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Digital Beam Forming in Radar
milstar: Improvements for Air-Surveillance Radar Merrill Skolnik Systems Directorate Naval Research Laboratory Washington, D. C. 20375 http://dasl.mem.drexel.edu/Hing/Improvements%20for%20Air-surveillance%20radar.pdf L band, from 1215 to 1400 MHz, has been a popular frequency for long-range air-surveillance radar. There is also a near-by band, extending from 850 to 942 MHz, in which radar is authorized to operate. The U. S. Navy's ANEPS-49 uses this band. The initial motivation for pursuing the Senrad concept was to develop and demonstrate a radar that would be less vulnerable to electronic countermeasures than a conventional radar. For this reason, we chose to design Senrad to operate within the frequency range from 850 to 1400 MHz, a relative bandwidth of about 50% A radar, of course, is not normally allowed to operate without restrictions over such a wide bandwidth since there are other important military and civilian electromagnetic services that occupy this band. Senrad operated simultaneously within the 1215-1400 MHz band and the 850-942 MHz band to demonstrate capabilities not available with conventional narrow- band air-surveillance radars systems. ---------------------- Naval Research Laboratory Systems Aspects of Digital Beam Forming Ubiquitous Radar MERRILL SKOLNIK Systems Directorate June 28, http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA403877&Location=U2&doc=GetTRDoc.pdf ----------------------------------- smotri gl. 2.13 M.Skolnik ,Radar izdanie 2008 goda http://www.scribd.com/doc/49249408/0071485473-Radar-Handbook3rd 2.13 Dynamic Range and A/D convesion cosiderations ----------------------------------- Dynamic Range and Stability requirement 4.24 ADC in Doppler radar http://www.scribd.com/doc/49249408/0071485473-Radar-Handbook3rd ...The most stressing dynamic range requirement is due to main beam clutter ,when searching for small low flying target ------------------------------------------- example 4.15 C/N 53 db na wisote RLS 1000 fut/300 metrow trebuetsja 12 bit dlja 63 db -------------------------------- 5.12 Glawa 5 Merrril Skolnik 2008 goda MULTIFUNCTIONAL RADAR SYSTEMS FOR FIGHTER AIRCRAFT 1.Real beam map 0.5 -10 mgz 2.Doppler beam sharp 5-25 mgz 3. SAR 10 -500 mgz 4.A-S range 1-50 mgz 5.PVU 1-10 mgz 6.TF/TA 3-15 mgz 7.Sea surface search 0.2 -500 mgz 8.Inverse SAR 5-100 mgz 9. GMTI 0.5-15 mgz 10.Fixed target track 1-50 mgz 11.GMTT 0.5 -15 mgz 12.Sea Surface track 0.2-10 mgz 13.Hi power Jam 1-100 mgz 14.CAl/A.G.C 1-500 mgz 15A-S data link 0.5-250 mgz -------------------------------------
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milstar: heterodyne Proven and trusted High performance Optimum spurious High dynamic range EMI immunity ------------ SWaP Many filters =================== direct conversion Maximum ADC bandwidth Simplest wideband option ---------- mage rejection I/Q balance In-band IF harmonics LO radiation EMI immunity (IP2) DC and 1/f noise ================ https://www.analog.com/en/technical-articles/advanced-technologies-pave-the-way-for-new-phased-array-radar-architectures.html The superheterodyne approach, which has been around for a hundred years now, is well proven and provides exceptional performance. Unfortunately, it is also the most complicated. It typically requires the most power and the largest physical footprint relative to the available bandwidth, and frequency planning can be quite challenging at large fractional bandwidths. The direct sampling approach has long been sought after, the obstacles being operating the converters at speeds commensurate with direct RF sampling and achieving large input bandwidth. Today, converters are available for direct sampling in higher Nyquist bands at both L- and S-band. In addition, advances are continuing with C-band sampling soon to be practical, and X-band sampling to follow. Direct conversion architectures provide the most efficient use of the data converter bandwidth. The data converters operate in the first Nyquist, where performance is optimum and low-pass filtering is easier. The two data converters work together sampling I/Q signals, thus increasing the user bandwidth without the challenges of interleaving. The dominant challenge that has plagued the direct conversion architecture for years has been to maintain I/Q balance for acceptable levels of image rejection, LO leakage, and dc offsets. In recent years, the advanced integration of the entire direct conversion signal chain, combined with digital calibrations, has overcome these challenges, and the direct conversion architecture is well positioned to be a very practical approach in many systems. Here at Analog Devices, we are continually advancing the technology for all the signal chain options described. The future will bring increased bandwidth and lower power, while maintaining high levels of performance, and integrating complete signal chains in system on chips (SoC), or system in packages (SiP) solutions.
