Artykuły w czasopismach: „Radar techniques”

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Djordjevic, Ivan B. "On Entanglement-Assisted Multistatic Radar Techniques". Entropy 24, nr 7 (17.07.2022): 990. http://dx.doi.org/10.3390/e24070990.

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Entanglement-based quantum sensors have much better sensitivity than corresponding classical sensors in a noisy and lossy regime. In our recent paper, we showed that the entanglement-assisted (EA) joint monostatic–bistatic quantum radar performs much better than conventional radars. Here, we propose an entanglement-assisted (EA) multistatic radar that significantly outperforms EA bistatic, coherent state-based quantum, and classical radars. The proposed EA multistatic radar employs multiple entangled transmitters performing transmit-side optical phase conjugation, multiple coherent detection-based receivers serving as EA detectors, and a joint detector.

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Isom, Bradley, Robert Palmer, Redmond Kelley, John Meier, David Bodine, Mark Yeary, Boon-Leng Cheong, Yan Zhang, Tian-You Yu i Michael I. Biggerstaff. "The Atmospheric Imaging Radar: Simultaneous Volumetric Observations Using a Phased Array Weather Radar". Journal of Atmospheric and Oceanic Technology 30, nr 4 (1.04.2013): 655–75. http://dx.doi.org/10.1175/jtech-d-12-00063.1.

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Abstract Mobile weather radars often utilize rapid-scan strategies when collecting observations of severe weather. Various techniques have been used to improve volume update times, including the use of agile and multibeam radars. Imaging radars, similar in some respects to phased arrays, steer the radar beam in software, thus requiring no physical motion. In contrast to phased arrays, imaging radars gather data for an entire volume simultaneously within the field of view (FOV) of the radar, which is defined by a broad transmit beam. As a result, imaging radars provide update rates significantly exceeding those of existing mobile radars, including phased arrays. The Advanced Radar Research Center (ARRC) at the University of Oklahoma (OU) is engaged in the design, construction, and testing of a mobile imaging weather radar system called the atmospheric imaging radar (AIR). Initial tests performed with the AIR demonstrate the benefits and versatility of utilizing beamforming techniques to achieve high spatial and temporal resolution. Specifically, point target analysis was performed using several digital beamforming techniques. Adaptive algorithms allow for improved resolution and clutter rejection when compared to traditional techniques. Additional experiments were conducted during two severe weather events in Oklahoma. Several digital beamforming methods were tested and analyzed, producing unique, simultaneous multibeam measurements using the AIR.

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Lakshmanan, Valliappa, Travis Smith, Kurt Hondl, Gregory J. Stumpf i Arthur Witt. "A Real-Time, Three-Dimensional, Rapidly Updating, Heterogeneous Radar Merger Technique for Reflectivity, Velocity, and Derived Products". Weather and Forecasting 21, nr 5 (1.10.2006): 802–23. http://dx.doi.org/10.1175/waf942.1.

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Abstract With the advent of real-time streaming data from various radar networks, including most Weather Surveillance Radars-1988 Doppler and several Terminal Doppler Weather Radars, it is now possible to combine data in real time to form 3D multiple-radar grids. Herein, a technique for taking the base radar data (reflectivity and radial velocity) and derived products from multiple radars and combining them in real time into a rapidly updating 3D merged grid is described. An estimate of that radar product combined from all the different radars can be extracted from the 3D grid at any time. This is accomplished through a formulation that accounts for the varying radar beam geometry with range, vertical gaps between radar scans, the lack of time synchronization between radars, storm movement, varying beam resolutions between different types of radars, beam blockage due to terrain, differing radar calibration, and inaccurate time stamps on radar data. Techniques for merging scalar products like reflectivity, and innovative, real-time techniques for combining velocity and velocity-derived products are demonstrated. Precomputation techniques that can be utilized to perform the merger in real time and derived products that can be computed from these three-dimensional merger grids are described.

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Trim, R. M. "Modern Radar Techniques". IEE Review 34, nr 2 (1988): 86. http://dx.doi.org/10.1049/ir:19880027.

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Baggaley, W. J. "RADAR Observations". Highlights of Astronomy 11, nr 2 (1998): 1015–16. http://dx.doi.org/10.1017/s1539299600019481.

