Global Navigation Satellite Systems

Man's exploration of new territories has forced him to locate either his own position or his destination. Initially, only overland travel was concerned. The question mainly concerned the ability to return to one's point of departure. This was achieved by means of specific landmarks, located in the landscape, which the traveler had to memorize. Quite quickly, particularly as it enabled the movement of heavy loads, sea transport became an important mode of transport. The absence of such landmarks (in the general case) created new needs for navigation. So, unless we were to consider only coastal navigation, a positioning technique was needed. Human curiosity being what it is, this was the starting point for the long history of "navigation", which today leads us to global satellite positioning systems, the main subject of this article.