7. Basics of Galileo Satellites

Since their inception, GPS satellites have been the primary GNSS (see Chap. 2), and in doing so, have attracted global usage. The Russian GLONASS has to a lesser extent been used, but it has faced maintenance problems and as such, has not been able to compete effectively with GPS. Both systems, however, have one thing in common, and that is, they are controlled by the military of their respective countries. Users from other countries have been at the mercies of the two providers and therefore do not have autonomous control or a say in the integrity of the systems. Integrity is the capability of a system to provide a timely alert to the user when it fails to meet the thresholds of accuracy for which it is designed. Similar to the two satellite providers above, the Chinese BeiDou is also to a large extent designed for military purposes.