Journal articles on the topic 'Radar theory'
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Junyent, Francesc, and V. Chandrasekar. "Theory and Characterization of Weather Radar Networks." Journal of Atmospheric and Oceanic Technology 26, no. 3 (March 1, 2009): 474–91. http://dx.doi.org/10.1175/2008jtecha1099.1.
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Abstract A dense weather radar network is an emerging concept advanced by the Engineering Research Center for Collaborative Adaptive Sensing of the Atmosphere (CASA). In a weather radar environment, the specific radar units employed and the network topology will influence the characteristics of the data obtained. To define this, a general framework is developed to describe the radar network space, and formulations are obtained that can be used for weather radar network characterization. The models developed are useful for quantifying and comparing the performance of different weather radar networks. Starting with system characteristics that are used to specify individual radars, a theoretical basis is developed to extend the concept to network configurations of interest. A general network elemental cell is defined and employed as the parameterized domain over which different coverage aspects (such as detection sensitivity, beam size, and minimum beam height) are studied using analytical tools developed in the paper. Other important parameters are the number of different radars with overlapping coverage at a given point in the network domain and the coverage area and number of radars of a network and its elemental cells. A combination of analytical and numerically derived expressions is employed to obtain these parameters for several configurations. The radar network characterization tools developed are applied to the comparison of individual radar and networked radar configurations of interest. The values used in the calculations illustrate the CASA Integrated Project 1 (IP1) radar network and are compared to other radar systems.
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Silva, Murilo Teixeira, Weimin Huang, and Eric W. Gill. "Bistatic High-Frequency Radar Cross-Section of the Ocean Surface with Arbitrary Wave Heights." Remote Sensing 12, no. 4 (February 18, 2020): 667. http://dx.doi.org/10.3390/rs12040667.
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The scattering theory developed in the past decades for high-frequency radio oceanography has been restricted to surfaces with small heights and small slopes. In the present work, the scattering theory for bistatic high-frequency radars is extended to ocean surfaces with arbitrary wave heights. Based on recent theoretical developments in the scattering theory for ocean surfaces with arbitrary heights for monostatic radars, the electric field equations for bistatic high-frequency radars in high sea states are developed. This results in an additional term related to the first-order electric field, which is only present when the small-height approximation is removed. Then, the radar cross-section for the additional term is derived and simulated, and its impact on the total radar cross-section at different radar configurations, dominant wave directions, and sea states is assessed. The proposed term is shown to impact the total radar cross-section at high sea states, dependent on radar configuration and dominant wave direction. The present work can contribute to the remote sensing of targets on the ocean surface, as well as the determination of the dominant wave direction of the ocean surface at high sea states.
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Volosyuk, Valeriy, and Semen Zhyla. "Statistical Theory of Optimal Stochastic Signals Processing in Multichannel Aerospace Imaging Radar Systems." Computation 10, no. 12 (December 18, 2022): 224. http://dx.doi.org/10.3390/computation10120224.
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The work is devoted to solving current scientific and applied problems of the development of radar imaging methods. These developments are based on statistical theory of optimal signal processing. These developments allow researchers to create coherent high-resolution information-enriched images as well as incoherent images. These methods can be practically applied in multichannel aerospace radars through the proposed programs and algorithms. Firstly, the following models of stochastic signals at the output of multichannel registration regions of scattered electro-magnetic fields, internal noise, and observation equations are developed and their statistical characteristics investigated. For the considered models of observation equations, the likelihood functional is defined. This definition is an important stage in optimizing spatial and temporal signal processing. These signals are distorted by internal receiver noises in radar systems. Secondly, by synthesising and analysing methods of measuring a radar cross section, the problem of incoherent imaging by aerospace radars with planar antenna array is solved. Thirdly, the obtained optimal mathematical operations are physically interpreted. The proposed interpretation helps to implement a quasi-optimal algorithm of radar cross section estimation in aerospace radar systems. Finally, to verify the proposed theory, a semi-natural experiment of real radio holograms processing was performed. These radio holograms are digital recordings of spatial and temporal signals by an airborne synthetic aperture radar (SAR) system. The results of the semi-natural experiment are presented and analysed in the paper. All the calculations, developments and results in this paper can be applied to new developments in areas such as remote sensing or non-destructive testing.
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Srinivasan, R. "Distributed radar detection theory." IEE Proceedings F Communications, Radar and Signal Processing 133, no. 1 (1986): 55. http://dx.doi.org/10.1049/ip-f-1.1986.0010.
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Kutuzov, V. M., V. I. Veremyev, Nguyen Van Tuan, and E. N. Vorobev. "Feasibility Study of Using 5G Signals for Illumination Purposes in Passive Radar." Journal of the Russian Universities. Radioelectronics 27, no. 1 (February 29, 2024): 67–78. http://dx.doi.org/10.32603/1993-8985-2024-27-1-67-78.
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Introduction. Passive radars perform target detection based on reflected signals emitted by third-party transmitters. The absence of its own transmitter determines the main advantages of passive radars compared to conventional active radars: lower cost, silent operation, no electromagnetic impact on other radio equipment and the environment. Third-party transmitters of different telecommunication systems are currently used as illuminators of opportunity in passive radars. The emergence of new telecommunication standards opens additional prospects for the development of passive radars. For instance, the deployment of the fifth generation of mobile communications standard 5G with a higher bandwidth can potentially improve the accuracy of target detection in passive radars. Investigating the possibility of using signals from 5G transmitters for radar targets illumination is a relevant research task.Aim. To analyze the possibilities, limitations and prospects of using 5G signals as illuminators of opportunity in passive radar systems.Materials and methods. The methods of passive radar theory, communication theory, and comparative analysis were used. Evaluation of potential characteristics of target detection was carried out using computer statistical modelling in the MATLAB environment.Results. The peculiarities of 5G signals from the point of view of their application as illumination signals in passive radars are investigated. The potential target detection characteristics of a passive radar using 5G signals for target illumination are evaluated and compared with those of passive radars operating on signals from other transmitters. The 5G signal provides an improved range and velocity resolution than signals from other telecommunication systems.Conclusion. The comparative analysis shows that 5G NR signal transmitters can be used as a promising source of illumination in passive radar systems over relatively small areas.
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Wang, Chun Yu, Xing Long Qi, Shuo Chang, and Lin Ren. "The Decision Method of Electromagnetic Compatibility between Radars Based on the Theory of Signal Detection." Applied Mechanics and Materials 513-517 (February 2014): 2959–62. http://dx.doi.org/10.4028/www.scientific.net/amm.513-517.2959.
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In order to determine the electromagnetic compatibility between radars better, this paper deduced the distribution character of signal+ noise+ jamming and the signal passing narrowband linear filtering system based on the signal detection theory, and established the quantitative relationship of the radar detection probability and jamming noise ratio on this basis, the detection probability was used to judge the electromagnetic compatibility between radars directly. The simulation experimental results showed that the detection probability was reduced with the increase of interference intensity, when the interference power exceeded the threshold of 1.7 dB, radar detection probability dropped to 50%.
