Artykuły w czasopismach: „Radar function”

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Chen, Duo, Ying Li, Yi Wen Wang i Jin Xu. "Research on Marine Radar Image Collection Technology Based on OpenCV". Advanced Materials Research 798-799 (wrzesień 2013): 578–81. http://dx.doi.org/10.4028/www.scientific.net/amr.798-799.578.

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Marine radar image collection technology has been applied in many fileds. It has been a research focus at home and abroad for a long time. This paper proposes an architecture of marine radar image collection system based on Sperry radar, HPX Rader Information Board, OpenCV, SPX Function Library. And implementation of key technologies was diccussed from three aspects, includ-ing radar image display, collection and clear functions. This system has worked well in practice.

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Blahak, Ulrich. "An Approximation to the Effective Beam Weighting Function for Scanning Meteorological Radars with an Axisymmetric Antenna Pattern". Journal of Atmospheric and Oceanic Technology 25, nr 7 (1.07.2008): 1182–96. http://dx.doi.org/10.1175/2007jtecha1010.1.

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Abstract To obtain statistically stable reflectivity measurements by meteorological radars, it is common practice to average over several consecutive pulses during which the antenna rotates at a certain angular velocity. Taking into account the antenna’s continuous motion, the measured reflectivity is determined by an effective beam weighting function, which is different from a single-pulse weighting function—a fact that is widely ignored in applications involving beam weighting. In this paper, the effective beam weighting function is investigated in detail. The theoretical derivation shows that the effective weighting function is essentially a simple moving sum of single-beam weighting functions. Assuming a Gaussian shape of a single pulse, a simple and easy-to-use parameterization of the effective beam weighting function is arrived at, which depends only on the single beamwidth and the ratio of the single beamwidth to the rotational angular averaging interval. The derived relation is formulated in the “radar system” (i.e., the spherical coordinate system consisting of azimuth and elevation angles) that is often applied in practice. Formulas for the “beam system” (two orthogonal angles relative to the beam axis) are also presented. The final parameterization should be applicable to almost all meteorological radars and might be used (i) in specialized radar data analyses (with ground-based or satellite radars) and (ii) for radar forward operators to calculate simulated radar parameters from the results of NWP models.

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Cho, Yo-Han, Gyu Won Lee, Kyung-Eak Kim i Isztar Zawadzki. "Identification and Removal of Ground Echoes and Anomalous Propagation Using the Characteristics of Radar Echoes". Journal of Atmospheric and Oceanic Technology 23, nr 9 (1.09.2006): 1206–22. http://dx.doi.org/10.1175/jtech1913.1.

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Abstract This paper explores the removal of normal ground echoes (GREs) and anomalous propagation (AP) in ground-based radars using a fuzzy logic approach. Membership functions and their weights are derived from the characteristics of radar echoes as a function of radar reflectivity. The dependence on echo intensity is shown to significantly improve the proper identification of GRE/AP. In addition, the proposed method has a better performance at lower elevation angles. The overall performance is comparable with that from a polarimetric approach and can thus be easily implemented in operational radars.

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Kosovets, M. A., i L. M. Tovstenko. "The practical aspect of using the artificial intellectual technology for building a multidimentional function CFAR for smart-handled LPI radar". PROBLEMS IN PROGRAMMING, nr 2-3 (wrzesień 2020): 304–12. http://dx.doi.org/10.15407/pp2020.02-03.304.

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The problem of the development of modern mobile smart-handled LPI radars using artificial intelligence technologies, the main difference of which is the construction of the CFAR function, which takes into account the influence of external and internal factors and requirements for the purpose, also distinguishes the developed radar among others in its class. The analysis of the publications was showed a great interest in modern radar systems and the lack of a unified approach to solving this problem. The purpose of the article is to reduce this gap, from collecting information from radar sensors and internal sensors to construct a generic multidimensional CFAR function and for organize its effect on the receiving and transmitting part of the radar. The application of artificial intelligence technologies in the construction of a modeling complex of LPI radars with CFAR function and their debugging in real time is covered.

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Cote, Stephane. "Naval multi-function radar". IEEE Aerospace and Electronic Systems Magazine 26, nr 9 (wrzesień 2011): 34–39. http://dx.doi.org/10.1109/maes.2011.6069903.

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Heys, Paul. "Progressive function". Radar 1, nr 1 (marzec 2010): 18–19. http://dx.doi.org/10.5920/radar.2010.1118.

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Frech, Michael, Cornelius Hald, Maximilian Schaper, Bertram Lange i Benjamin Rohrdantz. "Assessing and mitigating the radar–radar interference in the German C-band weather radar network". Atmospheric Measurement Techniques 16, nr 2 (20.01.2023): 295–309. http://dx.doi.org/10.5194/amt-16-295-2023.

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Abstract. The national German weather radar network operates in C-band between 5.6 and 5.65 GHz. In a radar network, individual transmit frequencies have to be chosen such that radar–radar-induced interferences are avoided. In a unique experiment the Hohenpeißenberg research radar and five operational systems from the radar network were used to characterize radar–radar-induced interferences as a function of the radar frequency. The results allow assessment of the possibility of adding additional C-band radars with magnetron transmitters into the existing network. Based on the experiment, at least a 15 MHz separation of the nominal radar frequency is needed to avoid a radar–radar interference. The most efficient mitigation of radar–radar interference is achieved by the “Radar Tango”, which refers to the synchronized scanning of all radar systems in the network. Based on those results, additional C-band radar systems can be added to the German weather radar network if a further improvement of the radar coverage is needed.

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Monakov, A. A. "A Versatile Algorithm for Autofocusing SAR Images". Journal of the Russian Universities. Radioelectronics 24, nr 1 (26.02.2021): 22–33. http://dx.doi.org/10.32603/1993-8985-2021-24-1-22-33.

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Introduction. Random deviations of the antenna phase centre of a synthetic aperture radar (SAR) are a source of phase errors for the received signal. These phase errors frequently cause blurring of the radar image. The image quality can be improved using various autofocus algorithms. Such algorithms estimate phase errors via optimization of an objective function, which defines the radar image quality. The image entropy and sharpness are well known examples of objective functions. The objective function extremum can be found by fast optimization methods, whose realization is a challenging computing task.Aim. To synthesize a versatile and computationally simple autofocusing algorithm allowing any objective function to used without changing its structure significantly.Materials and methods. An algorithm based on substituting the selected objective function with a simpler surrogate objective function, whose extremum can be found by a direct method, is proposed. This method has been referred as the MM optimization in scientific literature. It is proposed to use a quadratic function as a surrogate objective function.Results. The synthesized algorithm is straightforward, not requiring recursive methods for finding the optimal solution. These advantages determine the enhanced speed and stability of the proposed algorithm. Adjusting the algorithm for the selected objective function requires minimal software changes. Compared to the algorithm using a linear surrogate objective function, the proposed algorithm provides a 1.5 times decrease in the standard deviation of the phase error estimate, with an approximately 10 % decrease in the number of iterations.Conclusion. The proposed autofocusing algorithm can be used in synthetic aperture radars to compensate the arising phase errors. The algorithm is based on the MM-optimization of the quadratic surrogate objective functions for radar images. The computer simulation results confirm the efficiency of the proposed algorithm even in case of large phase errors.

