Design tools for GNSS

The process of GNSS constellation design can be divided into two parts. Firstly, it is possible to design a new configuration of satellites, given specific criteria which it must satisfy. Secondly, it is possible to analyse a given constellation, either resulting from the design process, or based on current satellites, to assess the degree to which it meets the specified requirements. A thorough description of the basic theoretical principles of the design of optimal satellite orbits, in terms of satellite availability, coverage, accuracy and integrity, as implemented in the IESSG design software, is given in this paper. As a demonstration of the analysis principles, a number of GNSS constellations have been tested. GNSSI is represented by the two scenarios of GPS plus augmentations.