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97-641: The Orfordness Rotating Wireless Beacon , known simply as the Orfordness Beacon or sometimes the Black Beacon , was an early radio navigation system introduced by the United Kingdom in July 1929. It allowed the angle to the station to be measured from any aircraft or ship with a conventional radio receiver, and was accurate to about a degree. A second station operating on the same principle

194-539: A directional antenna , one could determine the direction to the broadcasting antenna. A second measurement using another station was then taken. Using triangulation , the two directions can be plotted on a map where their intersection reveals the location of the navigator. 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, especially near airports and harbours. Early RDF systems normally used

291-403: A loop antenna , a small loop of metal wire that is mounted so it can be rotated around a vertical axis. At most angles the loop has a fairly flat reception pattern, but when it is aligned perpendicular to the station the signal received on one side of the loop cancels the signal in the other, producing a sharp drop in reception known as the "null". By rotating the loop and looking for the angle of

388-413: A 30 Hz AM reference signal, and a 1020 Hz 'marker' signal for station identification. Conversion from this audio signal into a usable navigation aid is done by a navigation converter, which takes the reference signal and compares the phasing with the variable signal. The phase difference in degrees is provided to navigational displays. Station identification is by listening to the audio directly, as

485-450: A computer. Satellite navigation systems send several signals that are used to decode the satellite's position, distance between the user satellite, and the user's precise time. One signal encodes the satellite's ephemeris data, which is used to accurately calculate the satellite's location at any time. Space weather and other effects causes the orbit to change over time so the ephemeris has to be updated periodically. Other signals send out

582-411: A dedicated navigator. The Orfordness Beacon was a simple solution to these problems, which essentially moved the loop antenna from the vehicle to the beacon. The station broadcast a continuous AM longwave signal at 288.5 kHz (1040 m) through a large loop antenna which was mechanically rotated at 1 rpm, or 6 degrees a second. As the antenna passed north, the signal was briefly keyed with

679-519: A different frequency to determine if the aircraft is pointed in the "right direction." Some aircraft will usually employ two VOR receiver systems, one in VOR-only mode to determine "right place" and another in ILS mode in conjunction with a glideslope receiver to determine "right direction." }The combination of both allows for a precision approach in foul weather. Beam systems broadcast narrow signals in

776-439: A few dozen satellites to provide worldwide coverage . As a result of these advantages, satellite navigation has led to almost all previous systems falling from use . LORAN, Omega, Decca, Consol and many other systems disappeared during the 1990s and 2000s . The only other systems still in use are aviation aids, which are also being turned off for long-range navigation while new differential GPS systems are being deployed to provide

873-432: A five-minute on-off pattern. This allowed for the construction of a second Beacon at RAE Farnborough , south-west of London. The Farnborough station broadcast on the same frequency as Orford, using the letters "G" (dash-dash-dot) for north and "W" (dot-dash-dash) for east. Orfordness broadcast on the first five minutes of every ten-minute period, and Farnborough on the second five minutes. Operations started in early 1930, but

970-404: A fix. Gee was accurate to about 165 yards (150 m) at short ranges, and up to a mile (1.6 km) at longer ranges over Germany. Gee remained in use long after World War II, and equipped RAF aircraft as late as the 1960s (approx freq was by then 68 MHz). With Gee entering operation in 1942, similar US efforts were seen to be superfluous. They turned their development efforts towards

1067-410: A landmark that would be visible to a radio receiver at very great ranges, hundreds of miles or more. The angle between the navigator and the beacon can be taken by using a simple mechanism known as a loop antenna which can be rotated around the vertical axis. As the antenna is rotated, the strength of the received signal varies, and drops to zero (the null ) when the loop is perpendicular to the line to

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1164-481: A much longer-ranged system based on the same principles, using much lower frequencies that allowed coverage across the Atlantic Ocean . The result was LORAN , for "LOng-range Aid to Navigation". The downside to the long-wavelength approach was that accuracy was greatly reduced compared to the high-frequency Gee. LORAN was widely used during convoy operations in the late war period. Another British system from

1261-411: A short pulse of a powerful radio signal, which is sent into space through broadcast antennas. When the signal reflects off a target, some of that signal is reflected back in the direction of the station, where it is received. The received signal is a tiny fraction of the broadcast power, and has to be powerfully amplified in order to be used. The same signals are also sent over local electrical wiring to

