You require 3 things to navigate by GPS – 1) A network of satellites broadcasting the current time, two) a receiver that can triangulate the signal from quite a few satellites to ascertain latest area, and 3) a electronic zoomable map to Display screen the current location and estimate routes http://costaricalivebusschedule11098.loginblogin.com/15031714/what-does-costa-rica-live-bus-map-mean