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Moharir, P. S., K. Venkata Rao i S. K. Varma. "Monogenic function range resolution radar". IEE Proceedings F Communications, Radar and Signal Processing 134, nr 6 (1987): 620. http://dx.doi.org/10.1049/ip-f-1.1987.0103.

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Simpson, Micheal J., i Neil I. Fox. "Dual-polarized quantitative precipitation estimation as a function of range". Hydrology and Earth System Sciences 22, nr 6 (18.06.2018): 3375–89. http://dx.doi.org/10.5194/hess-22-3375-2018.

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Abstract. Since the advent of dual-polarization radar technology, many studies have been conducted to determine the extent to which the differential reflectivity (ZDR) and specific differential phase shift (KDP) add benefits to estimating rain rates (R) compared to reflectivity (Z) alone. It has been previously noted that this new technology provides significant improvement to rain-rate estimation, primarily for ranges within 125 km of the radar. Beyond this range, it is unclear as to whether the National Weather Service (NWS) conventional R(Z)-convective algorithm is superior, as little research has investigated radar precipitation estimate performance at larger ranges. The current study investigates the performance of three radars – St. Louis (KLSX), Kansas City (KEAX), and Springfield (KSGF), MO – with 15 tipping bucket gauges serving as ground truth to the radars. With over 300 h of precipitation data being analyzed for the current study, it was found that, in general, performance degraded with range beyond, approximately, 150 km from each of the radars. Probability of detection (PoD) in addition to bias values decreased, while the false alarm rates increased as range increased. Bright-band contamination was observed to play a potential role as large increases in the absolute bias and overall error values near 120 km for the cool season and 150 km in the warm season. Furthermore, upwards of 60 % of the total error was due to precipitation being falsely estimated, while 20 % of the total error was due to missed precipitation. Correlation coefficient values increased by as much as 0.4 when these instances were removed from the analyses (i.e., hits only). Overall, due to the lowest normalized standard error (NSE) of less than 1.0, a National Severe Storms Laboratory (NSSL) R(Z,ZDR) equation was determined to be the most robust, while a R(ZDR,KDP) algorithm recorded NSE values as high as 5. The addition of dual-polarized technology was shown to estimate quantitative precipitation estimates (QPEs) better than the conventional equation. The analyses further our understanding of the strengths and limitations of the Next Generation Radar (NEXRAD) system overall and from a seasonal perspective.

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Al-Salehi, Abdul Rahman, Ijaz Mansoor Qureshi, Aqdas Naveed Malik, Wasim Khan i Abdul Basit. "Dual-function radar–communications: information transmission during FDA radar listening mode". International Journal of Microwave and Wireless Technologies 12, nr 1 (22.07.2019): 1–12. http://dx.doi.org/10.1017/s1759078719000990.

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AbstractWe investigate the frequency diverse array (FDA) for joint radar and communication systems. The basic idea is to use the transmitter/receiver modules of the radar system for communication purpose during listening mode as a secondary function. The radar will be performing its routine functions during the active mode as a primary function. An FDA at the transmitter side will be used to produce an orthogonal frequency division multiplexed signal, which is proposed for the communication system. The directivity of the radar antenna, FDA in this case, provides an additional advantage to mitigate the interferences other than the Direction of Interest (DoI). The proposed technique allows two beampatterns to be transmitted sequentially from the same FDA structure. Due to the communication signal transmission in the mainlobe of the second beampattern, the bit error rate achieved in the mainlobe is better than the existing techniques using the sidelobe transmission for communications. At the receiver, both incoming signals of radar and communication will share a different spatial angle. Simulation results indicate the novelty of the idea to suppress the interferences in terms of DoI. Furthermore, we analyzed the signal-to-interference ratio and Cramer–Rao lower bounds for angle and range estimation for the proposed technique.

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Chen, Jenn-Shyong, Ching-Lun Su, Yen-Hsyang Chu, Gernot Hassenpflug i Marius Zecha. "Extended Application of a Novel Phase Calibration Approach of Multiple-Frequency Range Imaging to the Chung-Li and MU VHF Radars". Journal of Atmospheric and Oceanic Technology 26, nr 11 (1.11.2009): 2488–500. http://dx.doi.org/10.1175/2009jtecha1295.1.

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Abstract Multiple-frequency range imaging (RIM), designed to improve the range resolution of radar echo distribution, is now available for the recently upgraded Chung-Li VHF radar (24.9°N, 121.1°E). To complete the RIM technique of this radar, a novel phase calibration approach, proposed initially for the Ostsee Wind (OSWIN) VHF radar, was employed to examine the effects of phase bias and the range-weighting function on the received radar echoes. The estimated phase bias indicated a time delay of ∼1.83 μs for the signal in the radar system. In contrast, such a time delay is more difficult to determine from the phase distribution of two-frequency cross-correlation functions. The same calibration approach was also applied successfully to the middle and upper atmosphere (MU) radar (34.85°N, 136.11°E) and revealed a time delay of ∼0.33 μs for the radar parameters employed. These calibration results for various radars demonstrate the general usability of the proposed calibration approach. With the high-resolution performance of RIM, some small-scale Kelvin–Helmholtz (KH) billows, double-layer structures, and plumelike structures in the troposphere that cannot be seen in height–time intensity plots have been recognized in present observations. The billows and double layers were found to be closely related to strong vertical wind shear and small Richardson number, supporting the hypothesis of a dynamic process of KH instability. On the other hand, the plumelike structures were observed to grow out of a wavy layer and could be attributed to saturation and breaking of gravity waves. These fine structures have shown some remarkable features resolved by the RIM method applied to VHF radars in the lower atmosphere.

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Chen, Jenn-Shyong, Ching-Lun Su, Yen-Hsyang Chu, Ruey-Ming Kuong i Jun-ichi Furumoto. "Measurement of Range-Weighting Function for Range Imaging of VHF Atmospheric Radars Using Range Oversampling". Journal of Atmospheric and Oceanic Technology 31, nr 1 (1.01.2014): 47–61. http://dx.doi.org/10.1175/jtech-d-12-00236.1.

