Радиоэлектронная разведка

Форум » Дискуссии » Радиоэлектронная разведка » Ответить

Радиоэлектронная разведка

milstar: 8 The mono-pulse or sum-difference RDF technique uses two antennas. The antennas are connected to a four-port combiner 180° hybrid that generates a sum and difference signal. Such sum and difference patterns are generated by means of closely spaced overlapping radiation patterns at boresight. These signals form sum and difference radiation patterns. The ratio of the sum and difference signals and knowledge of the sum and difference patterns are used to determine the direction of the transmitter. Phase information is used to determine on which side of the sum pattern the transmitter is. An advantage of this system is in its capability to determine the direction of a transmitter after receiving one pulse. Such pulse could be a mere few microseconds. Accuracies of 10meter over a 100Km distance has been reported. ------------------------------------------------------------- https://www.alarisantennas.com/wp-content/uploads/2020/12/An-Introduction-to-Radio-Direction-Finding.pdf https://www.alarisantennas.com/blog/an-introduction-to-radio-direction-finding/ --------------------------------------------------------------------------- Precision Receiver Inc. Precision Receivers Incorporated (PRI) New technology PRI has introduced proprietary technology to reduce spurious responses in analog to digital converter systems. All ADCs have quantization and timing errors creating spurs in the outputs of ADCs. These spurs degrade the sensitivity of Cellular, SIGINT, COMINT, ELINT and EW systems. Many schemes have been implemented to mitigate these problems such as clock dithering, but the schemes have tradeoffs and consequences including a reduction in the dynamic range of a system. PRI’s technology reduces the magnitude of all the spurs across the IF bandwidth and over the entire RF input bandwidth, nearly the entire Fs/2 as well as all the Nyquist zones. Figure 2 (next page) shows the ENOB performance of PRI’s new technology, current ADC chips and a competitor’s digitizer board. Figure 3 shows the SNR performance of PRI’s new technology. Existing competitive 2.5 GSPS systems struggles to achieve 10 effective bits or ENOB. PRIs technology achieves almost 11.5 bits of ENOB. Increased performance will serve to enhance future systems and PRI’s technology allows for an easy upgrade to existing platforms. Other BW’s are available as well as other clock rates and more ruggedized formfactors are being developed. Precision Receivers Incorporated Introduces 1st HDRR Receiver The HDRR-3.6G-12B is a single-channel signal collection and recording system incorporating PRI proprietary technology to reduce spurious responses in the analog to digital converter. The system collects and records signals across a large (>1GHz) BW. HDRR technology is described as the industry’s most effective way to improve the performance of direct-sampled receivers employed in electronic warfare, radar, signals and communications intelligence, spectrum monitoring, and wireless communications systems. HDRR technology provides an order-of- magnitude improvement in reducing unwanted spurious signals to levels previously unachievable using other methods and increases spurious-free dynamic range (SFDR) by up to 16 dB. HDRR-3.6G-12B PRI Inc 4111 Rutledge Ln, Marshall, VA 20115 Phone (202) 773-4252 info@precisionreceivers.com www.precisionreceivers.com Precision Receiver Inc. Precision Receivers Incorporated (PRI) New technology PRI has introduced proprietary technology to reduce spurious responses in analog to digital converter systems. All ADCs have quantization and timing errors creating spurs in the outputs of ADCs. These spurs degrade the sensitivity of Cellular, SIGINT, COMINT, ELINT and EW systems. Many schemes have been implemented to mitigate these problems such as clock dithering, but the schemes have tradeoffs and consequences including a reduction in the dynamic range of a system. PRI’s technology reduces the magnitude of all the spurs across the IF bandwidth and over the entire RF input bandwidth, nearly the entire Fs/2 as well as all the Nyquist zones. Figure 2 (next page) shows the ENOB performance of PRI’s new technology, current ADC chips and a competitor’s digitizer board. Figure 3 shows the SNR performance of PRI’s new technology. Existing competitive 2.5 GSPS systems struggles to achieve 10 effective bits or ENOB. PRIs technology achieves almost 11.5 bits of ENOB. Increased performance will serve to enhance future systems and PRI’s technology allows for an easy upgrade to existing platforms. Other BW’s are available as well as other clock rates and more ruggedized formfactors are being develop https://precisionreceivers.com/wp-content/uploads/2021/04/HDRR-3.6G-12B-Product-Sheet.pdf ############# SIGINT Direction finding comparsion Time Difference of Very High Precision, Very Complex, At Least 3 Aircraft; High Quality Arrival (Pulsed Signals) https://www.phys.hawaii.edu/~anita/new/papers/militaryHandbook/sig-sort.pdf WPI MQP Group: Daniel Guerin - ECE Shane Jackson - Physics Jonathan Kelly - CS/ECE Phase Interferometry Direction Finding Lincoln Laboratory https://web.wpi.edu/Pubs/E-project/Available/E-project-101012-211424/unrestricted/DirectionFindingPresentation.pdf Passive Direction Finding [DF] Techniques – DTOA (Difference Time of Arrival) Comparison Written By Riccardo Ardoino The Time-Of-Arrival (TOA) comparison measurement can be done with a two antennas receiver, a third antenna is used to eliminate ambiguity, and four antennas are used to cover 360° in Azimuth. Assuming two antennas at distance “B” between them (order 10m). Assuming incident radiation from the emitter >> B (≈ Infinite). The difference in Time of Arrival observed at the two antennas is ∆TOA, with ∆R = B x sin (DOA) equal to the optical path difference. https://www.emsopedia.org/entries/passive-direction-finding-df-techniques-dtoa-difference-time-of-arrival-comparison/