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Radar techniques can be a powerful adjunct for studying meteor storms in general because of their sensitivity, capacity for continuous observations and their use of current techniques facilitating the handling of data. While some radars are limited to only a range-time presentation (and so adequate for a time-profile description of a storm event), some facilities have the additional capacity to determine directional information or orbital elements which are valuable in delineating the dynamics and spatial structure of stream meteoroids. The following outlines the application of radar techniques to meteor storm recording and summarizes current and planned facilities.

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Johnston, Paul E., James R. Jordan, Allen B. White, David A. Carter, David M. Costa i Thomas E. Ayers. "The NOAA FM-CW Snow-Level Radar". Journal of Atmospheric and Oceanic Technology 34, nr 2 (luty 2017): 249–67. http://dx.doi.org/10.1175/jtech-d-16-0063.1.

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AbstractA vertically pointing radar for monitoring radar brightband height (BBH) has been developed. This new radar utilizes frequency-modulated continuous wave (FM-CW) techniques to provide high-resolution data at a fraction of the cost of comparable pulsed radars. This S-band radar provides details of the vertical structure of precipitating clouds, with full Doppler information. Details of the radar design are presented along with observations from one storm. Results from a calibration using these storm data show the radar meets the design goals. Eleven of these radars have been deployed and provide BBH data in near–real time.

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Sekine, Matsuo. "Advances in Radar Techniques". IEEJ Transactions on Fundamentals and Materials 125, nr 1 (2005): 15–16. http://dx.doi.org/10.1541/ieejfms.125.15.

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Trim, R. M. "Advances in Radar Techniques". Electronics and Power 32, nr 1 (1986): 77. http://dx.doi.org/10.1049/ep.1986.0041.

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Stove, A. G. "Linear FMCW radar techniques". IEE Proceedings F Radar and Signal Processing 139, nr 5 (1992): 343. http://dx.doi.org/10.1049/ip-f-2.1992.0048.

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Suzuki, T. "Radar beamwidth reduction techniques". IEEE Aerospace and Electronic Systems Magazine 13, nr 5 (maj 1998): 43–48. http://dx.doi.org/10.1109/62.673742.

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Kanona, M. E. A., M. G. Hamza, A. G. Abdalla i M. K. Hassan. "A Review of Ground Target Detection and Classification Techniques in Forward Scattering Radars". Engineering, Technology & Applied Science Research 8, nr 3 (19.06.2018): 3018–22. http://dx.doi.org/10.48084/etasr.2026.

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This paper presents a review of target detection and classification in forward scattering radar (FSR) which is a special state of bistatic radars, designed to detect and track moving targets in the narrow region along the transmitter-receiver base line. FSR has advantages and incredible features over other types of radar configurations. All previous studies proved that FSR can be used as an alternative system for ground target detection and classification. The radar and FSR fundamentals were addressed and classification algorithms and techniques were debated. On the other hand, the current and future applications and the limitations of FSR were discussed.

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Yoon, Jungsoo, Seokhwan Hwang, Dong-Ryul Lee i Narae Kang. "Operation Techniques and Hydrological Applications of X-band Dual-polarization Radar for Monitoring Flash Flood in Metropolitan Area". Journal of the Korean Society of Hazard Mitigation 20, nr 2 (30.04.2020): 25–33. http://dx.doi.org/10.9798/kosham.2020.20.2.25.

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Radar is useful for monitoring flash flood in urban areas because it provides rainfall data with high spatial and temporal resolution for a wide area. In 2014, the Korea Institute of Civil Engineering and Building Technology introduced the first X-band dual-polarization radar in Korea and has subsequently been researching on flash floods in the metropolitan area using the rainfall data. Considering the various advantages of X-band dual-polarization radar, the Water Hazard Information Platform in Korea introduced two X-band dual-polarization radars (KRU and YSU radars) into the metropolitan area, in 2017. This study described the characteristics of KRU and YSU radars, their observation strategies, and quality control techniques. Moreover, we also assessed the hydrological applications of the X-band dual-polarization radars in the metropolitan area by analyzing three years of rainfall data from 2017 to 2019.

