Copertura della Costellazione QZSS (Quasi-Zenith Satellite System)

The objective of this work is the study of the QZSS constellation coverage; QZSS is a satellite system planned by Japan space agency as a GPS augmentation, to improve performances above all in zones with high urbanization, characterized by the so-called “urban canyon”. In these zones a lot of GPS signals are blocked by buildings and they can’t be used by GPS receivers, so there are often bad satellite observation geometries with no precise or even impossible positioning. QZSS satellites, because their orbital parameters, stay for a lot of hours in a day above the served areas with great elevation angles and so they give a good solution to the blocking problem in the towns. In this analysis to verify the improving of GPS coverage on Japan territory with QZSS satellites, it’sbeen made a computer simulation, which confirm the QZSS usefulness. Such coverage improvement could be obtained in every place of earth, because of quasi-symmetry of GPS constellation, changing the reference meridian of QZSS ground tracks; so it’s been made the same simulation for Italy too, with more details obtained using a 3D model of an area of the centre of Naples.