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АРГСН-активные радиолокационные головки самонаведения,MARV &
milstar: Теоретически возможные величины ЭПР некоторых перспективных кораблей для длины волны 10 см = 3 Ghz S-Band (Aegis SPY-1) авианосец средняя > 25 000 м2,промежуточный КУ 900–1000 м2 эсминец ,фрегат 1 500–4 000 м2 ,промежуточный КУ 200 -300 м2 http://vpk-news.ru/articles/8474 Dlja srawneniya B-2 Spirit - 0.75 м2 ------------------------ NIIP Irbis-E s apperturoj diametrom 900mm ,srednej moschnostju 5 kwt/impulsnoj = 20 kwt dalnost dlja EPR 0.01 kw.metr = 50nmi ili 90 km dlja EPR 2.56 kw.metra =360 km http://www.ausairpower.net/APA-Flanker.html ------------------------------------------- Баллистическая ракета средней дальности Pershing-2 (MGM-31C) Система управления дополнялась системой наведения ГЧ на конечном участке траектории по радиолокационной карте местности (система RADAG). Такая система на баллистических ракетах ранее не применялась. Комплекс командных приборов располагался на стабилизированной платформе, помещенной в цилиндрический корпус, и имел свой электронный блок управления. Работу системы управления обеспечивал бортовой цифровой вычислстельный комплекс, размещенный в 12 съемных модулях, и защищенный алюминиевым корпусом. Система RADAG состояла из бортовой радиолокационной станции и коррелятора. РЛС экранировалась и имела два антенных блока. Один из них предназначался для получения радиолокационного яркостного изображения местности. Другой - для определения высоты полета. Изображение кольцевого типа под головной частью получалось за счет сканирования вокруг вертикальной оси с угловой скоростью 2 об/сек. Четыре эталонных изображения района цели для разных высот хранились в памяти ЦВМ в виде матрицы, каждая ячейка которой представляла собой радиолокационную яркость соответствующего участка местности, записанную двухзначным двоичным числом. К аналогичной матрице сводилось полученное от РЛС действительное изображение местности, при сравнении которого с эталонным можно было определить ошибку инерциальной системы. Полет головной части корректировался исполнительными органами - реактивными соплами, работавшими от баллона со сжатым газом вне атмосферы, и аэродинамическими рулями с гидравлическим приводом при входе в атмосферу http://rbase.new-factoria.ru/missile/wobb/pershing_2/pershing_2.shtml -------------------------------------------------------------------------------- Комплекс П-800 / 3К55 Оникс / Яхонт - SS-N-26 STROBILE Система управления и наведение - активно-пассивное РЛ-наведение, на ракете установлены активная РЛС ГСН и бортовая БЦВМ. Дальность обнаружения цели ГСН в активном режиме - 50 км (по одним данным) Дальность обнаружения цели класса "крейсер" ГСН в активном режиме - 75-77 км ============================== Дальность обнаружения цели ГСН в активном режиме минимальная - 1 км Сектор обнаружения ГСН - +-45 градусов Диаметр ракеты -700 mm После обнаружения и захвата цели ГСН ракеты, ГСН выключается и ракета "ныряет" под нижнюю границу зоны ПВО цели и управляется инерциально. После выхода за линию радиогоризонта ГСН вновь включается ГСН. Распределение целей происходит на первом этапе работы ГСН (на высоте). При групповом старте ПКР на первом этапе группа ракет перераспределяет цели по определенному алгоритму, исключая возможность поражения одной цели несколькими ракетами (если это не главная цель). Ракеты запрограммированы на совершение противоракетных маневров. В память бортовой БЦВМ заложены электронные "портреты" основных кораблей потенциальных противников и логика определения построения корабельных ордеров для выбора главной цели. http://militaryrussia.ru/blog/topic-92.htm ----------------------------------------------- Противокорабельная ракета 3М-54Э / 3М-54Э1 На дистанции около 30-40 км от цели ракета делает "горку" и происходит включение АРГС -54 (см.схему). После обнаружения и захвата цели головкой самонаведения у ракеты 3М-54Э происходит отделение второй ступени и начинает работать третья боевая твердотопливная ступень, развивающая скорость до 1000 м/с. На конечном участке полета протяженностью около 20км боевая ступень ракеты 3М-54Э снижается на высоту до 10м. У двухступенчатой ПКР 3М-54Э1 полет на всей траектории происходит на дозвуковой скорости, а непосредственно перед целью выполняется специальный зигзагообразный противоракетный маневр. Количество одновременно обстреливаемых целей -2, количество ракет в залпе - 8, интервал между пусками - 5-10с. Бортовая система управления ракет 3М-54Э / 3М-54Э1 построена на базе автономной инерциальной навигационной системы АБ-40Э (разработчик - Государственный НИИ Приборостроения). Наведение на конечном участке траектории осуществляется при помощи помехозащищенной активной радиолокационной головки самонаведения АРГС-54. АРГС-54 разработана фирмой "Радар-ММС" (г.