Ответов - 76, стр: 1 2 3 4 All

milstar: https://www.lockheedmartin.com/content/dam/lockheed-martin/rms/documents/electronic-warfare/AN-ALQ-217-brochure.pdf The Lockheed Martin AN/ALQ-217 Electronic Support Measures (ESM) system functions as the highly sophisticated ears of advanced tactical aircraft. As a passive sensor system, the AN/ALQ-217 protects the warfighter by identifying and locating sources of radio frequency (RF) emission and providing a full range of ESM operation The AN/ALQ-217, found on the U.S. and international Navy’s E-2C and new E-2D Advanced Hawkeye aircraft, offers the warfighter these significant attributes: • Unparalleled performance in dense littoral and open ocean environments • Adaptable system performance allows for dynamic user prioritization and mission customization • Hardware and software easily tailored to new platforms • Fast reaction time helps increase survivability of strike force

milstar: There are several examples of SIGINT attacks in recent events. One of the most common techniques used in attacks is satellite-based eavesdropping. This technique was used in 2009 by Iraqi hackers to eavesdrop on the video data from the Predator U.S. drone that was being transmitted to the central unit. The most notable aspect was that a $26 software package (the Russian SkyGrabber) was able to hack a U.S. drone transmitting sensitive information, showing the importance of proper SIGINT implementation. https://www.mpdigest.com/2022/08/22/using-sdrs-for-signals-intelligence-sigint/

milstar: 28 October 2022 Rohde & Schwarz (R&S) has developed a mobile system to provide electronic warfare awareness training and support for ground force exercises, which it provides as a training service to the US Marine Corps (USMC) at the Marine Corps Air Ground Combat Centre (MCAGCC) at 29 Palms in California. The SigBadger system consists of two vehicles, each with signals intelligence (SIGINT) capability. According to R&S documentation, this consists of direction finding (DF) and geolocation in the 300 kHz–6 GHz frequency band; signal analysis and spectrum monitoring of more than 300 kHz–26.500 GHz; and electronic intelligence (ELINT) of more than 20 MHz–40 GHz. The two vehicles have identical capabilities but only one is manned by operators, who exercise remote control over the equipment, in the other vehicle, which only needs a driver. R&S showcased the SigBadger capability at the Association of the United States Army (AUSA) 2022 annual convention in Washington, DC, in October, displaying the control vehicle, which contains a suite of intercept and analysis equipment plus two operator workstations. The vehicle is equipped with a R&S DDF550 wideband DF along with a further receiver and has two R&S ADDx multichannel DF antennas, one mast- and the other roof-mounted. The DDF550 provides a high DF-scan speed with an 80 MHz real-time bandwidth, giving a high probability of intercepting and locating short-duration and frequency-agile signals. It is integrated with the R&S CA120 multichannel signal analysis software, which provides automatic multichannel detection, classification, demodulation, and decoding of signals.

