What is DME (Distance Measurement Equipment)?

Distance measuring equipment (DME) is a radio navigation method that determines the range between an airplane and a ground station. DME is comparative in fundamental level to secondary radar ranging function, with the exception of the roles of the hardware in the airplane and on the ground are reversed. DME was a post-war improvement dependent on the recognizable IFF frameworks of World War II. It has timing the propagation delay of radio signals in the frequency band between 960 and 1215 megahertz (MHz).