109-413: The ZSU-23-4 " Shilka " is a lightly armored Soviet self-propelled, radar -guided anti-aircraft weapon system ( SPAAG ). It was superseded by the 2K22 Tunguska (SA-19 Grison). The acronym "ZSU" stands for Zenitnaya Samokhodnaya Ustanovka ( Russian : Зенитная Самоходная Установка ), meaning "anti-aircraft self-propelled system"; the "23" signifies the bore diameter in millimetres; the "4" signifies
218-470: A fractal surface, such as rocks or soil, and are used by navigation radars. A radar beam follows a linear path in vacuum but follows a somewhat curved path in atmosphere due to variation in the refractive index of air, which is called the radar horizon . Even when the beam is emitted parallel to the ground, the beam rises above the ground as the curvature of the Earth sinks below the horizon. Furthermore,
327-424: A transmitter that emits radio waves known as radar signals in predetermined directions. When these signals contact an object they are usually reflected or scattered in many directions, although some of them will be absorbed and penetrate into the target. Radar signals are reflected especially well by materials of considerable electrical conductivity —such as most metals, seawater , and wet ground. This makes
436-460: A basic tracking and lead calculating system. The ZSU-57-2 was not particularly successful despite its very powerful autocannons; given their large caliber, it could only carry 300 rounds, was inaccurate as it lacked radar and could not fire while on the move. The ZPU series armed with 14.5 mm heavy machine guns carried on a towed mount for stationary, point air defence had a much higher rate of fire. The 23 mm version of this weapon system
545-445: A deficient cooling system and made the early ZSU-23-4s dangerous even to friendly troops standing nearby if this happened. Despite the fact that this seldom happened, Soviet operators learned to give these machines a wide berth.( Perrett 1987:100 ) It was not recommended to perform continuous fire (bursts longer than 15 seconds without pause) on earlier models until the problem with autocannon reliability and overheating during intense fire
654-482: A different dielectric constant or diamagnetic constant from the first, the waves will reflect or scatter from the boundary between the materials. This means that a solid object in air or in a vacuum , or a significant change in atomic density between the object and what is surrounding it, will usually scatter radar (radio) waves from its surface. This is particularly true for electrically conductive materials such as metal and carbon fibre, making radar well-suited to
763-400: A direct-current generator (which provides 27 V and 54 V direct current or 220 V 400 Hz alternating current). Each water-cooled 23 mm 2A7 autocannon has a cyclic rate of 850–1,000 rounds per minute for a combined rate of fire of 3,400–4,000 rounds per minute, which gives a continuous fire time of 30–35 seconds before running out of ammunition (not considering the constraints that limit
872-540: A full radar system, that he called a telemobiloscope . It operated on a 50 cm wavelength and the pulsed radar signal was created via a spark-gap. His system already used the classic antenna setup of horn antenna with parabolic reflector and was presented to German military officials in practical tests in Cologne and Rotterdam harbour but was rejected. In 1915, Robert Watson-Watt used radio technology to provide advance warning of thunderstorms to airmen and during
981-580: A highly effective combination of mobility with heavy firepower and considerable accuracy. The ZSU-23-4 outclassed all NATO anti-aircraft guns at the time, and it is still regarded as posing a major threat for low-flying fixed-wing aircraft and helicopters. The system was widely fielded throughout the Warsaw Pact and among other pro-Soviet states. Around 2,500 ZSU-23-4s, of the total 6,500 produced, were exported to 23 countries. The Warsaw Pact's successor states continue to manufacture and supply variants of
1090-749: A physics instructor at the Imperial Russian Navy school in Kronstadt , developed an apparatus using a coherer tube for detecting distant lightning strikes. The next year, he added a spark-gap transmitter . In 1897, while testing this equipment for communicating between two ships in the Baltic Sea , he took note of an interference beat caused by the passage of a third vessel. In his report, Popov wrote that this phenomenon might be used for detecting objects, but he did nothing more with this observation. The German inventor Christian Hülsmeyer
1199-498: A proposal for further intensive research on radio-echo signals from moving targets to take place at NRL, where Taylor and Young were based at the time. Similarly, in the UK, L. S. Alder took out a secret provisional patent for Naval radar in 1928. W.A.S. Butement and P. E. Pollard developed a breadboard test unit, operating at 50 cm (600 MHz) and using pulsed modulation which gave successful laboratory results. In January 1931,
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#17327879643691308-732: A pulsed system, and the first such elementary apparatus was demonstrated in December 1934 by the American Robert M. Page , working at the Naval Research Laboratory . The following year, the United States Army successfully tested a primitive surface-to-surface radar to aim coastal battery searchlights at night. This design was followed by a pulsed system demonstrated in May 1935 by Rudolf Kühnhold and
1417-403: A rear drive sprocket with detachable sprocket rings (lantern-wheel gear) and one idler wheel per side. The first and fifth left, and sixth right road wheels have hydraulic shock absorbers. The track is 11.904 m long, 382 mm (15") wide and has 93 links. Because of a large number of different pipes and tubes to detach during maintenance, the repair procedure for some of the vehicle's mechanisms
1526-442: A rescue. For similar reasons, objects intended to avoid detection will not have inside corners or surfaces and edges perpendicular to likely detection directions, which leads to "odd" looking stealth aircraft . These precautions do not totally eliminate reflection because of diffraction , especially at longer wavelengths. Half wavelength long wires or strips of conducting material, such as chaff , are very reflective but do not direct