milstar: Traditionally, a SIGINT system requires special-purpose hardware (both RF and digital) and custom-design algorithms to rapidly and reliably detect targeted signals of interests known a priori. However, recent advances in wireless communications across the globe, especially low-cost software defined radios and their wide availability, readily allow our adversaries to devise and dynamically change communication schemes and patterns that are inherently much harder to detect using such conventional SIGINT means. Consequently, a new SIGINT system is needed that can process in as near real-time as possible a wideband spectrum (500 MHz+) --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- that will likely contain a mix of known and well-behaved signals as well as unknown signals with unpredictable properties and behaviors. We propose to develop, implement, and demonstrate a novel High-speed, dynamically Reconfigurable Signals Intelligence (HiReS) system with minimal latency based on COTS Digital Signal Processing (DSP) hardware base to simultaneously handle 100s of diverse, possibly overlapping signals for multi-functional situational awareness. The innovations of the proposed HiReS system consists of: (i) robust, computationally efficient signal acquisition and classification algorithms friendly to parallel processing hardware architecture; and (ii) highly parallelized COTS-based signal processing hardware platforms based on a mix of FPGAs, DSPs, and GPUs.

milstar: Home ProductsAerospace | Defense | SecurityRadiomonitoringReceivers and direction findersR&S®PR200 Portable monitoring receiver R&S®PR200 Portable monitoring receiver Detect, analyze and locate RF signals from 8 kHz to 8 GHz (20 GHz with R&S®HE400DC and 33 GHz with R&S®HE800-DC30) Extensive preselection filtering and automatic overload protection Comprehensive tool for frequency and time domain analysis with up to 40 MHz real-time bandwidth High-speed panorama scan with up to 60 GHz/s over the entire frequency range Optimized for demanding field operations with an intuitive application-oriented user interface and minimal size, weight and power consumption https://scdn.rohde-schwarz.com/ur/pws/dl_downloads/pdm/cl_brochures_and_datasheets/product_brochure/3606_9591_12/MP007_bro_en_3606-9591-12_v0600.pdf

milstar: https://scdn.rohde-schwarz.com/ur/pws/dl_downloads/premiumdownloads/premium_dl_brochures_and_datasheets/premium_dl_whitepaper/DF-accuracy-requirements-for-monitoring-stations_wp_en_3609-9840_52_v0100.pdf

milstar: Frequency range from 8 kHz to 40 GHz (base unit from 20 MHz to 18 GHz) Up to 2 GHz real-time bandwidth and scan speeds of up to 2500 GHz/s 8 DDC channels including pulse analyzers within real-time bandwidth Processing of up to 1 million pulses per second Simultaneous processing and analysis of data in time and frequency domain https://www.rohde-schwarz.com/us/products/aerospace-defense-security/elint/rs-wpu2000-wideband-processing-unit_63493-833006.html