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Anderson, Stuart. "Remote Sensing of the Polar Ice Zones with HF Radar." Remote Sensing 13, no. 21 (October 31, 2021): 4398. http://dx.doi.org/10.3390/rs13214398.
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Radars operating in the HF band are widely used for over-the-horizon remote sensing of ocean surface conditions, ionospheric studies and the monitoring of ship and aircraft traffic. Several hundreds of such radars are in operation, yet only a handful of experiments have been conducted to assess the prospect of utilizing this technology for the remote sensing of sea ice. Even then, the measurements carried out have addressed only the most basic questions: is there ice present, and can we measure its drift? Recently the theory that describes HF scattering from the dynamic sea surface was extended to handle situations where an ice cover is present. With this new tool, it becomes feasible to interpret the corresponding radar echoes in terms of the structural, mechanical, and electrical properties of the ice field. In this paper we look briefly at ice sensing from space-borne sensors before showing how the persistent and synoptic wide area surveillance capabilities of HF radar offer an alternative. The dispersion relations of different forms of sea ice are examined and used in a modified implementation of the electromagnetic scattering theory employed in HF radar oceanography to compute the corresponding radar signatures. Previous and present-day HF radar deployments at high latitudes are reviewed, noting the physical and technical challenges that confront the implementation of an operational HF radar in its ice monitoring capability.
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Goldstein, J. S., and I. S. Reed. "Theory of partially adaptive radar." IEEE Transactions on Aerospace and Electronic Systems 33, no. 4 (October 1997): 1309–25. http://dx.doi.org/10.1109/7.625132.
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Talich, Milan, Jan Havrlant, Lubomír Soukup, Tomáš Plachý, Michal Polák, Filip Antoš, Pavel Ryjáček, and Vojtěch Stančík. "Accuracy Analysis and Appropriate Strategy for Determining Dynamic and Quasi-Static Bridge Structural Response Using Simultaneous Measurements with Two Real Aperture Ground-Based Radars." Remote Sensing 15, no. 3 (February 2, 2023): 837. http://dx.doi.org/10.3390/rs15030837.
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Over the past 10 years, ground-based radar interferometry has become a frequently used technology for determining dynamic deflections of bridge structures induced by vehicle passages. When measuring with only one radar device, the so-called Interpretation Error (EI) considerably rises. When using two radars, it is possible to simultaneously determine, for example, vertical and longitudinal displacements and to eliminate the Interpretation Error. The aim of the article is to establish a suitable strategy for determining dynamic and quasi-static response of bridge structures based on the accuracy analysis of measurement by two radars. The necessary theory for displacements determination by means of two radar devices is presented. This is followed by an analysis of errors when measuring with only one radar. For the first time in the literature, mathematical formulas are derived here for determining the accuracy of the resulting displacements by simultaneous measurement with two radars. The practical examples of bridge structures displacements determination by measuring with two radar devices in the field are presented. The key contribution of the paper is the possibility to estimate and plan in advance the achievable accuracy of the resulting displacements for the given radar configurations in relation to the bridge structure.
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Bestugin, Aleksandr R., Maksim B. Ryzhikov, Yuliana A. Novikova, and Irina A. Kirshina. "Increasing the effectiveness of aircraft detection on catch-up courses in pulse-Doppler airborne radars with a low carrier flight altitude." T-Comm 17, no. 4 (2023): 11–16. http://dx.doi.org/10.36724/2072-8735-2023-17-4-11-16.
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Problem statement. The effectiveness of solving the problem of warning about possible collisions of small aircraft or unmanned aerial vehicles intended for the development of hard-to-reach territories depends on the time of early detection of another aircraft on intersecting trajectories. As a result of the comparative analysis of radar detection methods carried out in the article, taking into account the differences in the signal-interference situation characteristic of on-board pulse−Doppler radars for targets on catch-up courses in versions "multiple input - multiple output", "with joint a posteriori processing of results" and in traditional radar with active or passive phased antenna arrays have shown that the latter have energy advantages. Therefore, for this category of pulse-Doppler radars, a method for estimating the detection range on several frames is presented, which allows you to choose the logic of operation with an increase in the detection range. Research methods. The theory of antenna arrays and the theory of radar detection for pulse-Doppler radars were actively used in the work with the specified requirements for the probabilities of correct detection, false alarm and the selected model of fluctuations of the reflected useful signal. Purpose. To substantiate the advantages of technical solutions based on a traditional technical solution with phased antenna arrays for detection on catch-up courses and to develop recommendations for finding conditions that allow to increase the detection range. Results. The simulation results are presented, showing an improvement in the conditions for radar detection in onboard pulse-Doppler radars when finding the spectrum of the reflected radar signal in the Doppler frequency range, on which the spectrum of the reflected signal from the Earth's surface is superimposed when using radar with phased antenna arrays compared with spatial processing methods in MIMO and radars with joint a posteriori processing of results. A method for calculating the detection range on several adjacent frames has been developed and it is shown that in this case a longer range is achieved compared to the case of detection on a single frame. Practical significance. The results of the work can be used in small-sized onboard pulse radars of low-altitude carriers in order to increase the time of early warning of the presence of other aircraft on the flight path. This task seems to be especially relevant when flying radar carriers in hard-to-reach, developed territories.
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Duke, Jonathan, Eli Neville, and Jorge Vargas. "A Modulated Approach for Improving MFSK RADARS to Resolve Mutual Interference on Autonomous Vehicles (AVs)." Sensors 23, no. 16 (August 15, 2023): 7192. http://dx.doi.org/10.3390/s23167192.
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This paper proposes a novel automotive radar waveform involving the theory behind M-ary frequency shift key (MFSK) radar systems. Along with the MFSK theory, coding schemes are studied to provide a solution to mutual interference. The proposed MFSK waveform consists of frequency increments throughout the range of 76 GHz to 81 GHz with a step value of 1 GHz. Instead of stepping with a fixed frequency, a triangular chirp sequence allows for static and moving objects to be detected. Therefore, automotive radars will improve Doppler estimation and simultaneous range of various targets. In this paper, a binary coding scheme and a combined transform coding scheme used for radar waveform correlation are evaluated in order to provide unique signals. AVs have to perform in an environment with a high number of signals being sent through the automotive radar frequency band. Efficient coding methods are required to increase the number of signals that are generated. An evaluation method and experimental data of modulated frequencies as well as a comparison with other frequency method systems are presented.
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Marzano, F. S., and G. Ferrauto. "Relation between weather radar equation and first-order backscattering theory." Atmospheric Chemistry and Physics Discussions 3, no. 1 (January 13, 2003): 301–22. http://dx.doi.org/10.5194/acpd-3-301-2003.
