ABSTRACT
The capability to geocode GIS information in vector and raster form today depends on modern geopositioning systems.
The NAVSTAR-GPS (Navigation System with Time and Ranging – Global Positioning System) has been under development by the US military since 1973. From 1993, the system has consisted of twenty-one active satellites and three spares. The satellites orbit the earth at an altitude of 20200km. Their orbits are arranged in such a manner that at least four of them are in direct line of sight at any point of the earth’s surface, 24 hours a day, unless the line of sight is obstructed by buildings, vegetation or steep topography. The use of GPS has been developed for real-time navigation and for geodetic positioning. Figure 5.1 illustrates the global GPS satellite configuration.