milstar: https://www.researchdive.com/5478/signals-intelligence-sigint-market

milstar: Resolution bandwidth For basic spectrum measurements, resolution bandwidth is, by far, the most important setting. Most spectrum analyzers use heterodyne based analyzers to measure spectrum by sweeping across a span. The trace showing power versus frequency is drawn from left to right, usually repeatedly. One way to help understanding resolution bandwidth is to think of it as a window that moves across the span, measuring the level as it goes. Anyhow the resolution bandwidth filter or window isn’t square but has a Gaussian or similar shape. The window also doesn’t move, the spectrum is slid past the window instead. The result is the same, and many RF engineers do think of resolution bandwidth as a moving window or filter that crosses a span. Resolution bandwidth affects is the ability to separate or resolve closely spaced signals. Two narrow signals can only be separated, if the resolution bandwidth is smaller than the distance between these two signals. If a wider resolution bandwidth is used, both signals are covered by the filter as it sweeps past, and they appear as a single signal in the trace. https://www.rohde-schwarz.com/us/products/test-and-measurement/essentials-test-equipment/spectrum-analyzers/understanding-basic-spectrum-analyzer-operation_256005.html Average noise level Another aspect of resolution bandwidth is the effect it has is on noise. More specifically, resolution bandwidth affects the noise floor, also referred to as displayed average noise level, or DANL. The noise floor rises or falls depending on the chosen resolution bandwidth. What happens to the noise floor when the resolution bandwidth is decreased? As an example, a simple CW signal and a rather large span of 2 GHz is used. With a resolution bandwidth of 3 MHz, the average value of the noise floor is approximately -73 dBm Narrowing the resolution bandwidth to 300 kHz, drops the noise floor to – 84 dBm At an RBW of 30 kHz, the noise floor falls again to -93 dBm At RBW equals 3 kHz, the noise floor has an average value of -104 dBm. Resolution bandwidth and sweep time Lowering the resolution bandwidth provides better signal separation and lower noise, so why not always use the lowest possible resolution bandwidth? Resolution bandwidth is essentially a filter, and narrow filters take a longer time to settle, or get a stable result, compared to wider filters. This means sweeping slows down when using smaller resolution bandwidths in order to get accurate results. Sweeping too quickly leads to both amplitude and frequency errors. The main factor determining the sweep time of a spectrum analyzer is the resolution bandwidth. What’s the right sweep time? Most analyzers automatically compute sweep time based on resolution bandwidth and span. This setting can be overridden but decreasing the automatically calculated sweep time is usually not a good idea. The optimal resolution bandwidth is almost entirely a function of the signal being measured, and often must be determined by experimentation. There is a trade-off between speed and selectivity / noise. On most spectrum analyzers, not any arbitrary value for resolution bandwidth can be chosen, but can be selected in certain steps, e.g. 1 kHz, 3 kHz, 10 kHz, 30 kHz. Video bandwidth The last basic parameter is video bandwidth. To understand video bandwidth, the term video signal must be explained. Traces are essentially an envelope of the power at individual frequencies, and this envelope is called the video signal. It’s named video since, in the old days, this signal was applied to the vertical deflection of a cathode ray tube in order to draw a video trace on the screen. In modern spectrum analyzers, video bandwidth is a filter used to average or smooth out the displayed trace. Unlike resolution bandwidth, video bandwidth only affects how the signal is displayed, not the way it is measured or acquired. Lowering video bandwidth at a video bandwidth of 200 kHz a fair amount of noise can be seen on the signal. This noise is reduced, when the video bandwidth is lowered to 20 kHz, and decreases even further when video bandwidth is lowered to only 2 kHz. Lowering video bandwidth only reduces noise on the trace, it does not drop the noise floor like resolution bandwidth does. It also doesn’t improve the ability to resolve or separate closely based signals.

milstar: The original design brief was to achieve a receiver capable of scanning a band from 100 kHz to 6 GHz in less than 1 second. The additional requirements were: an instantaneous bandwidth of up to 20 MHz; a final IF suitable for feeding a digital receiver with around 100 Msps sample rate; a minimum signal sensitivity of -107 dBm and; a dynamic range of at least 80 dB. https://www.armms.org/media/uploads/1304696513.pdf 8 Figure 10 is a side view, showing more clearly the board interconnections and the various coaxial inputs and outputs. Finally, Figure 11 is a view of the Filter Board (screen lid removed) showing the very compact, low cost design – 14 separate switched filters on a board 103mm x 65mm x 7mm. CONCLUSIONS The overall performance objectives were met comfortably in all respects, with the possible exception of static spurs. These have, however, been reduced to below the specified level by the method of off- tuning the 1st and 2nd LO’s described above. The overall size of 165mm x 103mm x 25mm (6.5” x 4” x 1”) and the power consumption of approx 7 Watts at +9v allowed the end customer to stay well within his size and power constraints. The scan time from 100 kHz to 6 GHz in 20 MHz steps was well under 1second. Finally, the production cost target of sub £1000 was, originally, met comfortably although recent weakening of Sterling has affected this somewhat due to components priced in USD.