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Abstract Multifrequency range imaging (RIM) used with the atmospheric radars at ultra- and very high-frequency (VHF) bands is capable of retrieving the power distribution of the backscattered radar echoes in the range direction, with some inversion algorithms such as the Capon method. The retrieved power distribution, however, is weighted by the range-weighting function (RWF). Modification of the retrieved power distribution with a theoretical RWF may cause overcorrection around the edge of the sampling gate. In view of this, an effective RWF that is in a Gaussian form and varies with the signal-to-noise ratio (SNR) of radar echoes has been proposed to mitigate the range-weighting effect and thereby enhance the continuity of the power distribution at gate boundaries. Based on the previously proposed concept, an improved approach utilizing the range-oversampled signals is addressed in this article to inspect the range-weighting effects at different range locations. The shape of the Gaussian RWF for describing the range-weighting effect was found to vary with the off-center range location in addition to the SNR of radar echoes—that is, the effective RWF for the RIM was SNR and range dependent. The use of SNR- and range-dependent RWF can be of help to improve the range imaging to some degree at the range location outside the range extent of a sampling gate defined by the pulse length. To verify the proposed approach, several radar experiments were carried out with the Chung-Li (24.9°N, 121.1°E) and middle and upper atmosphere (MU; 34.85°N, 136.11°E) VHF radars.

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Seo, Jiho, Jonghyeok Lee, Jaehyun Park, Hyungju Kim i Sungjin You. "Distributed Two-Dimensional MUSIC for Joint Range and Angle Estimation with Distributed FMCW MIMO Radars". Sensors 21, nr 22 (16.11.2021): 7618. http://dx.doi.org/10.3390/s21227618.

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To estimate range and angle information of multiple targets, FMCW MIMO radars have been exploited with 2D MUSIC algorithms. To improve estimation accuracy, received signals from multiple FMCW MIMO radars are collected at the data fusion center and processed coherently, which increases data communication overhead and implementation complexity. To resolve them, we propose the distributed 2D MUSIC algorithm with coordinate transformation, in which 2D MUSIC algorithm is operated with respect to the reference radar’s coordinate at each radar in a distributed way. Rather than forwarding the raw data of received signal to the fusion center, each radar performs 2D MUSIC with its own received signal in the transformed coordinates. Accordingly, the distributed radars do not need to report all their measured signals to the data fusion center, but they forward their local cost function values of 2D MUSIC for the radar image region of interest. The data fusion center can then estimate the range and angle information of targets jointly from the aggregated cost function. By applying the proposed scheme to the experimentally measured data, its performance is verified in the real environment test.

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Tsao, T., M. Slamani, P. Varshney, D. Weiner, H. Schwarzlander i S. Borek. "Ambiguity function for a bistatic radar". IEEE Transactions on Aerospace and Electronic Systems 33, nr 3 (lipiec 1997): 1041–51. http://dx.doi.org/10.1109/7.599331.

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Qi, Minyou, i M. Y. Chi. "Radar ambiguity function inL p frame". Science in China Series A: Mathematics 43, nr 8 (sierpień 2000): 785–91. http://dx.doi.org/10.1007/bf02884176.

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Revenko, V. Yu. "RADAR CHARACTERISTICS OF PRECIPITATION AFFECTING THE TRACKING OF SHIP’S RADAR OBJECTS". Shipping & Navigation 33, nr 1 (1.12.2022): 106–10. http://dx.doi.org/10.31653/2306-5761.33.2022.106-110.

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In this paper, we consider the possibility of using the radar characteristics under precipitation conditions in order to reduce the echo signal’s negative impact on the object tracking performed by the ship’s radar. Precipitation particles’ size, state (solid or liquid phase), shape, and the factors that determine their combined action play an important role in echo signal formation. The rain particles’ size in comparison with the wavelength of the ship’s radar may contribute to the creation of a larger or smaller noise echo signal on the ship’s radar display. This signal’s power in the Rayleigh scattering area towards the radar is characterized by the effective scattering area. Raindrops represent a combination of randomly located reflectors. Their scattering properties depend on spatial distribution and movement regularity. At the same time, the radar characteristics of clouds with precipitation generated by them can be used in ship radars to determine the intensity of the atmospheric process along the ship’s route. The uncertainty in determining the power attenuation of an electromagnetic wave emitted by a ship’s radar antenna and passing through the precipitation zone can be reduced by the simultaneous use of two wavelengths on which a ship’s radars operate. The presented uncertainty function characterizes a narrow-band polarized scattered signal in regard to radar information about the distance to the sea object and the scatterer's speed. It characterizes the matched multidimensional coherent filter’s properties. This filter provides optimal echo reception against the background of an uncorrelated precipitation echo signal. The matched filter belongs to the class of optimal linear filters according to the criterion of the maximum signalto-noise ratio and is the main element for radar detection devices in the ship radar, which is optimal according to the Neyman-Pearson criteria. Keywords: radar characteristics of precipitation, precipitation intensity, effective scattering area, precipitation particle diameter, dielectric constant, energy attenuation, radio waves, wavelength.

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Ding, Fan, Chen Zhao, Zezong Chen i Jian Li. "Sea Echoes for Airborne HF/VHF Radar: Mathematical Model and Simulation". Remote Sensing 12, nr 22 (15.11.2020): 3755. http://dx.doi.org/10.3390/rs12223755.

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Currently, shore-based HF radars are widely used for coastal observations, and airborne radars are utilized for monitoring the ocean with a relatively large coverage offshore. In order to take the advantage of airborne radars, the theoretical mechanism of airborne HF/VHF radar for ocean surface observation has been studied in this paper. First, we describe the ocean surface wave height with the linear and nonlinear parts in a reasonable mathematical form and adopt the small perturbation method (SPM) to compute the HF/VHF radio scattered field induced by the sea surface. Second, the normalized radar cross section (NRCS) of the ocean surface is derived by tackling the field scattered from the random sea as a stochastic process. Third, the NRCS is simulated using the SPM under different sea states, at various radar operating frequencies and incident angles, and then the influences of these factors on radar sea echoes are investigated. At last, a comparison of NRCS using the SPM and the generalized function method (GFM) is done and analyzed. The mathematical model links the sea echoes and the ocean wave height spectrum, and it also offers a theoretical basis for designing a potential airborne HF/VHF radar for ocean surface remote sensing.

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Mofrad, Reza, i Ramazan Sadeghzadeh. "A New Algorithm for Phased Array Radar Search Function Improvement in Overload Situations". International Journal of Electronics and Telecommunications 57, nr 1 (1.03.2011): 55–63. http://dx.doi.org/10.2478/v10177-011-0008-9.

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A New Algorithm for Phased Array Radar Search Function Improvement in Overload SituationsA new algorithm is proposed for phased array radar search function resource allocation. The proposed algorithm adaptively priorities radar search regions and in overload situations, based on available resources, radar characteristics, maximum range and search regions, optimally allocates radar resources in order to maximize probability of detection. The performance of new algorithm is evaluated by the multifunction phased array radar simulation test bed. This simulation test bed provides capability to design and evaluate the performance of different radar resource management, target tracking and beam forming algorithms. Some results are presented that show capabilities of this simulation software for multifunction radar algorithms design and performance evaluation.

