth rotation and the satellite orbital dynamics. This paper presents three different case studies, one representing medium earth orbit constellations, the second low earth orbit inclined constellations and the third one low earth orbit highly inclined constellations. As is shown, satellite visibility from a TS location for a given NGSO constellation will depend basically on three parameters: the orbit height H₀, the orbital inclination i and the TS latitude. The paper demonstrates that for a given latitude the percentage of time that any satellite of a given NGSO constellation is in the TS antenna main beam would be dependent on the TS antenna azimuth. The paper further defines the worst case antenna pointing azimuths and develops a general formulation to calculate them for different TS locations and different NGSO constellation type