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Inverse Monopulse Seeker
An inverse monopulse seeker is a type of semi-active radar homing that offers significant advantages over earlier designs. The system requires electronics that can compare three signals at once, so this design did not become practically possible until the early 1970s. One of the first such examples was the Soviet Union R-40 air-to-air missiles used in MiG-25 The Mikoyan-Gurevich MiG-25 (russian: Микоян и Гуревич МиГ-25; NATO reporting name: Foxbat) is a supersonic interceptor and reconnaissance aircraft that is among the fastest military aircraft to enter service. Designed by th ...P introduced in service in 1970 and RAF's Skyflash missile introduced in 1978, an adaptation of the AIM-7 Sparrow that replaced the original Raytheon seeker with a monopulse model from Marconi Company, Marconi, followed by a very similar conversion by Selenia (company), Selenia for the Italian Aspide. The USAF adopted similar technology in the M model of the AIM-7 Sparrow, and s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Semi-active Radar Homing
Semi-active radar homing (SARH) is a common type of missile guidance system, perhaps the most common type for longer-range Air-to-air missile, air-to-air and surface-to-air missile systems. The name refers to the fact that the missile itself is only a passive radar, passive detector of a radar signal—Radar illumination, provided by an external ("offboard") source—as it reflects off the target (in contrast to active radar homing, which uses an active radar transceiver). Semi-active missile systems use bistatic radar, bistatic continuous-wave radar. The NATO Multiservice tactical brevity code, brevity code for a semi-active radar homing missile launch is Fox (code word), Fox One. Concept The basic concept of SARH is that since almost all detection and tracking systems consist of a radar system, duplicating this hardware on the missile itself is redundant. The weight of a transmitter reduces the range of any flying object, so passive systems have greater reach. In addition, t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Conical Scanning
Conical scanning is a system used in early radar units to improve their accuracy, as well as making it easier to steer the antenna properly to point at a target. Conical scanning is similar in concept to the earlier lobe switching concept used on some of the earliest radars, and many examples of lobe switching sets were modified in the field to conical scanning during World War II, notably the German Würzburg radar. Antenna guidance can be made entirely automatic, as in the American SCR-584. Potential failure modes and susceptibility to deception jamming led to the replacement of conical scan systems with monopulse radar sets. They are still used by the Deep Space Network for maintaining communications links to space probes. The spin-stabilized Pioneer 10 and Pioneer 11 probes used onboard conical scanning maneuvers to track Earth in its orbit. Concept A typical radar antenna commonly has a beam width of a few degrees. While this is adequate for locating the target in an earl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vacuum Tube
A vacuum tube, electron tube, valve (British usage), or tube (North America), is a device that controls electric current flow in a high vacuum between electrodes to which an electric voltage, potential difference has been applied. The type known as a thermionic tube or thermionic valve utilizes thermionic emission of electrons from a hot cathode for fundamental electronic functions such as signal amplifier, amplification and current rectifier, rectification. Non-thermionic types such as a vacuum phototube, however, achieve electron emission through the photoelectric effect, and are used for such purposes as the detection of light intensities. In both types, the electrons are accelerated from the cathode to the anode by the electric field in the tube. The simplest vacuum tube, the diode (i.e. Fleming valve), invented in 1904 by John Ambrose Fleming, contains only a heated electron-emitting cathode and an anode. Electrons can only flow in one direction through the device—fro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electronic Countermeasure
An electronic countermeasure (ECM) is an electrical or electronic device designed to trick or deceive radar, sonar, or other detection systems, like infrared (IR) or lasers. It may be used both offensively and defensively to deny targeting information to an enemy. The system may make many separate targets appear to the enemy, or make the real target appear to disappear or move about randomly. It is used effectively to protect aircraft from guided missiles. Most air forces use ECM to protect their aircraft from attack. It has also been deployed by military ships and recently on some advanced tanks to fool laser/IR guided missiles. It is frequently coupled with stealth advances so that the ECM systems have an easier job. Offensive ECM often takes the form of jamming. Self-protecting (defensive) ECM includes using blip enhancement Blip enhancement is an electronic warfare technique used to fool radar. When the radar transmits a burst of energy some of that energy is reflected off ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polarization (waves)
Polarization (also polarisation) is a property applying to transverse waves that specifies the geometrical orientation of the oscillations. In a transverse wave, the direction of the oscillation is perpendicular to the direction of motion of the wave. A simple example of a polarized transverse wave is vibrations traveling along a taut string ''(see image)''; for example, in a musical instrument like a guitar string. Depending on how the string is plucked, the vibrations can be in a vertical direction, horizontal direction, or at any angle perpendicular to the string. In contrast, in longitudinal waves, such as sound waves in a liquid or gas, the displacement of the particles in the oscillation is always in the direction of propagation, so these waves do not exhibit polarization. Transverse waves that exhibit polarization include electromagnetic waves such as light and radio waves, gravitational waves, and transverse sound waves (shear waves) in solids. An electromagnetic wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monopulse Radar
