NAVSTAR GPS is a very famous navigation facilities that are applied by a great amount of people nowadays. This system is made for detecting the position and speed of the objects at any place on Earth. It can be done almost in any weather conditions and in all the territories on Earth including polar territory and in outer space to 100 kilometers above Earth. The developer of Global Positioning System became the United States Department of Defense that has realized the project.
The situation is identified by the principle of measuring the distance from the spot with the definite coordinates to an object. The sending satellite spreads the signal to a GPS antenna and the delay time is calculated to detect the distance between the receiver and transmitter. 3-dimensional coordinates may be detected when GPS receiver will recognize the distance to 3 satellites and the time of the NAVSTAR GPS system. And to define a receiver's coordinates and altitude it has to apply minimum 4 transmitters' signals. Orbital force tracking is implemented from the main control station that is situated in Schriever base, Colorado.
GPS receivers are often used nowadays by civil persons, sailors, rescuers and the police for location and velocity definition of diverse objects. Handheld GPS systems are being traded in different shops and they are built in cell-phones, PCs and onboarders. A user may define his geographical position with the assistance of GPS receiver at any moment of time that he needs. The maximum precision is from 3 to 5 meters and with the correction radio signal from Earth it is to 1 millimeter.