milstar: High-Dynamic-Range Receivers for Digital Beam Forming Radar Systems https://ieeexplore.ieee.org/document/4250284 In principle, a DBF system with N receivers should attain a signal-to-noise ratio (SNR) improvement of N over that of a single receiver system, assuming the noise is decorrelated in all the receiver channels. However, the total single and two-tone, spur-free dynamic range (SFDR) may not achieve the N-fold improvement if errors and distortion in the system are correlated. ################# The receiver had two down-conversion stages from the S-Band range input (2.7 GHz to 3.7 GHz) to 75 MHz for operation in the second Nyquist zone using a 14-bit ADC sampled at 100MHz. The instantaneous receiver bandwidth was about 15 MHz, set by an anti-aliasing filter placed at the ADC input. A survey of five mixer candidates was conducted by measuring their spur levels. Lowest (−127dBc)5×4 spurs were obtained for mixer SM5TH by M/A-COM. The ADC increases the system noise figure by design, depending on the gain configuration. The ADC affects the output SNR significantly. The maximum output signal is limited by the ADC saturation, which is well below the saturation (OTOI −10 dB) of the analog portion of the receiver.
milstar: SystemsAspectsofDigitalBeamFormingUbiquitousRadarMERRILLSKOLNIKSystemsDirectorat NavalResearchLaboratory https://pdfs.semanticscholar.org/2cf7/6259bfcfeff6cc013278024f050f42892f48.pdf
milstar: Examples of Boeing satellite communications phased arrays employing analog beamforming are the 24-beam dual- polarized Ka-band transmit phased array developed for Spaceway [9], the 8-beam X-band transmit and receive phased arrays developed for the Wideband Global Satcom (WGS) program [10], and the multibeam S-band transmit and receive phased arrays developed for NASA’s Telemetry and Data Relay Satellites (TDRS) [11]. Additional examples are the 2-beam Ka-band transmit and receive phased arrays operating on the WINDS satellite [12], and the 16-beam L-band transmit/receive phased array antennas used on the Iridium satellites [13]. https://ieeexplore.ieee.org/document/7389972 DBF is also reportedly used in the 64-element X-band active receive antenna system (ARAS) on Skynet 5 [16], [17], which is an operational satellite providing military satellite communications (Milsatcom) for the United Kingdom. Extension of DBF to arrays operating at higher frequencies, or having broader instantaneous bandwidth and/or more radiating elements has not been possible until recently due to limitations of sample rate and power consumption.
milstar: This ability to organize various antenna patterns at the same time has only become possible with the technology of a digital receiver, because only digital signals can be copied any number of times without loss. In practice, the received signal is converted into an intermediate frequency and then digitized at once. At an IF of 75 MHz, the analogue to digital converter requires a sampling frequency of 100 MHz. http://www.idc-online.com/technical_references/pdfs/electronic_engineering/Digital_Beamforming.pdf ------------- po критериям NASA в 4 раза больше ,иначе ухудшаются динамические характеристики усложняется конструкция фильтров ,что ведет к ухудшению линейной и фазовой характеристики AD9467 259 msps ,SFDR 86-100 dbfs at 97-170 mhz AD9625 2-2.6 GSPS ,SFDR 80 dbc at 1 ghz
milstar: Direct RF/IF sampling in radar front ends offers several advantages compared to analog signal processing. First and foremost, it can enable a reduction in the number of components required, when an entire frequency downconversion stage can be eliminated (Fig. 3). Direct sampling also removes the need to design a frequency mixer for a uniquely tailored frequency plan. It can simplify the design of next-generation receivers for future signal bandwidths that become available as radar systems are modernized and updated. https://www.mwrf.com/technologies/mixed-signal-semiconductors/article/21846697/process-wide-bandwidths-in-aerospacedefense-systems
milstar: https://www.analog.com/media/en/technical-documentation/tech-articles/Review-of-Wideband-RF-Receiver-Architecture-Options.pdf A Review of Wideband RF Receiver Architecture Options