Санкт-Петербург) и имеет максимальную дальность действия до 65км. Длина головки - 70см, диаметр - 42см и вес - 40кг. АРГС-54 может функционировать при волнении моря до 6 баллов. http://rbase.new-factoria.ru/missile/wobb/3m54e1/3m54e1.shtml ---------------------------------------- Моноимпульсная головка самонаведения ракеты "Яхонт" http://rbase.new-factoria.ru/missile/wobb/jakhont/jakhont-head.shtml Головка самонаведения (ГСН) предназначена для поиска и обнаружения морских и наземных целей в условиях радиоэлектронного противодействия, селекции ложных целей, выбора цели по заданным критериям, захвата и сопровождения выбранной цели, выработки координат цели и выдачи их в систему автопилотирования бортовой аппаратуры системы управления (БАСУ) противокорабельной крылатой ракеты (ПКР) «Яхонт». ГСН выполняет указанные выше действия в любых погодных условиях при волнении моря до 7 баллов включительно. Состав аппаратуры ГСН представляет собой бортовой двухканальный активно-пассивный радиолокатор со сложным широкополосным когерентным сигналом с фазо-кодовой манипуляцией по случайному закону как в режиме обзора, так и в режиме сопровождения цели при работе в активном режиме. ГСН осуществляет перестройку частотно-временных параметров, обладает высокой помехозащищенностью по отношению к различным видам активных помех, уводящих по дальности и угловым координатам, и пассивных помех типа дипольных облаков и уголковых отражателей, адаптивна к помеховой обстановке и условиям применения. ГСН построена по модульному принципу: антенна, передатчик, приемник, устройство обработки информации (см.структурную схему). ГСН имеет средства встроенного самоконтроля. В ГСН воплощены новейшие научно-технические достижения ЦНИИ «Гранит» и других предприятий военно-промышленного комплекса России: функциональная СВЧ-микроэлектроника на базе тонко- и толстопленочной технологии; современная микропроцессорная техника и микро-ЭВМ; прогрессивные конструкции и технологические процессы изготовления; высокоэффективная система питания. Оригинальные решения, используемые в ГСН запатентованы. Все это позволило получить высокую степень интеграции при минимальных объемах аппаратуры, малое энергопотребление и низкую трудоемкость изготовления. Основные тактико-технические характеристики Дальность обнаружения цели в активном режиме не менее 50 км Максимальный угол поиска цели ± 45° Время готовности к работе с момента включения не более 2 мин Потребляемый ток по цепи 27В не более 38А Масса 85 кг -------------------------------------- АРГС для ракеты РВВ-АЕ http://www.mnii-agat.ru/expo/334/prod_2845_r.htm Многофункциональная моноимпульсная доплеровская активная радиолокационная головка самонаведения для ракеты РВВ-АЕ класса «воздух-воздух» обеспечивает: - поиск, захват и сопровождение цели по целеуказанию от инерциальной системы управления ракеты; - измерение угловых координат и угловых скоростей цели и скорости сближения ракета - цель и передача их в ракету для формирования сигналов управления. Режимы работы: - активный режим, полностью автономный ("пустил-забыл"), использующий только предварительное целеуказание, без радиолокационнной поддержки в полёте; - режим инерциального наведения с радиокоррекцией и активным наведением на конечном участке полета. Тактико-технические характеристики: 1. Состав: - управляемый координатор с антенной - передающий канал - приемный канал - бортовая вычислительная система 2. Тип системы наведения: - инерциальное наведение с радиокоррекцией и активное самонаведение 3. Канал радиокоррекции и АРГС обеспечивает пуск ракеты РВВ-АЕ с самолета типа МИГ-29 в ППС на максимальной дальности - до 80 км. 4. Время готовности после предварительного включения в течение 2 мин. - не более 1с 5. Длина (без обтекателя), мм - 604 6. Масса (без обтекателя), кГ - не более 16 7. Диаметр, мм - 200 Сотрудничество возможно в плане приобретения и испытаний ракеты РВВ-АЕ. По желанию Заказчика параметры АРГС могут изменяться.