1358-541: A sub-scale prototype for the larger 24-ft tunnel, but subsequently modified for use as a noise measurement facility. Both Q121 and R133 are now Grade I listed buildings . To the west of the Farnborough site is the 5-metre pressurised low-speed wind tunnel, which was commissioned in the late 1970s. This facility remains in operation by QinetiQ , primarily for the development and testing of aircraft high lift systems. The hero of Nevil Shute 's 1948 novel No Highway

1455-479: A target. These systems used some form of directional radio antenna to determine the location of a broadcast station on the ground. Conventional navigation techniques are then used to take a radio fix . These were introduced prior to World War I, and remain in use today. The first system of radio navigation was the Radio Direction Finder , or RDF. By tuning in a radio station and then using

1552-428: A time. This was addressed in the later Gee-H system by placing the transponder on the ground and broadcaster in the aircraft. The signals were then examined on existing Gee display units in the aircraft (see below). Gee-H did not offer the accuracy of Oboe, but could be used by as many as 90 aircraft at once. This basic concept has formed the basis of most distance measuring navigation systems to this day. The key to

1649-401: A transponder, or "beacon" in this role, with high accuracy. The British put this concept to use in their Rebecca/Eureka system, where battery-powered "Eureka" transponders were triggered by airborne "Rebecca" radios and then displayed on ASV Mk. II radar sets. Eureka's were provided to French resistance fighters, who used them to call in supply drops with high accuracy. The US quickly adopted

1746-569: Is (as of 2011) occupied by: The National Aerospace Library (NAL), located in the former Weapon Aerodynamics building (Q134 Building), has a collection of over 2,500 technical reports produced by the RAE. The historic Farnborough factory site houses three major wind tunnels , the 24 ft (7.3 m) low-speed wind tunnel (Q121 Building), constructed during the early 1930s, the No. 2 11 ft 6 in (3.51 m) low-speed wind tunnel (R136 Building) and

1843-454: Is 190–1750 kHz, but the same system can be used with any common AM-band commercial station. VHF omnidirectional range , or VOR, is an implementation of the reverse-RDF system, but one that is more accurate and able to be completely automated. The VOR station transmits two audio signals on a VHF carrier – one is Morse code at 1020 Hz to identify the station, the other is a continuous 9960 Hz audio modulated at 30 Hz, with

1940-449: Is almost always used in conjunction with VOR, and is normally co-located at a VOR station. This combination allows a single VOR/DME station to provide both angle and distance, and thereby provide a single-station fix. DME is also used as the distance-measuring basis for the military TACAN system, and their DME signals can be used by civilian receivers. Hyperbolic navigation systems are a modified form of transponder systems which eliminate

2037-536: Is an eccentric " boffin " at Farnborough who predicts metal fatigue in the United Kingdom's new airliner, the fictional "Rutland Reindeer". The Comets failed for just this reason in 1954, although in the case of the Comet I the problem was in the metal structure around the navigation windows, while the point of failure in the Reindeer aircraft was in the structure of the rear empennage/fuselage joints. A film version of

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2134-524: Is based on the same principles (see below). A great advance in the RDF technique was introduced in the form of phase comparisons of a signal as measured on two or more small antennas, or a single highly directional solenoid . These receivers were smaller, more accurate, and simpler to operate. Combined with the introduction of the transistor and integrated circuit , RDF systems were so reduced in size and complexity that they once again became quite common during

2231-440: Is sent. Amplified signals from the receiver are then sent to the Y input, where any received reflection causes the beam to move upward on the display. This causes a series of "blips" to appear along the horizontal axis, indicating reflected signals. By measuring the distance from the start of the sweep to the blip, which corresponds to the time between broadcast and reception, the distance to the object can be determined. Soon after

2328-565: The Austin Motor Company in 1918 and who went on to found the Redwing Aircraft Co in 1930 and Henry Folland – later chief designer at Gloster Aircraft Company , and founder of his own company Folland Aircraft . One of the designers in the engine department was Samuel Heron , who later went on to invent the sodium-filled poppet valve , instrumental in achieving greater power levels from piston engines. While at

2425-411: The F.E.2 (1914) . This last aircraft was the one that went into production and had three main variants, the F.E.2a, F.E.2b, and the F.E.2d. As if this wasn't enough, there is the F.E.2c; this was a generic description rather than a subtype proper, and refers to several one-off conversions of F.E.2b's that experimentally reversed the seating positions of the pilot and the observer. The B.E.1 was basically