1635-429: A result, off-road acceleration capabilities are sub-par, and the vehicle lags behind MBTs and IFVs on up-hill terrain. The ZSU-23-4 is equipped with an NBC system with an air filtration unit, fire-fighting equipment, TNA-2 navigational system, infrared vision device, R-123 radio set, R-124 intercom and electric power supply system consisting of a DG4M-1 single-shaft gas turbine engine (70 hp at 6,000 rpm) and
1744-585: A roof-mounted pod of six short-range SA-18 SAMs, or side-mounted SA-16s. The crew numbers four: driver, commander, gunner and radar operator. The driver's compartment is located in the nose part of the vehicle. The fighting compartment is in the center, and the engine compartment is in the rear part of the vehicle. The transmission consists of a multi-plate metal-contact main clutch, a manual gearbox with five forward gears, two planetary two-step steering gears with locking frictions and two final drive groups. The vehicle chassis has six single rubber tired road wheels,
1853-677: A system might do, Wilkins recalled the earlier report about aircraft causing radio interference. This revelation led to the Daventry Experiment of 26 February 1935, using a powerful BBC shortwave transmitter as the source and their GPO receiver setup in a field while a bomber flew around the site. When the plane was clearly detected, Hugh Dowding , the Air Member for Supply and Research , was very impressed with their system's potential and funds were immediately provided for further operational development. Watson-Watt's team patented
1962-427: A vertical range of 5.1 km (3.2 mi). The effective vertical range is 1.5 km (0.93 mi) at a direct range to target of 2.5 km (1.6 mi) and target speed of 250 m/s (up to 500 m/s if a modern fire control system is used). The usual autocannon burst consists of 3–10 projectiles and target lead angle is calculated for each burst (fire without adjustment) by computer. In attacking targets on
2071-514: A wide region and direct fighter aircraft towards targets. Marine radars are used to measure the bearing and distance of ships to prevent collision with other ships, to navigate, and to fix their position at sea when within range of shore or other fixed references such as islands, buoys, and lightships. In port or in harbour, vessel traffic service radar systems are used to monitor and regulate ship movements in busy waters. Meteorologists use radar to monitor precipitation and wind. It has become
2180-907: A writeup on the apparatus was entered in the Inventions Book maintained by the Royal Engineers. This is the first official record in Great Britain of the technology that was used in coastal defence and was incorporated into Chain Home as Chain Home (low) . Before the Second World War , researchers in the United Kingdom, France , Germany , Italy , Japan , the Netherlands , the Soviet Union , and
2289-452: Is a simplification for transmission in a vacuum without interference. The propagation factor accounts for the effects of multipath and shadowing and depends on the details of the environment. In a real-world situation, pathloss effects are also considered. Frequency shift is caused by motion that changes the number of wavelengths between the reflector and the radar. This can degrade or enhance radar performance depending upon how it affects
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#17327879643692398-436: 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 . A radar system consists of a transmitter producing electromagnetic waves in
2507-451: Is as follows, where F D {\displaystyle F_{D}} is Doppler frequency, F T {\displaystyle F_{T}} is transmit frequency, V R {\displaystyle V_{R}} is radial velocity, and C {\displaystyle C} is the speed of light: Passive radar is applicable to electronic countermeasures and radio astronomy as follows: Only
2616-404: Is hard (for example, replacement or repair of a starter). The electric drive of an air outlet hatch of a gas turbine engine (part of the vehicle's electric power supply system) has an inconvenient location (at the bottom of the hull) which causes overheating and sometimes, jamming of the electric drive. On the other hand, the construction of the electric power supply system is very reliable. Changing
2725-567: Is intended. Radar relies on its own transmissions rather than light from the Sun or the Moon, or from electromagnetic waves emitted by the target objects themselves, such as infrared radiation (heat). This process of directing artificial radio waves towards objects is called illumination , although radio waves are invisible to the human eye as well as optical cameras. If electromagnetic waves travelling through one material meet another material, having
2834-473: Is mounted on collapsible supports in the top rear of the turret. There is an optical alignment sight. The RPK-2 radar proved to have good protection against enemy passive electronic radar counter-measures. Nevertheless, the radar system of the ZSU-23-4 has a short detection range during target search, depending on weather conditions (mainly dependent on rain and snow conditions). It is hard to automatically track
2943-689: Is primarily because the guns can elevate much higher than a tank or APC cannon, enabling armored units equipped with ZSU-23-4s to return fire against ambushes from above. A small number of ZSU-23-4 SPAAGs are still in use by the Russian Naval Infantry (specifically the 61st Brigade of the Northern Fleet , the 336th Brigade of the Baltic Fleet , and the 155th Brigade of the Pacific Fleet ). Radar Radar
3052-414: Is still a widely used caliber; these include new ammunition types such as sub-caliber armor-piercing rounds and frangible ammunition. The following table lists the main characteristics of some of the available 23×152B mm ammunition used in 23mm AA guns: A typical loading of each ammunition belt contains 40 OFZT and 10 BZT rounds. They can be fired to a maximum horizontal range of 7 km (4.3 mi), and
3161-418: Is technically possible that each cannon shoots different type of ammunition, there were two types commonly used in late 1970s: OFZT incendiary fragmentation and BZT armour-piercing tracer, which were to be loaded in 3:1 ratio—three OFZT, then one BZT, every 10th BZT round equipped with so-called "copper remover" and marked. Operators were strongly discouraged from shooting from a single barrel. The appearance of