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Asif, Asma, i Sithamparanathan Kandeepan. "Cooperative Fusion Based Passive Multistatic Radar Detection". Sensors 21, nr 9 (5.05.2021): 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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Engler, N., W. Singer, R. Latteck i B. Strelnikov. "Comparison of wind measurements in the troposphere and mesosphere by VHF/MF radars and in-situ techniques". Annales Geophysicae 26, nr 12 (24.11.2008): 3693–705. http://dx.doi.org/10.5194/angeo-26-3693-2008.

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Abstract. Radar wind observations at frequencies between 1.98 and 53.5 MHz obtained at polar latitudes were compared to in-situ wind measurements by radiosondes at tropospheric altitudes and to winds from falling spheres at mesospheric altitudes. Comparisons are shown for several campaigns of radiosonde and falling sphere observations. The radar wind directions agree well to the radiosonde and falling sphere observations and are highly correlated. The winds estimated from radar measurements are less than the radiosonde data by about 15% for spaced antenna observations and by about 10% for the Doppler beam swinging experiment. At mesospheric altitudes the spaced antenna winds obtained from the wide-beam Andenes MF radar are underestimated in the order of 35% and winds from the narrow-beam Saura MF radar are underestimated by about 20% compared to falling sphere winds at altitudes between 70 and 80 km. Furthermore, the relation between wind measurements using narrow-beam and wide-beam antenna arrangements for the MF radars is discussed and VHF radar observations are compared to the wide-beam MF radar.

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Amir, Malik Muhammad Haris, Salvatore Maresca, Gaurav Pandey, Antonio Malacarne, Antonella Bogoni i Mirco Scaffardi. "Performance Evaluation of Photonics-Based Coherent MIMO Radar Systems for Maritime Surveillance". Inventions 8, nr 4 (7.08.2023): 99. http://dx.doi.org/10.3390/inventions8040099.

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Multiple-input multiple-output (MIMO) radars offer significant advantages over conventional standalone radars in terms of target detection and localization capabilities. However, to fully exploit their potential, such systems require excellent time and phase synchronization among the central unit and the radar heads. Only recently, thanks to microwave photonics (MWP) techniques, it has been possible to develop the first coherent MIMO radar demonstrators. In this paper, a simulation tool in MATLAB programming language is proposed to model coherent MIMO radars based on MWP techniques in maritime surveillance applications. Moreover, a novel approach for estimating the radar cross section of extended maritime targets is presented. The system performance in co-located and distributed MIMO configuration, as well as in single- and multi-band operations, is evaluated by means of relevant key performance indicators (KPIs). Simulations are carried out in two close-to-reality scenarios. In the first, a co-located MIMO radar is mounted on top of a patrolling vessel. In the second, a distributed MIMO radar is deployed inside a port. The proposed KPIs are analyzed in terms of both geometric and frequency diversities of the system, laying the foundations for general system optimization criteria valid in any given surveillance application.

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Wesson, Stephen M., i Geoffrey G. S. Pegram. "Radar rainfall image repair techniques". Hydrology and Earth System Sciences 8, nr 2 (30.04.2004): 220–34. http://dx.doi.org/10.5194/hess-8-220-2004.

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Abstract. There are various quality problems associated with radar rainfall data viewed in images that include ground clutter, beam blocking and anomalous propagation, to name a few. To obtain the best rainfall estimate possible, techniques for removing ground clutter (non-meteorological echoes that influence radar data quality) on 2-D radar rainfall image data sets are presented here. These techniques concentrate on repairing the images in both a computationally fast and accurate manner, and are nearest neighbour techniques of two sub-types: Individual Target and Border Tracing. The contaminated data is estimated through Kriging, considered the optimal technique for the spatial interpolation of Gaussian data, where the "screening effect" that occurs with the Kriging weighting distribution around target points is exploited to ensure computational efficiency. Matrix rank reduction techniques in combination with Singular Value Decomposition (SVD) are also suggested for finding an efficient solution to the Kriging Equations which can cope with near singular systems. Rainfall estimation at ground level from radar rainfall volume scan data is of interest and importance in earth bound applications such as hydrology and agriculture. As an extension of the above, Ordinary Kriging is applied to three-dimensional radar rainfall data to estimate rainfall rate at ground level. Keywords: ground clutter, data infilling, Ordinary Kriging, nearest neighbours, Singular Value Decomposition, border tracing, computation time, ground level rainfall estimation

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Clarke, John. "Techniques of Radar Reflectivity Measurement". Electronics and Power 31, nr 1 (1985): 86. http://dx.doi.org/10.1049/ep.1985.0064.

