Radio navigation or radionavigation is the application of radio frequencies to determine a position of an object on the Earth, either the vessel or an obstruction. Like radiolocation, it is a type of radiodetermination.
In aviation, the instrument landing system (ILS) is a precision radio navigation system that provides short-range guidance to aircraft to allow them to approach a runway at night or in bad weather. In its original form, it allows an aircraft to approach until it is 200 feet (61 m) over the ground, within a 1⁄2 mile (800 m) of the runway. At that point the runway should be visible to the pilot; if it is not, they perform a missed approach. Bringing the aircraft this close to the runway dramatically increases the range of weather conditions in which a safe landing can be made. Other versions of the system, or "categories", have further reduced the minimum altitudes, runway visual ranges (RVRs), and transmitter and monitoring configurations designed depending on the normal expected weather patterns and airport safety requirements.
A non-directional beacon (NDB) or non-directional radio beacon is a radio beacon which does not include inherent directional information. Radio beacons are radio transmitters at a known location, used as an aviation or marine navigational aid. NDB are in contrast to directional radio beacons and other navigational aids, such as low-frequency radio range, VHF omnidirectional range (VOR) and tactical air navigation system (TACAN).
An automatic direction finder (ADF) is a marine or aircraft radio-navigation instrument that automatically and continuously displays the relative bearing from the ship or aircraft to a suitable radio station. ADF receivers are normally tuned to aviation or marine NDBs operating in the LW band between 190 – 535 kHz. Like RDF units, most ADF receivers can also receive medium wave (AM) broadcast stations, though these are less reliable for navigational purposes.
Very High Frequency Omnidirectional Range Station (VOR) is a type of short-range radio navigation system for aircraft, enabling aircraft with a receiving unit to determine its position and stay on course by receiving radio signals transmitted by a network of fixed ground radio beacons. It uses frequencies in the very high frequency (VHF) band from 108.00 to 117.95 MHz. Developed in the United States beginning in 1937 and deployed by 1946, VOR became the standard air navigational system in the world, used by both commercial and general aviation, until supplanted by satellite navigation systems such as GPS in the early 21st century. As such, VOR stations are being gradually decommissioned. In 2000 there were about 3,000 VOR stations operating around the world, including 1,033 in the US, but by 2013 the number in the US had been reduced to 967. The United States is decommissioning approximately half of its VOR stations and other legacy navigation aids as part of a move to performance-based navigation, while still retaining a "Minimum Operational Network" of VOR stations as a backup to GPS. In 2015, the UK planned to reduce the number of stations from 44 to 19 by 2020.
In aviation, distance measuring equipment (DME) is a radio navigation technology that measures the slant range (distance) between an aircraft and a ground station by timing the propagation delay of radio signals in the frequency band between 960 and 1215 megahertz (MHz). Line-of-visibility between the aircraft and ground station is required. An interrogator (airborne) initiates an exchange by transmitting a pulse pair, on an assigned 'channel', to the transponder ground station. The channel assignment specifies the carrier frequency and the spacing between the pulses. After a known delay, the transponder replies by transmitting a pulse pair on a frequency that is offset from the interrogation frequency by 63 MHz and having specified separation.
The Wide Area Augmentation System (WAAS) is an air navigation aid developed by the Federal Aviation Administration to augment the Global Positioning System (GPS), with the goal of improving its accuracy, integrity, and availability. Essentially, WAAS is intended to enable aircraft to rely on GPS for all phases of flight, including precision approaches to any airport within its coverage area. It may be further enhanced with the Local Area Augmentation System (LAAS) also known by the preferred ICAO term Ground-Based Augmentation System (GBAS) in critical areas.
An instrument landing system localizer, or simply localizer, is a system of horizontal guidance in the instrument landing system, which is used to guide aircraft along the axis of the runway.