3270-417: Is the range. This yields: This shows that the received power declines as the fourth power of the range, which means that the received power from distant targets is relatively very small. Additional filtering and pulse integration modifies the radar equation slightly for pulse-Doppler radar performance , which can be used to increase detection range and reduce transmit power. The equation above with F = 1
3379-561: Is used against ground targets. The quad automatic anti-aircraft gun AZP-23 "Amur" has a range of elevation from −4° to +85°. The GRAU designation for ZSU-23-4 turret with 23 mm (0.9") AZP-23 "Amur" quad automatic gun is 2A10. An armoured plate inside the turret protects crew members from fire and explosive gas during intense firing. Ammunition capacity is 2,000 rounds stowed aboard (520 rounds per each upper autocannon and 480 rounds per each lower autocannon) loaded in 50-round or shorter belts. The water-cooled 2A7 23mm guns of ZSU-23-4 fire
ZSU-23-4 Shilka - Misplaced Pages Continue
3488-591: The GM-575 tracked vehicle chassis, which used components from the PT-76 light amphibious tank, the ZSU-23-4 mounts an armored turret holding four liquid-cooled 23 mm (0.9") 2A7 autocannons linked to an RPK-2 "Tobol" radar (NATO designator: "Gun Dish"). The vehicle weighs 19 tonnes (late modifications up to 21 tonnes), has a movement range of 450 km (280 mi) and a top speed of 50 km/h (31 mph). Additional firepower of late modifications can be supplied by
3597-486: The KGB . The Democratic Republic of Afghanistan was initially led by Nur Muhammad Taraki , who was pro-Soviet Union, which resulted in cordial Afghan–Soviet relations. In September 1979, Taraki was deposed by Hafizullah Amin, due to intra- party strife. After this event and the suspicious death of Taraki (an apparent assassination by Amin's orders), Afghan–Soviet relations started to deteriorate. The KGB claimed that Amin
3706-476: The New York Times on 27 December 1979, was "Amin had been sentenced to death at a revolutionary trial for crimes against the state and that sentence had been carried out". One story at the time was Amin was killed by Sayed Mohammad Gulabzoy , a previous Minister of Communication until ousted by Amin, who was present with two other previous ministers during the assault to give credence to accounts that it
3815-628: The Nyquist frequency , since the returned frequency otherwise cannot be distinguished from shifting of a harmonic frequency above or below, thus requiring: Or when substituting with F D {\displaystyle F_{D}} : As an example, a Doppler weather radar with a pulse rate of 2 kHz and transmit frequency of 1 GHz can reliably measure weather speed up to at most 150 m/s (340 mph), thus cannot reliably determine radial velocity of aircraft moving 1,000 m/s (2,200 mph). In all electromagnetic radiation ,
3924-717: The RAF's Pathfinder . The information provided by radar includes the bearing and range (and therefore position) of the object from the radar scanner. It is thus used in many different fields where the need for such positioning is crucial. The first use of radar was for military purposes: to locate air, ground and sea targets. This evolved in the civilian field into applications for aircraft, ships, and automobiles. In aviation , aircraft can be equipped with radar devices that warn of aircraft or other obstacles in or approaching their path, display weather information, and give accurate altitude readings. The first commercial device fitted to aircraft
4033-597: The Soviet–Afghan War ZSU-23-4 units were used widely and to great effect against mujahideen positions in the mountains, the ZSU-23-4's guns being able to elevate much higher than the weapons on BMPs , BTRs , T-55s , or T-62s . They were also used to suppress defensive positions around the presidential palace during the initial coup in Kabul at the start of the Soviet-Afghan war. The Russian Army used
4142-594: The Tajbeg Palace , where General Secretary Amin was in residence with his family at the suggestion of his KGB security advisers, took place around 7 p.m. on 27 December 1979. The Tajbeg Palace was guarded by the Afghan National Army . During the attack, Amin still believed the Soviet Union was on his side, and told his adjutant, "The Soviets will help us." The adjutant replied that it was
4251-637: The dissolution of the Soviet Union in the 1990s revealed that the Soviet leadership believed Amin had secret contacts within the American embassy in Kabul and "was capable of reaching an agreement with the United States "; however, allegations of Amin colluding with the Americans have been widely discredited, with the Soviet archives revealing that the story of Amin as a CIA agent had been planted by
4360-440: The electromagnetic spectrum . One example is lidar , which uses predominantly infrared light from lasers rather than radio waves. With the emergence of driverless vehicles, radar is expected to assist the automated platform to monitor its environment, thus preventing unwanted incidents. As early as 1886, German physicist Heinrich Hertz showed that radio waves could be reflected from solid objects. In 1895, Alexander Popov ,
4469-460: The radio or microwaves 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 information about the objects' locations and speeds. Radar was developed secretly for military use by several countries in
ZSU-23-4 Shilka - Misplaced Pages Continue
4578-407: The reflective surfaces . A corner reflector consists of three flat surfaces meeting like the inside corner of a cube. The structure will reflect waves entering its opening directly back to the source. They are commonly used as radar reflectors to make otherwise difficult-to-detect objects easier to detect. Corner reflectors on boats, for example, make them more detectable to avoid collision or during
4687-616: The "Shilka" caused significant changes in NATO tactics in aircraft use at low altitude over the battlefield. Despite its present obsolescence as a modern short-range anti-aircraft weapon, the ZSU-23-4 is still deadly for enemy light armoured vehicles, infantry and firing points as an infantry-support vehicle. With its high rate of accurate fire, the ZSU-23-4 can even neutralize tanks by destroying their gun sights, radio antennas, or other vulnerable parts. ZSU-23-4s, especially late models, have excellent performance and good systems reliability. Based on