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Borkar, V., A. Ghosh, R. Singh i N. Chourasia. "Radar Cross-section Measurement Techniques". Defence Science Journal 60, nr 2 (25.03.2010): 204–12. http://dx.doi.org/10.14429/dsj.60.341.

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Singhroy, Vernon H. "Radar geology: Techniques and results". Episodes 15, nr 1 (1.03.1992): 15–20. http://dx.doi.org/10.18814/epiiugs/1992/v15i1/004.

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Stove, A. G. "Erratum: Linear FMCW radar techniques". IEE Proceedings F Radar and Signal Processing 140, nr 2 (1993): 137. http://dx.doi.org/10.1049/ip-f-2.1993.0019.

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Ryzhkov, Alexander, Pengfei Zhang, Petar Bukovčić, Jian Zhang i Stephen Cocks. "Polarimetric Radar Quantitative Precipitation Estimation". Remote Sensing 14, nr 7 (31.03.2022): 1695. http://dx.doi.org/10.3390/rs14071695.

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Radar quantitative precipitation estimation (QPE) is one of the primary tasks of weather radars. The QPE quality was substantially improved after polarimetric upgrade of the radars. This study provides an overview of existing polarimetric methodologies for rain and snow estimation and their operational implementation. The variability of drop size distributions (DSDs) is a primary factor affecting the quality of rainfall estimation and its impact on the performance of various radar rainfall relations at S, C, and X microwave frequency bands is one of the focuses of this review. The radar rainfall estimation algorithms based on the use of specific attenuation A and specific differential phase KDP are the most efficient. Their brief description is presented and possible ways for their further optimization are discussed. Polarimetric techniques for the vertical profile of reflectivity (VPR) correction at longer distances from the radar are also summarized. Radar quantification of snow is particularly challenging and it is demonstrated that polarimetric methods for snow measurements show good promise. Finally, the article presents a summary of the latest operational radar QPE products available in the US by integration of the information from the WSR-88D radars via the Multi-Radar Multi-Sensor (MRMS) platform.

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Ahmed, Shahzad, Karam Dad Kallu, Sarfaraz Ahmed i Sung Ho Cho. "Hand Gestures Recognition Using Radar Sensors for Human-Computer-Interaction: A Review". Remote Sensing 13, nr 3 (2.02.2021): 527. http://dx.doi.org/10.3390/rs13030527.

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Human–Computer Interfaces (HCI) deals with the study of interface between humans and computers. The use of radar and other RF sensors to develop HCI based on Hand Gesture Recognition (HGR) has gained increasing attention over the past decade. Today, devices have built-in radars for recognizing and categorizing hand movements. In this article, we present the first ever review related to HGR using radar sensors. We review the available techniques for multi-domain hand gestures data representation for different signal processing and deep-learning-based HGR algorithms. We classify the radars used for HGR as pulsed and continuous-wave radars, and both the hardware and the algorithmic details of each category is presented in detail. Quantitative and qualitative analysis of ongoing trends related to radar-based HCI, and available radar hardware and algorithms is also presented. At the end, developed devices and applications based on gesture-recognition through radar are discussed. Limitations, future aspects and research directions related to this field are also discussed.

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Anderson, Stuart. "Bistatic and Stereoscopic Configurations for HF Radar". Remote Sensing 12, nr 4 (20.02.2020): 689. http://dx.doi.org/10.3390/rs12040689.

