l Very High Frequency Omnidirectional Range, more commonly known as VOR, is an aircraft radio navigation system; Since 1949, ICAO has defined it as a standard for short- and medium-range navigation, replacing low-frequency four-arm radio paths.
A VOR ground station, also called a beacon, transmits VHF radio waves that are picked up by an on-board receiver that processes them and provides useful information to the pilot to understand its position with respect to the beacon.
The signal sent indicates both the station identifier (in Morse code) and the location of the aircraft relative to the latter in reference to the magnetic North, thus indicating to the pilot its detection with respect to the station. Using the radial system - distance, you can get the position on the radial compared to the VOR of the aircraft. Many ground stations are also equipped with the DME (Distance Measuring Equipment) which allows the receiver to measure its distance from the broadcaster.