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Hambali, Roby, Djoko Legono i Rachmad Jayadi. "Correcting Radar Rainfall Estimates Based on Ground Elevation Function". Journal of the Civil Engineering Forum 5, nr 3 (18.09.2019): 300. http://dx.doi.org/10.22146/jcef.49395.

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X-band radar gives several advantages for quantitative rainfall estimation, involving higher spatial and temporal resolution, also the ability to reduce attenuation effects and hardware calibration errors. However, the estimates error due to attenuation in heavy rainfall condition cannot be avoided. In the mountainous region, the impact of topography is considered to contribute to radar rainfall estimates error. To have more reliable estimated radar rainfall to be used in various applications, a rainfall estimates correction needs to be applied. This paper discusses evaluation and correction techniques for radar rainfall estimates based on ground elevation function. The G/R ratio is used as a primary method in the correction process. The novel approach proposed in this study is the use of correction factor derived from the relationship between Log (G/R) parameter and elevation difference between radar and rain gauge stations. A total of 4590 pairs of rainfall data from X-band MP radar and 15 rain gauge stations in the Mt. Merapi region were used in evaluation and correction process. The results show the correction method based on the elevation function is relatively good in correcting radar rainfall depth with values of Log (G/R) decreased up to 81.1%, particularly for light rainfall (≤ 20 mm/hour) condition. Also, the method is simple to apply in a real-time system.

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Dokter, Adriaan M., Felix Liechti, Herbert Stark, Laurent Delobbe, Pierre Tabary i Iwan Holleman. "Bird migration flight altitudes studied by a network of operational weather radars". Journal of The Royal Society Interface 8, nr 54 (2.06.2010): 30–43. http://dx.doi.org/10.1098/rsif.2010.0116.

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A fully automated method for the detection and quantification of bird migration was developed for operational C-band weather radar, measuring bird density, speed and direction as a function of altitude. These weather radar bird observations have been validated with data from a high-accuracy dedicated bird radar, which was stationed in the measurement volume of weather radar sites in The Netherlands, Belgium and France for a full migration season during autumn 2007 and spring 2008. We show that weather radar can extract near real-time bird density altitude profiles that closely correspond to the density profiles measured by dedicated bird radar. Doppler weather radar can thus be used as a reliable sensor for quantifying bird densities aloft in an operational setting, which—when extended to multiple radars—enables the mapping and continuous monitoring of bird migration flyways. By applying the automated method to a network of weather radars, we observed how mesoscale variability in weather conditions structured the timing and altitude profile of bird migration within single nights. Bird density altitude profiles were observed that consisted of multiple layers, which could be explained from the distinct wind conditions at different take-off sites. Consistently lower bird densities are recorded in The Netherlands compared with sites in France and eastern Belgium, which reveals some of the spatial extent of the dominant Scandinavian flyway over continental Europe.

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Lakshmi, K. Jansi, i K. Surya Narayana Reddy. "Implementation of High Speed Self Switching Frequency Agile RADAR". International Journal of Reconfigurable and Embedded Systems (IJRES) 3, nr 1 (1.03.2013): 11. http://dx.doi.org/10.11591/ijres.v3.i1.pp11-17.

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<div class="WordSection1"><p><strong><a href="mailto:suryak1986@yahoo.com"></a></strong></p></div><strong> </strong>The radar has to resist diversified jamming; High Speed self-adaptive frequency agility is an important and effective function for radars to resist jamming. The procedure to achieve this function are described, and the function is realized with FPGA using Hardware description Language, the validity is proved by on- line sampling and simulation. The High speed self-adaptive frequency agility module can analyze the type of jamming to select transmitting frequency to avoid the frequencies which have interference, under frequency diversity and fixed frequency, respectively. The general application on a searching radar shows that the module has good real-time and anti- jamming capacity.

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Kollias, Pavlos, Bernat Puigdomènech Treserras i Alain Protat. "Calibration of the 2007–2017 record of Atmospheric Radiation Measurements cloud radar observations using CloudSat". Atmospheric Measurement Techniques 12, nr 9 (12.09.2019): 4949–64. http://dx.doi.org/10.5194/amt-12-4949-2019.

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Abstract. The U.S. Department of Energy (DOE) Atmospheric Radiation Measurements (ARM) facility has been at the forefront of millimeter-wavelength radar development and operations since the late 1990s. The operational performance of the ARM cloud radar network is very high; however, the calibration of the historical record is not well established. Here, a well-characterized spaceborne 94 GHz cloud profiling radar (CloudSat) is used to characterize the calibration of the ARM cloud radars. The calibration extends from 2007 to 2017 and includes both fixed and mobile deployments. Collectively, over 43 years of ARM profiling cloud radar observations are compared to CloudSat and the calibration offsets are reported as a function of time using a sliding window of 6 months. The study also provides the calibration offsets for each operating mode of the ARM cloud radars. Overall, significant calibration offsets are found that exceed the uncertainty of the technique (1–2 dB). The findings of this study are critical to past, ongoing, and planned studies of cloud and precipitation and should assist the DOE ARM to build a legacy decadal ground-based cloud radar dataset for global climate model validation.

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Bestugin, A. R., M. B. Ryzhikov i Iu A. Novikova. "The frequency range selection for airborne weather radar with the search for areas with the visibility of landmarks for flight and landing". Radio industry 28, nr 3 (29.08.2018): 8–17. http://dx.doi.org/10.21778/2413-9599-2018-28-3-8-17.

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A radar dome of a small aircraft can accommodate an antenna with a small aperture only. The energy potential and radiation parameters required for detection of hazardous weather events are thereby impaired. Mathematical modeling of the effect of wavelength change on the quality of radar meteorological forecast has been performed. Performance parameters of small-sized weather radars have been evaluated for enhancing the safety of the flights of small aircraft. Mathematics have been presented for comparing the efficiency of detecting dangerous thunderstorm areas with allowance for the signal reflection from the ground surface. The formula take into account the wavelength, the directional function of the antenna system, the radar reflectivity of the ground surface, the speed and altitude of flight. The efficiency of the weather radar with a small-sized antenna aperture operating in3 cmand8 mmwave lengths has been reviewed. The detection range of small aircraft radars with different wavelengths in different weather conditions has been determined. A flight envelope search mode is proposed with a possibility of visual orientation and landing in bad weather conditions. The mode is based on measuring the radar reflectivity of moisture targets.

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Dai, Xiangrong, Chenguang Shi, Ziwei Wang i Jianjiang Zhou. "Coalition Game Theoretic Power Allocation Strategy for Multi-Target Detection in Distributed Radar Networks". Remote Sensing 15, nr 15 (31.07.2023): 3804. http://dx.doi.org/10.3390/rs15153804.

