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Radio navigation or radionavigation is the application of radio frequencies to determining a position on the Earth. Radio is the transmission of signals by Modulation of electromagnetic waves with frequencies below those of visible Light. EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 Like radiolocation, it is a type of radiodetermination. Radiolocation is the process of finding the location of something through the use of Radio waves It generally refers to passive uses particularly Radar As defined by FS-1037C, radiodetermination is the determination of the position Velocity and/or other characteristics of an object or the obtaining of information

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RDF / ADF / NDB

The first system of radio navigation was the Radio Direction Finder, or RDF. A radio direction finder ( RDF) is a device for finding the direction to a Radio source By tuning in a radio station and then using a directional antenna to find the direction to the broadcasting antenna, radio sources replaced the stars and planets of celestial navigation with a system that could be used in all weather and times of day. This article is about radio broadcasting for other uses see Radio (disambiguation. A directional antenna or beam antenna is an antenna which radiates greater power in one or more directions allowing for increased performance on transmit and receive A star is a massive luminous ball of plasma. The nearest star to Earth is the Sun, which is the source of most of the Energy on Earth A planet, as defined by the International Astronomical Union (IAU is a celestial body Orbiting a Star or stellar remnant that is Celestial navigation, also known as astronavigation, is a Position fixing technique that was devised to help sailors cross the featureless oceans without having to The weather is a set of all the phenomena occurring in a given Atmosphere at a given Time. By using triangulation, two such measurements can be plotted on a map where their intersection is the position. In Trigonometry and Geometry, triangulation is the process of determining the location of a point by measuring angles to it from known points at either Commercial AM radio stations can be used for this task due to their long range and high power, but strings of low-power radio beacons were also set up specifically for this task. A Non-directional beacon ( NDB) is a Radio transmitter at a known location used as an aviation or marine Navigational aid Early systems used a loop antenna that was rotated by hand to find the angle to the signal, while modern systems use a much more directional solenoid that is rotated rapidly by a motor, with electronics calculating the angle. A loop antenna has a continuous conducting path leading from one conductor of a two-wire transmission line to the other conductor A solenoid is a three-dimensional Coil. In Physics, the term solenoid refers to a loop of wire often wrapped around a Metallic core which An electric motor uses Electrical energy to produce Mechanical energy. These later systems were also called Automatic Direction Finders, or ADF. A radio direction finder ( RDF) is a device for finding the direction to a Radio source

Lorenz

Main article: Lorenz (navigation)

In the 1930s German radio engineers developed a new system, called the "Ultrakurzwellen-Landefunkfeuer" (LFF), or simply "Leitstrahl" (guiding beam) but referred to outside Germany as Lorenz, the name of the company manufacturing the equipments. Prior to the World War II the Germans had deployed the Lorenz blind-landing aid at many Airports and equipped most of their bombers with the radio equipment Germany, officially the Federal Republic of Germany ( ˈbʊndəsʁepuˌbliːk ˈdɔʏtʃlant is a Country in Central Europe. Prior to the World War II the Germans had deployed the Lorenz blind-landing aid at many Airports and equipped most of their bombers with the radio equipment In Lorenz two signals were broadcast on the same frequencies from highly directional antennas with beams a few degrees wide. This article describes the unit of angle For other meanings see Degree. One was pointed slightly to the left of the other, with a small angle in the middle where they overlapped. The signals were chosen as dots and dashes, timed so that when the aircraft was in the small area in the middle the sound was continuous. Planes would fly into the beams by listening to the signal to identify which side of middle they were on, and then corrected until they were in the center.

Originally developed as a night and bad-weather landing system, in the late 1930s they also started developing long-range versions for night bombing. A bomb is any of a range of devices that typically rely on the Exothermic Chemical reaction of an Explosive material to produce an extremely In this case a second set of signals were broadcast at right angles to the first, and indicated the point at which to drop the bombs. The system was highly accurate and a battle of the beams broke out when United Kingdom intelligence services attempted, and then succeeded, in rendering the system useless. The Battle of the Beams was a period in early World War II when bombers of the German Air Force ( Luftwaffe) started using Radio navigation for The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom, the UK or Britain,is a Sovereign state located An intelligence agency is a governmental agency that is devoted to the Information gathering (known in the context as " intelligence "

In the post-war era similar systems were widely deployed, notably in the United States where a system of long range "airways" was created spanning the country with stations about 200 miles (320km) apart. The United States of America —commonly referred to as the The signals were chosen as the A and N letters from morse code, dot-dash and dash-dot respectively. Morse code is a Character encoding for transmitting telegraphic information using standardized sequences of short and long elements to represent the letters numerals However, new developments soon rendered these systems obsolete.