In aviation, an instrument approach or instrument approach procedure (IAP) is a series of predetermined maneuvers for the orderly transfer of an aircraft operating under instrument flight rules from the beginning of the initial approach to a landing, or to a point from which a landing may be made visually. These approaches are approved in the European Union by EASA and the respective country authorities and in the United States by the FAA or the United States Department of Defense for the military. The ICAO defines an instrument approach as "a series of predetermined maneuvers by reference to flight instruments with specific protection from obstacles from the initial approach fix, or where applicable, from the beginning of a defined arrival route to a point from which a landing can be completed and thereafter, if landing is not completed, to a position at which holding or en route obstacle clearance criteria apply."
The microwave landing system (MLS) is an all-weather, precision radio guidance system intended to be installed at large airports to assist aircraft in landing, including 'blind landings'. MLS enables an approaching aircraft to determine when it is aligned with the destination runway and on the correct glidepath for a safe landing. MLS was intended to replace or supplement the instrument landing systems (ILS). MLS has a number of operational advantages over ILS, including a wider selection of channels to avoid interference with nearby installations, excellent performance in all weather, a small "footprint" at the airports, and wide vertical and horizontal "capture" angles that allowed approaches from wider areas around the airport.
A course deviation indicator (CDI) is an avionics instrument used in aircraft navigation to determine an aircraft's lateral position in relation to a course to or from a radio navigation beacon. If the location of the aircraft is to the left of this course, the needle deflects to the right, and vice versa.
The local-area augmentation system (LAAS) is an all-weather aircraft landing system based on real-time differential correction of the GPS signal. Local reference receivers located around the airport send data to a central location at the airport. This data is used to formulate a correction message, which is then transmitted to users via a VHF Data Link. A receiver on an aircraft uses this information to correct GPS signals, which then provides a standard instrument landing system (ILS)-style display to use while flying a precision approach. The FAA has stopped using the term LAAS and has transitioned to the International Civil Aviation Organization (ICAO) terminology of ground-based augmentation system (GBAS). While the FAA has indefinitely delayed plans for federal GBAS acquisition, the system can be purchased by airports and installed as a Non-Federal navigation aid.
A transponder landing system (TLS) is an all-weather, precision landing system that uses existing airborne transponder and instrument landing system (ILS) equipment to create a precision approach at a location where an ILS would normally not be available.
The Lorenz beam was a blind-landing radio navigation system developed by C. Lorenz AG in Berlin. The first system had been installed in 1932 at Berlin-Tempelhof Central Airport, followed by Dübendorf in Switzerland (1934) and others all over the world. The Lorenz company referred to it simply as the Ultrakurzwellen-Landefunkfeuer, German for "ultra-short-wave landing radio beacon", or LFF. In the UK it was known as Standard Beam Approach (SBA).
In navigation, a radio beacon or radiobeacon is a kind of beacon, a device that marks a fixed location and allows direction-finding equipment to find relative bearing. But instead of employing visible light, radio beacons transmit electromagnetic radiation in the radio wave band. They are used for direction-finding systems on ships, aircraft and vehicles.
In aeronautics, the final approach is the last leg in an aircraft's approach to landing, when the aircraft is lined up with the runway and descending for landing. In aviation radio terminology, it is often shortened to "final".
Space modulation is a radio amplitude modulation technique used in instrument landing systems (ILS) that incorporates the use of multiple antennas fed with various radio frequency powers and phases to create different depths of modulation within various volumes of three-dimensional airspace. This modulation method differs from internal modulation methods inside most other radio transmitters in that the phases and powers of the two individual signals mix within airspace, rather than in a modulator.
The low-frequency radio range, also known as the four-course radio range, LF/MF four-course radio range, A-N radio range, Adcock radio range, or commonly "the range", was the main navigation system used by aircraft for instrument flying in the 1930s and 1940s, until the advent of the VHF omnidirectional range (VOR), beginning in the late 1940s. It was used for en route navigation as well as instrument approaches and holds.
Sonne was a radio navigation system developed in Germany during World War II. It was developed from an earlier experimental system known as Elektra, and therefore the system is also known as Elektra-sonnen. When the British learned of the system they started using it as well, under the name Consol, meaning "by the sun".
In aviation, instrument landing system glide path, commonly referred to as a glide path (G/P) or glide slope (G/S), is "a system of vertical guidance embodied in the instrument landing system which indicates the vertical deviation of the aircraft from its optimum path of descent".
