Radio navigation is the application of frequencies, which is radio in order to determine the position of any object on the Earth, which either can be a vessel or any obstruction. Like radiolocation, this is a type of radiodetermination system. The first system of this navigation was the Radio Direction Finder, abbreviated as RDF. By only tuning in any radio station and using a directional antenna, we could determine the direction to where the broadcast is being done. For the second measurement, the next station is taken.GPS, which is the Global Positioning System, is a space-based radio-navigation system that broadcasts highly the exact navigation which pulses the users on or near the Earth. In the States' Navstar GPS, 24 main satellites in 6 orbits circle Earth every 12 hours.