2522-481: The morse code signal for the letter "V" (dot-dot-dot-dash), before returning again to a continuous signal. At two points during the antenna's rotation, it would be perpendicular to the receiver. During these instants, the audible signal would disappear, an event known as a "null". Navigation using the Orfordness Beacon was quite simple. Navigators simply tuned in the station on their radios and waited for

2619-479: The "A" or "N" tone would become louder and the pilot knew to make a correction. The beams were typically aligned with other stations to produce a set of airways , allowing an aircraft to travel from airport to airport by following a selected set of stations. Effective course accuracy was about three degrees, which near the station provided sufficient safety margins for instrument approaches down to low minimums. At its peak deployment, there were over 400 LFR stations in

2716-498: The 0-degree referenced to magnetic north. This signal is rotated mechanically or electrically at 30 Hz, which appears as a 30 Hz AM signal added to the previous two signals, the phasing of which is dependent on the position of the aircraft relative to the VOR station. The VOR signal is a single RF carrier that is demodulated into a composite audio signal composed of a 9960 Hz reference signal frequency modulated at 30 Hz,

2813-540: The 1930s provided a way to directly determine the distance to an object even at long distances. Navigation systems based on these concepts soon appeared, and remained in widespread use until recently. Today they are used primarily for aviation, although GPS has largely supplanted this role. Early radar systems, like the UK's Chain Home , consisted of large transmitters and separate receivers. The transmitter periodically sends out

2910-572: The 1960s, and were known by the new name, automatic direction finder , or ADF. This also led to a revival in the operation of simple radio beacons for use with these RDF systems, now referred to as non-directional beacons (NDB). As the LF/MF signals used by NDBs can follow the curvature of earth, NDB has a much greater range than VOR which travels only in line of sight . NDB can be categorized as long range or short range depending on their power. The frequency band allotted to non-directional beacons

3007-493: The 8 ft × 6 ft (2.4 m × 1.8 m) transonic wind tunnel within R133 Building, which was originally commissioned in the early 1940s as a 10 ft × 7 ft (3.0 m × 2.1 m) high subsonic speed tunnel but converted during the mid-1950s. A smaller 2 ft × 1.5 ft (0.61 m × 0.46 m) transonic tunnel is housed in R133 Building, while R52 Building contains

Orfordness Beacon - Misplaced Pages Continue

3104-427: The 9960 Hz and 30 Hz signals are filtered out of the aircraft internal communication system, leaving only the 1020 Hz Morse-code station identification. The system may be used with a compatible glideslope and marker beacon receiver, making the aircraft ILS-capable (Instrument Landing System)}. Once the aircraft's approach is accurate (the aircraft is in the "right place"), the VOR receiver will be used on

3201-521: The B.E.12 and B.E.12a were indisputable failures. Some of this criticism was prejudiced and ill-informed. Some aviation historians continue to perpetuate the resulting belittling of the important experimental work of the Factory during this period, and the exaggeration of the failings of Factory production types, several of which were described in sensationally derogatory terms. A modern, rather more "pro-factory" point of view, can be found in several of

3298-804: The RAE was renamed the Royal Aerospace Establishment. On 1 April 1991 the RAE was merged into the Defence Research Agency (DRA), the MOD 's new research organisation. Then, on 1 April 1995 the DRA and other MOD organisations merged to form the Defence Evaluation and Research Agency (DERA). The Bedford site was largely shut down in 1994. In 2001 DERA was part-privatised by the MOD, resulting in two separate organisations,

3395-755: The RAF, Heron designed a radial engine that he was not able to build during his time there, however upon leaving the RAF he then went to Siddeley-Deasy where the design, the RAF.8, was developed as the Jaguar . Heron later moved to the United States where he worked on the design of the Wright Whirlwind . Other engineers included Major F.M. Green , G.S. Wilkinson, James E. "Jimmy" Ellor, Prof. A.H. Gibson, and A.A. Griffith . Both Ellor and Griffith would later go on to work for Rolls-Royce Limited . In 1918

3492-479: The Royal Aircraft Factory produced a number of aircraft designs. Most of these were essentially research aircraft, but a few actually went into mass production, especially during the war period. Some orders were met by the factory itself, but the bulk of production was by private British companies, some of which had not previously built aircraft. Up to about 1913 the designation letters referred to