milstar: Figure 3. Improved frequency plan: The IF harmonics are outside the IF band, which means the image filtering is realizable. Figure 3 shows a comparison when the same RF operating band is sampled in the 2nd Nyquist zone. The higher IF frequency results in the image frequency that is much further away from the operating band and the RF image filters are significantly easier to implement. In addition, any harmonics created in the IF amplifiers can be filtered by the antialiasing filter and the only IF harmonics that will be created are the ones inside the ADC itself. In general, a higher IF frequency in the 2nd or 3rd ADC Nyquist zone is preferred from a spurious perspective. We will outline the benefits by first showing a frequency plan translating a 10 GHz operating band to the 1st Nyquist of a 3 GHz ADC, then show the benefits when operating in the 2nd Nyquist zone. https://www.analog.com/en/technical-articles/28-nm-adcs-enable-next-gen-electronic-warfare-rec-sys.html Figure 2 shows the frequency translation of a 1 GHz operating band at 10 GHz to the 1st Nyquist zone of a 3 GSPS ADC. Two primary issues are illustrated. First, the RF image frequency is very closely spaced to the operating band requiring a very difficult filter for image suppression. Second, any IF created from the IF amplification stages are in-band and unable to be filtered by the antialiasing filter. Realizing New Receiver Architectures Heterodyne receiver architectures are well understood and have been proven over many years. Historically, many microwave receivers have been implemented with dual downconversion architectures. With the ADCs available in previous generations, the large ratio of operating band frequencies to ADC input frequencies made image filtering impractical with a single downconversion receiver architecture. New ADCs increasing in both sample rate and analog input bandwidth now make high performance wideband single downconversion architectures practical and easily realizable. An example single downconversion receiver architecture is shown in Figure 1. The front-end LNA is chosen for noise figure performance. If needed, a limiter is added in front of the LNA to increase the survive power capability of the front end. An operating band filter is next to attenuate out-of-band interference. Next, additional gain and/or gain control can be added as needed. Prior to the mixer, a low-pass filter can reduce RF harmonics that add to mixing spurious output. The mixer is a critical building block and chosen to optimize performance in the frequency translation bands of interest. Another low-pass filter following the mixer filters upper sidebands prior to amplification. Additional IF gain is added as needed. The anti-aliasing filter is typically the final component prior to the ADC and rejects any frequencies that can fold in band through the sampling process. The ADC is next and, although it is last in the chain, is typically the first component chosen while the rest of the receiver is built around the ADC. As high speed ADCs continue to push to higher sample rates, bit depths, and bandwidth, integrating DDCs and ADCs becomes more attractive to wideband EW receiver system designers since the enormous amount of digital data from the ADC can become difficult to process with a low SWaP processor. For more information on DDCs and some practical examples, please see “What’s Up with Digital Downconverters” Part 1 and Part 2 by Jonathan Harris.

milstar: A common question is “how much instantaneous bandwidth can I achieve with the highest spurious-free dynamic range (SFDR)?” For a direct RF sampling architecture, this question can be interpreted as “how much instantaneous bandwidth can I achieve while avoiding HD2, HD3, and their alias products?” https://www.analog.com/en/technical-articles/considering-gsps-adcs-in-rf-systems.html https://www.analog.com/media/en/technical-documentation/tech-articles/considering-gsps-adcs-in-rf-systems.pdf The AD9082 is a state-of-the-art, direct RF sampling transceiver with two 6 GSPS ADCs and four 12 GSPS digital-to-analog converters (DACs). For the pur- pose of this analysis, the focus is only on the ADCs. https://www.analog.com/en/products/AD9082.html As the decimation increases, performance improvements for both SFDR and SNR are observed. For SFDR, the increases are obtained by filtering out the HD2 prod- uct. As decimation increases from 2× to 4×, the HD2 product falls out of band and is digitally filtered out. For decimation from 8× to 16×, the HD3 product falls out of band and is digitally filtered out. For all decimation settings above 8× the SFDR of the AD9082 is roughly 100 dB or higher. In a wideband mode, the AD9082 can achieve SNR of ~56 dBFS and SFDR of ~70 dBc, and through a software reconfiguration to a narrow-band mode the AD9082 can achieve SNR of ~73 dBFS and SFDR of ~105 dBc. That flexibility between narrow-band and wideband modes while maintaining best-in-class performance in both is unique to devices like the AD9082. It also requires that the engineering team designing these direct RF sampling transceivers consider many aspects of receiver design while optimizing the radio design.

milstar: Figure 4. The AD9082 with decimation set to 96×. Measured SNR is 72.8 dB and measured SFDR is 105 dB. SNR is a more linear improvement, as the decimation filters reduce the amount of integrated noise for the receiver chain. With no decimation, the SNR is 56.4 dBFS; at 8× decimation, the SNR is 63.5 dBFS; and at 96× decimation, the SNR is 72.8 dBFS. As a point of comparison, best-in-class data converter performance for ~100 MSPS devices like the AD9467 and LTC2208 is an SNR of 75 dB and an SFDR of 100 dBc. This class of performance has long been required by the heterodyne signal chains in which ADCs like the AD9467 were commonly used. The AD9082 can achieve the same noise and dynamic range, while eliminating the heterodyne signal chain size, weight, power, and cost—and it is also able to scale to much higher instantaneous bandwidths as required! https://www.analog.com/media/en/technical-documentation/tech-articles/considering-gsps-adcs-in-rf-systems.pdf