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This paper studies a coalition game theoretic power allocation algorithm for multi-target detection in radar networks based on low probability of intercept (LPI). The main goal of the algorithm is to reduce the total radiated power of the radar networks while satisfying the predetermined target detection performance of each radar. Firstly, a utility function that comprehensively considers both target detection performance and the radiated power of the radar networks is designed with LPI performance as the guiding principle. Secondly, it causes a coalition to form between cooperating radars, and radars within the same coalition share information. On this basis, a mathematical model for power allocation in radar networks based on coalition game theory is established. The model takes the given target detection performance as a constraint and maximizing system energy efficiency and optimal power allocation as the optimization objective. Furthermore, this paper proposes a game algorithm for joint coalition formation and power allocation in a multi-target detection scenario. Finally, the existence and uniqueness of the Nash equilibrium (NE) solution are proven through strict mathematical deduction. Simulation results validate the effectiveness and feasibility of the proposed algorithm.

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Rutkowski, Adam. "A Concept of a Passive Radar with Quadrature Microwave Phase Discriminators". Metrology and Measurement Systems 19, nr 1 (1.01.2012): 95–104. http://dx.doi.org/10.2478/v10178-012-0008-9.

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A Concept of a Passive Radar with Quadrature Microwave Phase Discriminators Passive radar does not have its own emitter. It uses so-called signals of opportunity emitted by non-cooperative illuminators. During the detection of reflected signals, a direct signal from a non-cooperative emitter is used as the reference signal. Detection of electromagnetic echoes is, in present day radars, performed by finding the maximum of the cross ambiguity function. This function is based on the multiplication of the received signal and the reference signal. Detection of echoes by means of a quadrature microwave phase discriminator QMPD was proposed in the work as an alternative solution for ambiguity function evaluation. This discriminator carries out vectorial summing of the received and the reference signals. The summing operations in QMPD are carried out with the aid of microwave elements and without the use of expensive digital signal processors. Definitions of the phase and phase difference of the so-called simple signals and noise signals were described. A proposal of a passive radar equipped with several independent quadrature microwave phase discriminators was presented. Ideas of algorithms of object detection and of the distance-to-object estimation designed for this radar have been also sketched.

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Zhang, Yuanshi, Minghai Pan i Qinghua Han. "Joint Sensor Selection and Power Allocation Algorithm for Multiple-Target Tracking of Unmanned Cluster Based on Fuzzy Logic Reasoning". Sensors 20, nr 5 (2.03.2020): 1371. http://dx.doi.org/10.3390/s20051371.

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The unmanned aerial vehicle (UAV) cluster is gradually attracting more attention, which takes advantage over a traditional single manned platform. Because the size of the UAV platform limits the transmitting power of its own radar, how to reduce the transmitting power while meeting the detection accuracy is necessary. Aim at multiple-target tracking (MTT), a joint radar node selection and power allocation algorithm for radar networks is proposed. The algorithm first uses fuzzy logic reasoning (FLR) to obtain the priority of targets to radars, and designs a radar clustering algorithm based on the priority to form several subradar networks. The radar clustering algorithm simplifies the problem of multiple-radar tracking multiple-target into several problems of multiple-radar tracking a single target, which avoids complex calculations caused by multiple variables in the objective function of joint radar node selection and power allocation model. Considering the uncertainty of the target RCS in practice, the chance-constraint programming (CCP) is used to balance power resource and tracking accuracy. Through the joint radar node selection and power allocation algorithm, the radar networks can use less power resource to achieve a given tracking performance, which is more suitable for working on drone platforms. Finally, the simulation proves the effectiveness of the algorithm.

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Ning, Qianhao, Hongyuan Wang, Zhiqiang Yan, Xiang Liu i Yinxi Lu. "Space-Based THz Radar Fly-Around Imaging Simulation for Space Targets Based on Improved Path Tracing". Remote Sensing 15, nr 16 (13.08.2023): 4010. http://dx.doi.org/10.3390/rs15164010.

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Aiming at the space target detection application of a space-based terahertz (THz) radar, according to the imaging mechanism of broadband THz radars, a THz radar imaging simulation method based on improved path tracing is proposed. Firstly, the characterization method of THz scattering characteristics based on Kirchhoff’s approximation method is introduced. The multi-parameter THz bidirectional reflectance distribution function (THz-BRDF) models of aluminum (Al), white-painted Al, and polyimide film at 0.215 THz are fitted according to the theoretical data, with fitting errors below 4%. Then, the THz radar imaging simulation method based on improved path tracing is presented in detail. The simulation method utilizes path tracing to simulate parallelized THz radar echo signal data, considering multi-path energy scattering based on the THz-BRDF model. Finally, we conducted THz radar imaging simulation experiments. The influences in the imaging process of different fly-around motions are analyzed, and a comparison experiment is conducted with the fast-physical optics (FPO) method. The comparative results indicate that the proposed method exhibits richer and more realistic features compared with the FPO method. The simulation experiments results demonstrate that the proposed method can provide a data source for ground algorithm testing of THz radars, particularly in evaluating the target detection and recognition algorithm based on deep learning, providing strong support for the application of space-based THz radars in the future.

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ÇINAR, Rıdvan Fırat, Fatih KOCADAĞ i Aşkın DEMİRKOL. "Radar range profile processing using Green’s function". International Journal of Applied Mathematics Electronics and Computers 10, nr 3 (6.08.2022): 57–60. http://dx.doi.org/10.18100/ijamec.1058257.

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In this study, a useful method for synthesizing range profiles to be used in ultra-wideband radar operations is discussed. One-dimensional transmission-reflection geometry of the radar scenario, which consists of a single receiver and single transmitter, is formulated by using the Green’s function. A one-dimensional time domain Green’s function is employed in the formulation and the impulsive characteristic of this function, which provides focus on the target position, has been determined. This characteristic represents the impulse response of the propagating medium to the electromagnetic wave. The resulting derivation offers a framework that can also be used in higher dimensional and complex radar problems by taking the advantage of its flexibility. Proposed method has been detailed and tested on an exemplary implementation and successful results that provide good focus on the target positions are shown in the conclusions. Finally, outcomes and benefits are discussed.

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HUANG, DE-SHUANG. "APPLICATION OF GENERALIZED RADIAL BASIS FUNCTION NETWORKS TO RECOGNITION OF RADAR TARGETS". International Journal of Pattern Recognition and Artificial Intelligence 13, nr 06 (wrzesień 1999): 945–62. http://dx.doi.org/10.1142/s0218001499000525.