3589-712: The Royal Aircraft Factory was once more renamed, becoming the Royal Aircraft Establishment (RAE) to avoid confusion with the Royal Air Force , which was formed on 1 April 1918, and because it had relinquished its manufacturing role to concentrate on research. During WWII the Marine Aircraft Experimental Establishment , which had moved from Felixstowe to a safer location at Helensburgh in Scotland,

3686-502: The US. The remaining widely used beam systems are glide path and the localizer of the instrument landing system (ILS). ILS uses a localizer to provide horizontal position and glide path to provide vertical positioning. ILS can provide enough accuracy and redundancy to allow automated landings. For more information see also: Positions can be determined with any two measures of angle or distance. The introduction of radar in

3783-483: The V signal to be broadcast. They noted the time of the V and counted off the seconds until they heard the null. This could be easily accomplished with the use of a stopwatch . The time in seconds between the ending of the V and hearing the null was then multiplied by 6 to produce the angle from the station to the receiver. This led to the possibility of the user being confused as to which null they were located on, as there are two, located 180 degrees apart (either side of

3880-566: The aegis of the UK Ministry of Defence (MoD), before finally losing its identity in mergers with other institutions. The British Army Balloon Factory was established on Farnborough Common in the early 1900s. By 1912 it had come under civilian control and was the Royal Aircraft Factory ( RAF ) In 1918 it was renamed Royal Aircraft Establishment to prevent confusion with the newly created Royal Air Force. The first site

3977-409: The antenna). In practice this is a relatively minor concern, as traditional navigation methods are normally able to resolve this discrepancy – only one of the angles makes sense at a given time. In order to help resolve even this minor problem, the system also broadcast the letter "B" (dash-dot-dot-dot) as it passed east, helping the listener to identify the lobes. This also served the purpose of allowing

Orfordness Beacon - Misplaced Pages Continue

4074-435: The beacon. This technique, known as radio direction finding (RDF), is useful but only moderately accurate. Measurements better than a few degrees are difficult with a small antenna, and because of the electrical characteristics, it is not always easy to make a larger version that might provide more accuracy. Moreover, the addition of a loop antenna may be difficult on smaller vehicles, or difficult to operate for those without

4171-530: The beam systems before it, civilian use of LORAN-C was short-lived when GPS technology drove it from the market. Similar hyperbolic systems included the US global-wide VLF / Omega Navigation System , and the similar Alpha deployed by the USSR. These systems determined pulse timing not by comparison of two signals, but by comparison of a single signal with a local atomic clock . The expensive-to-maintain Omega system

4268-460: The beams, and were thus less flexible in use. The rapid miniaturization of electronics during and after World War II made systems like VOR practical, and most beam systems rapidly disappeared. In the post-World War I era, the Lorenz company of Germany developed a means of projecting two narrow radio signals with a slight overlap in the center. By broadcasting different audio signals in the two beams,

4365-511: The bomber crew over voice channels, and indicated when to drop the bombs. The British introduced similar systems, notably the Oboe system. This used two stations in England that operated on different frequencies and allowed the aircraft to be triangulated in space. To ease pilot workload only one of these was used for navigation – prior to the mission a circle was drawn over the target from one of

4462-411: The circuitry for driving this display was quite small, Decca systems normally used three such displays, allowing quick and accurate reading of multiple fixes. Decca found its greatest use post-war on ships, and remained in use into the 1990s. Almost immediately after the introduction of LORAN, in 1952 work started on a greatly improved version. LORAN-C (the original retroactively became LORAN-A) combined

4559-542: The command of Colonel James Templer , relocated from Aldershot to the edge of Farnborough Common in order to have enough space to inflate the new "dirigible balloon" or airship which was then under construction. Templer's place was taken by Colonel John Capper and Templer himself retired in 1908. Besides balloons and airships, the factory also experimented with Samuel Franklin Cody 's war kites and aeroplanes designed both by Cody and J. W. Dunne . In October 1908 Cody made

4656-549: The days as the Army Balloon Factory. These include the airships as well as the Cody and Dunne designs. Subsequent Royal Aircraft Factory type designations are inconsistent and confusing. For instance the " F.E.2 " designation refers to three quite distinct types, with only the same broad layout in common, the F.E.2 (1911), the F.E.2 (1913), and finally the famous wartime two-seat fighter and general-purpose design,

4753-518: The development of missiles. Research included wind tunnel testing and other aeronautical research, areas which offered rare opportunities for women in STEM fields at this time with examples including Frances Bradfield who worked at the RAE for her entire career from 1919 to her retirement; Muriel Glauert (née Barker) joined in 1918 as a researcher working in aerodynamics and Beatrice Shilling who went on to invent Miss Shilling's orifice , to improve