milstar: In comparison with AMRAAM, the Active Skyflash is likely to exhibit lower peak power output, BAe believe however that the seeker offers comparable acquisition range performance to the AMRAAM which suggests a more sensitive receiver and possibly the use of pulse compression techniques. The receiver is a multiple channel monopulse design, with a single radar frequency which is heterodyned down twice to two intermediate frequencies, before detection and digitising for consumption by the missile's digital signal processor (DSP). The DSP performs target search and identification, and then tracking in azimuth, elevation, range and velocity to provide inputs for the guidance section. The DSP software is resident in EPROM memory devices (firmware) and BAe stress the comprehensive ECCM (counter-countermeasures) features in the code. Again the sensitive nature of such features precludes open discussion. The seeker has a variable PRF capability which allows it to adapt PRF to target engagement geometry, much like AMRAAM. This design strategy allows optimisation for closing or receding targets. http://www.ausairpower.net/skyflash-slammer.html
milstar: Поставка первых УР Meteor запланирована на 2012 год. Общий объем закупок ракет европейскими заказчиками оценивается в 8 тыс. единиц. В ВВС Великобритании начальная готовность к боевому применению запланирована на 2014-2015 гг. Агентство по материальному обеспечению армии (FMV) Швеции сообщило, что ракеты Meteor пополнят номенклатуру вооружений шведских истребителей до конца 2013 года. Германия запланировала покупку 600 ракет на сумму 544 млн.евро. http://rbase.new-factoria.ru/missile/wobb/meteor/comp-meteor.shtml Двигательная установка комбинированная с интегральной компоновкой, состоит из маршевого прямоточного воздушно-реактивного двигателя (ПВРД) с регулируемой по модулю тягой и стартового ускорителя, которые размещаются в едином корпусе. Стартовый ускоритель оснащен зарядом малодымного смесевого топлива и после отделения ракеты от самолета-носителя обеспечивает ее разгон до скорости запуска маршевого ПВРД. Заряд газогенератора маршевого ПВРД выполнен на основе тяжелого борсодержащего топлива с объёмной теплотой сгорания более 5х104МДж/м3. Расход и состав генерируемого газа может изменяться в достаточно широких пределах в соответствии с условиями полета и режимом работы прямоточного контура для всех условий боевого применения ракеты. Глубина регулирования расхода генерируемого газа ПВРД составляет более 10:1 и обеспечивается специальным клапаном в сопле газогенератора. Камера сгорания и газогенератор двигателя изготовлены из жаропрочной стали. Воздухозаборники, расположенные на внешней стороне корпуса ракеты, изготовлены из титана. Двигатель разработан фирмой Bayern-Chemie Protac. Использование ПВРД обеспечивает увеличение среднетраекторной скорости полета ракеты и дальности стрельбы. По рекламным материалам максимальная дальность полета ракеты достигает 150км. Боевая часть осколочно-фугасная массой 25кг, оснащается радиолокационным неконтактным и контактным взрывателями. Взрыватель имеет четыре антенны, расположенные в носовой части, и при обнаружении цели обеспечивает подрыв БЧ на расстоянии оптимальном для нанесения максимального повреждения. Взрыватель разработан шведской компанией Saab Bofors Dynamics http://rbase.new-factoria.ru/missile/wobb/meteor/meteor.shtml Тактико-технические характеристики Максимальная дальность стрельбы, км >100 Максимальная скорость полета, М 4.5 Скорость необходимая для запуска прямоточного двигателя, М 1.8 Габариты, мм: - длина -3650 mm - диаметр -180 mm - размах крыла -400 mm - размах оперения -630 mm Стартовая масса, кг 165 Масса боевой части, кг 25 Допустимый диапазон перегрузок цели, единицы до 11 Совершенствование УР Meteor и наращивание ее боевых возможностей продолжается. Проводятся исследования и опытно-конструкторские работы по использованию её в качестве средства поражения в составе зенитных комплексов MEADS и SLAMRAAM. ВВС Великобритании выражают заинтересованность в разработке на базе УР Meteor новой противорадиолокационной ракеты дальнего действия для замены AGM-88 HARM.