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Abstract. Aim of this work is to provide a new insight into the physical basis of the meteorological-radar theory in attenuating media. Starting form the general integral form of the weather radar equation, a modified form of the classical weather radar equation at attenuating wavelength is derived. This modified radar equation includes a new parameter, called the range-bin extinction factor, taking into account the rainfall path attenuation within each range bin. It is shown that, only in the case of low-to-moderate attenuating media, the classical radar equation at attenuating wavelength can be used. These theoretical results are corroborated by using the radiative transfer theory where multiple scattering phenomena can be quantified. From a new definition of the radar reflectivity, in terms of backscattered specific intensity, a generalised radar equation is deduced. Within the assumption of first-order backscattering, the generalised radar equation is reduced to the modified radar equation, previously obtained. This analysis supports the conclusion that the description of radar observations at attenuating wavelength should include, in principle, first-order scattering effects. Numerical simulations are performed by using statistical relationships among the radar reflectivity, rain rate and specific attenuation, derived from literature. Results confirm that the effect of the range-bin extinction factor, depending on the considered frequency and range resolution, can be significant at X band for intense rain, while at Ka band and above it can become appreciable even for moderate rain. A discussion on the impact of these theoretical and numerical results is finally included.
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Marzano, F. S., and G. Ferrauto. "Relation between weather radar equation and first-order backscattering theory." Atmospheric Chemistry and Physics 3, no. 3 (June 20, 2003): 813–21. http://dx.doi.org/10.5194/acp-3-813-2003.
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Abstract. Aim of this work is to provide a new insight into the physical basis of the meteorological-radar theory in attenuating media. Starting form the general integral form of the weather radar equation, a modified form of the classical weather radar equation at attenuating wavelength is derived. This modified radar equation includes a new parameter, called the range-bin extinction factor, taking into account the rainfall path attenuation within each range bin. It is shown that, only in the case of low-to-moderate attenuating media, the classical radar equation at attenuating wavelength can be used. These theoretical results are corroborated by using the radiative transfer theory where multiple scattering phenomena can be quantified. From a new definition of the radar reflectivity, in terms of backscattered specific intensity, a generalised radar equation is deduced. Within the assumption of first-order backscattering, the generalised radar equation is reduced to the modified radar equation, previously obtained. This analysis supports the conclusion that the description of radar observations at attenuating wavelength should include, in principle, first-order scattering effects. Numerical simulations are performed by using statistical relationships among the radar reflectivity, rain rate and specific attenuation, derived from literature. Results confirm that the effect of the range-bin extinction factor, depending on the considered frequency and range resolution, can be significant at X band for intense rain, while at Ka band and above it can become appreciable even for moderate rain. A discussion on the impact of these theoretical and numerical results is finally included.
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Dai, Xiangrong, Chenguang Shi, Ziwei Wang, and Jianjiang Zhou. "Coalition Game Theoretic Power Allocation Strategy for Multi-Target Detection in Distributed Radar Networks." Remote Sensing 15, no. 15 (July 31, 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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Zhyla, Simeon, Valerii Volosyuk, Vladimir Pavlikov, Nikolay Ruzhentsev, Eduard Tserne, Anatoliy Popov, Oleksandr Shmatko, et al. "Statistical synthesis of aerospace radars structure with optimal spatio-temporal signal processing, extended observation area and high spatial resolution." RADIOELECTRONIC AND COMPUTER SYSTEMS, no. 1 (February 23, 2022): 178–94. http://dx.doi.org/10.32620/reks.2022.1.14.
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Using the statistical theory of optimization of radio engineering systems the optimal method of coherent radar imaging of surfaces in airborne synthetic aperture radar with planar antenna arrays is developed. This method summarizes several modes of terrain observation and it is fully consistent with current trends in the development of cognitive radars with the possibilities of radiation pattern restructuring in space and adaptive reception of reflected signals. Possible modifications of the obtained optimal method for the operation of high-precision airborne radars with a wide swath are presented. The idea is to create a theoretical basis and lay the foundations for its practical application in solving a wide range of issues of statistical optimization of methods and algorithms for optimal spatiotemporal signal processing in cognitive radar systems for the formation of both high-precision and global radar images. To implement the idea, the article highlights the concept of statistical optimization of spatio-temporal processing of electromagnetic fields in on-board cognitive radar systems, which will be based on the synthesis and analysis of methods, algorithms and structures of radar devices for coherent imaging, the study of limiting errors in restoring the spatial distribution of the complex scattering coefficient, the synthesis of optimal feedback for receiver and transmitter adaptations in accordance with a priori information about the parameters of the objects of study, the area of observation and the existing sources of interference. Objective is to develop the theory and fundamentals of the technical implementation of airborne radar systems for the formation of high-precision radar images in an extended field of view from aerospace carriers. Tasks. To reach the objective it is necessary to solve following tasks:– formalize mathematical models of spatiotemporal stochastic radio signals and develop likelihood functional for observation equations in which the useful signal, receiver internal noise and interference radiation of anthropogenic objects are random processes;– to synthesize algorithms for optimal processing of spatio-temporal stochastic signals in multi-channel radar systems located on aerospace-based mobile platforms;- in accordance with the synthesized methods, to substantiate the block diagrams of their implementation;– obtain analytical expressions for the potential characteristics of the quality of radar imaging and determine the class of probing signals and space scanning methods necessary to perform various tasks of radar surveillance;‒ to confirm some of the theoretical results by simulation methods, in which to reveal the features of the technical implementation of aerospace remote sensing radar systems.
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Bell, M. R. "Information theory and radar waveform design." IEEE Transactions on Information Theory 39, no. 5 (1993): 1578–97. http://dx.doi.org/10.1109/18.259642.
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Mel'nik, V. N. "Plasma theory of solar radar echoes." Radio Science 38, no. 3 (May 13, 2003): n/a. http://dx.doi.org/10.1029/2000rs002454.
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Auslander, L., and R. Tolimieri. "Radar Ambiguity Functions and Group Theory." SIAM Journal on Mathematical Analysis 16, no. 3 (May 1985): 577–601. http://dx.doi.org/10.1137/0516043.
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Angulo, I., O. Grande, D. Jenn, D. Guerra, and D. de la Vega. "Estimating reflectivity values from wind turbines for analyzing the potential impact on weather radar services." Atmospheric Measurement Techniques Discussions 8, no. 2 (February 3, 2015): 1477–509. http://dx.doi.org/10.5194/amtd-8-1477-2015.
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Abstract. The World Meteorological Organization (WMO) has repeatedly expressed concern over the increasing number of impact cases of wind turbine farms on weather radars. Since nowadays signal processing techniques to mitigate Wind Turbine Clutter (WTC) are scarce, the most practical approach to this issue is the assessment of the potential interference from a wind farm before it is installed. To do so, and in order to obtain a WTC reflectivity model, it is crucial to estimate the Radar Cross Section (RCS) of the wind turbines to be built, which represents the power percentage of the radar signal that is backscattered to the radar receiver. This paper first characterizes the RCS of wind turbines in the weather radar frequency bands by means of computer simulations based on the Physical Optics theory, and then proposes a simplified model to estimate wind turbine RCS values. This model is of great help in the evaluation of the potential impact of a certain wind farm on the weather radar operation.