4850-479: The engine performance of RAF Hurricane and Spitfire fighters during the Battle of Britain as part of wider work at the RAE on aircraft engine problems during World War II . Johanna Weber , a German mathematician who joined the RAE after World War II as part of Operation Surgeon to employ German aeronautical researchers and technicians and bring them to the UK, to prevent their technical knowledge falling into

4947-651: The fan-like beams of the Lorenz signal, for instance. As the distance between the broadcaster and receiver grows, the area covered by the fan increases, decreasing the accuracy of location within it. In comparison, transponder-based systems measure the timing between two signals, and the accuracy of that measure is largely a function of the equipment and nothing else. This allows these systems to remain accurate over very long range. The latest transponder systems (mode S) can also provide position information, possibly derived from GNSS , allowing for even more precise positioning of targets. The first distance-based navigation system

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5044-530: The first aeroplane flight in the United Kingdom at Farnborough. In 1909 Army work on aeroplanes ceased and the Factory was brought under civilian control. Capper was replaced as Superintendent by Mervyn O'Gorman . In 1912 the Balloon Factory was renamed the Royal Aircraft Factory (RAF). Its first new designer was Geoffrey de Havilland who later founded his own company. Later colleagues included John Kenworthy who became chief engineer and designer at

5141-432: The front line to direct the aircraft to points in front of them, directing fire on the enemy. Beacons were widely used for temporary or mobile navigation as well, as the transponder systems were generally small and low-powered, able to be man portable or mounted on a Jeep . In the post-war era, a general navigation system using transponder-based systems was deployed as the distance measuring equipment (DME) system. DME

5238-427: The general layout of the aircraft, derived from a French manufacturer or designer famous for that type: From 1913/4 onwards this was changed to a designation based on the role for which the aircraft was designed: The B.S.1 of 1913 was a one-off anomaly, combining both systems: B lériot (tractor) S cout (fighter). R.T. & T.E. were also used for strictly one-off prototypes. Several aircraft were produced during

5335-718: The hands of the Soviet occupying forces in Germany. In 1930 the RAE developed the Robot Air Pilot, an autopilot that used a gyro and flight controls that functioned by compressed air. Aircraft that were developed or tested at the RAE included the Hawker Siddeley Harrier and Concorde . In the late fifties and through the sixties work proceeded at the RAE on several rocket projects – all of which were eventually abandoned The former RAE Farnborough site

5432-429: The installation more difficult. During the era between World War I and World War II , a number of systems were introduced that placed the rotating antenna on the ground. As the antenna rotated through a fixed position, typically due north, the antenna was keyed with the morse code signal of the station's identification letters so the receiver could ensure they were listening to the right station. Then they waited for

5529-408: The introduction of radar, the radio transponder appeared. Transponders are a combination of receiver and transmitter whose operation is automated – upon reception of a particular signal, normally a pulse on a particular frequency, the transponder sends out a pulse in response, typically delayed by some very short time. Transponders were initially used as the basis for early IFF systems; aircraft with

5626-473: The late 1970s, LORAN-C units were the size of a stereo amplifier and were commonly found on almost all commercial ships as well as some larger aircraft. By the 1980s, this had been further reduced to the size of a conventional radio, and it became common even on pleasure boats and personal aircraft. It was the most popular navigation system in use through the 1980s and 90s, and its popularity led to many older systems being shut down, like Gee and Decca. However, like

5723-421: The line-of-sight to prominent landmarks, like a lighthouse . After taking the two measurements, lines of position are drawn radiating from the landmark along the reverse angle. They will cross at some point, and their intersection determines the location of the navigator. The introduction of portable radio systems in the early 20th century gave rise to the possibility of using radio broadcasters ( beacons ) as

5820-601: The local accuracy needed for blind landings. Radionavigation service (short: RNS ) is – according to Article 1.42 of the International Telecommunication Union's (ITU) Radio Regulations (RR) – defined as A radiodetermination service for the purpose of radionavigation , including obstruction warning.' RAE Farnborough The Royal Aircraft Establishment ( RAE ) was a British research establishment, known by several different names during its history, that eventually came under