milstar: MBDA Meteor Datalink Meteor will be 'network-enabled'. A two-way datalink will allow the launch aircraft to provide mid-course target updates or retargeting if required, including data from offboard third-parties. The datalink will be able to transmit missile information such as functional and kinematic status, information on multiple targets, and notification of target acquisition by the seeker. The two-way datalink is compatible with Eurofighter and Gripen but not with Rafale which is fitted with a one-way link originally designed for use with MICA. French missiles will be fitted with a different unit. The datalink electronics are mounted in the starboard intake fairing, ahead of the FAS. The antenna is mounted in the rear of the fairing. http://www.allmilitaryweapons.com/2011/06/mbda-meteor-british-aam.html
milstar: http://www.peachtreeroost.org/Peachtree%20Roost%20March%2006%20Meeting%20slides.pdf Provides Simultaneous Dual-Polarization in Shared Aperture ● Provides Simultaneous Dual-Band Operation in Shared Aperture ● Balanced, Polarizations Allow Tracked Dual-Pol Linear Option ● Same Advantages as Standard Slot Arrays ● High Efficiency ● Fine Illumination Control ● Any Aperture Shape ● Handles Harsh Environments ● High Production Yields / Low Standard Deviations
milstar: Joint Strike Fighter literature refers to this optimization in terms of “breaking the kill chain”, the intent being to deny the effective use of X-band engagement radars and X/Ku-Band missile seekers, but not acquisition radars in lower bands. The second major departure from established stealth conventions is that the Joint Strike Fighter is designed to perform in the X-band, and upper portions of the S-band, with little effort expended in optimizing for the lower L-band, UHF-band and VHF-band. This design strategy is consistent with defeating mobile battlefield short range point defence SAM and AAA systems such as the SA-8 Gecko, SA-9 Gaskin, Chapparel, Crotale, Roland, SA-15 Gauntlet, SA-19 Grison and SA-22 “Greyhound”, where limited radar antenna size forces all acquisition and engagement functions into the X-band and upper S-band. Joint Strike Fighter literature refers to this optimization in terms of “breaking the kill chain”, the intent being to deny the effective use of X-band engagement radars and X/Ku-Band missile seekers, but not acquisition radars in lower bands. Such SAM systems are the category of “residual” threat which a battlefield interdiction aircraft will encounter once the F-22A force has “sanitized” an area by destroying the long range search/acquisition radars and area defence SAM batteries. With limited range and coverage footprint, but high mobility and autonomous capability, battlefield short range point defence SAM and AAA systems can “pop-up” from hidden locations and ambush interdiction aircraft at medium to low altitudes. Significantly, in a “sanitized” environment such air defence weapons are operating without external support from other sensors or the top cover provided by long range area defence SAMs such as the SA-12/23, SA-20 and SA-21. The engine nozzle presents a good case study of the band dependency of stealth performance in the Joint Strike Fighter design. In the upper X-band and Ku-band, the individual nozzle segments present as flat panels with a serrated trailing edge. The result will be a circular pattern of narrow reflecting lobes which will produce mostly good effect in these bands. However, in the lower bands this arrangement will rapidly degrade in behaviour to that of a truncated conical shape, which is a strong specular reflector. The resulting external shape related signature will be much the same as a conventional exhaust nozzle on a non-stealthy fighter, with an outer skin contribution and rim contribution. While the interior of the nozzle will be coated with broadband lossy materials and a tailpipe blocker used to obscure the turbine face, the signature of the nozzle exterior below the X-band cannot qualify as “stealthy”. Refer Annex C. http://www.ausairpower.net/APA-2009-01.html#mozTocId269596 Diagram 4 summarises the qualitative comparisons of Joint Strike Fighter shaping aspect and band dependency, with green denoting performance which qualifies as Very Low Observable, yellow as Low Observable, and red as order of magnitude closest to conventional reduced signature aircraft designs. The aircraft performs best in the X-band, and Ku-band, with performance declining through the S-band with increasing wavelength. In the L-band the axisymmetric nozzle design no longer produces useful effect, and the length of the inlet edges sits in resonant mode scattering rather than clean optical scattering, degrading performance. In the VHF band (~2 metres) Joint Strike Fighter airframe shaping has become largely ineffective. The aircraft will have a credible ability to defeat S-band search/acquisition radars, X-band engagement radars and X/Ku/K/Ka-band missile seekers only in the narrow ±14.5° angular sector under the nose. As the angle relative to the threat radars increases, the unfortunate lower fuselage shaping features will produce an increasingly strong effect with a cluster of “flare spot” peaks around 90° where the longitudinal panel and door edge joins produce effect. In the narrow ±14.5° angular sector under the tail, the design will produce best effect against X/Ku/K/Ka-band missile seekers, but less useful effect against X-band engagement radars due to their higher power-aperture performance. At S-band the nozzle exterior signature will become increasingly prominent, leading to loss of effect in the vicinity of the L-band. It is clear that these design choices were intentional and no accident. By confining proper stealth shaping technique only to the forward fuselage and inlet geometry, the designers avoided incurring the development, and to a lesser extent, the associated manufacturing costs of a fully stealthy design, with the YF-23A and F-22A presenting good comparisons.