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Asif, Asma, and Sithamparanathan Kandeepan. "Cooperative Fusion Based Passive Multistatic Radar Detection." Sensors 21, no. 9 (May 5, 2021): 3209. http://dx.doi.org/10.3390/s21093209.
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Passive multistatic radars have gained a lot of interest in recent years as they offer many benefits contrary to conventional radars. Here in this research, our aim is detection of target in a passive multistatic radar system. The system contains a single transmitter and multiple spatially distributed receivers comprised of both the surveillance and reference antennas. The system consists of two main parts: 1. Local receiver, and 2. Fusion center. Each local receiver detects the signal, processes it, and passes the information to the fusion center for final detection. To take the advantage of spatial diversity, we apply major fusion techniques consisting of hard fusion and soft fusion for the case of multistatic passive radars. Hard fusion techniques are analyzed for the case of different local radar detectors. In terms of soft fusion, a blind technique called equal gain soft fusion technique with random matrix theory-based local detector is analytically and theoretically analyzed under null hypothesis along with the calculation of detection threshold. Furthermore, six novel random matrix theory-based soft fusion techniques are proposed. All the techniques are blind in nature and hence do not require any knowledge of transmitted signal or channel information. Simulation results illustrate that proposed fusion techniques increase detection performance to a reasonable extent compared to other blind fusion techniques.
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Wang, Chun Yu, Xing Long Qi, Run Lan Tian, and Lin Ren. "The Radar Signal Detection Based on Higher Order Statistics." Applied Mechanics and Materials 310 (February 2013): 421–23. http://dx.doi.org/10.4028/www.scientific.net/amm.310.421.
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Radar signal detection theory is significant for the radar signal detection, and there are many radar signal detection method at present. In this paper, higher order statistics was used to achieve the radar signal detection. It analyzed the basic theory of higher order statistics and higher order statistics in radar signal detection. And it achieved radar signal detection in the MATLAB software, colored Gaussian noise signal detection method based on dual-spectrum was used to detect the radar signal mixed with man-made noise.
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Pietkiewicz, Tadeusz. "Fusion of Identification Information from ESM Sensors and Radars Using Dezert–Smarandache Theory Rules." Remote Sensing 15, no. 16 (August 10, 2023): 3977. http://dx.doi.org/10.3390/rs15163977.
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This paper presents a method of fusion of identification (attribute) information provided by two types of sensors: combined primary and secondary (IFF) surveillance radars and ESMs (electronic support measures). In the first section, the basic taxonomy of attribute identification is adopted in accordance with the standards of STANAG 1241 ed. 5 and STANAG 1241 ed. 6 (draft). These standards provide the following basic values of the attribute identifications: FRIEND; HOSTILE; NEUTRAL; UNKNOWN; and additional values, namely ASSUMED FRIEND and SUSPECT. The basis of theoretical considerations is Dezert–Smarandache theory (DSmT) of inference. This paper presents and uses in practice six information-fusion rules proposed by DSmT, i.e., the proportional conflict redistribution rules (PCR1, PCR2, PCR3, PCR4, PCR5, and PCR6), for combining identification information from different ESM sensors and radars. This paper demonstrates the rules of determining attribute information by an ESM sensor equipped with the database of radar emitters. It is proposed that each signal vector sent by the ESM sensor contains an extension specifying a randomized identification declaration (hypothesis)—a basic belief assignment (BBA). This paper also presents a model for determining the basic belief assignment for a combined primary and secondary radar. Results of the PCR rules of sensor information combining for different scenarios of a radio electronic situation (deterministic and Monte Carlo) are presented in the final part of this paper. They confirm the legitimacy of the use of Dezert–Smarandache theory in information fusion for primary radars, secondary radars, and ESM sensors.
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Eshleman, Von R. "The radar-glory theory for icy moons with implications for radar mapping." Advances in Space Research 7, no. 5 (1987): 133–36. http://dx.doi.org/10.1016/0273-1177(87)90365-6.
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Konopel'kin, M. Yu, S. V. Petrov, and D. A. Smirnyagina. "Implementation of stochastic signal processing algorithms in radar CAD." Russian Technological Journal 10, no. 5 (October 21, 2022): 49–59. http://dx.doi.org/10.32362/2500-316x-2022-10-5-49-59.
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Objectives. In 2020, development work on the creation of a Russian computer-assisted design system for radars (radar CAD) was completed. Radar CAD provides extensive opportunities for creating simulation models for developing the hardware-software complex of radar algorithms, which take into account the specific conditions of aerospace environment observation. The purpose of the present work is to review and demonstrate the capabilities of radar CAD in terms of implementing and testing algorithms for processing stochastic signals.Methods. The work is based on the mathematical apparatus of linear algebra. Analysis of algorithms characteristics was carried out using the simulation method.Results. A simulation model of a sector surveillance radar with a digital antenna array was created in the radar CAD visual functional editor. The passive channel included the following algorithms: algorithm for detecting stochastic signals; algorithm for estimating the number of stochastic signals; direction finding algorithm for stochastic signal sources; adaptive spatial filtering algorithm. In the process of simulation, the algorithms for detecting and estimating the number of stochastic signals produced a correct detection sign and an estimate of the number of signals. The direction-finding algorithm estimated the angular position of the sources with an accuracy of fractions of degrees. The adaptive spatial filtering algorithm suppressed interfering signals to a level below the antenna's intrinsic noise power.Conclusions. The processing of various types of signals can be simulated in detail on the basis of the Russian radar CAD system for the development of functional radar models. According to the results of the simulation, coordinates of observing objects were obtained and an assessment of the effectiveness of the algorithms was given. The obtained results are fully consistent with the theoretical prediction. The capabilities of radar CAD systems demonstrated in this work can be used by specialists in the field of radar and signal processing.
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Schlegel, K., and A. V. Gurevich. "Radar backscatter from plasma irregularities of the lower E region induced by neutral turbulence." Annales Geophysicae 15, no. 7 (July 31, 1997): 870–77. http://dx.doi.org/10.1007/s00585-997-0870-z.
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Abstract. Recently, one of the authors (A. V. G.) developed a theory of low-frequency plasma irregularities which are created as a consequence of neutral turbulence in the D and lower E regions. In the following this theory will be applied to coherent backscatter experiments with radars in a frequency range between 5 and 150 MHz. We discuss the dependence of the backscatter cross-section on ionospheric as well as on turbulence parameters. The backscatter increases strongly with decreasing radar frequency. Above 15 MHz the effects discussed here can probably only be detected by very powerful radars with large antenna arrays.
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Xue, Chenyan, Ling Wang, and Daiyin Zhu. "Dwell Time Allocation Algorithm for Multiple Target Tracking in LPI Radar Network Based on Cooperative Game." Sensors 20, no. 20 (October 21, 2020): 5944. http://dx.doi.org/10.3390/s20205944.