5917-438: The navigator to check that the system was operating properly by timing the period between the V and B, and checking that it was the expected 15 seconds. The original Orfordness Beacon was constructed in a small building that looked similar to the lower portion of a Dutch windmill. Painted black, it remains a prominent landmark today. The system went online in July 1929. The Orfordness Beacon did not broadcast continuously, but on

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6014-423: The navigator to determine a line of position on his chart of all the positions at that distance from both stations. More typically, the signal from one station would be received earlier than the other. The difference in timing between the two signals would reveal them to be along a curve of possible locations. By making similar measurements with other stations, additional lines of position can be produced, leading to

6111-421: The need for an airborne transponder. The name refers to the fact that they do not produce a single distance or angle, but instead indicate a location along any number of hyperbolic lines in space. Two such measurements produces a fix. As these systems are almost always used with a specific navigational chart with the hyperbolic lines plotted on it, they generally reveal the receiver's location directly, eliminating

6208-403: The need for manual triangulation. As these charts were digitized, they became the first true location-indication navigational systems, outputting the location of the receiver as latitude and longitude. Hyperbolic systems were introduced during World War II and remained the main long-range advanced navigation systems until GPS replaced them in the 1990s. The first hyperbolic system to be developed

6305-429: The null, the relative bearing of the station can be determined. Loop antennas can be seen on most pre-1950s aircraft and ships. The main problem with RDF is that it required a special antenna on the vehicle, which may not be easy to mount on smaller vehicles or single-crew aircraft. A smaller problem is that the accuracy of the system is based to a degree on the size of the antenna, but larger antennas would likewise make

6402-406: The operator's station, which is equipped with an oscilloscope . Electronics attached to the oscilloscope provides a signal that increases in voltage over a short period of time, a few microseconds. When sent to the X input of the oscilloscope, this causes a horizontal line to be displayed on the scope. This "sweep" is triggered by a signal tapped off the broadcaster, so the sweep begins when the pulse

6499-408: The proper transponder would appear on the display as part of the normal radar operation, but then the signal from the transponder would cause a second blip to appear a short time later. Single blips were enemies, double blips friendly. Transponder-based distance-distance navigation systems have a significant advantage in terms of positional accuracy. Any radio signal spreads out over distance, forming

6596-419: The prototype for the early B.E.2 but the B.E.2c was almost a completely new aeroplane, with very little common with the earlier B.E.2 types apart from engine and fuselage. On the other hand, the B.E.3 to the B.E.7 were all effectively working prototypes for the B.E.8 and were all very similar in design, with progressive minor modifications of the kind that many aircraft undergo during a production run. The B.E.8a

6693-427: The receiver could position themselves very accurately down the centreline by listening to the signal in their headphones. The system was accurate to less than a degree in some forms. Originally known as "Ultrakurzwellen-Landefunkfeuer" (LFF), or simply "Leitstrahl" (guiding beam), little money was available to develop a network of stations. The first widespread radio navigation network, using Low and Medium Frequencies,

6790-436: The receiver within a wide area. Finer accuracy was then provided by measuring the phase difference of the signals, overlaying that second measure on the first. By 1962, high-power LORAN-C was in place in at least 15 countries. LORAN-C was fairly complex to use, requiring a room of equipment to pull out the different signals. However, with the introduction of integrated circuits , this was quickly reduced further and further. By

6887-507: The remaining 4 ft × 3 ft (1.22 m × 0.91 m) low turbulence wind tunnel. R52 Building had previously housed two early 10 ft x 7 ft low-speed tunnels in separate bays, which were replaced by the No. 1 11.5' and 4ft x 3ft tunnels respectively. The former remains in operation at the University of Southampton. R52 building also previously contained a 5 ft (1.5 m) open jet low-speed tunnel, originally built as

6984-408: The same era was Decca Navigator. This differed from Gee primarily in that the signals were not pulses delayed in time, but continuous signals delayed in phase. By comparing the phase of the two signals, the time difference information as Gee was returned. However, this was far easier to display; the system could output the phase angle to a pointer on a dial removing any need for visual interpretation. As

7081-588: The signal to either peak or disappear as the antenna briefly pointed in their direction. By timing the delay between the morse signal and the peak/null, then dividing by the known rotational rate of the station, the bearing of the station could be calculated. The first such system was the German Telefunken Kompass Sender , which began operations in 1907 and was used operationally by the Zeppelin fleet until 1918. An improved version