milstar: http://advtecheng.com/uploads/ATEI_DARPA_Phase_II_OVs.pdf DARPA Phase II SBIR “Highly Integrated Silicon (Si)-based RF Electronics” for Emerging MIMO Radar
milstar: L-3 Electron Devices Offers New Ku-Band Radar Microwave Power Module SAN CARLOS, Calif., March 17, 2011 – The M28 series is an 80-watt Ku-Band Microwave Power Module (MPM) designed for airborne (-40 to +85 ̊C temp range) synthetic aperture radar (SAR) applications and is packaged in a world-class, performance-leading 7.4 x 6.25 x 1.0 form factor weighing in at less than 4 pounds. Operating in pulse mode, up to a 35% duty cycle, the MPM draws just 200 watts of 270 VDC prime power while offering excellent spectral (-50 dBc) purity. http://www2.l-3com.com/edd/pdfs/L3EDDKuMPM%20M28%20Series.pdf SAN CARLOS, Calif., March 28, 2011 – L-3 Electron Devices announced today the introduction of its new M1291 high-power density Microwave Power Module (MPM). The M1291 is capable of producing 110 watts of saturated RF output power at 33% efficiency over the 30 to 31 GHz frequency band and operates from 270 VDC prime power. A pre-distortion linearizer allows the M1291 MPM to provide 50 watts of MIL-STD-188-164 linear power with excellent spurious performance at -60 dBc. Advanced packaging techniques provide an ultracompact 9” x 8” x 2.75” form factor, which features an integrated heatsink and is available with forced air cooling for airborne operation in the -55 to +85°C temperature range. The unit is fully MIL- STD-461E compliant. http://www2.l-3com.com/edd/pdfs/L3EDDKaMPM%201291%203%2027%2011.pdf
milstar: http://www.davi.ws/skolnik/Skolnik_chapter_17.pdf http://www.turma-aguia.com/davi/skolnik/Skolnik_chapter_14.pdf
milstar: Initially, at Ka-band the MMW was capable of achieving a S/N = 17 dB (= 50) against a 1 m2 target at a range of 1,000 km (and at a 30˚ clear-weather elevation) with a single 50 μs pulse. All of the radar’s waveforms (narrowband and wideband) used a 50 μs pulse at a PRF of 2,000. http://mostlymissiledefense.com/2012/06/19/space-surveillance-sensors-millimeter-wave-mmw-radar-june-19-2012/ The upgrades to the 35 GHz capability, made over a number of years, included enhanced pulse-pulse-compression and integration capabilities, a new beam waveguide system that significantly reduced losses, and more a more powerful transmitter, including a second traveling-wave tube. The new travelling wave tubes each had a peak power of about 50-60 kW. These changes reportedly increased the MMW’s single-pulse detection range to over 2,000 km, and its tracking range (multiple pulses) to about 2,500 km. In addition, the MMW’s bandwidth at Ka was doubled to 2 GHZ, giving a range resolution of about 0.12 m. A 2001 Naval Research Laboratory report stated that upgrading the MMW radar “by equipping it with higher-power, broader-band amplifiers for increased S/N on target as well as increased radar bandwidth, is needed for TBMD and National Missile Defense (NMD) evaluation. In Ka-band, the desired output power is 100 kw peak, 20% duty factor, with 4 GHz instantaneous bandwidth.”[3] In 2005, a 4 GHz upgrade program for the MMW was begun.[4] This upgrade involved a new wider-bandwidth transmitter tube, a more sensitive receiver, improved radio-frequency hardware and a more capable signal processor, and reportedly produced a doubling of the radar’s tracking range. It doubled both the radar’s pulse length (to 100 μs) and duty factor (to 20%, corresponding to 2,000 pulses per second). The upgrade doubled the radar’s bandwidth to 4 GHz, giving a range resolution of about 6 cm. The imaging range window (which gives the maximum size object that could be imaged) was increased from 37.5 m to 63 m. ---------------------------- The upgraded radar became operational in March 2011. ------ Space Surveillance Sensors: Haystack LRIR (May 25, 2012) http://mostlymissiledefense.com/2012/05/25/space-surveillance-sensors-haystack-lrir-may-22-2012/#more-231
milstar: After 30 years of searching for an optimum set, mostmodern medium PRF modes have devolved to a range of PRFs between 8 and 20 kHzin a detection set of 8 for the time on target. 44,56–61 These PRFs are chosen to minimizerange and velocity blind zones while simultaneously allowing unambiguous resolu-tion of target range and doppler returns in a sparse target space. 62,63,64 Range blindzones are those ranges in which a target is eclipsed by the transmitted pulse. Target detec-tion requires detections in at least 3 of the 8 PRFs with all PRFs clear at maximumrange. The PRF selection criteria usually requires that the PRF set is 96% clear—inother words, at least a specified number (typically 3) of PRFs must have an abovethreshold return echo for the minimum specified target for the full specified range-doppler coverage. http://de.scribd.com/doc/17533868/Chapter-5-Multi-Functional-Radar-Systems-for-Fighter-Aircraft False alarms are a critical issue in most radar modes. These are usually suppressedfor thermal noise by constant false alarm rate thresholding, coincidence detection,and post-detection integration with frequency agility. Clutter false alarms are sup-pressed by adaptive aperture tapering, low-noise front-end hardware, wide dynamicrange A/Ds, clutter rejection filtering (including STAP), pulse compression sidelobesuppression, doppler filter sidelobe control, guard channel processing, radome reflec-tion lobe compensation, angle ratio tests (see Figure 5.37 and the “fringe region” foran example angle-ratio- test), and adaptive PRF selection