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This paper extends general radial basis function networks (RBFN) with Gaussian kernel functions to generalized radial basis function networks (GRBFN) with Parzen window functions, and discusses applying the GRBFNs to recognition of radar targets. The equivalence between the RBFN classifiers (RBFNC) with outer-supervised signals of 0 or 1 and the estimate of Parzen windowed probabilistic density is proved. It is pointed out that the I/O functions of the hidden units in the RBFNC can be extended to general Parzen window functions (or called as potential functions). We present using recursive least square-backpropagation (RLS–BP) learning algorithm to train the GRBFNCs to classify five types of radar targets by means of their one-dimensional cross profiles. The concepts about the rate of recognition and confidence in the process of testing classification performance of the GRBFNCs are introduced. Six generalized kernel functions such as Gaussian, Double-Exponential, Triangle, Hyperbolic, Sinc and Cauchy, are used as the hidden I/O functions of the RBFNCs, and the classification performance of corresponding GRBFNCs for classifying one-dimensional cross profiles of radar targets is discussed.

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Fasoula, Angie, Hans Driessen i Piet van Genderen. "De-ghosting of tomographic images in a radar network with sparse angular sampling". International Journal of Microwave and Wireless Technologies 2, nr 3-4 (sierpień 2010): 359–67. http://dx.doi.org/10.1017/s1759078710000358.

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Taking into account sparsity of the reflectivity function of several radar targets of interest, efficient low-complexity automatic target recognition (ATR) systems can be designed. Such ATR systems would be based on two-dimensional (2D) spatial target models of low dimensionality, where critical information on the radar target signature is summarized. Discrete 2D radar target models can be estimated using high range resolution (HRR) data, measured at a sparse system of view angles. This being the main objective, incoherent tomographic processing of HRR data from a distributed surveillance system, made up of several radar nodes, is studied in this paper. A sparse angular sampling scheme is proposed, which exploits diversity due to both the distributed radar system and the target motion. The novelty is in the exploitation of this locally dense, but otherwise sparse set of viewing angles of the targets, obtained using a sparse network of radars. The de-ghosting efficiency of such a sampling scheme is demonstrated geometrically. This results in identification of minimal information resources for unambiguous estimation of a 2D target model, useful for radar target classification.

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Xu, Qin, Li Wei i Kang Nai. "Analyzing Vortex Winds in Radar-Observed Tornadic Mesocyclones for Nowcast Applications". Weather and Forecasting 30, nr 5 (1.10.2015): 1140–57. http://dx.doi.org/10.1175/waf-d-15-0046.1.

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Abstract A computationally efficient method is developed to analyze the vortex wind fields of radar-observed mesocyclones. The method has the following features. (i) The analysis is performed in a nested domain over the mesocyclone area on a selected tilt of radar low-elevation scan. (ii) The background error correlation function is formulated with a desired vortex-flow dependence in the cylindrical coordinates cocentered with the mesocyclone. (iii) The square root of the background error covariance matrix is derived analytically to precondition the cost function and thus enhance the computational efficiency. Using this method, the vortex wind analysis can be performed efficiently either in a stand-alone fashion or as an additional step of targeted finescale analysis in the existing radar wind analysis system developed for nowcast applications. The effectiveness and performance of the method are demonstrated by examples of analyzed wind fields for the tornadic mesocyclones observed by operational Doppler radars in Oklahoma on 24 May 2011 and 20 May 2013.

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Zhang, Yonghong, Sutong Geng, Wei Tian, Guangyi Ma, Huajun Zhao, Donglin Xie, Huanyu Lu i Kenny Thiam Choy Lim Kam Sian. "Weather Radar Echo Extrapolation with Dynamic Weight Loss". Remote Sensing 15, nr 12 (15.06.2023): 3138. http://dx.doi.org/10.3390/rs15123138.

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Precipitation nowcasting is an important tool for economic and social services, especially for forecasting severe weather. The crucial and challenging part of radar echo image prediction is the focus of radar-based precipitation nowcasting. Recently, a number of deep learning models have been designed to solve the problem of extrapolating radar images. Although these methods can generate better results than traditional extrapolation methods, the issue of error accumulation in precipitation forecasting is exacerbated by using only the mean square error (MSE) and mean absolute error (MAE) as loss functions. In this paper, we approach the problem from the perspective of the loss function and propose dynamic weight loss (DWL), a simple but effective loss function for radar echo extrapolation. The method adds model self-adjusted dynamic weights to the weighted loss function and structural similarity index measures. Radar echo extrapolation experiments are performed on four models, ConvLSTM, ConvGRU, PredRNN, and PredRNN++. Radar reflectivity is predicted using Nanjing University C-band Polarimetric (NJU-CPOL) weather radar data. The quantitative statistics show that using the DWL method reduces the MAE of the four models by up to 10.61%, 5.31%, 14.8%, and 13.63%, respectively, over a 1 h prediction period. The results show that the DWL approach is effective in reducing the accumulation of errors over time, improving the predictive performance of currently popular deep learning models.

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Levanon, N., i A. Freedman. "Ambiguity function of quadriphase coded radar pulse". IEEE Transactions on Aerospace and Electronic Systems 25, nr 6 (1989): 848–53. http://dx.doi.org/10.1109/7.40724.

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Hassanien, Aboulnasr, Moeness G. Amin, Yimin D. Zhang i Fauzia Ahmad. "Phase‐modulation based dual‐function radar‐communications". IET Radar, Sonar & Navigation 10, nr 8 (październik 2016): 1411–21. http://dx.doi.org/10.1049/iet-rsn.2015.0484.

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Ilioudis, Christos V., Carmine Clemente, Ian K. Proudler i John Soraghan. "Generalized Ambiguity Function for MIMO Radar Systems". IEEE Transactions on Aerospace and Electronic Systems 55, nr 6 (grudzień 2019): 2629–46. http://dx.doi.org/10.1109/taes.2019.2907390.

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Chen, Haowen, Yiping Chen, Zhaocheng Yang i Xiang Li. "Extended ambiguity function for bistatic MIMO radar". Journal of Systems Engineering and Electronics 23, nr 2 (kwiecień 2012): 195–200. http://dx.doi.org/10.1109/jsee.2012.00025.

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Xie, Hong Sen, Jin Bo Shi, Bao Kuan Luan, Hua Ming Tian i Peng Zhou. "Analysis and Simulation of Radar Clutter Using Spherically Invariant Random Processe". Advanced Materials Research 765-767 (wrzesień 2013): 431–35. http://dx.doi.org/10.4028/www.scientific.net/amr.765-767.431.

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Non-Gaussian probability distribution radar clutter not only is temporal correlated between different pulses, but also is spatial correlated between different range bins. In this paper, the method of simulation and validation of radar clutter is proposed using spherically invariant random processes (SIRP). The amplitude probability function and temporal correlation function of radar clutter can be controlled respectively, and the spatial correlation function can be also specified. The computer simulation of K-distribution and CHI-distribution radar clutter is used to validate the method, and is to validate the amplitude probability function, temporal-spatial 2D correlation function.

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Li, Ting Jun. "Simulation and Validation of Temporal-Spatial 2-Dimensional Correlated Radar Clutter Based on SIRP". Key Engineering Materials 474-476 (kwiecień 2011): 1161–67. http://dx.doi.org/10.4028/www.scientific.net/kem.474-476.1161.

