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Global Positioning System is a really popular navigation system that is used by a great number of people nowadays. This system gives a possibility to identify the location and speed of the objects at any place on Earth, including polar areas, almost in all weather conditions, and in outer space to 100 kilometers above Earth. Global Positioning System was developed and realized by the United States Department of Defense.

The main principle of functioning is definition of the position by the method of measuring the distance to an object from the spot with definite coordinates. The distance is defined by the counting the delay time of radio signal spreading from the satellite-transmitter to a GPS antenna which becomes a receiver. 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 want to define coordinates and altitude of GPS receiver we have to use minimum 4 radio signals from 4 satellites. The control over the satellites from Earth is realized in the control station that is situated in Schriever base, Colorado.

GPS receivers are frequently used nowadays by average people, sailors, rescuers and the police for location and velocity detection of diverse objects. If you need GPS devices you may get it almost everywhere today. It is also built in the most personal computers, mobile telephones and onboarders. A customer can detect his geographical location with the assistance of GPS receiver at any period of time that he needs. The accuracy of the definition of the signal position is from 3 to 5 meters and it is really improved with the correction radio signal from Earth and the calculating mistake is 1 millimeter.

You may get GPS mapping software as well. Such system gives you an opportunity to define your geographical position on the electronic map.

2 types of electronic maps are differentiated in GPS system. The first kind of raster electronic maps is the most open and the simplest type. It is the image of an area where the coordinates of a receiver are used. The scale of this kind of map depends on the initial variant of it. It can be both a picture from satellite and scanned paper map.

And vector electronic maps are created with their own data system inside that makes them really useful. There are all information about surrounding objects, the place you are located in and other helpful information for a traveler. The country information includes the data about the entire object beginning from rivers and finishing with hills that are situated in this area. And of course, both raster and vector Global Positioning System maps will show you the information about the motels, cafes and restaurants, service stations around. So you can get also portable GPS that will bring you a comfort on the trip.

And of course as everything that is made by people GPS has its own drawbacks. The main disadvantage is that Global Positioning System is radio-navigation equipment and due to it radio signal would not be received in some circumstances. A user will be almost invisible for GPS signal in reinforced concrete buildings. None the less it remains to be the best way of the location defining for the present period of time.