milstar: 5.18 RADAR HANDBOOK MPRF-Typical Range-Doppler Blind Map. For example, a typical MPRF setfor X band with range-doppler coverage of 150 km–100 kHz is shown in Figure 5.16.This set is for a 3 ° antenna beamwidth, ownship (i.e., the radar carrying fighter)velocity of 300 m/s, and an angle off the velocity vector of 30 ° . The PRF set is 8.88,10.85, 12.04, 12.82, 14.11, 14.80, 15.98, and 16.77 kHz. Historically, a PRF set wascalculated during design and remained fixed during deployment. Modern multifunc-tional radar computing is so robust that PRF sets can be selected in real time basedon situation geometry and look angle. The set, which generated Figure 5.16, on theaverage is clear on 5.6 out of 8 PRFs for a single target. Except for two small dopplerregions, all the PRFs are clear at maximum range, which provides maximum detec-tion and minimum loss at the design range. For some pulse compression waveforms,the eclipsing loss is almost linear and partial overlap still allows shorter-range detec-tion. Eclipsing loss is that diminishment of received power when the receiver isoff during the transmitted pulse. It is often the largest single loss in high duty ratiowaveforms. The bad news is that the average detection power loss is slightly over3 dB (see Figure 5.21)
milstar: Range-Gated High PRF. Range-gated high PRF (RGHPRF) performance isdramatically better for detection of higher speed closing targets. 44,54,55,70 (Range gatesare often smaller than range resolution cells or bins). RGHPRF produces the longestdetection range against closing low cross section targets. 71 Ultra-low noise frequencyreferences are required to improve subclutter visibility on low RCS targets even usingSTAP. Range gating dramatically improves sidelobe clutter rejection, which allowsoperation at lower ownship altitudes. Principal limitations of RGHPRF closing targetdetection performance are eclipsing (a radar return when the receiver is off during thetransmitted pulse) and range gate straddle losses (the range gate sampling time missesthe peak of the radar return). 15 Figure 5.18 shows TP i with eclipsing and straddle lossesnear maximum range for a high performance RGHPRF. This mode is optimized for lowcross section targets out to just beyond 75 km maximum range. The particular examplehas overlapping range gates to minimize straddle loss and two PRFs to allow at leastone clear PRF near maximum range. The PRFs are 101.7 kHz and 101.3 kHz. Dutyratio is 10% with 15 dB required detection SNR. Averaged over all possible target posi-tions and closing dopplers, the losses for this mode are a surprisingly small 0.4 dB.The range-doppler blind zones plot is shown in Figure 5.19 corresponding to theFigure 5.18 waveform. Compared to the medium PRF plot shown in Figure 5.16, theclear region (and corresponding losses) is dramatically better. Unfortunately, rangeis very ambiguous. Normally, a RGHPRF range-while-search (RWS) mode is inter-leaved with the highest performance velocity-search (VS) mode to range on previ-ously detected target
milstar: For example, assume V a = 300 m/s , l = 0.03 m, h = 5000 m, q = 0.5, e = 0.1, B az , B el = 0.05, U 0 , U 1 = 2.3, R swath = 2 km, R min = 32 km, desired mapping range, R 1 = 50 km,Duty max = 0.25, selecting a first guess for R p = 8000 m; then 186 < PRI < 906 µ sec,R min is the equivalent of 213 µ sec, and the next allowable ambiguity would be past theswath at 400 µ sec; therefore, a PRI of 213 or 400 µsec could be used with a transmittedpulse of approximately 50 or 100 µ sec respectively. ----------------- http://de.scribd.com/doc/17533868/Chapter-5-Multi-Functional-Radar-Systems-for-Fighter-Aircraft
milstar: http://www.ep.liu.se/ecp/008/posters/019/ecp00819p.pdf 7.6-8.6GHZ TUNABLE ACTIVE MMIC FILTER FOR AGILE ON-CHIP X-BAND RADAR RECEIVER FRONT-ENDS The filter is tunable to eight different center frequencies between 7.6-8.6GHz. Typical measured data for all eight tuning states show a maximum gain that varies between 13-26dB, a 4-5dB noise figure and a spurious-free dynamic range of 58-67dB. The presented filter could potentially be utilized as an important building block to realize agile compact on-chip receiver front-ends for future adaptive X-band radar array antennas, for example. This mixer has been designed in two versions with an IF of 1GHz and 360MHz respectively. Measured results for these two mixer circuits show that it is possible to obtain 40-50dB of image rejection when using these mixers. Thus, if a mixer of that kind is combined with a tunable bandpass filter, the requirement on filter out-of-band rejection at fimage can be reduced to 10-20dB. The tunable filter evaluated in this paper can achieve an out-of-band rejection of 22-32dB at 2GHz below fc. This corresponds to an equally high image rejection when an IF of 1GHz is assumed. According to measured front-end results (see [7]) it can achieve at least 50-85dB of image rejection and up to 13dB of conversion gain together with a 6.4dB minimum value of NF and 60-65dB of SFDR over the 7.6- 8.6GHz agile bandwidth, respectively. In the receivers of a digital beamforming antenna AD- converters with 10-14 bits are normally required [2]. The relatively high IF of 1GHz for the front-end in [7] implies a second down-converting stage will be needed, since an IF of that order is too high for today’s standard ADC’s when such a high number of bits are required. It is believed that an IF in the order of a couple of hundreds of MHz or more could in a near future (or may already) be considered low enough for 10-14 bits bandpass-sampling ADC’s. The maximum out-of-band rejection that can be achieved for the filter evaluated in this paper when we assume an IF of 360MHz varies between 12- 25dB over the agile bandwidth (see Table II). This amount of filter image rejection could be sufficiently high if we assume the filter is combined with the 360MHz-IF mixer presented in [2]. The filter could thus in such case potentially also be utilized to realize an on-chip single-stage low-noise down-converter with close to 60dB of image rejection and spurious-free dynamic range, respectively.
