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Gee (navigation)
Gee, sometimes written GEE, was a radio-navigation system used by the Royal Air Force during World War II. It measured the time delay between two radio signals to produce a Fix (position), fix, with accuracy on the order of a few hundred metres at ranges up to about . It was the first hyperbolic navigation system to be used operationally, entering service with RAF Bomber Command in 1942. Gee was devised by Robert Dippy as a short-range Instrument approach, blind-landing system to improve safety during night operations. In the course of development by the Telecommunications Research Establishment (TRE) at Swanage, the range was found to be far better than expected. It then developed into a long-range, general navigation system. For large, fixed targets, such as cities that were attacked at night, Gee offered enough accuracy to be used as an aiming reference without the need to use a bombsight or other external references. Radar jamming and deception, Jamming reduced its usefulne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
J M Briscoe24 07 200713 05 14IMG2104 GEE AIRBORNE
J, or j, is the tenth Letter (alphabet), letter of the Latin alphabet, used in the English alphabet, modern English alphabet, the alphabets of other western European languages and others worldwide. Its usual name in English is English alphabet#Letter names, ''jay'' (pronounced ), with a now-uncommon variant ''jy'' ."J", ''Oxford English Dictionary,'' 2nd edition (1989) When used in the International Phonetic Alphabet for the palatal approximant, voiced palatal approximant (the sound of "y" in "yes") it may be called ''yod'' or ''jod'' (pronounced or ). History The letter ''J'' used to be used as the swash (typography), swash letter ''I'', used for the letter I at the end of Roman numerals when following another I, as in XXIIJ or xxiij instead of XXIII or xxiii for the Roman numeral twenty-three. A distinctive usage emerged in Middle High German. Gian Giorgio Trissino (1478–1550) was the first to explicitly distinguish I and J as representing separate sounds, in his ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radar
Radar is a system that uses radio waves to determine the distance ('' ranging''), direction ( azimuth and elevation angles), and radial velocity of objects relative to the site. It is a radiodetermination method used to detect and track aircraft, ships, spacecraft, guided missiles, motor vehicles, map weather formations, and terrain. The term ''RADAR'' was coined in 1940 by the United States Navy as an acronym for "radio detection and ranging". The term ''radar'' has since entered English and other languages as an anacronym, a common noun, losing all capitalization. A radar system consists of a transmitter producing electromagnetic waves in the radio or microwave domain, a transmitting antenna, a receiving antenna (often the same antenna is used for transmitting and receiving) and a receiver and processor to determine properties of the objects. Radio waves (pulsed or continuous) from the transmitter reflect off the objects and return to the receiver, giving ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dead Reckoning
In navigation, dead reckoning is the process of calculating the current position of a moving object by using a previously determined position, or fix, and incorporating estimates of speed, heading (or direction or course), and elapsed time. The corresponding term in biology, to describe the processes by which animals update their estimates of position or heading, is path integration. Advances in navigational aids that give accurate information on position, in particular satellite navigation using the Global Positioning System, have made simple dead reckoning by humans obsolete for most purposes. However, inertial navigation systems, which provide very accurate directional information, use dead reckoning and are very widely applied. Etymology Contrary to myth, the term "dead reckoning" was not originally used to abbreviate "deduced reckoning", nor is it a misspelling of the term "ded reckoning". The use of "ded" or "deduced reckoning" is not known to have appeared earlier th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shortwave
Shortwave radio is radio transmission using radio frequencies in the shortwave bands (SW). There is no official definition of the band range, but it always includes all of the high frequency band (HF), which extends from 3 to 30 MHz (approximately 100 to 10 metres in wavelength). It lies between the medium frequency band (MF) and the bottom of the VHF band. Radio waves in the shortwave band can be reflected or refracted from a layer of electrically charged atoms in the atmosphere called the ionosphere. Therefore, short waves directed at an angle into the sky can be reflected back to Earth at great distances, beyond the horizon. This is called skywave or "skip" propagation. Thus shortwave radio can be used for communication over very long distances, in contrast to radio waves of higher frequency, which travel in straight lines (line-of-sight propagation) and are generally limited by the visual horizon, about 64 km (40 miles). Shortwave broadcasts of radio pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fighter Aircraft
Fighter aircraft (early on also ''pursuit aircraft'') are military aircraft designed primarily for air-to-air combat. In military conflict, the role of fighter aircraft is to establish air supremacy, air superiority of the battlespace. Domination of the airspace above a battlefield permits bombers and attack aircraft to engage in tactical bombing, tactical and strategic bombing of enemy targets, and helps prevent the enemy from doing the same. The key performance features of a fighter include not only its firepower but also its high speed and maneuverability relative to the target aircraft. The success or failure of a combatant's efforts to gain air superiority hinges on several factors including the skill of its pilots, the tactical soundness of its doctrine for deploying its fighters, and the numbers and performance of those fighters. Many modern fighter aircraft also have secondary capabilities such as ground-attack aircraft, ground attack and some types, such as fighter-b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Battle Of The Heligoland Bight (1939)