7178-472: The sky, and navigation is accomplished by keeping the aircraft centred in the beam. A number of stations are used to create an airway , with the navigator tuning in different stations along the direction of travel. These systems were common in the era when electronics were large and expensive, as they placed minimum requirements on the receivers – they were simply voice radio sets tuned to the selected frequencies. However, they did not provide navigation outside of

7275-431: The state-owned Defence Science and Technology Laboratory (DSTL), and the privatised company QinetiQ . The unit used various aircraft such as : Hawker Hunter, English Electric Canberra B.6 WK163 & B.6 WH953, BAC One-Eleven Series 402 XX919, Hawker Siddeley HS.125 XW930, and Douglas Dakota ZA947 . During February 1988 the last Westland Wessex left after 30 years of trials work. Between 1911 and 1918

7372-459: The stations, and the aircraft was directed to fly along this circle on instructions from the ground operator. The second station was used, as in Y-Gerät, to time the bomb drop. Unlike Y-Gerät, Oboe was deliberately built to offer very high accuracy, as good as 35 m, much better than even the best optical bombsights . One problem with Oboe was that it allowed only one aircraft to be guided at

7469-519: The system for paratroop operations, dropping the Eureka with pathfinder forces or partisans, and then homing in on those signals to mark the drop zones. The beacon system was widely used in the post-war era for blind bombing systems. Of particular note were systems used by the US Marines that allowed the signal to be delayed in such a way to offset the drop point. These systems allowed the troops at

7566-408: The system was generically known simply as a "Lorenz beam". Lorenz was an early predecessor to the modern Instrument Landing System . In the immediate pre-World War II era the same concept was also developed as a blind-bombing system. This used very large antennas to provide the required accuracy at long distances (over England), and very powerful transmitters. Two such beams were used, crossing over

7663-559: The target to triangulate it. Bombers would enter one of the beams and use it for guidance until they heard the second one in a second radio receiver, using that signal to time the dropping of their bombs. The system was highly accurate, and the ' Battle of the Beams ' broke out when United Kingdom intelligence services attempted, and then succeeded, in rendering the system useless through electronic warfare . The low-frequency radio range (LFR, also "Four Course Radio Range" among other names)

7760-478: The techniques of pulse timing in Gee with the phase comparison of Decca. The resulting system (operating in the low frequency (LF) radio spectrum from 90 to 110 kHz) that was both long-ranged (for 60 kW stations, up to 3400 miles) and accurate. To do this, LORAN-C sent a pulsed signal, but modulated the pulses with an AM signal within it. Gross positioning was determined using the same methods as Gee, locating

7857-553: The time as measured by the satellite's onboard atomic clock . By measuring signal times of arrival (TOAs) from at least four satellites, the user's receiver can re-build an accurate clock signal of its own and allows hyperbolic navigation to be carried out. Satellite navigation systems offer better accuracy than any land-based system, are available at almost all locations on the Earth, can be implemented (receiver-side) at modest cost and complexity, with modern electronics, and require only

7954-412: The transponder concept is that it can be used with existing radar systems. The ASV radar introduced by RAF Coastal Command was designed to track down submarines and ships by displaying the signal from two antennas side by side and allowing the operator to compare their relative strength. Adding a ground-based transponder immediately turned the same display into a system able to guide the aircraft towards

8051-559: The volumes of War Planes of the First World War , by J.M. Bruce—MacDonald, London, 1965. The Superintendents of the School of Ballooning were James Templer (1878–1906) and John Capper (1906 – 1909). The following have served as Superintendents of the Royal Aircraft Factory / Establishment: After the end of the First World War, the design and development of aircraft types ended – although work continued on general research and

8148-561: The wreck, in some cases, not even the engine. At the time of the " Fokker Scourge " in 1915, there was a press campaign against the standardisation of Royal Aircraft Factory types in the Royal Flying Corps , allegedly in favour of superior designs available from the design departments of private British firms. This slowly gained currency, especially because of the undeniable fact that the B.E.2c and B.E.2e were kept in production and in service long after they were obsolete and that

8245-475: Was "keyed" with the Morse code signal "A", dit-dah, and the second pattern "N", dah-dit. This created two opposed "A" quadrants and two opposed "N" quadrants around the station. The borders between these quadrants created four course legs or "beams" and if the pilot flew down these lines, the "A" and "N" signal merged into a steady "on course" tone and the pilot was "on the beam". If the pilot deviated to either side

