Navstar is the US designation for the constellation of the GPS system (Global PositioningSystem
). It was conceived by the Departmend of Defense (DoD) and realized already in the 80s. From the designation NavigationSatellite Timing and Ranging (NAVSTAR) it is clear that the navigation satellites are intended for timing and positioning
. TheNavstar system (GPS) consists of 24 satellites orbiting the earth
at a nominal altitude of 20,000 km.The GPS system is used to determine the exact location of stationary and mobile receivers and GPS rece
ivers.The navigation system can be used equally in aviation and navigation, in motor vehicles and in mobile devices
for the exact determination of position. The individual satellites of the GPS system have been constantly further developed and equipped with increasingly precise atomic frequency standards, with rubidium and caesium standards.