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Most HF radars operate in a monostatic or quasi-monostatic configuration. The collocation of transmit and receive facilities simplifies testing and maintenance, reduces demands on communications networks, and enables the use of established and relatively straightforward signal processing and data interpretation techniques. Radars of this type are well-suited to missions such as current mapping, waveheight measurement, and the detection of ships and aircraft. The high scientific, defense, and economic value of the radar products is evident from the fact that hundreds of HF radars are presently in operation, the great majority of them relying on the surface wave mode of propagation, though some systems employ line-of-sight or skywave modalities. Yet, notwithstanding the versatility and proven capabilities of monostatic HF radars, there are some types of observations for which the monostatic geometry renders them less effective. In these cases, one must turn to more general radar configurations, including those that employ a multiplicity of propagation modalities to achieve the desired illumination, scattering selectivity, and echo reception. In this paper, we survey some of the considerations that arise with bistatic HF radar configurations, explore some of the missions for which they are optimal, and describe some practical techniques that can guide their design and deployment.

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Justin Sagayaraj, M., Jithesh V., J. B. Singh, Dange Roshani i K. G. Srinivasa. "A Hybrid Approach to Cognition in Radars". Defence Science Journal 68, nr 2 (13.03.2018): 183. http://dx.doi.org/10.14429/dsj.68.12228.

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In many engineering domains, cognition is emerging to play vital role. Cognition will play crucial role in radar engineering as well for the development of next generation radars. In this paper, a cognitive architecture for radars is introduced, based on hybrid cognitive architectures. The paper proposes deep learning applications for integrated target classification based on high-resolution radar range profile measurements and target revisit time calculation as case studies. The proposed architecture is based on the artificial cognitive systems concepts and provides a basis for addressing cognition in radars, which is inadequately explored for radar systems. Initial experimental studies on the applicability of deep learning techniques under this approach provided promising results.

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Wang, Wen-Qin. "Detecting and Mitigating Wind Turbine Clutter for Airspace Radar Systems". Scientific World Journal 2013 (2013): 1–8. http://dx.doi.org/10.1155/2013/385182.

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It is well recognized that a wind turbine has a large radar cross-section (RCS) and, due to the movement of the blades, the wind turbine will generate a Doppler frequency shift. This scattering behavior may cause severe interferences on existing radar systems including static ground-based radars and spaceborne or airborne radars. To resolve this problem, efficient techniques or algorithms should be developed to mitigate the effects of wind farms on radars. Herein, one transponder-based mitigation technique is presented. The transponder is not a new concept, which has been proposed for calibrating high-resolution imaging radars. It modulates the radar signal in a manner that the retransmitted signals can be separated from the scene echoes. As wind farms often occupy only a small area, mitigation processing in the whole radar operation will be redundant and cost inefficient. Hence, this paper uses a transponder to determine whether the radar is impacted by the wind farms. If so, the effects of wind farms are then mitigated with subsequent Kalman filtering or plot target extraction algorithms. Taking airborne synthetic aperture radar (SAR) and pulse Doppler radar as the examples, this paper provides the corresponding system configuration and processing algorithms. The effectiveness of the mitigation technique is validated by numerical simulation results.

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Hocking, W. K. "Strengths and limitations of MST radar measurements of middle-atmosphere winds". Annales Geophysicae 15, nr 9 (30.09.1997): 1111–22. http://dx.doi.org/10.1007/s00585-997-1111-1.

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Abstract. Radars have been used successfully for many years to measure atmospheric motions over a wide range of altitudes, from ground level up to heights of several hundred kilometres into the ionosphere. In this paper we particularly wish to concentrate on the accuracy of these measurements for winds in the middle atmosphere (i.e. 10–100-km altitude). We begin by briefly reviewing the literature relating to comparisons between radar methods and other techniques. We demonstrate where the radar data are most and least reliable and then, in parallel with a discussion about the basic principles of the method, discuss why these different regimes have the different accuracies and precisions they do. This discussion is used to highlight the strengths and weaknesses of radar methods. Issues like radar volume, aspect sensitivity, gravity wave effects and scatterer intermittency in producing wind biases, and the degree by which the intermittent generation of scatterers at quasi-random points in space could skew the radar measurements, are all considered. We also investigate the possibility that MF radar techniques can be contaminated by E-region scatter to heights as low as 92–95-km altitude (i.e. up to 8–10 km below the ionospheric peak echo). Within all these comments, however, we also recognize that radar methods still represent powerful techniques which have an important future at all levels of the atmosphere.