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To solve the problem of dwell time management for multiple target tracking in Low Probability of Intercept (LPI) radar network, a Nash bargaining solution (NBS) dwell time allocation algorithm based on cooperative game theory is proposed. This algorithm can achieve the desired low interception performance by optimizing the allocation of the dwell time of each radar under the constraints of the given target detection performance, minimizing the total dwell time of radar network. By introducing two variables, dwell time and target allocation indicators, we decompose the dwell time and target allocation into two subproblems. Firstly, combining the Lagrange relaxation algorithm with the Newton iteration method, we derive the iterative formula for the dwell time of each radar. The dwell time allocation of the radars corresponding to each target is obtained. Secondly, we use the fixed Hungarian algorithm to determine the target allocation scheme based on the dwell time allocation results. Simulation results show that the proposed algorithm can effectively reduce the total dwell time of the radar network, and hence, improve the LPI performance.
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Angulo, I., O. Grande, D. Jenn, D. Guerra, and D. de la Vega. "Estimating reflectivity values from wind turbines for analyzing the potential impact on weather radar services." Atmospheric Measurement Techniques 8, no. 5 (May 27, 2015): 2183–93. http://dx.doi.org/10.5194/amt-8-2183-2015.
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Abstract. The World Meteorological Organization (WMO) has repeatedly expressed concern over the increasing number of impact cases of wind turbine farms on weather radars. Current signal processing techniques to mitigate wind turbine clutter (WTC) are scarce, so the most practical approach to this issue is the assessment of the potential interference from a wind farm before it is installed. To do so, and in order to obtain a WTC reflectivity model, it is crucial to estimate the radar cross section (RCS) of the wind turbines to be built, which represents the power percentage of the radar signal that is backscattered to the radar receiver. For the proposed model, a representative scenario has been chosen in which both the weather radar and the wind farm are placed on clear areas; i.e., wind turbines are supposed to be illuminated only by the lowest elevation angles of the radar beam. This paper first characterizes the RCS of wind turbines in the weather radar frequency bands by means of computer simulations based on the physical optics theory and then proposes a simplified model to estimate wind turbine RCS values. This model is of great help in the evaluation of the potential impact of a certain wind farm on the weather radar operation.
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Mel’nik, Valentin. "Plasma Theory of Solar Radar Echoes after Thirty Years." Highlights of Astronomy 12 (2002): 389. http://dx.doi.org/10.1017/s1539299600013836.
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In 1967 Gordon made the revolutionary assumption that reflection of radar signal from the Sun can be explained by its scattering on microturbulence (Gordon 1973). In his first model it was ion-sound turbulence. Later he considered radar scattering on Langmuir turbulence. The principal opportunity to explain frequency displacements of radar echoes observed in James’ experiments (James 1966, 1970) was shown. However, it turned out (Gerasimova 1979) that the mechanism needed an impermissible high level of isotropic turbulence for the reflection with cross-sectionsσ= 10πR2ʘ.
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Wei, Yuan, Tao Hong, and Michel Kadoch. "Improved Kalman Filter Variants for UAV Tracking with Radar Motion Models." Electronics 9, no. 5 (May 7, 2020): 768. http://dx.doi.org/10.3390/electronics9050768.
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Unmanned aerial vehicles (UAV) have made a huge influence on our everyday life with maturity of technology and more extensive applications. Tracking UAVs has become more and more significant because of not only their beneficial location-based service, but also their potential threats. UAVs are low-altitude, slow-speed, and small targets, which makes it possible to track them with mobile radars, such as vehicle radars and UAVs with radars. Kalman filter and its variant algorithms are widely used to extract useful trajectory information from data mixed with noise. Applying those filter algorithms in east-north-up (ENU) coordinates with mobile radars causes filter performance degradation. To improve this, we made a derivation on the motion-model consistency of mobile radar with constant velocity. Then, extending common filter algorithms into earth-centered earth-fixed (ECEF) coordinates to filter out random errors is proposed. The theory analysis and simulation shows that the improved algorithms provide more efficiency and compatibility in mobile radar scenes.
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Dolan, Brenda, and Steven A. Rutledge. "A Theory-Based Hydrometeor Identification Algorithm for X-Band Polarimetric Radars." Journal of Atmospheric and Oceanic Technology 26, no. 10 (October 1, 2009): 2071–88. http://dx.doi.org/10.1175/2009jtecha1208.1.
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Abstract Although much work has been done at S band to automatically identify hydrometeors by using polarimetric radar, several challenges are presented when adapting such algorithms to X band. At X band, attenuation and non-Rayleigh scattering can pose significant problems. This study seeks to develop a hydrometeor identification (HID) algorithm for X band based on theoretical simulations using the T-matrix scattering model of seven different hydrometeor types: rain, drizzle, aggregates, pristine ice crystals, low-density graupel, high-density graupel, and vertical ice. Hail and mixed-phase hydrometeors are excluded for the purposes of this study. Non-Rayleigh scattering effects are explored by comparison with S-band simulations. Variable ranges based on the theoretical simulations are used to create one-dimensional fuzzy-logic membership beta functions that form the basis of the new X-band HID. The theory-based X-band HID is applied to a case from the Collaborative Adaptive Sensing of the Atmosphere (CASA) Integrated Project 1 (IP1) network of X-band radars, and comparisons are made with similar S-band hydrometeor identification algorithms applied to data from the S-band polarimetric Next Generation Weather Radar (NEXRAD) prototype radar, KOUN. The X-band HID shows promise for illustrating bulk hydrometeor types and qualitatively agrees with analysis from KOUN. A simple reflectivity- and temperature-only HID is also applied to both KOUN and CASA IP1 data to reveal benefits of the polarimetric-based HID algorithms, especially in the classification of ice hydrometeors and oriented ice crystals.
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Toker, Onur, and Marius Brinkmann. "A Novel Nonlinearity Correction Algorithm for FMCW Radar Systems for Optimal Range Accuracy and Improved Multitarget Detection Capability." Electronics 8, no. 11 (November 5, 2019): 1290. http://dx.doi.org/10.3390/electronics8111290.
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Frequency-modulated continuous wave (FMCW) radars are an important class of radar systems, and they are quite popular because of their simpler architecture and lower cost. A fundamental problem in FMCW radars is the nonlinearity of the voltage-controlled oscillator (VCO), which results in a range of measurement errors, problems in multitarget detection, and degradation in synthetic aperture radar (SAR) images. In this paper, we first introduce a novel upsampling theory, then propose new algorithms to improve range accuracy and multitarget detection capability. These improvements are demonstrated both by simulations and actual lab experiments on a 2.4 GHz radar system. There are several techniques reported in the literature for VCO nonlinearity correction, but what makes the proposed approach different is that we focus on real-time processing on low-cost hardware and optimize the design subject to this constraint. We first developed an optimal upsampling theory which is based on almost-causal finite impulse response (FIR) filters. Compared to the sinc-based noncausal interpolation-based upsamplers, the proposed approach is based on using interpolation filters with few number of coefficients. Furthermore, interpolators are trained for a specific class of signals rather than a highly general signal set. Therefore, the proposed approach can be implemented on lower-cost hardware and perform quite well compared to more expensive systems.
