Introduction:
The global Positioning System (GPS) is a U.S space based global navigation satellite system.It provides reliable positioning,navigation,and timing services to worldwide users on a continuouse basis in all weather,day and night anywhereor near the Earth which has an unobstructed view of four or more GPS satellite.
GPS is made up of three segments space,control and user. The space segment is composed of 24 to 32 satellite in medium earth orbit and also includes the booster required to launch them in orbit. The control segment is composed of master control station and a host of dedicated shared antennas and monitor stations.The user segment became composed of thousands of millitary users of the secure GPS positioning service.It broadcasts signals from space thatprovides GPS user three dimensional location plus precise time.
GPS has become widely used aid to navigation worldwide and a useful tool for map making ,land surveying,commerce,scientific uses,tracking and hobbying such as geocaching and waymarketing . It has become a mainstay of transportation worldwide, providing navigation for marine,ground and maritime operations.
History:
The design of the GPS is based on the simple ground based radio network ,such as Loran and decca navigator developed during world war II.To achieve accuracy requirements, GPS uses principles of general relatively to correct the satellites'atomic clocks.
Functions:
Many civilian and government based application benefit from GPS signals using one or more of three basic componentsof GPS: absolute location,relative movement, and time transfer. Te ability to determine the receiver'sabsolute location allows GPS receivers to perform as surveying tools or as an aid for navigation. The capacity to determine the relative movement enables a user to calculate the relative velocity and orientation ,useful in vessels or observation of earth.