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Non-Gaussian probability distribution radar clutter not only is temporal correlated between different pulses, but also is spatial correlated between different range bins. In this paper, the method of simulation and validation of radar clutter is proposed using spherically invariant random processes (SIRP). The amplitude probability function and temporal correlation function of radar clutter can be controlled respectively, and the spatial correlation function can be also specified. The computer simulation of K-distribution and CHI-distribution radar clutter is used to validate the method, and is to validate the amplitude probability function, temporal-spatial 2D correlation function.

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Volosyuk, Valeriy, Simeon Zhyla, Vladimir Pavlikov, Dmitriy Vlasenko, Vladimir Kosharskiy, Denis Kolesnikov, Olga Inkarbaeva i Kseniya Nezhalskaya. "Optimal radar cross section estimation in synthetic aperture radar with planar antenna array". RADIOELECTRONIC AND COMPUTER SYSTEMS, nr 1 (27.02.2021): 50–59. http://dx.doi.org/10.32620/reks.2021.1.04.

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The optimization problem of statistical synthesis of the method for radar cross section estimation in synthetic aperture radar with planar antenna array is solved. The desired radar cross section is given as a statistical characteristic of a spatially inhomogeneous complex scattering coefficient of the studying media. In fact it is developed new methods of inverse problems solution not with respect to the restoration of coherent images in the form of spatial distribution of complex scattering coefficient but with respect to the statistical characteristics of inhomogeneous (spatially nonstationary) random processes. The electrophysical parameters of surfaces and their statistical characteristics are considered as functions of spatial coordinates. The maximum likelihood method was chosen as the optimization method. The obtained results make it possible to determine the multichannel structure, the optimal method of surface observation and the potential spatial resolution in aerospace scatterometric radars with antenna array. Optimal operations for processing space-time signals are determined and a modified method for synthesizing antenna aperture is proposed, which in contrast to the classical algorithm for synthesizing antenna aperture that integrates the product of the received signal and the reference signal equal to a single signal additionally implements the decorrelation of signals reflected from the earth's surface, The new operation of the scattered signals decorrelation consists in their integration with the space-time inverse correlation function. To confirm the reliability of the results obtained, simulation modeling of the classical method for the synthesis of coherent images and the proposed optimal one was carried out. From the analysis of the results it flows that propose method has higher quality and smaller size of spackle noise. The results obtained in the article can be used to develop and substantiate the requirements for the tactical and technical characteristics of promising aerospace-based scatterometric radars with planar phased antenna arrays.

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Schipper, Tom, Marlene Harter, Tobias Mahler, Oliver Kern i Thomas Zwick. "Discussion of the operating range of frequency modulated radars in the presence of interference". International Journal of Microwave and Wireless Technologies 6, nr 3-4 (19.03.2014): 371–78. http://dx.doi.org/10.1017/s1759078714000221.

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This paper discusses the operating range of frequency modulated (FM) radars in the presence of interference. For this purpose, radar- and path loss equations are used to draw the equipotential lines for a given signal-to-interference ratio as a function of the spatial distribution of targets and interferers in order to identify relevant scenario constellations. Further the factors influencing the gain of signal versus deterministic interference are discussed based on measurements and simulations. Finally, the influence of different kinds of interference on the spectrum of a frequency modulated continuous wave radar is shown.

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42

Qi, Youcun, i Jian Zhang. "A Physically Based Two-Dimensional Seamless Reflectivity Mosaic for Radar QPE in the MRMS System". Journal of Hydrometeorology 18, nr 5 (12.04.2017): 1327–40. http://dx.doi.org/10.1175/jhm-d-16-0197.1.

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Abstract The U.S. Weather Surveillance Radar-1988 Doppler (WSR-88D) network has provided meteorologists and hydrologists with quantitative precipitation observations at an unprecedented high spatial–temporal resolution since its deployment in the mid-1990s. Since each single radar can only cover a maximum range of 460 km, a mosaic of multiple-radar observations is needed to generate any national-scale products. The Multi-Radar Multi-Sensor (MRMS) system utilizes a physically based two-dimensional mosaicking algorithm of the WSR-88D data to generate seamless national quantitative precipitation estimation (QPE) products. For areas covered by multiple radars, the mosaicking scheme first determines if precipitation is present by checking the lowest-altitude observation. If the lowest observed radar data indicate no precipitation, then the mosaicked value is set to no precipitation. Otherwise, a weighted mean of multiple-radar observations is taken as the mosaicked value. The weighting function is based on multiple factors, including the distance from the radar and the height of the observation with respect to the melting layer. The mosaic algorithm uses the physically lowest radar observations with no/little blockage while maintaining a spatial continuity in the mosaicked field. The performance of the MRMS seamless radar mosaic algorithm was examined for various precipitation events of different characteristics. The results of these case evaluations are presented in this paper.

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43

Cervera, M. A., i W. G. Elford. "The meteor radar response function: Theory and application to narrow beam MST radar". Planetary and Space Science 52, nr 7 (czerwiec 2004): 591–602. http://dx.doi.org/10.1016/j.pss.2003.12.004.

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Golbon-Haghighi, Mohammad-Hossein, i Guifu Zhang. "Detection of Ground Clutter for Dual-Polarization Weather Radar Using a Novel 3D Discriminant Function". Journal of Atmospheric and Oceanic Technology 36, nr 7 (lipiec 2019): 1285–96. http://dx.doi.org/10.1175/jtech-d-18-0147.1.

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AbstractA novel 3D discriminant function is introduced as part of a ground clutter detection algorithm for improving weather radar observations. The 3D discriminant function utilizes the phase fluctuations of the received signals for horizontal and vertical polarizations and the dual-scan cross-correlation coefficient. An optimal decision based on the 3D discriminant function is made using a simple Bayesian classifier to distinguish clutter from weather signals. For convenience of use, a multivariate Gaussian mixture model is used to represent the probability density functions of discriminant functions. The model parameters are estimated based on the maximum likelihood using the expectation–maximization (ML-EM) method. The performance improvements are demonstrated by applying the proposed detection algorithm to radar data collected by the polarimetric Norman, Oklahoma (KOUN), weather radar. This algorithm is compared to other clutter detection algorithms and the results indicate that, using the proposed detection algorithm, a better probability of detection can be achieved.

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45

Feng, Jun-Jie, Gong Zhang i Fang-Qing Wen. "MIMO Radar Imaging Based on Smoothedl0Norm". Mathematical Problems in Engineering 2015 (2015): 1–10. http://dx.doi.org/10.1155/2015/841986.