The Battle of the Heligoland Bight was the first "named" air battle of the Second World War, which began the longest air campaign of the war on 3 September 1939, the Defence of the Reich. After the declaration of war, RAF Bomber Command began operations against Nazi Germany but limited their attacks to those targets that were purely military and had little risk of civilian casualties. This largely limited their efforts to attacks on the ''Kriegsmarine'' (German Navy) warships in German ports to prevent their use in the Battle of the Atlantic. Early operations led the RAF to conclude that fighter aircraft were not a serious threat against modern bombers. They were also marked by a lack of coordination and minor issues like bad weather and communication problems that meant none of these early operations was very intense. The RAF implemented changes to ensure more aircraft could be launched more rapidly to make up for these issues. On 18 December 1939, a force of three squadro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radar Display
A radar display is an electronic device that presents radar data to the operator. The radar system transmits pulses or continuous waves of electromagnetic radiation, a small portion of which backscatter off targets (intended or otherwise) and return to the radar system. The receiver converts all received electromagnetic radiation into a continuous electronic analog signal of varying (or oscillating) voltage that can be converted then to a screen display. Modern systems typically use some sort of raster graphics, raster scan display to produce a map-like image. Early in radar development, however, numerous circumstances made such displays difficult to produce. People developed several different display types. Oscilloscopes Early radar displays used adapted oscilloscopes with various inputs. An oscilloscope generally receives three ''channels'' of varying (or oscillating) voltage as input and displays this information on a cathode ray tube. The oscilloscope amplifies the input vo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Suffolk
Suffolk ( ) is a ceremonial county in the East of England and East Anglia. It is bordered by Norfolk to the north, the North Sea to the east, Essex to the south, and Cambridgeshire to the west. Ipswich is the largest settlement and the county town. The county has an area of and a population of 758,556. After Ipswich (144,957) in the south, the largest towns are Lowestoft (73,800) in the north-east and Bury St Edmunds (40,664) in the west. Suffolk contains five Non-metropolitan district, local government districts, which are part of a two-tier non-metropolitan county administered by Suffolk County Council. The Suffolk coastline, which includes parts of the Suffolk & Essex Coast & Heaths National Landscape, is a complex habitat, formed by London Clay and Crag Group, crag underlain by chalk and therefore susceptible to erosion. It contains several deep Estuary, estuaries, including those of the rivers River Blyth, Suffolk, Blyth, River Deben, Deben, River Orwell, Orwell, River S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RAF Bawdsey
Royal Air Force Bawdsey or more simply RAF Bawdsey is a former Royal Air Force station situated on the eastern coast in Suffolk, England. Also known as Bawdsey Research Station (BRS), the first Chain Home radar station was built there, characterized by eight tall masts, four for transmitting and four for receiving. When the research group moved to Dundee in September 1939, the radar station was left active under the name RAF Bawdsey. The site later hosted a Bristol Bloodhound surface-to-air missile station until 1990, with the station closing in 1991. History Bawdsey Manor, dating from 1886, was taken over in March 1936 by the Air Ministry for developing the Chain Home (CH) RDF (radar) system. The station's Superintendent was initially Robert Watson-Watt, later followed by A.P. Rowe. The experimental radar station was located just northeast of the Manor, about distant. When war was declared in September 1939, fears of a possible commando raid on the group led to the develo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Robert Watson-Watt
Sir Robert Alexander Watson-Watt (13 April 1892 – 5 December 1973) was a Scottish radio engineer and pioneer of radio direction finding and radar technology. Watt began his career in radio physics with a job at the Met Office, where he began looking for accurate ways to track thunderstorms using the radio waves given off by lightning. This led to the 1920s development of a system later known as high-frequency direction finding (HFDF or "huff-duff"). Although well publicized at the time, the system's enormous military potential was not developed until the late 1930s. Huff-duff allowed operators to determine the location of an enemy radio transmitter in seconds and it became a major part of the network of systems that helped defeat the threat of German U-boats during World War II. It is estimated that huff-duff was used in about a quarter of all attacks on U-boats. In 1935, Watt was asked to comment on reports of a German death ray based on radio. Watt and his assistant A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trilateration
Trilateration is the use of distances (or "ranges") for determining the unknown position coordinates of a point of interest, often around Earth ( geopositioning). When more than three distances are involved, it may be called multilateration, for emphasis. The distances or ranges might be ordinary Euclidean distances ( slant ranges) or spherical distances (scaled central angles), as in '' true-range multilateration''; or biased distances ( pseudo-ranges), as in ''pseudo-range multilateration''. Trilateration or multilateration should not be confused with ''triangulation'', which uses angles for positioning; and '' direction finding'', which determines the line of sight direction to a target without determining the radial distance. Terminology Multiple, sometimes overlapping and conflicting terms are employed for similar concepts – e.g., ''multilateration'' without modification has been used for aviation systems employing both true-ranges and pseudo-ranges."Multilateratio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Slant Range
In radio electronics, especially radar terminology, slant range or slant distance is the distance along the relative direction (geometry), relative direction between two points. If the two points are at the same level (coordinate), level (relative to a specific Datum (geodesy), datum), the slant distance equals the horizontal distance. An example of slant range is the distance to an aircraft flying at high altitude with respect to that of the radar antenna (electronics), antenna. The slant range (1) is the hypotenuse of the triangle represented by the altitude of the aircraft and the distance between the radar antenna and the aircraft's Course (navigation), ground track (point (3) on the earth directly below the aircraft). In the absence of altitude information, for example from a height finder, the aircraft location would be plotted further (2) from the antenna than its actual ground track. See also *Ranging *Spherical range *Line-of-sight_propagation References * * Ant ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