milstar: 1. Географические климатические условия Гибель Испанской армады потеря флота Хубилая при попытке высадки в Японию «Божественный ветер» будет бушевать двое суток, сметая всё на своём пути Жесткие требования мореходности ( 9000 т для консервативного проекта, нe с малой площади ватерлинии жесткие требования выбора диапазонов РЛС L 750-1250 mhz и X 7600-8400 mhz 2. РЛС диапазона L лучше в условиях плохой погоды для обнаружения малозаметных низколетящих крылатых ракет требует меньше компонентов для апертуры с полным заполнением, легче удовлетворить требования пo отводу тепла и компоненты более дешевы недостаток большая площадь апертуры,однако этот диапазон используется на фрегатах водоизмещением 4100 тонн AN/SPS-49 7.3 m × 4.3 m https://en.wikipedia.org/wiki/AN/SPS-49 в самолете СУ-57 ( площадь апертуры еще меньше ) 3. для сдвоенной апертуры (как в ФРЕГАТ-М2 ) Источник: http://bastion-karpenko.ru/fregat-m2em-rls/ ВТС «БАСТИОН» A.V.Karpenko с размерами 7.3 m × 4.3 m для АФАР с полным заполнением 1000 mhz h/2 =150 mm потребуется 2*49*30 э=2940 элементов 4. концепция повсеместного(ubiquitous ) радара Naval Research Laboratory https://apps.dtic.mil/dtic/tr/fulltext/u2/a403877.pdf имеет ряд преимуществ пo сравнению с классической АФАР 5. в случае использования супергетеродина с 2 преобразованиями частоты 490 mhz ,70 mhz как в Радаре Cobra Dane https://fas.org/spp/military/program/track/cobra_dane.htm может быть реализована на "отечественных" аналого-цифровых преобразователях https://mri-progress.ru/products/bis-i-sbis/spetsialnye-sbis/sbis-16-razryadnogo-atsp/ СБИС 16-разрядного АЦП конвейерного типа с частотой дискретизации 200 МГц изготовлена по КМОП 90-нм технологии и предназначена для аналого-цифрового преобразования диффе- ренциальных аналоговых сигналов. В микросхеме реализован алгоритм встроенной калибров- ки передаточной характеристики. Функциональный аналог ADS5485 фирмы Texas Instruments. https://mri-progress.ru/products/all-lists/K5111HB015.pdf ############################################################### 6. в случае использования AD9625 12 bit 2-2.6 GSPS SFDR 80dbc возможен отказ от супергетеродина и смесителей RF Sampling NLEQ добавит 10 db to 80 dbc https://www.analog.com/media/en/technical-documentation/tech-articles/Review-of-Wideband-RF-Receiver-Architecture-Options.pdf https://archive.ll.mit.edu/HPEC/agendas/proc09/Day2/S4_1405_Song_presentation.pdf https://dspace.mit.edu/bitstream/handle/1721.1/119717/1078637048-MIT.pdf?sequence=1&isAllowed=y ad9625 2-2.6 GSPS SFDR 80 dbc at 1000 mhz NLEQ добавит 10 db это уже приличный результат для радара с полностью цифровым формированием луча ############################################# 7. AD9625 price 642$ per 1 https://www.analog.com/en/products/ad9625.html#product-overview https://www.analog.com/media/en/technical-documentation/data-sheets/AD9625.pdf The AD9625 architecture includes two DDCs, each designed to extract a portion of the full digital spectrum captured by the ADC. Each tuner consists of an independent frequency synthesizer and quadrature mixer; a chain of low-pass filters for rate conversion follows these components. Assuming a sampling frequency of 2.500 GSPS, the frequency synthesizer (10-bit NCO) allows for 1024 discrete tuning frequencies, ranging from −1.2499 GHz to +1.2500 GHz, in steps of 2500/1024 = 2.44 MHz. The low-pass filters allow for two modes of decimation. A high bandwidth mode, 240 MHz wide (from −120 MHz to +120 MHz), sampled at 2.5 GHz/8 = 312.5 MHz for the I and Q branches separately. The 16-bit samples from the I and Q branches are transmitted through a dedicated JESD204B interface. A low bandwidth mode, 120 MHz wide (from −60 MHz to +60 MHz), sampled at 2.5 GHz/16 = 156.25 MHz for the I and Q branches separately. The 16-bit samples from the I and Q branches are transmitted through a dedicated JESD204B interface. 8. примеры различных РЛС диапазона L Su-57,Cobra Dane ,FPS-117, Gamma DE,AN/SPS-49,Protivnik ,smart-l mm http://ausairpower.net/APA-Rus-Low-Band-Radars.html#mozTocId829681 https://lockheedmartin.com/content/dam/lockheed-martin/rms/documents/ground-based-air-surveillance-radars/FPS-117-fact-sheet.pdf https://www.radartutorial.eu/19.kartei/01.oth/karte003.en.html https://www.thalesgroup.com/en/smart-l-mm
milstar: https://techtime.news/2018/01/15/analog-devices-phased-array-radar/ The Way to a New Phased Array Radar Architecture 15 January, 2018 Sponsored Article: Digital beamforming phased arrays are now common, and rapid proliferation is expected with a huge range of frequencies and architectures being developed from L-band through to W-band
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