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For radar imaging, a target usually has only a few strong scatterers which are sparsely distributed. In this paper, we propose a compressive sensing MIMO radar imaging algorithm based on smoothedl0norm. An approximate hyperbolic tangent function is proposed as the smoothed function to measure the sparsity. A revised Newton method is used to solve the optimization problem by deriving the new revised Newton directions for the sequence of approximate hyperbolic tangent functions. In order to improve robustness of the imaging algorithm, main value weighted method is proposed. Simulation results show that the proposed algorithm is superior to Orthogonal Matching Pursuit (OMP), smoothedl0method (SL0), and Bayesian method with Laplace prior in performance of sparse signal reconstruction. Two-dimensional image quality of MIMO radar using the new method has great improvement comparing with aforementioned reconstruction algorithm.

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Alattabi, Zaid R., Douglas Cahl i George Voulgaris. "Swell and Wind Wave Inversion Using a Single Very High Frequency (VHF) Radar". Journal of Atmospheric and Oceanic Technology 36, nr 6 (czerwiec 2019): 987–1013. http://dx.doi.org/10.1175/jtech-d-18-0166.1.

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AbstractA hybrid, empirical radar wave inversion technique that treats swell and wind waves separately is presented and evaluated using a single 48-MHz radar unit and in situ wave measurements. This hybrid approach greatly reduces errors in radar wave inversion during swell seas. Our analysis suggests that, prior to the inversion, the second-order spectrum should be normalized using Barrick’s weighting function because this process removes harmonic and corner reflection peaks from the inversion and improves the results. In addition, the resulting calibration constants for the wind wave component are not wave-frequency dependent and are similar in magnitude to those found in previous studies using different operating-frequency radars. This result suggests radar frequency independence, although additional experimental verification is required. The swell component of the model presented here ignores the effect of swell’s propagation direction on the radar signal. Although this approach has several limitations and may only be useful near the coast (where swell propagates close to perpendicular to the coastline), the resulting wave inversion is accurate even when swell is propagating close to perpendicular to the radar beam direction. RMS differences relative to in situ wave height measurements range from 0.16 to 0.25 m as the radar beam angle increases from 22° to 56°.

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Pan, Jifei, Shengli Zhang, Lingsi Xia, Long Tan i Linqing Guo. "Embedding Soft Thresholding Function into Deep Learning Models for Noisy Radar Emitter Signal Recognition". Electronics 11, nr 14 (8.07.2022): 2142. http://dx.doi.org/10.3390/electronics11142142.

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Radar emitter signal recognition under noisy background is one of the focus areas in research on radar signal processing. In this study, the soft thresholding function is embedded into deep learning network models as a novel nonlinear activation function, achieving advanced radar emitter signal recognition results. Specifically, an embedded sub-network is used to learn the threshold of soft thresholding function according to the input feature, which results in each input feature having its own independent nonlinear activation function. Compared with conventional activation functions, the soft thresholding function is characterized by flexible nonlinear conversion and the ability to obtain more discriminative features. By this way, the noise features can be flexibly filtered while retaining signal features, thus improving recognition accuracy. Under the condition of Gaussian and Laplacian noise with signal-to-noise ratio of −8 dB to −2 dB, experimental results show that the overall average accuracy of soft thresholding function reached 88.55%, which was 11.82%, 8.12%, 2.16%, and 1.46% higher than those of Sigmoid, PReLU, ReLU, ELU, and SELU, respectively.

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Xing, Huaixi, Qinghua Xing i Kun Wang. "Radar Anti-Jamming Countermeasures Intelligent Decision-Making: A Partially Observable Markov Decision Process Approach". Aerospace 10, nr 3 (27.02.2023): 236. http://dx.doi.org/10.3390/aerospace10030236.

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Current electronic warfare jammers and radar countermeasures are characterized by dynamism and uncertainty. This paper focuses on a decision-making framework of radar anti-jamming countermeasures. The characteristics and implementation process of radar intelligent anti-jamming systems are analyzed, and a scheduling method for radar anti-jamming action based on the Partially Observable Markov Process (POMDP) is proposed. The sample-based belief distribution is used to reflect the radar’s cognition of the environment and describes the uncertainty of the recognition of jamming patterns in the belief state space. The belief state of jamming patterns is updated with Bayesian rules. The reward function is used as the evaluation criterion to select the best anti-jamming strategy, so that the radar is in a low threat state as often as possible. Numerical simulation combines the behavioral prior knowledge base of radars and jammers and obtains the behavioral confrontation benefit matrix from the past experience of experts. The radar controls the output according to the POMDP policy, and dynamically performs the best anti-jamming action according to the change of jamming state. The results show that the POMDP anti-jamming policy is better than the conventional policy. The POMDP approach improves the adaptive anti-jamming capability of the radar and can quickly realize the anti-jamming decision to jammers. This work provides some design ideas for the subsequent development of an intelligent radar.

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Uijlenhoet, R., S. H. van der Wielen i A. Berne. "Uncertainties in rainfall retrievals from ground-based weather radar: overview, case study, and simulation experiment". Hydrology and Earth System Sciences Discussions 3, nr 4 (28.08.2006): 2385–436. http://dx.doi.org/10.5194/hessd-3-2385-2006.

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Abstract. Because rainfall constitutes the main source of water for the terrestrial hydrological processes, accurate and reliable measurement and prediction of its spatial and temporal distribution over a wide range of scales is an important goal for hydrology. We investigate the potential of ground-based weather radar to provide such measurements through a detailed analysis of the associated observation uncertainties. First, a historical perspective on measuring the space-time distribution of rainfall, from the rain gauge to the radar era, is presented. Subsequently, we provide an overview of the various errors and uncertainties affecting radar rainfall retrievals. As an example, we present a case study of the relation between measurements from an operational C-band weather radar and a network of tipping bucket rain gauges as a function of range. Finally, a recently developed stochastic model of range profiles of rainfall microstructure is employed in a simulation experiment designed to investigate the rainfall retrieval uncertainties associated with weather radars operating in different widely used frequency bands.

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Jin, Fu Lu, Yun Peng Li i Hong Rui Wang. "Design and Implementation on Auto Test Set of an Airborne Radar". Advanced Materials Research 756-759 (wrzesień 2013): 489–92. http://dx.doi.org/10.4028/www.scientific.net/amr.756-759.489.

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To automatic test the function and performance of an airborne radar, changeable test adapter is adopted to implement the hardware and software design of the automatic test set of the antenna, transceiver and indicator of the radar based on AT89C52. Problems such as t the different types of interfaces, the various kinds of signals and the test of microwave signal are solved successfully and the objectives of resource sharing and automatic test are realized. The test software is designed by modular structure, and with the help of automatic test set hardware, the required test items of the radar system are experimented and the test process control succeeded. Experiment results show that the automatic test set performs steadily and the results meet the requirements of the airborne radar. The set has the advantages of intelligent, manageable and reducing artificial errors. It provides effective guarantees for radars maintenance, fault diagnosis and fault detection, and has a wide application prospect with low cost.

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