4796-534: The "new boy" Arnold Frederic Wilkins to conduct an extensive review of available shortwave units. Wilkins would select a General Post Office model after noting its manual's description of a "fading" effect (the common term for interference at the time) when aircraft flew overhead. By placing a transmitter and receiver on opposite sides of the Potomac River in 1922, U.S. Navy researchers A. Hoyt Taylor and Leo C. Young discovered that ships passing through
4905-413: The 1920s went on to lead the U.K. research establishment to make many advances using radio techniques, including the probing of the ionosphere and the detection of lightning at long distances. Through his lightning experiments, Watson-Watt became an expert on the use of radio direction finding before turning his inquiry to shortwave transmission. Requiring a suitable receiver for such studies, he told
5014-561: The KGB contingent, Col. Boyarinov, was killed. All the surviving participants in the KGB troops in the operation were wounded. Also, Soviet army doctor Colonel Viktor Kuznechenkov, who was treating General Secretary Amin, was killed by friendly fire in the palace and was posthumously awarded the Order of the Red Banner. According to Oleg Balashov, who was second in command of the assault group,
5123-593: The PDPA's Parcham faction, as Amin's successor. Several other government buildings were seized from Amin's Khalqist government during the operation, including those for the Ministry of Interior Affairs , KAM , and the General Staff ( Darul Aman Palace ). Veterans of the Soviet Union's Alpha Group have stated that Operation Storm-333 was one of the most successful in the unit's history. Documents released following
5232-722: The Soviet Army. The PPRU-1 ("Ovod-M-SV") vehicle is based on MT-LBu armoured tracked chassis and it was intended for control of motor rifle or tank regimental anti-aircraft unit equipped with ZSU-23-4 SPAAGs and 9K31 "Strela-1M" mobile surface-to-air missile systems. The PPRU-1 is equipped with the "Luk-23" radar and an automatic fire control system associated with the divisional air defence system. The guns are useful against low-flying aircraft and lightly protected ground targets. Due to its effectiveness against ground targets, ZSU-23-4s have been used in urban environments (e.g., Afghanistan , Abkhazia , Chechnya, Syria and Lebanon ). This
5341-462: The Soviet operation; 30 Afghan palace guards and over 300 army guards were killed while another 150 were captured. Two of Amin's sons, an 11-year-old and a 9-year-old, died from shrapnel wounds sustained during the clashes. In the aftermath of the operation, a total of 1,700 Afghan soldiers who surrendered to Soviet forces were taken prisoner, and the Soviets installed Babrak Karmal , the leader of
5450-592: The Soviets who were attacking them; Amin initially replied that this was a lie. Only after he tried but failed to contact the Chief of the General Staff, he muttered, "I guessed it. It's all true." He was captured alive by Grom troops, but semi-conscious, suffering convulsions due to interrupted medical treatment related to a poisoning that occurred on 16 December of the same year. The exact details of his later death have never been confirmed by any eye witness. The official announcement of his death on Kabul Radio, as reported by
5559-787: The United States, independently and in great secrecy, developed technologies that led to the modern version of radar. Australia, Canada, New Zealand, and South Africa followed prewar Great Britain's radar development, Hungary and Sweden generated its radar technology during the war. In France in 1934, following systematic studies on the split-anode magnetron , the research branch of the Compagnie générale de la télégraphie sans fil (CSF) headed by Maurice Ponte with Henri Gutton, Sylvain Berline and M. Hugon, began developing an obstacle-locating radio apparatus, aspects of which were installed on
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#17327879643695668-539: The ZSU-23-4 for mountain combat in Chechnya . The radar-guided ZSU-23-4 "Shilka" SPAAG, with its four 23 mm (0.90") autocannons, was a revolutionary SPAAG, proving to be an extremely effective weapon against enemy attack aircraft and helicopters under every weather and light condition. The ZSU-23-4 has a very high density, rate and accuracy of fire, as well as the capability for each of the four autocannons to fire its own type of projectile from separate belts. While it
5777-916: The ZSU-23-4, notably the Ukrainian "Donets" and Polish "Biala" variants. ZSU-23-4 units saw active service in the Yom Kippur War (1973) and other Arab-Israeli conflicts, the Iran–Iraq War (1980–1988), and the First Gulf War (1990). During the Yom Kippur War, the system was particularly effective against the Israeli Air Force . Israeli pilots attempting to fly low in order to avoid SA-6 missiles were often shot down by ZSU-23-4s as in Operation Doogman 5 . During
5886-427: The air defence guns have slightly higher muzzle velocity, and explosive rounds also have slightly larger HE fillings. The VYa ammunition has brass cases, while 2A7/2A14 ammunition has steel cases. Three main types of 23mm anti-aircraft ammunition were manufactured post-war: API-T, HEI and HEI-T. In addition to the original Soviet rounds, a number of ammunition manufacturers have since begun to produce ammunition for what
5995-537: The arrest of Oshchepkov and his subsequent gulag sentence. In total, only 607 Redut stations were produced during the war. The first Russian airborne radar, Gneiss-2 , entered into service in June 1943 on Pe-2 dive bombers. More than 230 Gneiss-2 stations were produced by the end of 1944. The French and Soviet systems, however, featured continuous-wave operation that did not provide the full performance ultimately synonymous with modern radar systems. Full radar evolved as
6104-479: The beam path caused the received signal to fade in and out. Taylor submitted a report, suggesting that this phenomenon might be used to detect the presence of ships in low visibility, but the Navy did not immediately continue the work. Eight years later, Lawrence A. Hyland at the Naval Research Laboratory (NRL) observed similar fading effects from passing aircraft; this revelation led to a patent application as well as