milstar: https://spacenews.com/northrop-grumman-army-testing-new-sigint-payload-uavs/ 2010 The CSS-1500 payload is designed to replace currently fielded signals intelligence systems and was developed entirely with internal funds, Carter said. The unit utilizes 15 processors to create six channels that scan the entire radio frequency communications spectrum six times each second,

milstar: SIGINT operational activities, on the basis of the emitted electromagnetic signals, sent by, for example, the enemy communication systems. A single kit, along with the relevant hardware, is not to weigh more than 9 kilograms. The system is also going to be tailored to being mounted on vehicles, it should also be operable in a stationary setting, within the framework of a surveillance and tracking outposts network, at night and during the day. The backpack SIGINT package is expected to be capable of covering the bandwidth between 20 MHz – 8 GHz, with the bandwidth of 3 MHz – 8 GHz defined as the preferred one. The operational temperature range requirement has been set between -10 and +40 degrees Celsius. 2017 https://defence24.com/portable-sigint-kit-for-the-army-new-equipment-for-the-territorial-defence-forces

milstar: HPack Full On-the-Move (OTM) & At-the-Halt (ATH) Manpack Collection & Geolocation Solution Radio: HTLx-T2 Wideband Transceiver 2 MHz - 18GHz Rx/Tx 4 Independent or Phase Coherent Channels 80 MHz IF Bandwidth per HPack Channel USB Control & COTS MANET Interfaces / Config-C Compliant User Interface via Rugged Windows Tablet https://www.herricktechlabs.com/htl-products-and-solutions/mission-solutions/ https://www.herricktechlabs.com/htl-products-and-solutions/htl-core-radios/ HTLx2-U Small Form-Factor Multichannel VHF/UHF/Microwave Transceiver The HTLx2-U is a 4 channel Software Defined Radio designed to support various missions. Extended frequency range 2 MHz-20,000 MHz. 100 MHz instantaneous BW/channel, 400 MHz total Herrick Technology Laboratories Inc. (HTL) is a leading provider of high performance, SIGINT/EW/Communications products and systems to the US Department of Defense. HTL designs and manufactures integrated hardware and software products and systems implemented through a Core Software Defined Radio (SDR) platform. The SDR platform incorporates high performance, multi-channel RF and Microwave receive and transmit (transceiver) functionality along with mission specific firmware/software applications. HTL products are deployed in demanding mission environments, requiring best in class SWaP-C (Size, Weight and Power - Cost). https://www.herricktechlabs.com/about/company-overview/ HTLw-U Small Form-Factor Multichannel HF/VHF/UHF/Microwave Transceiver The HTLw-U is a 4 channel Software Defined Radio designed to support various missions. Extended frequency range 2 MHz-18 GHz with 1 GHz IFBW per channel (4 GHz total coverage)

milstar: In this letter, a three-step approach is proposed to achieve an accuracy below 0.1° RMSE. At first, the condition of the value of the maximum phase-different error required to resolve the ambiguity is obtained. Next, the method to obtain an unambiguous array spacing with the maximum phase difference error for multiple-element array is presented. Finally, the set of the array spacing having both the long baseline for satisfying the required DF accuracy and the maximum phase-different error for appropriately resolving the ambiguity is selected. The simulation results show that a DF accuracy of less than 0.1° RMSE can be achieved by using a set of array spacing with five-element arrays in a wide range of frequencies. https://www.onacademic.com/detail/journal_1000040234113210_8106.html

milstar: To obtain accurate emitter location data in electronic warfare (EW) applications, high direction-finding (DF) accuracy on the order of 0.1° to 1° root mean square error (RMSE) is required https://ietresearch.onlinelibrary.wiley.com/doi/10.1049/el.2019.2274 A novel method to obtain approximate DF ambiguity probabilities for four- and five-element arrays was presented in this Letter. As the results of comparisons between the proposed method and other methods including simulations showed, the DF ambiguity probability obtained by the proposed method for the five-element array was in good agreement with the results of simulations.

milstar: Introduction into Theory of Direction Finding https://cdn.rohde-schwarz.com/us/campaigns_2/a_d/Introduction-Into-Theory-of-Direction-Finding.pdf

milstar: 2003 Thales • Sub-degree DF accuracy on E to J bands • 100 % Probability of Intercept (POI) • All polarisations (H, V, LHC, RHC) https://www.thalesgroup.com/sites/default/files/database/d7/asset/document/HADF-Product-Brochure-Aug.2003.pdf

полная версия страницы