NAVSTAR GPS is a very famous navigation system that is applied by a great number of people nowadays. This system is created for ascertaining 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 GPS became the United States Department of Defense that has accomplished this system.

The principle of the position detecting is in measuring the distance from the point with the definite coordinates to an object. The sending satellite spreads radio signal to a GPS antenna and the delay time is calculated to define the distance between the receiver and transmitter. 3-D coordinates may be defined when GPS receiver will know the distance to 3 satellites and the time of the NAVSTAR GPS system. And when we need to define coordinates and altitude of a receiver we are to apply minimum 4 signals from 4 transmitters. Orbital force supervision is realized from the main control station that is located in Schriever base, Colorado.

A great amount of usual people as well as the police, sailors and rescuers apply Global Positioning System for different needs, mostly for navigation, position and velocity detection. GPS systems are being sold in different shops and they are built in cell-phones, personal computers and onboarders. GPS receiver allows a consumer to detect geographical coordinates of the receiver's situation at the present moment of time. The exactness of the detection of the signal position is from 3 to 5 meters and it is really heightened with the correction radio signal from Earth and the calculating error is one millimeter.

GPS mapping software is also suggested to customers. This system helps a client define his position that is displayed on the electronic navigation map.

Two kinds of electronic maps are differentiated in Global Positioning System. The first type is raster electronic maps, the simplest and the most available ones. Factually it is the picture of an area to which geographical position is related. The primary variant of such a map will assign its scale. This electronic map can be a simple photo from space or a scanned navigation map.

Vector maps, instead, are the maps with their own data base within. There are all facts about surrounding objects, the territory you are situated in and other helpful information for a traveler. For example the country information includes the streams, lakes, hills and other objects that are located in this area. The similarity among these two kinds of maps is in the data about all the motels, restaurants and filling stations. They have all the data about the places you will need to rest in. So you may buy also portable automotive that will give you a comfort during the trip.

But we are to say some words about the disadvantages of this produce. As in any radio-navigation arrangement GPS signals would not come from the satellite to a receiver and visa versa owing to diverse conditions. So if you are in a reinforced concrete building it is practically impossible to identify your position. But anyway it is the greatest way of defining your geographical coordinates for today.