Monopulse radar is a radar system that uses additional encoding of the radio signal to provide accurate directional information. The name refers to its ability to extract range and direction from a single signal pulse. Monopulse radar avoids problems seen in conical scanning radar systems, which can be confused by rapid changes in signal strength. The system also makes electronic warfare, jamming more difficult. Most radars designed since the 1960s are monopulse systems. The monopulse method is also used in passive systems, such as electronic support measures and radio astronomy. Monopulse radar systems can be constructed with reflector (antenna) , reflector antennas, lens antenna , lens antennas or array antennas. Historically, monopulse systems have been classified as either phase-comparison monopulse or amplitude monopulse. Modern systems determine the direction from the monopulse ratio, which contain both amplitude and phase information. The monopulse method does not requir ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chaff (countermeasure)
Chaff, originally called Window by the British and ''Düppel'' by the Second World War era German Luftwaffe (from the Berlin suburb where it was first developed), is a radar countermeasure in which aircraft or other targets spread a cloud of small, thin pieces of aluminium, metallized glass fibre or plastic, which either appears as a cluster of primary targets on radar screens or swamps the screen with multiple returns, in order to confuse and distract. Modern armed forces use chaff (in naval applications, for instance, using short-range SRBOC rockets) to distract radar-guided missiles from their targets. Most military aircraft and warships have chaff dispensing systems for self-defense. An intercontinental ballistic missile may release in its midcourse phase several independent warheads as well as penetration aids such as decoy balloons and chaff. Modern radar systems can distinguish chaff from target objects by measuring the Doppler shift; chaff quickly loses speed compared ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Range Gate
A range gate is an electronic circuit that selects signals within a given time period; the "gate" allows signals to pass through only within the selected time. The term is mostly used in radar, where range gates are used to select certain targets for further processing. It is also used in lidar, time-of-flight cameras and similar roles. In early military radars, range gates were used to select a single target and then pass on this information to other displays where more information could be seen. An example is the AI Mk. IX radar, where the radar operator would use a ''strobe'', an on-screen cursor, to select a single target. A range gate would then filter out all the other targets that might be visible to the radar. The return within that gate was then automatically tracked without further operator intervention. In weather radar, it is common to have a series of continual range gates that separate out returns at different distances and then process them to extract Doppler shift ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scintillation (radar)
Scintillation is a fluctuation in the amplitude of a target on a radar display. It is closely related to target glint, or wander, an apparent displacement of the target from its mean There are several kinds of mean in mathematics, especially in statistics. Each mean serves to summarize a given group of data, often to better understand the overall value (magnitude and sign) of a given data set. For a data set, the ''arithme ... position. This effect can be caused by a shift of the effective reflection point on the target, but has other causes as well. The fluctuations can be slow (scan-to-scan) or rapid (pulse-to-pulse). It appears especially at seaside level. Scintillation and glint are actually two manifestations of the same phenomenon and are most properly linked to one another in target modeling. References * * Radar {{electronics-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
USAF
The United States Air Force (USAF) is the air service branch of the United States Armed Forces, and is one of the eight uniformed services of the United States. Originally created on 1 August 1907, as a part of the United States Army Signal Corps, the USAF was established as a separate branch of the United States Armed Forces in 1947 with the enactment of the National Security Act of 1947. It is the second youngest branch of the United States Armed Forces and the fourth in order of precedence. The United States Air Force articulates its core missions as air supremacy, global integrated intelligence, surveillance and reconnaissance, rapid global mobility, global strike, and command and control. The United States Air Force is a military service branch organized within the Department of the Air Force, one of the three military departments of the Department of Defense. The Air Force through the Department of the Air Force is headed by the civilian Secretary of the Air For ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Soviet Union
The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen national republics; in practice, both its government and its economy were highly centralized until its final years. It was a one-party state governed by the Communist Party of the Soviet Union, with the city of Moscow serving as its capital as well as that of its largest and most populous republic: the Russian SFSR. Other major cities included Leningrad (Russian SFSR), Kiev (Ukrainian SSR), Minsk ( Byelorussian SSR), Tashkent (Uzbek SSR), Alma-Ata (Kazakh SSR), and Novosibirsk (Russian SFSR). It was the largest country in the world, covering over and spanning eleven time zones. The country's roots lay in the October Revolution of 1917, when the Bolsheviks, under the leadership of Vladimir Lenin, overthrew the Russian Provisional Government ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aspide
Aspide (the Italian name for the asp) is an Italian medium range air-to-air and surface-to-air missile produced by Selenia (then by Alenia Aeronautica, now a part of Leonardo S.p.A.). It is provided with semi-active radar homing seeker. It is very similar to the American AIM-7 Sparrow, using the same airframe, but uses an inverse monopulse seeker that is far more accurate and much less susceptible to ECM than the original conical scanning version. This resemblance, and that Selenia was provided with the technology know-how of the AIM-7 (around 1,000 of which it had produced under licence), has generally led non-Italian press to refer to the Aspide as a Sparrow variant. However, the Aspide had original electronics and warhead, and a new and more powerful engine. Closed-loop hydraulics were also substituted for Sparrow's open-loop type, which gave Aspide better downrange maneuverability. Even the control surfaces are different, replacing the original triangular wings, fixed i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