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Alpers, Werner. "Theory of radar imaging of internal waves." Nature 314, no. 6008 (March 1985): 245–47. http://dx.doi.org/10.1038/314245a0.
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van Zyl, Jakob J., Howard A. Zebker, and Charles Elachi. "Imaging radar polarization signatures: Theory and observation." Radio Science 22, no. 4 (July 1987): 529–43. http://dx.doi.org/10.1029/rs022i004p00529.
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Wang, H. L., W. Li, H. Wang, J. Y. Xu, and J. L. Zhao. "Radar Waveform Strategy Based on Game Theory." Radioengineering 28, no. 4 (December 13, 2019): 757–64. http://dx.doi.org/10.13164/re.2019.0757.
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D'Addio, E., and A. Farina. "Overview of detection theory in multistatic radar." IEE Proceedings F Communications, Radar and Signal Processing 133, no. 7 (1986): 613. http://dx.doi.org/10.1049/ip-f-1.1986.0098.
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Jensen, J. R. "Radar altimeter gate tracking: theory and extension." IEEE Transactions on Geoscience and Remote Sensing 37, no. 2 (March 1999): 651–58. http://dx.doi.org/10.1109/36.752182.
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Druzhynin, V., N. Tsopa, H. Zhyrov, and I. Chetverikov. "CURRENT STATUS AND DEVELOPMENT TRENDS OF RADAR SYSTEMS AIRBORNE BASED WITH TIME-VARYING RELATIVE SPATIAL CONFIGURATION." Collection of scientific works of the Military Institute of Kyiv National Taras Shevchenko University, no. 66 (2019): 6–14. http://dx.doi.org/10.17721/2519-481x/2020/66-01.
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The work is devoted to the review of the current state and development trends of airborne-based radar systems with a time-varying relative spatial configuration. The relevance of consideration of the state and tendencies of development of radar systems of aviation-ground based with time-varying relative spatial configuration due to the practical need to obtain radar images (radars) of objects in the front area of the system review, taking into account the growing requirements for promptness and accuracy of image detection of real-time surveillance in a complex signal-interference environment. The generalized structure of the construction of the systems considered in the work is presented and the main prospects for their practical application in solving the problems of classifying radar objects and monitoring radio emission sources are determined. Estimates are given of the main qualitative characteristics of the images of radar objects when applied when using the systems considered and the accuracy of determining the coordinates of radio emission sources is estimated based on an approved mathematical apparatus. The priority areas of scientific research on the further development of the theory of multi-positional reception of radar information in the conditions of information uncertainty when using systems with a time-variable relative spatial configuration are determined.
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Cui, Yuanhao, Visa Koivunen, and Xiaojun Jing. "Precoder and Decoder Co-Designs for Radar and Communication Spectrum Sharing." Sensors 22, no. 7 (March 29, 2022): 2619. http://dx.doi.org/10.3390/s22072619.
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The coexistence of radar and communication systems is necessary to facilitate new wireless systems and services due to the shortage of the useful radio spectrum. Moreover, changes in spectrum regulation will be introduced in which the spectrum is allocated in larger chunks and different radio systems need to share the spectrum. For example, 5G NR, LTE and Wi-Fi systems have to share the spectrum with S-band radars. Managing interference is a key task in coexistence scenarios. Cognitive radio and radar technologies facilitate using the spectrum in a flexible manner and sharing channel awareness between the two subsystems. In this paper, we propose a nullspace-based joint precoder–decoder design for coexisting multicarrier radar and multiuser multicarrier communication systems. The maximizing signal interference noise ratio (max-SINR) criterion and interference alignment (IA) constraints are employed in finding the precoder and decoder. By taking advantage of IA theory, a maximum degree of freedom upper bound for the K+1-radar-communication-user interference channel can be achieved. Our simulation studies demonstrate that interference can be practically fully canceled in both communication and radar systems. This leads to improved detection performance in radar and a higher rate in communication subsystems. A significant performance gain over a nullspace-based precoder-only design is also obtained.
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Battiston, Geoffray, Rémi Régnier, and Olivier Galibert. "Evaluation Protocol for Analogue Intelligent Medical Radars: Towards a Systematic Approach Based on Theory and a State of the Art." Sensors 23, no. 6 (March 11, 2023): 3036. http://dx.doi.org/10.3390/s23063036.
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We propose the basis for a systematised approach to the performance evaluation of analogue intelligent medical radars. In the first part, we review the literature on the evaluation of medical radars and compare the provided experimental elements with models from radar theory in order to identify the key physical parameters that will be useful to develop a comprehensive protocol. In the second part, we present our experimental equipment, protocol and metrics to carry out such an evaluation.
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Cervera, M. A., and W. G. Elford. "The meteor radar response function: Theory and application to narrow beam MST radar." Planetary and Space Science 52, no. 7 (June 2004): 591–602. http://dx.doi.org/10.1016/j.pss.2003.12.004.
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Briggs, John N. "Detection of Marine Radar Targets." Journal of Navigation 49, no. 3 (September 1996): 394–409. http://dx.doi.org/10.1017/s0373463300013618.
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A radar must detect targets before it can display them. Yet manufacturers' data sheets rarely tell us what the products will detect at what range. Many of the bigger radars are Type Approved so we consult the relevant IMO performance standard A 477 (XII). Paraphrasing Section 3.1 of the draft forthcoming revision (NAV 41/6): under normal propagation conditions with the scanner at height of 15 m, in the absence of clutter, the radar is required to give clear indication of an object such as a navigational buoy having a radar cross section area (RCS) of 10 m2 at 2 n.m. and, as examples, coastlines whose ground rises to 60/6 m at ranges of 20/7 n.m., a ship of 5000 tons at any aspect at 7 n.m. and a small vessel 10 m long at 3 n.m.This helps, but suppose we must pick up a 5 m2 buoy at g km? What happens in clutter? Should we prefer S- or X-band? To answer such questions we use equations which define the performance of surveillance radars, but the textbooks and specialist papers containing them often generalize with aeronautical and defence topics, making life difficult for the nonspecialist.This paper attempts a concise and self-contained engineering account of all main factors affecting detection of passive and active targets on civil marine and vessel traffic service (VTS) radars. We develop a set of equations for X- and S-band (3 and 10 cm, centred on 9400 and 3000 MHz respectively), suited for spreadsheet calculation.Sufficient theory is sketched in to indicate where results should be valid. Some simplifications of conventional treatments have been identified.
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Mel'nik, V. N. "Interpretation of James' Experiments in Plasma Theory of Solar Radar Echoes." Symposium - International Astronomical Union 199 (2002): 434–36. http://dx.doi.org/10.1017/s0074180900169530.