milstar: Sea Surface Search, Acquisition, and Track. Sea surface search, acquisition,and track are oriented toward three types of targets: surface ships, submarines snorkel-ing or near the surface, and search and rescue. Tracking may be preliminary to attack with antiship weapons. Although most ships are large radar targets, they move rela-tively slowly compared to land vehicles and aircraft. In addition, sea clutter exhibitsboth current and wind-driven motion as well as “spiky” behavior. These facts oftenrequire high resolution and multiple looks in frequency or time to allow smoothing of sea clutter for stable detection and track. 16,45 If the target is a significant surface ves-sel, then RCS might be 1000 m 2 , and a 30 m range resolution might be used for search MULTIFUNCTIONAL RADAR SYSTEMS FOR FIGHTER AIRCRAFT 5.31 and acquisition. If the target is a periscope or person in a life raft then 0.3 m resolu-tion might be used since the RCS might be less than 1 m 2 and smoothing is especiallyimportant. DPCA and doppler processing is often interleaved with traditional bright(20 dB or greater above background) target detection. Lower PRFs are usually used,which imply relatively high pulse compression ratios, as shown in Table 5.1. Scanrates are often slow with one bar taking 10 seconds.A high range resolution profile can be used to recognize a ship just as with anaircraft. 72 It naturally has the same weakness previously mentioned, and the aspector attitude must be known. If the attitude is known, then the major scatterers can bemapped into a range profile and correlated with the ship power return in each cell. Anexample of a ship range profile is shown in Figure 5.28. These profiles are usuallygenerated in track when the profile is stabilized in range ---- Inverse SAR. A far more reliable method of ship recognition is inverse syntheticaperture radar (ISAR). 16,72 The basic notion is that the motion of a rigid object can beresolved into a translation and rotation with respect to the line of sight to the target. Therotation gives rise to a differential rate of phase change across the object. The phasehistory differences can be match filtered to resolve individual scatterers in a range cell.Conceptually, such a matched filter is no different than a filter used to match a phase-coded pulse compression waveform. This is the basis of all SAR, RCS range imaging,observed geometric target acceleration, turntable imaging, and ISAR.A ship in open water exhibits roll, pitch, and yaw motions about its center of grav-ity (c.g.). For example, Figure 5.29 shows a rolling motion of ± 2.3 ° that might beexhibited by a ship in calm seas. The roll motion might have a period of 10 seconds.The motion of almost all the scatterers on a large combatant are moving in arcs of circles projected as segments of ellipses to a radar observer. 45 For a radar observer thechange in range, dR, associated with a roll movement is a function of the height, 5.32 RADAR HANDBOOK of the scatterer above the center of gravity. The approximate range rate for each scat-terer in rolling (pitch, yaw) motion at a height, h , is the time derivative of R shown inFigure 5.29. For a given desired cross range resolution with reasonable sidelobes, ∆ r c , b must be equal to ∆ r c / l . For the example, 5 ft cross range resolution is obtainablewith a 10-second observation time. The corresponding doppler and doppler rates arealso given in Figure 5.29.For a ship whose principal scatterers are less than 85 ft above the center of gravity,the dopplers will be in the range of ± 50 Hz at X band with a rate of change of up to ± 31 Hz/s. As long as the image resolution is not too great, each range-doppler bin canbe match filtered using the hypothesized motion for each scatterer and an image canbe formed on the ship. Each range bin may contain multiple scatterers from the shipin a given roll plane, and they may be distinguished by their differing phase history.However, scatterers in the pitch axis at the same range and roll height cannot be sepa-rated. Although pitch and yaw motions are slower, they also exist and allow separationin other similar planes.Reasonably good images coupled with experienced radar operators allow recogni-tion of most surface combatants. Recognition aids using prestored ship profiles allowidentification to hull number in many cases. An example of a single ISAR image of a landing assault ship is given in Figure 5.30. T the ship from the bow at 30 km and 6 ° grazing. The bright scatterers exhibit crossrange sidelobes, which can be partially reduced by sensing large returns, then apply-ing amplitude weighting and display compression, as has been done in this image.Integration of multiple ISAR images dramatically improves quality
milstar: http://publications.lib.chalmers.se/records/fulltext/129953.pdf Figure 15: Illustration of the destroyer model used in the simulations. The ship is constructed of point scatterers spaced by approximately 1 m. As inspiration for this model a typical destroyer has been used giving a ship size of about 154 m in length and 18 m in width.
