Just as in ancient maritime navigation large lighthouses were built to guide navigators to ports, aviation has developed different types of aids to facilitate navigation for aircraft pilots, one such aid is the Very High-Frequency Omnidirectional Radio Beacons; VOR, for its acronym in English.
Navigation assistance
This technology is one of the aids for pilots to fly from one place to another without getting lost. Just like the old lighthouses that emitted a light signal indicating the direction of the pier at night to boaters, VOR technology has ground stations, “radio beacons”, located at each airport and also at different locations along the route which are called “fixed”; these form a reference guide on which to follow the path of the aircraft to its destination.
The functioning of the VOR
The beacon stations have an antenna that emits a VHF radio frequency signal in all directions, therefore the name “omnidirectional”, this signal has a maximum range of about 320 kilometer radius and an altitude of 11,430 meters above the VOR ground station. The aircraft has an instrument called CDI, (Course Deviation Indicator), which determines the position of the aircraft in relation to the guidance emitted by the beacon. This instrument is similar to a compass, but instead of pointing north, it permanently indicates the direction of the beacon. The VOR system is used to navigate with the IFR or Instrument Flight Rules, that is, navigation that dispenses with the pilot’s sense perception, and uses the instruments to orient itself to the destination. It should be noted that, for VOR navigation, it is always necessary to have the assistance of an air traffic controller at the ground station of the beacon. Instrumental flight rules are useful in cases where visibility is null due to the time of day, or weather conditions, due to lack of knowledge of the terrain, or as we saw in the last article, due to disorientation in the pilots.
The VOR radio beacon emits three signals: The first is a signal with the terrestrial installation in Morse code to identify itself with that station, the other two emissions consist of sine waves of 30 Hz that vary from one another, and one is called the reference signal and the other variable signal.
The reference signal keeps its phase constant; on the other hand, the variable signal modifies its phase according to the direction in which it is emitted. When the VOR signal decoder equipment in the aircraft receives the emissions, it demodulates the three signals and makes a comparison between the reference signal and the variable signal, determining the phase difference between the two, and resulting in the knowledge of the tuned radial of the VOR, and therefore, the location in relation to the emitting radio beacon and the magnetic north of the earth is known with great accuracy.
What do you think about this topic? What other navigation systems do you know?
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