Electromagnetic Analysis for Multi-constellation GNSS Satellite Visibility Determination in Urban Areas

The satellite visibility of global navigation satellite systems in urban areas is investigated with electromagnetic ray-based methods and 3D city models. The satellite position is computed with satellite orbital parameters and the SGP4 standard mathematical model of satellite orbits. The obstruction, reflection and diffraction of satellite signals due to the presence of buildings are taken into account in the prediction of satellite visibility, with the satellite signal propagation paths being determined by using the ray tracing and 3D city models. In some cases where it is hard for a receiver to detect a satellite due to too low signal level, there do exist predicted signal propagation paths from the satellite to the receiver via reflection or diffraction. The received signal level is also estimated with the electromagnetic ray-based methods to enable the predicted satellite visibility to be correlated with that observed.