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Plessey AR-3D
The AR-3D was a military air traffic control and early warning radar developed by Plessey and first produced in 1975. It used a pencil beam and simple frequency scanning system known as " squint scan" to produce a low-cost 3D radar system that was also relatively mobile. About 23 were produced in total and found sales around the world into the early 1980s. The frequency scanning system had the disadvantage that a target aircraft would always be "painted" by the same frequency signal, which made the task of jamming the radar simpler. This limited its sales prospects to military users, and shortly after delivering the AR-3D the company began negotiations with the US company ITT-Gillifan to incorporate their multi-frequency scanning with the AR-3D's receivers and display systems to produce the Plessey AR-320. History Squint During the installation of the first high-power microwave frequency radars using slot antennas, operators of the AMES Type 14 noticed that the apparent angle o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plessey
The Plessey Company plc was a British electronics, defence and telecommunications company. It originated in 1917, growing and diversifying into electronics. It expanded after World War II by acquisition of companies and formed overseas companies. It was listed on the London Stock Exchange and was a constituent of the FTSE 100 Index. In 1989, it was taken over by a consortium formed by GEC and Siemens which split the assets of the Plessey group. The majority of Plessey's defence assets were amalgamated into BAE Systems in 1999 when British Aerospace merged with the defence arm of GEC, Marconi Electronic Systems (MES). A small portion of the defence market, mostly embedded electronic systems and circuitcards remained with GE, formerly GE Fanuc and GE Intelligent Platforms (GE-IP) and now Abaco Systems based in Huntsville, Alabama, and in Towcester, Northamptonshire. The bulk of Plessey's telecommunications assets were acquired by Ericsson through its 2005 acquisition of Marconi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pulse Compression
Pulse compression is a signal processing technique commonly used by radar, sonar and echography to increase the range resolution as well as the signal to noise ratio. This is achieved by modulating the transmitted pulse and then correlating the received signal with the transmitted pulse. Simple pulse Signal description The simplest signal a pulse radar can transmit is a sinusoidal-amplitude pulse, A and carrier frequency, f_0, truncated by a rectangular function of width, T. The pulse is transmitted periodically, but that is not the main topic of this article; we will consider only a single pulse, s. If we assume the pulse to start at time t=0, the signal can be written the following way, using the complex notation: :s(t) = \begin A e^ &\text \; 0 \leq t where it reaches its maximum 1, and it decreases linearly on ,\frac{1}{2}/math> until it reaches 0 again. Figures at the end of this paragraph show the shape of the intercorrelation for a sample signal (in red), ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intermediate Frequency
In communications and electronic engineering, an intermediate frequency (IF) is a frequency to which a carrier wave is shifted as an intermediate step in transmission or reception. The intermediate frequency is created by mixing the carrier signal with a local oscillator signal in a process called heterodyning, resulting in a signal at the difference or beat frequency. Intermediate frequencies are used in superheterodyne radio receivers, in which an incoming signal is shifted to an IF for amplification before final detection is done. Conversion to an intermediate frequency is useful for several reasons. When several stages of filters are used, they can all be set to a fixed frequency, which makes them easier to build and to tune. Lower frequency transistors generally have higher gains so fewer stages are required. It's easier to make sharply selective filters at lower fixed frequencies. There may be several such stages of intermediate frequency in a superheterodyne receiver; t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Klystron
A klystron is a specialized linear-beam vacuum tube, invented in 1937 by American electrical engineers Russell and Sigurd Varian,Pond, Norman H. "The Tube Guys". Russ Cochran, 2008 p.31-40 which is used as an amplifier for high radio frequencies, from UHF up into the microwave range. Low-power klystrons are used as oscillators in terrestrial microwave relay communications links, while high-power klystrons are used as output tubes in UHF television transmitters, satellite communication, radar transmitters, and to generate the drive power for modern particle accelerators. In a klystron, an electron beam interacts with radio waves as it passes through resonant cavities, metal boxes along the length of a tube. The electron beam first passes through a cavity to which the input signal is applied. The energy of the electron beam amplifies the signal, and the amplified signal is taken from a cavity at the other end of the tube. The output signal can be coupled back into the input cavi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Travelling Wave Tube
A traveling-wave tube (TWT, pronounced "twit") or traveling-wave tube amplifier (TWTA, pronounced "tweeta") is a specialized vacuum tube that is used in electronics to amplify radio frequency (RF) signals in the microwave range. The TWT belongs to a category of "linear beam" tubes, such as the klystron, in which the radio wave is amplified by absorbing power from a beam of electrons as it passes down the tube. Although there are various types of TWT, two major categories are: *''Helix TWT'' - in which the radio waves interact with the electron beam while traveling down a wire helix which surrounds the beam. These have wide bandwidth, but output power is limited to a few hundred watts. *''Coupled cavity TWT'' - in which the radio wave interacts with the beam in a series of cavity resonators through which the beam passes. These function as narrowband power amplifiers. A major advantage of the TWT over some other microwave tubes is its ability to amplify a wide range of frequencie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prime Mover (tractor Unit)