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Frame, D. J., B. N. Lawrence, G. J. Fraser i M. D. Burrage. "A comparison between mesospheric wind measurements made near Christchurch (44°S, 173°E) using the high resolution doppler imager (HRDI) and a medium frequency (MF) radar". Annales Geophysicae 18, nr 5 (31.05.2000): 555–65. http://dx.doi.org/10.1007/s00585-000-0555-3.

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Abstract. We report on the comparison of winds measured by a medium frequency (MF) radar near Christchurch, New Zealand, and by the high resolution doppler imager (HRDI). Previous comparisons have demonstrated that there can be significant differences in the winds obtained by the two techniques, and our results are no different. However, these data show relatively good agreement in the meridional direction, but large differences in the zonal direction, where the radar is regularly measuring the zonal wind as too easterly. To do the comparison, overpasses from the satellite must be obtained when it is close to the radar site. The radar data are averaged in time around the overpass because we know the radars sample phenomena which have spatial and temporal scales which make them invisible to HRDI. There are a limited number of overpass comparisons which limit our confidence in these results, but a detailed analysis of these data show that the proximity of the overpass is often an important factor in the differences obtained. Other factors examined include the influence of the local time of the overpass, and the amount of radar data averaged around the overpass time.Key words: Atmospheric composition and structure (instruments and techniques) · Meteorology and atmospheric dynamics (middle atmosphere dynamics; instruments and techniques)

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Ilcev, Dimov Stojce. "Introduction to Coastal HF Maritime Surveillance Radars". Polish Maritime Research 26, nr 3 (1.09.2019): 153–62. http://dx.doi.org/10.2478/pomr-2019-0056.

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Abstract This paper presents the main technical characteristics and working performances of coastal maritime surveillance radars, such as low-power High-Frequency Surface Wave Radars (HFSWR) and Over the Horizon Radars (OTHR). These radars have demonstrated to be a cost-effective long-range early-warning sensor for ship detection and tracking in coastal waters, sea channels and passages. In this work, multi-target tracking and data fusion techniques are applied to live-recorded data from a network of oceanographic HFSWR stations installed in Jindalee Operational Radar Network (JORN), Wellen Radar (WERA) in Ligurian Sea (Mediterranean Sea), CODAR Ocean Sebsorsin and in the German Bight (North Sea). The coastal Imaging Sciences Research (ISR) HFSWR system, Multi-static ISR HF Radar, Ship Classification using Multi-Frequency HF Radar, Coastal HF radar surveillance of pirate boats and Different projects of coastal HF radars for vessels detecting are described. Ship reports from the Automatic Identification System (AIS), recorded from both coastal and satellite Land Earth Stations (LES) are exploited as ground truth information and a methodology is applied to classify the fused tracks and to estimate system performances. Experimental results for all above solutions are presented and discussed, together with an outline for future integration and infrastructures.

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Louf, Valentin, Alain Protat, Robert A. Warren, Scott M. Collis, David B. Wolff, Surendra Raunyiar, Christian Jakob i Walter A. Petersen. "An Integrated Approach to Weather Radar Calibration and Monitoring Using Ground Clutter and Satellite Comparisons". Journal of Atmospheric and Oceanic Technology 36, nr 1 (styczeń 2019): 17–39. http://dx.doi.org/10.1175/jtech-d-18-0007.1.

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AbstractThe stability and accuracy of weather radar reflectivity calibration are imperative for quantitative applications, such as rainfall estimation, severe weather monitoring and nowcasting, and assimilation in numerical weather prediction models. Various radar calibration and monitoring techniques have been developed, but only recently have integrated approaches been proposed, that is, using different calibration techniques in combination. In this paper the following three techniques are used: 1) ground clutter monitoring, 2) comparisons with spaceborne radars, and 3) the self-consistency of polarimetric variables. These techniques are applied to a C-band polarimetric radar (CPOL) located in the Australian tropics since 1998. The ground clutter monitoring technique is applied to each radar volumetric scan and provides a means to reliably detect changes in calibration, relative to a baseline. It is remarkably stable to within a standard deviation of 0.1 dB. To obtain an absolute calibration value, CPOL observations are compared to spaceborne radars on board TRMM and GPM using a volume-matching technique. Using an iterative procedure and stable calibration periods identified by the ground echoes technique, we improve the accuracy of this technique to about 1 dB. Finally, we review the self-consistency technique and constrain its assumptions using results from the hybrid TRMM–GPM and ground echo technique. Small changes in the self-consistency parameterization can lead to 5 dB of variation in the reflectivity calibration. We find that the drop-shape model of Brandes et al. with a standard deviation of the canting angle of 12° best matches our dataset.

