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G-H (navigation)
Gee-H, sometimes written G-H or GEE-H, was a radio navigation system developed by Britain during World War II to aid RAF Bomber Command. The name refers to the system's use of the earlier Gee equipment, as well as its use of the "H principle" or "twin-range principle" of location determination. Its official name was AMES Type 100. Gee-H was used to supplant the Oboe bombing system which worked along similar lines. By measuring and keeping a fixed distance to a radio station, the bomber could navigate along an arc in the sky. The bombs were dropped when they reached a set distance from a second station. The main difference between Oboe and Gee-H was the location of the equipment; Oboe used large displays in ground stations to take very accurate measurements but could only direct one aircraft at a time. Gee-H used much smaller systems onboard aircraft and while somewhat less accurate, could direct as many as 80 aircraft at a time. Gee-H entered service in October 1943 and first us ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio Navigation
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. The basic principles are measurements from/to electric beacons, especially * Angular directions, e.g. by bearing, radio phases or interferometry, * Distances, e.g. ranging by measurement of time of flight between one transmitter and multiple receivers or vice versa, * Distance ''differences'' by measurement of times of arrival of signals from one transmitter to multiple receivers or vice versa * Partly also velocity, e.g. by means of radio Doppler shift. Combinations of these measurement principles also are important—e.g., many radars measure range and azimuth of a target. Bearing-measurement systems These systems used some form of directional radio antenna to determine the location of a broadcast station on the ground. Conventional navigation techniques a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Knickebein
The Battle of the Beams was a period early in the Second World War when bombers of the German Air Force (''Luftwaffe'') used a number of increasingly accurate systems of radio navigation for night bombing in the United Kingdom. British scientific intelligence at the Air Ministry fought back with a variety of their own increasingly effective means, involving jamming and deception signals. The period ended when the Wehrmacht moved their forces to the East in May 1941, in preparation for the attack on the Soviet Union. The idea of "beam" based navigation was developed during the 1930s, initially as a blind landing aid. The basic concept is to produce two directional radio signals that are aimed slightly to the left and right of a runway's midline. Radio operators in the aircraft listen for these signals and determine which of the two beams they are flying in. This is normally accomplished by sending Morse code signals into the two beams, to identify right and left. For bombing, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Avro Lancaster - Waddington - Aircraft Of The Royal Air Force In The Second World War 1939-1945 MH6448
AVRO, short for Algemene Vereniging Radio Omroep ("General Association of Radio Broadcasting"), was a Dutch public broadcasting association operating within the framework of the Nederlandse Publieke Omroep system. It was the first public broadcaster in the Netherlands. In 2014 AVRO merged with fellow broadcaster TROS to form AVROTROS. History On 8 July 1923, Hilversumsche Draadlooze Omroep was launched by the Nederlandsche Seintoestellen Fabriek (in English: Dutch Transmitter Factory) under supervision of Willem Vogt. On 21 July 1923, it provided the very first regular radio broadcast in the Netherlands. In 1927 it changed its name into Algemeene Nederlandsche Radio Omroep (ANRO), followed soon by a merger with Nederlandsche Omroep Vereeniging (NOV). On 28 December 1927, the two merged broadcasters continued as Algemeene Vereeniging Radio Omroep (A.V.R.O., in English: "General Association of Radio Broadcasting"). In 1938, AVRO sponsored what was the strongest chess tournamen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio Receiver
In radio communications, a radio receiver, also known as a receiver, a wireless, or simply a radio, is an electronic device that receives radio waves and converts the information carried by them to a usable form. It is used with an antenna. The antenna intercepts radio waves (electromagnetic waves of radio frequency) and converts them to tiny alternating currents which are applied to the receiver, and the receiver extracts the desired information. The receiver uses electronic filters to separate the desired radio frequency signal from all the other signals picked up by the antenna, an electronic amplifier to increase the power of the signal for further processing, and finally recovers the desired information through demodulation. Radio receivers are essential components of all systems that use radio. The information produced by the receiver may be in the form of sound, video (television), or digital data. A radio receiver may be a separate piece of electronic equipment, or an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transmitter
In electronics and telecommunications, a radio transmitter or just transmitter is an electronic device which produces radio waves with an antenna (radio), antenna. The transmitter itself generates a radio frequency alternating current, which is applied to the Antenna (radio), antenna. When excited by this alternating current, the antenna radiates radio waves. Transmitters are necessary component parts of all electronic devices that communicate by radio communication, radio, such as radio broadcasting, radio and television broadcasting stations, cell phones, walkie-talkies, Wireless LAN, wireless computer networks, Bluetooth enabled devices, garage door openers, two-way radios in aircraft, ships, spacecraft, radar sets and navigational beacons. The term ''transmitter'' is usually limited to equipment that generates radio waves for Communication engineering, communication purposes; or radiolocation, such as radar and navigational transmitters. Generators of radio waves for heatin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Envelope (waves)