6213-610: The clashes and died shortly after. Amin's wife and daughter were wounded, but survived. 347 other Afghans, including 30 of Amin's most personal guards from Palace and Leader's guards, also died in the fighting, and part of the palace went up in flames. 150 of the 180 Palace and Leader's guards, who were regular troops, surrendered when they realized the attacking troops were from the USSR, not from an Afghan unit. A total of 1,700 Afghan soldiers surrendered to Soviet troops and were taken prisoner. The whole operation took about 40 minutes. It
6322-405: The dead zones of 2K12 Kub (SA-6 Gainful) surface-to-air missile systems belonging to the divisional level. Since the 1980s Soviet motor rifle and tank regiments were equipped with an anti-aircraft artillery battalion of three batteries (one was equipped with ZSU-23-4 or 9K22 Tunguska SPAAGs, the second one was equipped with 9K35 Strela-10 (SA-13 Gopher) short-range surface-to-air missile systems and
6431-408: The detection of aircraft and ships. Radar absorbing material , containing resistive and sometimes magnetic substances, is used on military vehicles to reduce radar reflection . This is the radio equivalent of painting something a dark colour so that it cannot be seen by the eye at night. Radar waves scatter in a variety of ways depending on the size (wavelength) of the radio wave and the shape of
6540-476: The detection process. As an example, moving target indication can interact with Doppler to produce signal cancellation at certain radial velocities, which degrades performance. Sea-based radar systems, semi-active radar homing , active radar homing , weather radar , military aircraft, and radar astronomy rely on the Doppler effect to enhance performance. This produces information about target velocity during
6649-411: The detection process. This also allows small objects to be detected in an environment containing much larger nearby slow moving objects. Doppler shift depends upon whether the radar configuration is active or passive. Active radar transmits a signal that is reflected back to the receiver. Passive radar depends upon the object sending a signal to the receiver. The Doppler frequency shift for active radar
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#17327879643696758-626: The device in patent GB593017. Development of radar greatly expanded on 1 September 1936, when Watson-Watt became superintendent of a new establishment under the British Air Ministry , Bawdsey Research Station located in Bawdsey Manor , near Felixstowe, Suffolk. Work there resulted in the design and installation of aircraft detection and tracking stations called " Chain Home " along the East and South coasts of England in time for
6867-538: The electric field is perpendicular to the direction of propagation, and the electric field direction is the polarization of the wave. For a transmitted radar signal, the polarization can be controlled to yield different effects. Radars use horizontal, vertical, linear, and circular polarization to detect different types of reflections. For example, circular polarization is used to minimize the interference caused by rain. Linear polarization returns usually indicate metal surfaces. Random polarization returns usually indicate
6976-473: The entire area in front of it, and then used one of Watson-Watt's own radio direction finders to determine the direction of the returned echoes. This fact meant CH transmitters had to be much more powerful and have better antennas than competing systems but allowed its rapid introduction using existing technologies. A key development was the cavity magnetron in the UK, which allowed the creation of relatively small systems with sub-meter resolution. Britain shared
7085-466: The firm GEMA [ de ] in Germany and then another in June 1935 by an Air Ministry team led by Robert Watson-Watt in Great Britain. In 1935, Watson-Watt was asked to judge recent reports of a German radio-based death ray and turned the request over to Wilkins. Wilkins returned a set of calculations demonstrating the system was basically impossible. When Watson-Watt then asked what such
7194-622: The front BMP and, when the BMP was immobilized by fire from Amin's troops, ordered them to abandon the BMP and run to the palace. All five were quickly wounded by intensive fire from the guards, but were saved by bulletproof vests and helmets. This account generally agrees with that of Aleksandr Lyakhovskiy, Soviet war historian and former director of the USSR Defense Ministry in Afghanistan, who gives more details and accentuates
7303-451: The ground, its effective range is around 2.5 km (1.6 mi). The short range of its 23 mm autocannons and relatively low explosive effect of its small-calibre projectiles mean it is less able to engage threats such as jet attack aircraft and cruise missiles than modern systems like the 2K22 Tunguska armed with more powerful 30 mm autocannons and integrated missile armaments. A special 23 mm round with composite projectiles
7412-463: The group was led by two elite units of Alpha and Vympel (15–20 each). The Alpha group targeted Amin, and the Vympel group had the task of collecting factual evidence that Amin was collaborating with the United States. Both groups were brought to Afghanistan secretly and blended with Muslim Battalions to make an impression that the operation was carried out by local units, whereas in reality nearly all work
7521-402: The guns would get so hot that chambered rounds would " cook off " even if the operator was not pulling the trigger – discharging the weapon and chambering a new round, which would then also cook off, and continue to do so. This would sometimes continue until the entire belt of ammunition had been expended. Overheating barrels could jam and even break away from the vehicle. The problem resulted from
7630-534: The hardline ideology espoused by the rival Khalq faction; a number of Soviet troops crossed the Amu Darya and entered Afghanistan by land while others flew to airbases around the country with exiled Parchamis in preparation for the assassination. The Tajbeg Palace, located on a high and steep hill in Kabul, was surrounded by landmines and guarded by extraordinarily large contingents of the Afghan National Army . Nonetheless, Afghan forces suffered major losses during