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Дудуш, А. С., І. І. Сачук, Сальман Оваід i А. К. Бідун. "Science & technology trends in cognitive radar concept". Системи обробки інформації, nr 3(166) (24.09.2021): 22–34. http://dx.doi.org/10.30748/soi.2021.166.02.

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Currently, human operators provide cognition in a radar system. However, advances in the “digitization” of radar front-ends, including digital arbitrary waveform generators (AWG) and advanced high performance embedded computing (HPEC) make it possible to vary all key radar parameters (power, pulse length, number of pulses, pulse repetition frequency (PRF), modulation, frequency, polarization) on a pulse-by-pulse basis within ns or ms and over a wide operating range. This timescale is much faster than the decision-making ability of a human operator. The cognitive-inspired techniques in radar, that are intensively developing last years, mimic elements of human cognition and the use of external knowledge to use the available system resources in an optimal way for the current goal and environment. Radar systems based on the perception-action cycle of cognition that senses the environment, learns relevant information from it about the target and the background and then adapts the radar to optimally satisfy the needs of the mission according to a desired goal are called cognitive radars. In the article, recent ideas and applications of cognitive radars were analyzed.

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Millán, L., M. Lebsock, N. Livesey, S. Tanelli i G. Stephens. "Differential absorption radar techniques: surface pressure". Atmospheric Measurement Techniques 7, nr 11 (27.11.2014): 3959–70. http://dx.doi.org/10.5194/amt-7-3959-2014.

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Abstract. Two radar pulses sent at different frequencies near the 60 GHz O2 absorption band can be used to determine surface pressure by measuring the differential absorption on and off the band. Results of inverting synthetic data assuming an airborne radar are presented. The analysis includes the effects of temperature, water vapor, and hydrometeors, as well as particle size distributions and surface backscatter uncertainties. Results show that an airborne radar (with sensitivity of −20 and 0.05 dBZ speckle and relative calibration uncertainties) can estimate surface pressure with a precision of ~ 1.0 hPa and accuracy better than 1.0 hPa for clear-sky and cloudy conditions and better than 3.5 hPa for precipitating conditions. Generally, accuracy would be around 0.5 and 2 hPa for non-precipitating and precipitating conditions, respectively.

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Sekine, Matsuo, i Shuji Sayama. "Advances in Radar Signal Processing Techniques". IEEJ Transactions on Fundamentals and Materials 124, nr 1 (2004): 31–34. http://dx.doi.org/10.1541/ieejfms.124.31.

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Bar-Shalom, Yaakov. "Kalman filtering techniques for radar tracking". Automatica 37, nr 6 (czerwiec 2001): 957–58. http://dx.doi.org/10.1016/s0005-1098(01)00040-1.

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Hartl, Ph, F. Heel, W. Keydel i H. Kietzmann. "Radar calibration techniques including propagation effects". Advances in Space Research 7, nr 11 (styczeń 1987): 259–68. http://dx.doi.org/10.1016/0273-1177(87)90322-x.

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Sammartino, Pier Francesco, Christopher J. Baker i Hugh D. Griffiths. "Frequency Diverse MIMO Techniques for Radar". IEEE Transactions on Aerospace and Electronic Systems 49, nr 1 (styczeń 2013): 201–22. http://dx.doi.org/10.1109/taes.2013.6404099.

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Moharir, P. S., V. M. Maru i R. Singh. "Untrapping techniques for radar signal design". Electronics Letters 33, nr 7 (1997): 631. http://dx.doi.org/10.1049/el:19970369.

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Galle, Bo, Anders Sunesson i Wilhelm Wendt. "NO2-Mapping using laser-radar techniques". Atmospheric Environment (1967) 22, nr 3 (styczeń 1988): 569–73. http://dx.doi.org/10.1016/0004-6981(88)90201-6.

