Grmena Abstract

NAVSTAR GPS is a very famous navigation system that is applied by a large number of people today. The purpose of this arrangement is the detecting of the speed and location of the objects. It may detect the object at any area on Earth, even in polar areas and in outer space to 100 kilometers above Earth in any weather conditions. The developer of GPS became the United States Department of Defense that has realized this system.

The location is defined by the principle of measuring the distance from the spot with the fixed coordinates to an object. The distance is detected by the counting the delay time of the signal sending from the satellite-transmitter to a GPS antenna which is a receiver. You can see that GPS receiver must recognize the distance to three satellites and the time of the GPS system to identify 3-dimensional coordinates. And to define a receiver's coordinates and altitude it must apply minimum 4 transmitters' signals. The direction of the transmitters from Earth is realized in the control station that is located in Schriever base, Colorado.

GPS receivers are frequently used nowadays by average people, sailors, rescuers and the police for location and speed definition of diverse objects. If you need GPS systems you may purchase it almost everywhere nowadays. It is also built in the most computers, mobile telephones and onboarders. GPS receiver gives you a possibility to detect geographical coordinates of the receiver's location at the present moment of time. The accuracy of the position definition is from 3 to 5 meters and when radio signal is improved from Earth it becomes better and can be to 1 millimeter.

GPS mapping software is also offered to consumers. This arrangement permits you to see your location on the electronic map.

Two types of electronic maps are differentiated in GPS system. Raster maps are connected with the first kind of maps that are the simplest and the most available. Actually it is the image of a country to which geographical coordinates are related. The scale of such an electronic map depends on the primary variant of it. It can be either a picture from satellite or scanned variant of a usual geographical map.

And vector electronic maps are made with their own database inside that makes them really helpful. They have all useful information about objects, their characteristics and location. The area information contains the data about the entire object beginning from rivers and finishing with mountains that are situated in this territory. And of course, both raster and vector GPS maps would show you the information about the hotels, cafes and restaurants, service stations around. Portable GPS is you advantage over usual paper maps.

And of course as anything that is made by human Global Positioning System has its own shortcomings. The basic shortcoming of all radio-navigation arrangements is that radio signal may not reach the receiver owing to some circumstances. A user will be practically invisible for GPS signal in reinforced concrete constructions. But nowadays it really is the greatest system of the geographical coordinates defining in the world.