8342-614: Was at Farnborough Airfield ("RAE Farnborough") in Hampshire to which was added a second site RAE Bedford ( Bedfordshire ) in 1946. On 1 May 1988 it was renamed the Royal Aerospace Establishment ( RAE ) before merging with other research entities to become part of the new Defence Research Agency in 1991. In 1904–1906 the Army Balloon Factory, which was part of the Army School of Ballooning , under

8439-447: Was at least as different from the B.E.8 as the B.E.7 was. The S.E.4a had nothing in common at all with the S.E.4, while the S.E.5a was simply a late production S.E.5 with a more powerful engine. Several early RAF designs were officially "reconstructions" of existing aircraft because the Factory did not initially have official authority to build aircraft to their own design. In most cases, the type in question used no parts whatever from

8536-789: Was first used only experimentally, for short periods on weekdays. A report compiled for the Merchant Marine demonstrated an effective range of about 100 miles, day or night. During the day, a minimum accuracy of 2 degrees measured, and 1 degree was common. However, at night the system degraded considerably, with measurement errors as great as 20 degrees. 52°05′01.08″N 01°34′02.46″E  /  52.0836333°N 1.5673500°E  / 52.0836333; 1.5673500 Radio navigation The basic principles are measurements from/to electric beacons , especially Combinations of these measurement principles also are important—e.g., many radars measure range and azimuth of

8633-444: Was identical to Gee-H in concept, but used new electronics to automatically measure the time delay and display it as a number, rather than having the operator time the signals manually on an oscilloscope. This led to the possibility that DME interrogation pulses from different aircraft might be confused, but this was solved by having each aircraft send out a different series of pulses which the ground-based transponder repeated back. DME

8730-532: Was instead led by the US (see LFF, below). Development was restarted in Germany in the 1930s as a short-range system deployed at airports as a blind landing aid. Although there was some interest in deploying a medium-range system like the US LFF, deployment had not yet started when the beam system was combined with the Orfordness timing concepts to produce the highly accurate Sonne system. In all of these roles,

8827-446: Was introduced by the UK as the Orfordness Beacon in 1929 and used until the mid-1930s. A number of improved versions followed, replacing the mechanical motion of the antennas with phasing techniques that produced the same output pattern with no moving parts. One of the longest lasting examples was Sonne , which went into operation just before World War II and was used operationally under the name Consol until 1991. The modern VOR system

8924-424: Was set up to provide wider area coverage and allow two-bearing fixes between Orford Ness and Farnborough Airport . The system was similar to the earlier German Telefunken Kompass Sender and the later Sonne system. In navigation, the determination of a " fix " requires two measurements to be taken. Using classical triangulation techniques, this was normally the measurement of two angles, or bearings , along

9021-444: Was shut down in 1997 as the US military migrated to using GPS . Alpha is still in use. Since the 1960s, navigation has increasingly moved to satellite navigation systems . These are essentially hyperbolic systems whose transmitters are in orbits. That the satellites move with respect to the receiver requires that the calculation of the positions of the satellites must be taken into account, which can only be handled effectively with

9118-519: Was the British Gee system, developed during World War II . Gee used a series of transmitters sending out precisely timed signals, with the signals leaving the stations at fixed delays. An aircraft using Gee, RAF Bomber Command 's heavy bombers , examined the time of arrival on an oscilloscope at the navigator's station. If the signal from two stations arrived at the same time, the aircraft must be an equal distance from both transmitters, allowing

9215-476: Was the German Y-Gerät blind-bombing system. This used a Lorenz beam for horizontal positioning, and a transponder for ranging. A ground-based system periodically sent out pulses which the airborne transponder returned. By measuring the total round-trip time on a radar's oscilloscope, the aircraft's range could be accurately determined even at very long ranges. An operator then relayed this information to

9312-440: Was the main navigation system used by aircraft for instrument flying in the 1930s and 1940s in the U.S. and other countries, until the advent of the VOR in the late 1940s. It was used for both en route navigation as well as instrument approaches . The ground stations consisted of a set of four antennas that projected two overlapping directional figure-eight signal patterns at a 90-degree angle to each other. One of these patterns

9409-459: Was under the control of the RAE. In 1946 work began to convert RAF Thurleigh into RAE Bedford. Engineers at the Royal Aircraft Establishment invented high strength carbon fibre in 1963. In 1961, the world's first grooved runway for reduced aquaplaning was constructed. In 1965, a US delegation visited to view the new surfacing practice and initiated a study by the FAA and NASA . On 1 May 1988

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