In physics and engineering, the envelope of an oscillating signal is a smooth curve outlining its extremes. The envelope thus generalizes the concept of a constant amplitude into an instantaneous amplitude. The figure illustrates a modulated sine wave varying between an ''upper envelope'' and a ''lower envelope''. The envelope function may be a function of time, space, angle, or indeed of any variable. In beating waves A common situation resulting in an envelope function in both space ''x'' and time ''t'' is the superposition of two waves of almost the same wavelength and frequency: : \begin F(x, \ t) & = \sin \left 2 \pi \left( \frac - ( f + \Delta f )t \right) \right+ \sin \left 2 \pi \left( \frac - ( f - \Delta f )t \right) \right\\ pt& \approx 2\cos \left 2 \pi \left( \frac - \Delta f \ t \right) \right\ \sin \left 2 \pi \left( \frac - f \ t \right) \right\end which uses the trigonometric formula for the addition of two sine waves, and the approximation&nbs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Target Marker
Target indicators, also known as target markers or TI's for short, were flares used by the RAF's Bomber Command during World War II. TIs were normally dropped by Pathfinders onto the target, providing an easily seen visual aiming point for the following "main force" of bombers to aim at. After their introduction, the use of TIs expanded to include en-route markers to gather up lost aircraft, additional TI drops to keep the target lit over long periods, and various changes in technique to address German defences. The use of TIs allowed the RAF to concentrate its advanced navigational systems in the Pathfinder units. Most widely used were the H2S ground scanning radar and Oboe navigation system, the former requiring considerable training to be useful, the latter able to guide only a single aircraft at a time. The limited number of navigational units meant that spreading them through the force would have limited effects. By concentrating these in a single Group (No. 8 Group RAF) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Morse Code
Morse code is a method used in telecommunication to encode text characters as standardized sequences of two different signal durations, called ''dots'' and ''dashes'', or ''dits'' and ''dahs''. Morse code is named after Samuel Morse, one of the inventors of the telegraph. International Morse code encodes the 26 basic Latin letters through , one accented Latin letter (), the Arabic numerals, and a small set of punctuation and procedural signals ( prosigns). There is no distinction between upper and lower case letters. Each Morse code symbol is formed by a sequence of ''dits'' and ''dahs''. The ''dit'' duration is the basic unit of time measurement in Morse code transmission. The duration of a ''dah'' is three times the duration of a ''dit''. Each ''dit'' or ''dah'' within an encoded character is followed by a period of signal absence, called a ''space'', equal to the ''dit'' duration. The letters of a word are separated by a space of duration equal to three ''dits'', ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dead Reckoning
In navigation, dead reckoning is the process of calculating current position of some moving object by using a previously determined position, or fix, and then incorporating estimates of speed, heading direction, and course over elapsed time. The corresponding term in biology, used to describe the processes by which animals update their estimates of position or heading, is path integration. Dead reckoning is subject to cumulative errors. 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 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" ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
De Havilland Mosquito
The de Havilland DH.98 Mosquito is a British twin-engined, shoulder-winged, multirole combat aircraft, introduced during the Second World War. Unusual in that its frame was constructed mostly of wood, it was nicknamed the "Wooden Wonder", or "Mossie". Lord Beaverbrook, Minister of Aircraft Production, nicknamed it "Freeman's Folly", alluding to Air Chief Marshal Sir Wilfrid Freeman, who defended Geoffrey de Havilland and his design concept against orders to scrap the project. In 1941, it was one of the fastest operational aircraft in the world.Bowman 2005, p. 21. Originally conceived as an unarmed fast bomber, the Mosquito's use evolved during the war into many roles, including low- to medium-altitude daytime tactical bomber, high-altitude night bomber, pathfinder, day or night fighter, fighter-bomber, intruder, maritime strike, and photo-reconnaissance aircraft. It was also used by the British Overseas Airways Corporation as a fast transport to carry small, high-value c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Walmer
Walmer is a town in Dover District, the district of Dover, Kent, in England. Located on the coast, the parish of Walmer is south-east of Sandwich, Kent. Largely residential, its coastline and castle attract many visitors. It has a population of 6,693 (2001), increasing to 8,178 at the United Kingdom Census 2011, 2011 Census. Walmer is closely associated with its adjoining neighbour, the town of Deal, Kent, Deal - sharing many amenities and services and benefiting from Deal's High Street shopping area. Walmer railway station is on the Kent Coast Line. History Julius Caesar Julius Caesar Caesar's invasions of Britain, reputedly landed on the beach here in 55 BC and 54 BC. It is only one possible landing place, proposed judging from the distances given in his account of the landings in his Commentarii de Bello Gallico, ''Gallic Wars''. In the 19th century it was thought that he had landed by Deal Castle – hence a house there with SPQR emblazoned on its gate – but in 1907 the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pathfinder Force
The Pathfinders were target-marking squadrons in RAF Bomber Command during World War II. They located and marked targets with flares, which a main bomber force could aim at, increasing the accuracy of their bombing. The Pathfinders were normally the first to receive new blind-bombing aids like Gee, Oboe and the H2S radar. The early Pathfinder Force (PFF) squadrons was expanded to become a group, No. 8 (Pathfinder Force) Group in January 1943. The initial Pathfinder Force was five squadrons, while No. 8 Group ultimately grew to a strength of 19 squadrons. While the majority of Pathfinder squadrons and personnel were from the Royal Air Force, the group also included many from the air forces of other Commonwealth countries. History Background At the start of the war in September 1939, RAF Bomber Command's doctrine was based on tight formations of heavily armed bombers attacking during daylight and fending off attacks by fighters with their defensive guns. In early missions ov ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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