7739-664: The heavily fortified Tajbeg Palace in Kabul and assassinated Afghan leader Hafizullah Amin , a Khalqist of the People's Democratic Party of Afghanistan (PDPA) who had taken power in the Saur Revolution of April 1978. It was the start of the Soviet–Afghan War . The assassination of Amin was part of a larger Soviet plan to secure and take control of Afghanistan with support from the PDPA's Parcham faction, which opposed
7848-411: The main engine oil and coolant is easy, as is replacement of fuel and oil filters, and sections of the air filter. The ZSU-23-4 can cross vertical obstacles 0.7 m (2.3') high, trenches 2.5 m (8.2') wide, has a 1.0 m (3.3') fording depth and can climb 30° gradients. The ZSU-23-4 has good maneuverability and cross-country ability, but its diesel engine's power is insufficient for a vehicle of its weight. As
7957-469: The main forces, usually 600–1000 m behind objectives when on the defensive or 400–600 m behind the leading tanks on the offensive. ZSU-23-4 SPAAGs are divided evenly along the troop columns on the march. At first each ZSU-23-4 operated in combat autonomously, without target marking from regimental or divisional air defence. In 1978, the PPRU-1 (mobile reconnaissance and control post) was passed into service of
8066-417: The march; originally, the more powerful guns of "Yenisei" were judged to be effective at covering the inner dead-zone of Soviet surface-to-air missile systems despite the increased weight of the vehicle, but commonality prevailed. Initially, tank regiments should have had the anti-aircraft artillery battalion of "Shilka" (consisting of two batteries, four ZSU-23-4s in each). At the end of the 1960s, one battery
8175-631: The number of gun barrels. It is named after the Shilka River in Russia. Afghan soldiers nicknamed it the " sewing machine " due to the sound of its cannons firing. It is also referred to by its nickname of " Zeus ", derived from the Russian acronym. The previous Soviet self-propelled anti-aircraft gun ( SPAAG ), the ZSU-57-2 , was armed with two 57 mm autocannons ; it was aimed optically using
8284-508: The ocean liner Normandie in 1935. During the same period, Soviet military engineer P.K. Oshchepkov , in collaboration with the Leningrad Electrotechnical Institute , produced an experimental apparatus, RAPID, capable of detecting an aircraft within 3 km of a receiver. The Soviets produced their first mass production radars RUS-1 and RUS-2 Redut in 1939 but further development was slowed following
8393-531: The outbreak of World War II in 1939. This system provided the vital advance information that helped the Royal Air Force win the Battle of Britain ; without it, significant numbers of fighter aircraft, which Great Britain did not have available, would always have needed to be in the air to respond quickly. The radar formed part of the " Dowding system " for collecting reports of enemy aircraft and coordinating
8502-1370: The period before and during World War II . A key development was the cavity magnetron in the United Kingdom , which allowed the creation of relatively small systems with sub-meter resolution. 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 . The modern uses of radar are highly diverse, including air and terrestrial traffic control, radar astronomy , air-defense systems , anti-missile systems , marine radars to locate landmarks and other ships, aircraft anti-collision systems, ocean surveillance systems, outer space surveillance and rendezvous systems, meteorological precipitation monitoring, radar remote sensing , altimetry and flight control systems , guided missile target locating systems, self-driving cars , and ground-penetrating radar for geological observations. Modern high tech radar systems use digital signal processing and machine learning and are capable of extracting useful information from very high noise levels. Other systems which are similar to radar make use of other parts of
8611-458: The practical rate of fire, such as barrel overheating). The welded turret has a race ring transplanted from a T-54 medium tank with a 1,840 mm (6 ft 0 in) diameter. The 360° rotating turret is fully stabilised and capable of firing on the move. The turret rotation and autocannon elevation mechanisms provide very good speed and guidance accuracy. The hydraulically driven aiming mechanisms have been proven to be very reliable. Manual aim
8720-706: The primary tool for short-term weather forecasting and watching for severe weather such as thunderstorms , tornadoes , winter storms , precipitation types, etc. Geologists use specialized ground-penetrating radars to map the composition of Earth's crust . Police forces use radar guns to monitor vehicle speeds on the roads. Automotive radars are used for adaptive cruise control and emergency breaking on vehicles by ignoring stationary roadside objects that could cause incorrect brake application and instead measuring moving objects to prevent collision with other vehicles. As part of Intelligent Transport Systems , fixed-position stopped vehicle detection (SVD) radars are mounted on
8829-432: The radial component of the velocity is relevant. When the reflector is moving at right angle to the radar beam, it has no relative velocity. Objects moving parallel to the radar beam produce the maximum Doppler frequency shift. When the transmit frequency ( F T {\displaystyle F_{T}} ) is pulsed, using a pulse repeat frequency of F R {\displaystyle F_{R}} ,
8938-414: The response. Given all required funding and development support, the team produced working radar systems in 1935 and began deployment. By 1936, the first five Chain Home (CH) systems were operational and by 1940 stretched across the entire UK including Northern Ireland. Even by standards of the era, CH was crude; instead of broadcasting and receiving from an aimed antenna, CH broadcast a signal floodlighting
9047-410: The resulting frequency spectrum will contain harmonic frequencies above and below F T {\displaystyle F_{T}} with a distance of F R {\displaystyle F_{R}} . As a result, the Doppler measurement is only non-ambiguous if the Doppler frequency shift is less than half of F R {\displaystyle F_{R}} , called