VOR

Main article: VHF omnidirectional range

The next major advance in "beam based" navigation system was the use of two signals that varied not in sound, but in phase. This article is about the radio navigation aid see VOR for other uses In these systems, known as VHF omnidirectional range, or VOR, a single master signal is sent out continually from the station, and a highly directional second signal is sent out that varies in phase 30 times a second compared to the master. This article is about the radio navigation aid see VOR for other uses The phase of an oscillation or wave is the fraction of a complete cycle corresponding to an offset in the displacement from a specified reference point at time t = 0 This signal is timed so that the phase varies as the secondary antenna spins, such that when the antenna is 90 degrees from north, the signal is 90 degrees out of phase of the master. The phase of an oscillation or wave is the fraction of a complete cycle corresponding to an offset in the displacement from a specified reference point at time t = 0 By comparing the phase of the secondary signal to the master, the angle can be determined without any physical motion in the receiver. This angle is then displayed in the cockpit of the aircraft, and can be used to take a fix just like the earlier RDF systems, although it is, in theory, easier to use and more accurate. A cockpit is the area usually near the front of an Aircraft, from which a pilot controls the aircraft Position fixing is the branch of Navigation concerned with the use of a variety of visual and electronic methods to determine the position of a Ship,

Hyperbolic Systems

Systems based on the measurement of the difference of signal arrival times from two or more locations are called hyperbolic systems due to the shape of the lines of position on the chart. These include:

GEE

The British GEE system was developed during World War II. GEE or AMES Type 7000 was a British Radio navigation system used by the Royal Air Force during World War II. World War II, or the Second World War, (often abbreviated WWII) was a global military conflict which involved a majority of the world's nations, including GEE used a series of transmitters sending out precisely timed signals, and the aircraft using GEE, RAF Bomber Command's heavy bombers, examined the time of arrival on an oscilloscope at the navigator's station. RAF Bomber Command was the organisation that controlled the RAF 's bomber forces from 1936 to 1968 A bomber is a Military aircraft designed to attack ground and sea targets primarily by dropping Bombs on them An oscilloscope (commonly abbreviated to scope or O-scope) is a type of Electronic test equipment that allows signal Voltages to be viewed If the signal from two stations arrived at the same time, the aircraft must be an equal distance from both transmitters, allowing the navigator to determine a line of position on his chart of all the positions at that distance from both stations. By making similar measurements with other stations, additional lines of position can be produced, leading to a fix. GEE was accurate to about 165 yards (150 m) at short ranges, and up to a mile (1. 6km) at longer ranges over Germany. Used after WWII as late as the 1960s in the RAF (approx freq was by then 68MHZ).

LORAN

Other "time based" radio navigation systems were developed from the basic GEE principle. Most capable of these was LORAN, for "LOng-range RAdio Navigation", originally developed for navigation over the Atlantic. LORAN ( LO ng R ange A id to N avigation is a terrestrial Radio navigation system using Low frequency Radio transmitters In LORAN a single "master" station broadcast a series of short pulses, which were picked up and re-broadcast by a series of "slave" stations, together making a "chain". Since the time between the reception and re-broadcast of the pulses by the slaves was tightly controlled, the time it took for the radio signal to travel from station to station could be measured by listening to the signals. Since the time for the re-broadcasts to reach a remote receiver varies with its distance from the slaves, the distance to each slave could be determined. By plotting the circles representing the ranges on a map, the area where they overlapped formed a fix.

At first the electronics needed to make these accurate measurements was expensive, and using it was difficult. As the sophistication of computer systems grew to the point where they could be placed on a single chip, LORAN suddenly became very simple to use, and quickly appeared in civilian systems intended for use on boats starting in the 1980s. However, like the beam systems before it, civilian use of LORAN was short-lived when newer technology quickly drove it from the market.

Other Hyperbolic Systems

Similar hyperbolic systems included the British/US Decca Navigator System used in the English Channel area, the US global-wide VLF/Omega Navigation System, and the similar Alpha deployed by the USSR. The Decca Navigator System was a hyperbolic Low frequency Radio navigation system (also known as Multilateration) that was first deployed during Very low frequency or VLF refers to radio frequencies (RF in the range of 3 KHz to 30 KHz. OMEGA was the first truly global Radio navigation system for aircraft operated by the United States in cooperation with six partner nations Alpha (also called RSDN-20) is a Russian system for long range Radio navigation. The expensive to maintain Omega system was shut down in 1997 as the US military migrated to using GPS, while Alpha is still in use. Basic concept of GPS operation A GPS receiver calculates its position by carefully timing the signals sent by the constellation of GPS Satellites high above the Earth

GPS

Main article: Global Navigation Satellite System

The most recent are satellite navigation systems. Global Navigation Satellite System (GNSS is the standard generic term for satellite navigation systems that provide autonomous geo-spatial positioning with global coverage Global Navigation Satellite System (GNSS is the standard generic term for satellite navigation systems that provide autonomous geo-spatial positioning with global coverage From early Transit (satellite) (doppler effect) systems, where one satellite provided a fix of varying quality dependent on a number of factors (one being altitude of the observer), we now see the Global Positioning System's constellation of satellites providing high quality positions based on high frequency signals providing near constant highly accurate positions in three dimensions. The TRANSIT system also known as NAVSAT (for Navy Navigation Satellite System) was the first Satellite navigation system to be used operationally The Doppler effect (or Doppler shift) named after Christian Doppler, is the change in Frequency and Wavelength of a Wave for Basic concept of GPS operation A GPS receiver calculates its position by carefully timing the signals sent by the constellation of GPS Satellites high above the Earth . . . .

See also

Radio navigation systems

External links

History

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