milstar: To place a target in the wideband window, we first acquire the target with a continuous-wave acquisition pulse that is variable in length from 256 μsec (for short-range targets) to 50 msec (for long-range targets). An acquired target is then placed in active tracking by using 10-MHz- bandwidth chirped pulses, again of variable length, from 256 μsec to 50 msec. The wideband window is then designated to the target http://www.ll.mit.edu/publications/journal/pdf/vol12_no2/12_2widebandradar.pdf The range resolution of 0.25 m is matched by a cross-range resolution of 0.25 m for tar- gets that rotate at least 3.44° during the Doppler-pro- cessing interval. The wideband waveform is 256 μsec long and the bandwidth of 1024 MHz is generated by linear frequency modulation. The pulse-repetition frequency is 1200 pulses per second. The LRIR em- ploys a time-bandwidth exchange process similar to that of ALCOR to reduce signal bandwidth from 1024 MHz to a maximum of 4 MHz, corresponding to a range window of 120 m, while preserving the range resolution of 0.25 m. http://www.orbitaldebris.jsc.nasa.gov/newsletter/pdfs/ODQNv9i1.pdf http://mostlymissiledefense.com/category/space-surveillance-sensors/
milstar: http://www.ece.uah.edu/courses/material/EE619-2011/RadarBasics(1)2011.pdf Ambiguous range is a problem in search, but not track. In track, the radar tracking filters or algorithms have an idea of target range and can “look” in the proper place, even if the returns are ambiguous. Although the measurement of Doppler frequency is not easy, it is doable. To measure Doppler frequency the transmit pulse must be very long (in the order of ms rather than μs) or the Doppler measurement must be based on processing several pulses.
milstar: http://helitavia.com/skolnik/Skolnik_chapter_19.pdf Alternatively, the illuminator can be the transmit-only portion of a radar slaved to a tracking radar—a mechanically scanned track-while-search (TWS) ra- dar or a phased array which simultaneously maintains multiple target tracks with its electronically steered agile beam. In the third approach, where space con- straints preclude use of separate antennas, such as in a fighter aircraft, a conven- tional pulse or PD radar tracks the target and the CW illumination is injected into the transmission port of the antenna from a separate transmitter. Traditionally, the illuminator must continuously illuminate the target through- out the engagement. A system is therefore limited in its simultaneous-engagement capability by the number of available illuminators. A given illuminator must re- main dedicated to its assigned target until the missile has achieved intercept; only then can it be reassigned to another. One of the primary reasons for active seek- ers is to remove this system firepower limitation, since each missile provides its own illumination. Another approach to avoiding the one-illuminator-one-target constraint is to use sampled data and time-share one illuminator (phased array or TWS) among several missiles. quency (the spin frequency jammer). The monopulse system extracts the angular information instantaneously by comparing the difference and sum channel signals. The gain normalization can therefore be made instantaneous (fast or instantaneous AGC), and the external amplitude variations, since they affect sum and difference channels by the same relative amount, are never detected as erroneous guidance signals.
milstar: tter excitation (or drive) signal, as shown in Fig. 19.9. Active seekers, since they use a single antenna both to transmit and to re- ceive, cannot use CW because of the very limited isolation achievable. Noncoherent pulse or coherent PD waveforms have been employed, and either the central-line processing or the range-gated approach can be used for coherent operation. 4 5 17 Surface Targets. ' ' Noncoherent pulse waveforms have been widely used in active seekers designed for attacking large-cross-section surface targets. For example, in antiship applications the slow target speed prevents effective doppler resolution from clutter, but the large target reflectivity provides an effective discriminant since the target return exceeds sea clutter by several orders of mag- nitude (large signal-to-clutter ratio). Even in antitank applications, such contrast discrimination of the target can be achieved if the size of the competing clutter patch can be reduced by the use of narrow-beamwidth antennas and narrow range gates. These noncoherent systems utilize low-duty-cycle short pulses or highly coded waveforms to achieve narrow range resolution. The resolution cell is determined by the range-gate duration in the range dimension and by antenna beamwidth in the cross-range (azimuth) dimension. The resulting surface clutter return, even for rough seas and fairly severe ground reflections, will contribute much less energy than the target echo even when the target fills only a small por- tion of the resolution cell. Thus the angle information derived will be primarily from the target, because of its large contrast with respect to the clutter back- ground, and accurate homing can be achieved. It should be noted that radar cross sections of ships can be several thousand square meters, while those of tanks typ- 2 17 ically range from 25 to 125 m .
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