Global Positioning System (GPS)

               Global positioning system (GPS) is a system for determining the position of stationary or moving objects. Global positioning system may be related to certain coordinate system, it may be related to a well defined coordinate system like a three dimensional one or it may be related to some other point as the origin of a local coordinate system.
                The first system is referred to as a point positioning and the second as relative positioning. Further if the object positioned is stationary it is called stationary positioning and if it is a moving it is called kinetic positioning. Point positioning is used in surveying whereas kinetic positioning is used in navigation.
                  Global positioning system uses satellite and digital computers to compute the positions anywhere on the earth. That is it based on satellite ranging. As a matter of fact the position of the observer on the earth is determine by measuring a distance from a group of satellites orbiting the earth.