A satellite navigationsystem is the standard generic term for satellite navigation systems that iscapable of providing autonomous geo-spatial positioning with global coverage.The navigation system supports in determining the longitude, latitude andaltitude of a particular object with in a limited area with the help of smallelectronic receivers. The location determination is done with the support oftime signals transmitted along a line of sight by radio from satellites. It is possible tocalculate the precise time with Hexagonal wood screws the support of receivers on the ground with afixed position for the reference as scientific experiments. Navstar GlobalPositioning System from United States was the only fully operationalGNSS till now. 

But Galileo positioning system of the European Unionis now on way of getting fully operationalised in 2010. Even Glosnass ofRussia is in process of getting restored to full operation. Beidou navigationsystem of China is also on the way of gettingexpanded into a global system. India also hopes that IRNSS, its nextgeneration GNSS to get operational around 2012.

Generally GNSS isclassified into various types based on its features:GNSS-1, the combinationof existing satellite navigation systems with Satellite Based AugmentationSystems belong to the first generation system. GNSS-2, the secondgeneration of navigation systems independently supports a fullcivilian satellite navigation system, which is exemplified by the EuropeanGalileo positioning system. In early stages, the satellite navigationsystems used terrestrial long wave radio transmitters in the place ofsatellites. Transit, the first satellite navigation system was deployed by the US military in the 1960's which operated on thebasis of the Doppler effect.