9156-427: The roadside to detect stranded vehicles, obstructions and debris by inverting the automotive radar approach and ignoring moving objects. Smaller radar systems are used to detect human movement . Examples are breathing pattern detection for sleep monitoring and hand and finger gesture detection for computer interaction. Automatic door opening, light activation and intruder sensing are also common. A radar system has
9265-527: The same 23×152B mm caliber ammunition as the 2A14 guns of the twin-barrel ZU-23-2 towed gun. While the 23mm Volkov-Yartsev VYa-23 aircraft gun used in the Second World War era Il-2 Sturmovik also fired ammunition of the same cartridge case dimensions, the rounds differed in loading and primer, and are thus not interchangeable with the post-war AA gun ammunition. Compared to the VYa and its ammunition,
9374-407: The scattered energy back toward the source. The extent to which an object reflects or scatters radio waves is called its radar cross-section . The power P r returning to the receiving antenna is given by the equation: where In the common case where the transmitter and the receiver are at the same location, R t = R r and the term R t ² R r ² can be replaced by R , where R
9483-511: The signal is attenuated by the medium the beam crosses, and the beam disperses. The maximum range of conventional radar can be limited by a number of factors: Operation Storm-333 The Tajbeg Palace assault , known by the military codename Operation Storm-333 ( Russian : Шторм-333 , Štorm-333 ), was a military raid executed by the Soviet Union in Afghanistan on 27 December 1979. Special forces and airborne troops stormed
9592-531: The southern republics of the USSR. This motorized rifle battalion had been formed in the USSR earlier in 1979 at the specific request of the Afghan leader to guard his residence as he could not rely on Afghan troops. These support troops were not issued armor or helmets, but one of them recalls that a magazine tucked inside his clothes protected him from an SMG bullet. The teams were assisted by Sayed Mohammad Gulabzoy in leading it to Tajbeg Palace. The raid on
9701-469: The target at ranges less than 7–8 km (4.3–5.0 mi) because of the high angular speed of the target at close distances. The radar needs to be reset quite often because of the unstable parameters of electronic cathode-ray tubes of the target selection system. The absence of an automatic laser range finder requires a skilful commander and gunner. Early versions of the ZSU-23-4 sometimes had problems with "runaway guns": after prolonged periods of firing,
9810-455: The target parameters received from the 1RL33 RPK-2 ( gun dish ) radar, and the correction angle received from the GAG (gyroscope) unit. Soviet doctrine supplied the vehicle since 1965 in an anti-aircraft artillery battery of two, four-vehicle platoons for anti-aircraft defence of motor rifle and tank regiments. At the end of the 1960s one platoon was equipped with ZSU-23-4 SPAAGs while another one
9919-491: The target. If the wavelength is much shorter than the target's size, the wave will bounce off in a way similar to the way light is reflected by a mirror . If the wavelength is much longer than the size of the target, the target may not be visible because of poor reflection. Low-frequency radar technology is dependent on resonances for detection, but not identification, of targets. This is described by Rayleigh scattering , an effect that creates Earth's blue sky and red sunsets. When
10028-585: The technology with the U.S. during the 1940 Tizard Mission . In April 1940, Popular Science showed an example of a radar unit using the Watson-Watt patent in an article on air defence. Also, in late 1941 Popular Mechanics had an article in which a U.S. scientist speculated about the British early warning system on the English east coast and came close to what it was and how it worked. Watson-Watt
10137-433: The third battery with 9K38 Igla man-portable surface-to-air missiles on IFVs or APCs. The ZSU-23-4 is very vulnerable to enemy anti-tank missiles, cannons and heavy machine guns; the armour is thin (not exceeding 15 mm) and the exposed wheels, tracks, radar, and gun barrels can easily be damaged in combat. Firing positions of ZSU-23-4 SPAAGs are typically placed near the forward edge of the battle area ( FEBA ) but behind
10246-879: The transmitter. The reflected radar signals captured by the receiving antenna are usually very weak. They can be strengthened by electronic amplifiers . More sophisticated methods of signal processing are also used in order to recover useful radar signals. The weak absorption of radio waves by the medium through which they pass is what enables radar sets to detect objects at relatively long ranges—ranges at which other electromagnetic wavelengths, such as visible light , infrared light , and ultraviolet light , are too strongly attenuated. Weather phenomena, such as fog, clouds, rain, falling snow, and sleet, that block visible light are usually transparent to radio waves. Certain radio frequencies that are absorbed or scattered by water vapour, raindrops, or atmospheric gases (especially oxygen) are avoided when designing radars, except when their detection
10355-487: The two length scales are comparable, there may be resonances . Early radars used very long wavelengths that were larger than the targets and thus received a vague signal, whereas many modern systems use shorter wavelengths (a few centimetres or less) that can image objects as small as a loaf of bread. Short radio waves reflect from curves and corners in a way similar to glint from a rounded piece of glass. The most reflective targets for short wavelengths have 90° angles between
10464-472: The use of radar altimeters possible in certain cases. The radar signals that are reflected back towards the radar receiver are the desirable ones that make radar detection work. If the object is moving either toward or away from the transmitter, there will be a slight change in the frequency of the radio waves due to the Doppler effect . Radar receivers are usually, but not always, in the same location as
10573-507: The Гром ( Grom – "Thunder") unit of Alpha Group , and 30 operators from a special KGB group Зенит ( Zenit – "Zenith"), later known as Vympel and Гром ( Grom - "Thunder"). There were also 87 troops of a company of the 345th Independent Guards Airborne Regiment . 520 men from the 154th Separate Spetsnaz Detachment of the USSR Ministry of Defence known as the " Muslim Battalion " because it consisted exclusively of soldiers from