A tractor unit (also known as a truck unit, power unit, prime mover, ten-wheeler, semi-tractor, tractor truck, semi-truck, tractor cab, truck cab, tractor rig, truck rig or big rig or simply a tractor, truck, semi or rig) is a characteristically heavy-duty towing engine that provides motive power for hauling a towed or trailered load. These fall into two categories: heavy- and medium-duty military and commercial rear-wheel-drive semi-tractors used for hauling semi-trailers, and very heavy-duty typically off-road-capable, often 6×6, military and commercial tractor units, including ballast tractors. Overview Tractor units typically have large displacement diesel engines for power, durability, and economy; several axles; and a multi-ratio transmission (10, 13, or 18 gears) for maximum flexibility in gearing. The tractor-trailer combination distributes a load across multiple axles while being more maneuverable than an equivalently sized rigid truck. The most common trailer a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Los Angeles
Los Angeles ( ; es, Los Ángeles, link=no , ), often referred to by its initials L.A., is the largest city in the state of California and the second most populous city in the United States after New York City, as well as one of the world's most populous megacities. Los Angeles is the commercial, financial, and cultural center of Southern California. With a population of roughly 3.9 million residents within the city limits , Los Angeles is known for its Mediterranean climate, ethnic and cultural diversity, being the home of the Hollywood film industry, and its sprawling metropolitan area. The city of Los Angeles lies in a basin in Southern California adjacent to the Pacific Ocean in the west and extending through the Santa Monica Mountains and north into the San Fernando Valley, with the city bordering the San Gabriel Valley to it's east. It covers about , and is the county seat of Los Angeles County, which is the most populous county in the United States with an estim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ITT-Gilfillan
ITT-Gilfillan was an American electronics company located in Los Angeles, best known for their radar systems. They changed names several times, and might be referred to as ITT Corporation Electronic Systems Radar Systems - Gilfillan or ITT Industries, Gilfillan Division, depending on the source. They were spun off by ITT in 2011 to form a division of the newly created Exelis Inc. Exelis was in turn purchased in 2015 by Harris Corporation and then merged in 2019 to become part of L3Harris Technologies. History The company traces its history to 1912, when Sennet Gilfillan took over his uncle's smelting company, which processed precious metals such as platinum and iridium. He was joined by his brother Jay to form Gilfillan Brothers in 1914. During World War I they produced platinum points for automobile ignition systems and branched out to aircraft parts. In the 1920s they began making radio receivers and were best known for their Bakelite radios based on the Neutrodyne system. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frequency Agile
Frequency agility is the ability of a radar system to quickly shift its operating frequency to account for atmospheric effects, jamming, mutual interference with friendly sources, or to make it more difficult to locate the radar broadcaster through radio direction finding. The term can also be applied to other fields, including lasers or traditional radio transceivers using frequency-division multiplexing, but it remains most closely associated with the radar field and these other roles generally use the more generic term "frequency hopping". Description Jamming Radar systems generally operate by sending out short pulses of radio energy and then turning off the broadcaster and listening for the returning echoes from various objects. Because efficient signal reception requires careful tuning throughout the electronics in the transceiver, each operating frequency required a dedicated transceiver. Due to the size of the tube-based electronics used to construct the transceivers, early ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Falkland Islands
The Falkland Islands (; es, Islas Malvinas, link=no ) is an archipelago in the South Atlantic Ocean on the Patagonian Shelf. The principal islands are about east of South America's southern Patagonian coast and about from Cape Dubouzet at the northern tip of the Antarctic Peninsula, at a latitude of about 52°S. The archipelago, with an area of , comprises East Falkland, West Falkland, and 776 smaller islands. As a British overseas territory, the Falklands have internal self-governance, but the United Kingdom takes responsibility for their defence and foreign affairs. The capital and largest settlement is Stanley on East Falkland. Controversy exists over the Falklands' discovery and subsequent colonisation by Europeans. At various times, the islands have had French, British, Spanish, and Argentine settlements. Britain reasserted its rule in 1833, but Argentina maintains its claim to the islands. In April 1982, Argentine military forces invaded the islands. British a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RAF Gatow
Royal Air Force Gatow, or more commonly RAF Gatow, was a British Royal Air Force station (military airbase) in the district of Gatow in south-western Berlin, west of the Havel river, in the borough of Spandau. It was the home for the only known operational use of flying boats in central Europe, and was later used for photographic reconnaissance missions by de Havilland Canada DHC-1 Chipmunks over East Germany. Part of the former airfield is now called General Steinhoff-Kaserne, and is home to the Luftwaffenmuseum der Bundeswehr, the German Air Force Museum. Also on the site of the former Royal Air Force station, but not part of ''General Steinhoff-Kaserne'', is a school, the Hans-Carossa-Gymnasium, as well as houses for government employees of the Federal Republic of Germany. This part of the former airfield has since 2003 been part of the district of Berlin-Kladow. History Luftwaffe use, 1934–1945 The airfield was originally constructed in 1934 and 1935 by the Luftwaff ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boeing Chinook (UK Variants)
The Boeing Chinook is a large, tandem rotor helicopter operated by the Royal Air Force (RAF). A series of variants based on the United States Army's Boeing CH-47 Chinook, the RAF Chinook fleet is the largest outside the United States. RAF Chinooks have seen extensive service in the Falklands War, the Balkans, Northern Ireland, Iraq, and Afghanistan. The Chinook, normally based at RAF Odiham in England, provides heavy-lift support and transport across all branches of the British armed forces. The RAF has a total of sixty Chinooks in active inventory as of 2015. In 2018, the UK issued a request to the United States to purchase sixteen additional aircraft. The Chinook is expected to remain in RAF service until the 2040s. Design and development Chinook HC1 In March 1967, the United Kingdom placed an order for fifteen Boeing Vertol CH-47B Chinook to replace the Royal Air Force's Bristol Belvedere HC.1 fleet. In British service the new aircraft was to be designated as the Chinook ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