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In the framework of the plasma theory of solar radar echoes results of the known James' experiments such as the values of effective cross-sections, the anisotropy of reflections, the spectrum of reflected signals, the heights of radar scattering and others are explained. In particular in this theory reflection of radar signal with high effective cross-sections (σ = (10 − 100)πR2⊙) occur in processes t + l ⇌ t + l on the Langmuir turbulance generated by Type III electrons at altitudes (1.4—1.6)-R⊙ when electron streams propagate towards the Earth. If the electrons move away from the Earth then the scattering cross-sections due to process t + l ⇌ t + l are small (σ < πR2⊙). Reflections from the heights up to 5R⊙ can occur at scattering of radar wave on the ion-sound turbulance (processes t + s ⇌ t) accompanied the Langmuir turbulance.
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Lamer, Katia, Mariko Oue, Alessandro Battaglia, Richard J. Roy, Ken B. Cooper, Ranvir Dhillon, and Pavlos Kollias. "Multifrequency radar observations of clouds and precipitation including the G-band." Atmospheric Measurement Techniques 14, no. 5 (May 20, 2021): 3615–29. http://dx.doi.org/10.5194/amt-14-3615-2021.
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Abstract. Observations collected during the 25 February 2020 deployment of the Vapor In-Cloud Profiling Radar at the Stony Brook Radar Observatory clearly demonstrate the potential of G-band radars for cloud and precipitation research, something that until now was only discussed in theory. The field experiment, which coordinated an X-, Ka-, W- and G-band radar, revealed that the Ka–G pairing can generate differential reflectivity signal several decibels larger than the traditional Ka–W pairing underpinning an increased sensitivity to smaller amounts of liquid and ice water mass and sizes. The observations also showed that G-band signals experience non-Rayleigh scattering in regions where Ka- and W-band signal do not, thus demonstrating the potential of G-band radars for sizing sub-millimeter ice crystals and droplets. Observed peculiar radar reflectivity patterns also suggest that G-band radars could be used to gain insight into the melting behavior of small ice crystals. G-band signal interpretation is challenging, because attenuation and non-Rayleigh effects are typically intertwined. An ideal liquid-free period allowed us to use triple-frequency Ka–W–G observations to test existing ice scattering libraries, and the results raise questions on their comprehensiveness. Overall, this work reinforces the importance of deploying radars (1) with sensitivity sufficient enough to detect small Rayleigh scatters at cloud top in order to derive estimates of path-integrated hydrometeor attenuation, a key constraint for microphysical retrievals; (2) with sensitivity sufficient enough to overcome liquid attenuation, to reveal the larger differential signals generated from using the G-band as part of a multifrequency deployment; and (3) capable of monitoring atmospheric gases to reduce related uncertainty.
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Bhutani, Akanksha, Sören Marahrens, Michael Gehringer, Benjamin Göttel, Mario Pauli, and Thomas Zwick. "The Role of Millimeter-Waves in the Distance Measurement Accuracy of an FMCW Radar Sensor." Sensors 19, no. 18 (September 12, 2019): 3938. http://dx.doi.org/10.3390/s19183938.
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High-accuracy, short-range distance measurement is required in a variety of industrial applications e.g., positioning of robots in a fully automated production process, level measurement of liquids in small containers. An FMCW radar sensor is suitable for this purpose, since many of these applications involve harsh environments. Due to the progress in the field of semiconductor technology, FMCW radar sensors operating in different millimeter-wave frequency bands are available today. An important question in this context, which has not been investigated so far is how does a millimeter-wave frequency band influence the sensor accuracy, when thousands of distance measurements are performed with a sensor. This topic has been dealt with for the first time in this paper. The method used for analyzing the FMCW radar signal combines a frequency- and phase-estimation algorithm. The frequency-estimation algorithm based on the fast Fourier transform and the chirp-z transform provides a coarse estimate of the target distance. Subsequently, the phase-estimation algorithm based on a cross-correlation function provides a fine estimate of the target distance. The novel aspects of this paper are as follows. First, the estimation theory concept of Cramér-Rao lower bound (CRLB) has been used to compare the accuracy of two millimeter-wave FMCW radars operating at 60 GHz and 122 GHz. In this comparison, the measurement parameters (e.g., bandwidth, signal-to-noise ratio) as well as the signal-processing algorithm used for both the radars are the same, thus ensuring an unbiased comparison of the FMCW radars, solely based on the choice of millimeter-wave frequency band. Second, the improvement in distance measurement accuracy obtained after each step of the combined frequency- and phase-estimation algorithm has been experimentally demonstrated for both the radars. A total of 5100 short-range distance measurements are made using the 60 GHz and 122 GHz FMCW radar. The measurement results are analyzed at various stages of the frequency- and phase-estimation algorithm and the measurement error is calculated using a nanometer-precision linear motor. At every stage, the mean error values measured with the 60 GHz and 122 GHz FMCW radars are compared. The final accuracy achieved using both radars is of the order of a few micrometers. The measured standard deviation values of the 60 GHz and 122 GHz FMCW radar have been compared against the CRLB. As predicted by the CRLB, this paper experimentally validates for the first time that the 122 GHz FMCW radar provides a higher repeatability of micrometer-accuracy distance measurements than the 60 GHz FMCW radar.
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Belova, E., P. Dalin, and S. Kirkwood. "Polar mesosphere summer echoes: a comparison of simultaneous observations at three wavelengths." Annales Geophysicae 25, no. 12 (January 2, 2007): 2487–96. http://dx.doi.org/10.5194/angeo-25-2487-2007.
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Abstract. On 5 July 2005, simultaneous observations of Polar Mesosphere Summer Echoes (PMSE) were made using the EISCAT VHF (224 MHz) and UHF (933 MHz) radars located near Tromsø, Norway and the ALWIN VHF radar (53.5 MHz) situated on Andøya, 120 km SW of the EISCAT site. During the short interval from 12:20 UT until 12:26 UT strong echoes at about 84 km altitude were detected with all three radars. The radar volume reflectivities were found to be 4×10−13 m−1, 1.5×10−14 m−1 and 1.5×10−18 m−1 for the ALWIN, EISCAT-VHF and UHF radars, respectively. We have calculated the reflectivity ratios for each pair of radars and have compared them to ratios obtained from the turbulence-theory model proposed by Hill (1978a). We have tested different values of the turbulent energy dissipation rate ε and Schmidt number Sc, which are free parameters in the model, to try to fit theoretical reflectivity ratios to the experimental ones. No single combination of the parameters ε and Sc could be found to give a good fit. Spectral widths for the EISCAT radars were estimated from the spectra computed from the autocorrelation functions obtained in the experiment. After correction for beam-width broadening, the spectral widths are about 4 m/s for the EISCAT-VHF and 1.5–2 m/s for the UHF radar. However, according to the turbulence theory, the spectral widths in m/s should be the same for both radars. We also tested an incoherent scatter (IS) model developed by Cho et al. (1998), which takes into account the presence of charged aerosols/dust at the summer mesopause. It required very different sizes of particles for the EISCAT-VHF and UHF cases, to be able to fit the experimental spectra with model spectra. This implies that the IS model cannot explain PMSE spectra, at least not for monodisperse distributions of particles.