10682-619: Was a "smooth-talking fascist who was secretly pro-western". By December the Soviet leadership had established an alliance with Babrak Karmal. The Soviet Union declared its plan to intervene in Afghanistan on 12 December 1979, and the Soviet leadership initiated Operation Storm-333 (the first phase of the intervention) on 27 December 1979. Storm-333 was part of a bigger operation, Baikal-79, aimed at taking control over approximately 20 key strongholds in and around Kabul, which included major military headquarters, communication centers and jails. The core of Storm-333 assault team included 25 men from
10791-608: Was a 1938 Bell Lab unit on some United Air Lines aircraft. Aircraft can land in fog at airports equipped with radar-assisted ground-controlled approach systems in which the plane's position is observed on precision approach radar screens by operators who thereby give radio landing instructions to the pilot, maintaining the aircraft on a defined approach path to the runway. Military fighter aircraft are usually fitted with air-to-air targeting radars, to detect and target enemy aircraft. In addition, larger specialized military aircraft carry powerful airborne radars to observe air traffic over
10900-415: Was an Afghan-controlled operation. Gulabzoy and Mohammad Aslam Watanjar , the previous Minister for Defense, later confirmed his death. This story of his death after a summary trial is supported by the fate of Amin supporters who were executed on the spot with a bullet in the back of the neck, after a 'Revolutionary Troika' arrested and sentenced them to death. Amin's two sons sustained shrapnel wounds during
11009-482: Was developed for a modern variant of SPAAG (ZSU-23-4M4) to be used against cruise missiles. The RPK-2 "Tobol" a.k.a. 1RL33 radar operates in the Ku band and can detect aircraft up to 20 km (12 mi) away. It has excellent target tracking capability and is relatively hard to detect by the enemy. However, the radar picks up many false returns ( ground clutter ) under 60 m (200 ft) of altitude. The radar antenna
11118-447: Was done by Alpha and Vympel. Before the operation, Balashov surveyed the area in the guise of a bodyguard of a Soviet diplomat. His unit knew that they were going to a death zone and felt uncomfortable about it – about 80% of them were wounded shortly after they left their vehicles, yet they continued the assault. As Balashov expected, Amin's troops targeted the first and last vehicle in the convoy of six. He placed his team of five men in
11227-454: Was equipped with ZSU-23-4s and the other with ZSU-57-2s. Motorized rifle and tank regiment standard anti-aircraft batteries consisted of two platoons later (one platoon was equipped with four ZSU-23-4s and another with four mobile surface-to-air missile systems 9K31 Strela-1 or 9K35 Strela-10 ). The ZSU-23-4 combined a proven radar system, the non-amphibious chassis based on GM-575 tracked vehicle, and four 23 mm autocannons. This delivered
11336-530: Was known as the ZU-23-2 , a towed mount carrying two 23 mm cannons. However, these towed or improvised truck-mounted weapons had similar disadvantages. The development of the ZSU-23-4 "Shilka" began in 1957 along with ZSU-37-2 "Yenisei" and the vehicle was brought into service in 1965, replacing all ZSU-57-2s in air defense units toward the beginning of the 1970s. The ZSU-23-4 was intended for AA defense of military facilities, troops, and mechanized columns on
11445-549: Was later determined in 2009 that Amin was mortally wounded by a fragment of a grenade that was thrown by Senior lieutenant Alexander Nikolaevich Plyusnin (1949–2022). The wife of the Minister of Foreign Affairs , Shah Wali (born 1939), was also killed in the operation. During the assault on the Tajbeg five officers of the KGB special forces, seven troops from the "Muslim Battalion", and two paratroopers were killed. The commander of
11554-748: Was sent to the U.S. in 1941 to advise on air defense after Japan's attack on Pearl Harbor . Alfred Lee Loomis organized the secret MIT Radiation Laboratory at Massachusetts Institute of Technology , Cambridge, Massachusetts which developed microwave radar technology in the years 1941–45. Later, in 1943, Page greatly improved radar with the monopulse technique that was used for many years in most radar applications. The war precipitated research to find better resolution, more portability, and more features for radar, including small, lightweight sets to equip night fighters ( aircraft interception radar ) and maritime patrol aircraft ( air-to-surface-vessel radar ), and complementary navigation systems like Oboe used by
11663-636: Was solved on ZSU-23-4M (welded tubes of coolant outlet were replaced with flexible pipes). After the autocannon cooling system was improved, the autocannons became extremely reliable. The ZSU-23-4 has an 1A7 SRP electro-mechanical fire solution calculator, weighing 180 kg, that occupies all of the space before the Commander. It contains 60 electric motors driving 110 axles over different potentiometers , shafts, rods, cams , gears and linkages to mechanically calculate ammunition flight time until impact, elevation lead angle , and azimuth lead angle using
11772-455: Was still equipped with ZSU-57-2 SPAAGs. ZSU-57-2 was completely replaced with ZSU-23-4 by the beginning of the 1970s. In the 1970s, Soviet motor rifle and tank regiments were equipped with an anti-aircraft missile artillery battery consisting of two platoons, one equipped with four ZSU-23-4 SPAAGs and the other with four 9K31 Strela-1 (SA-9 Gaskin) or later with four 9K35 Strela-10 (SA-13 Gopher) short-range surface-to-air missile systems which cover
11881-463: Was the first to use radio waves to detect "the presence of distant metallic objects". In 1904, he demonstrated the feasibility of detecting a ship in dense fog, but not its distance from the transmitter. He obtained a patent for his detection device in April 1904 and later a patent for a related amendment for estimating the distance to the ship. He also obtained a British patent on 23 September 1904 for
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