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He, Yaomin, Huizhang Yang, Huafeng He, Junjun Yin, and Jian Yang. "A Ship Discrimination Method Based on High-Frequency Electromagnetic Theory." Remote Sensing 14, no. 16 (August 11, 2022): 3893. http://dx.doi.org/10.3390/rs14163893.
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Ship target detection using radar has important applications in the military and civilian fields. As a decoy, the corner reflector (CR) can successfully deceive a radar by its strong radar cross-section (RCS) to protect a ship. In order to discriminate between a CR and ship, this paper proposes a discrimination method based on three-dimensional characteristics. First, we deduce the basic scattering of CR by the high-frequency electromagnetic theory, and propose a CR decomposition which can solve the problem that the Krogager decomposition has terrible errors in clutter. Then, we introduce the definition of the main scattering polarization and give the multi-dimensional characteristic of CR. Subsequently, we analyze the spatial-time characteristic of radar based on the three-dimensional proportional guidance. With the CR mean square error (MSE), a CR discrimination method is proposed based on the time-spatial-polarization (TSP) joint domains. Finally, the proposed method is analyzed and compared using the fully polarimetric data of Feko software, which can achieve 95% discrimination probability and 4.1% false alarm probability.
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Teng, Yupeng, Tianyan Li, Hongbin Chen, Shuqing Ma, Lei Wu, Yunjie Xia, and Siteng Li. "A New Perspective on the Scattering Mechanism of S-Band Weather Radar Clear-Air Echoes Based on Communication Models." Remote Sensing 16, no. 15 (July 23, 2024): 2691. http://dx.doi.org/10.3390/rs16152691.
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Clear-air echo studies are usually based on isotropic turbulence theory. But the theory has been considered incomplete by modern turbulence theory. The intermittence of turbulence can reveal obvious shortcomings in the existing studies of clear-air echoes. The mechanism of clear-air echo scattering needs to be supplemented. This paper introduces the troposcatter theory, normally used in over-the-horizon communication, to fill the gap left by Bragg scattering. By treating radar as a self-transmitted and self-received device, the equivalent transmission loss of weather radar is established and compared with the recommendations of the Radiocommunication Sector of the International Telecommunication Union (ITU-R). The results show that the S-band radar transmission loss aligns with ITU-R recommendations. There is also a linear regression relationship between the radar transmission loss and height, which conforms to the troposcatter theory. This means that the theory of troposcatter scattering is a supplement to the theory of Bragg scattering. Tropospheric scattering can be thought of as general Bragg scattering. Meanwhile, based on ITU-R recommendations, this study also provides a new way for the recognition of biological echoes.
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Zhang, Zhi Chun, Wen Xu, Zhuang Xiong, Kun Xu, and Song Yan Lu. "Airborne Weather Radar Cloud Simulation Based on Fractal Theory." Advanced Materials Research 909 (March 2014): 423–27. http://dx.doi.org/10.4028/www.scientific.net/amr.909.423.
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This paper describes a cloud simulation method of an airborne weather radar simulator based on the atmosphere characteristics of real clouds. With the fractal theory, an improved Successive Random Additions (SRA) to instruct cloud data modeling was chosen and an appropriate locus of control surfaces was selected. On the basis of the locus of control surfaces and the surface generated in the way of fractal this surface, weighted fusion generated a predetermined shape of the cloud data model. According to the generating rules, the data model was mapped to color values in the corresponding points, and the corresponding relation between height and color values was constructed. Finally, the screen cloud image of the airborne weather radar was drawn. The implementation shows that the method is real time and can be used to generate satisfied simulation radar image.
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Seker, Ilgin, and Marco Lavalle. "Tomographic Performance of Multi-Static Radar Formations: Theory and Simulations." Remote Sensing 13, no. 4 (February 17, 2021): 737. http://dx.doi.org/10.3390/rs13040737.
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3D imaging of Earth’s surface layers (such as canopy, sub-surface, or ice) requires not just the penetration of radar signal into the medium, but also the ability to discriminate multiple scatterers within a slant-range and azimuth resolution cell. The latter requires having multiple radar channels distributed in across-track direction. Here, we describe the theory of multi-static radar tomography with emphasis on resolution, SNR, sidelobes, and nearest ambiguity location vs. platform distribution, observation geometry, and different multi-static modes. Signal-based 1D and 2D simulations are developed and results for various observation geometries, target distributions, acquisition modes, and radar parameters are shown and compared with the theory. Pros and cons of multi-static modes are compared and discussed. Results for various platform formations are shown, revealing that unequal spacing is useful to suppress ambiguities at the cost of increased multiplicative noise. In particular, we demonstrate that the multiple-input multiple-output (MIMO) mode, in combination with nonlinear spacing, outperforms the other modes in terms of ambiguity, sidelobe levels, and noise suppression. These findings are key to guiding the design of tomographic SAR formations for accurate surface topography and vegetation mapping.
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Hogan, Robin J., Lin Tian, Philip R. A. Brown, Christopher D. Westbrook, Andrew J. Heymsfield, and Jon D. Eastment. "Radar Scattering from Ice Aggregates Using the Horizontally Aligned Oblate Spheroid Approximation." Journal of Applied Meteorology and Climatology 51, no. 3 (March 2012): 655–71. http://dx.doi.org/10.1175/jamc-d-11-074.1.
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AbstractThe assumed relationship between ice particle mass and size is profoundly important in radar retrievals of ice clouds, but, for millimeter-wave radars, shape and preferred orientation are important as well. In this paper the authors first examine the consequences of the fact that the widely used “Brown and Francis” mass–size relationship has often been applied to maximum particle dimension observed by aircraft Dmax rather than to the mean of the particle dimensions in two orthogonal directions Dmean, which was originally used by Brown and Francis. Analysis of particle images reveals that Dmax ≃ 1.25Dmean, and therefore, for clouds for which this mass–size relationship holds, the consequences are overestimates of ice water content by around 53% and of Rayleigh-scattering radar reflectivity factor by 3.7 dB. Simultaneous radar and aircraft measurements demonstrate that much better agreement in reflectivity factor is provided by using this mass–size relationship with Dmean. The authors then examine the importance of particle shape and fall orientation for millimeter-wave radars. Simultaneous radar measurements and aircraft calculations of differential reflectivity and dual-wavelength ratio are presented to demonstrate that ice particles may usually be treated as horizontally aligned oblate spheroids with an axial ratio of 0.6, consistent with them being aggregates. An accurate formula is presented for the backscatter cross section apparent to a vertically pointing millimeter-wave radar on the basis of a modified version of Rayleigh–Gans theory. It is then shown that the consequence of treating ice particles as Mie-scattering spheres is to substantially underestimate millimeter-wave reflectivity factor when millimeter-sized particles are present, which can lead to retrieved ice water content being overestimated by a factor of 4.