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Baggaley, W. J., i J. Grant. "Techniques For Measuring Radar Meteor Speeds". Earth, Moon, and Planets 95, nr 1-4 (29.09.2005): 601–15. http://dx.doi.org/10.1007/s11038-005-1641-z.

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Isom, B. M., R. D. Palmer, G. S. Secrest, R. D. Rhoton, D. Saxion, T. L. Allmon, J. Reed, T. Crum i R. Vogt. "Detailed Observations of Wind Turbine Clutter with Scanning Weather Radars". Journal of Atmospheric and Oceanic Technology 26, nr 5 (1.05.2009): 894–910. http://dx.doi.org/10.1175/2008jtecha1136.1.

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Abstract The wind power industry has seen tremendous growth over the past decade and with it has come the need for clutter mitigation techniques for nearby radar systems. Wind turbines can impart upon these radars a unique type of interference that is not removed with conventional clutter-filtering methods. Time series data from Weather Surveillance Radar-1988 Doppler (WSR-88D) stations near wind farms were collected and spectral analysis was used to investigate the detailed characteristics of wind turbine clutter. Techniques to mask wind turbine clutter were developed that utilize multiquadric interpolation in two and three dimensions and can be applied to both the spectral moments and spectral components. In an effort to improve performance, a nowcasting algorithm was incorporated into the interpolation scheme via a least mean squares criterion. The masking techniques described in this paper will be shown to reduce the impact of wind turbine clutter on weather radar systems at the expense of spatial resolution.

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Essen, Helmut, Manfred Hägelen, Alfred Wahlen, Karsten Schulz, Klaus Jäger i Marcus Hebel. "ISAR imaging of helicopters using millimeter wave radars". International Journal of Microwave and Wireless Technologies 1, nr 3 (czerwiec 2009): 171–78. http://dx.doi.org/10.1017/s1759078709000257.

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The capabilities of millimeter wave radars have been demonstrated for a long period of time for missile seeker applications and for automotive radars. The technological advantages of this type of radar can be adapted to security applications in air traffic management at short and medium range as well as on the ground. The application discussed in this paper focuses on inverse synthetic aperture radar (ISAR) imaging techniques for the derivation of high-resolution signatures of helicopters in the air and the determination of reference images using turntable measurements.

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Wright, D. M., J. A. Davies, T. R. Robinson, P. J. Chapman, T. K. Yeoman, E. C. Thomas, M. Lester i in. "Space Plasma Exploration by Active Radar (SPEAR): an overview of a future radar facility". Annales Geophysicae 18, nr 9 (30.09.2000): 1248–55. http://dx.doi.org/10.1007/s00585-000-1248-7.

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Abstract. SPEAR is a new polar cap HF radar facility which is to be deployed on Svalbard. The principal capabilities of SPEAR will include the generation of artificial plasma irregularities, operation as an 'all-sky' HF radar, the excitation of ULF waves, and remote sounding of the magnetosphere. Operation of SPEAR in conjunction with the multitude of other instruments on Svalbard, including the EISCAT Svalbard radar, and the overlap of its extensive field-of-view with that of several of the HF radars in the SuperDARN network, will enable in-depth diagnosis of many geophysical and plasma phenomena associated with the cusp region and the substorm expansion phase. Moreover, its ability to produce artificial radar aurora will provide a means for the other instruments to undertake polar cap plasma physics experiments in a controlled manner. Another potential use of the facility is in 'field-line tagging' experiments, for coordinated ground-satellite experiments. Here the scientific objectives of SPEAR are detailed, along with the proposed technical specifications of the system.Key words: Ionosphere (active experiments) – Radio science (instruments and techniques) – Space plasma physics (instruments and techniques)

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Lim, Chang Heon, Eun Sook Jin i Chang Joo Kim. "Spectrum Sensing Techniques for Detection of Radar Signals in Radar Bands". Journal of Korean Institute of Communications and Information Sciences 43, nr 12 (31.12.2018): 2048–56. http://dx.doi.org/10.7840/kics.2018.43.12.2048.

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Berenguer, Marc, Carles Corral, Rafael Sánchez-Diezma i Daniel Sempere-Torres. "Hydrological Validation of a Radar-Based Nowcasting Technique". Journal of Hydrometeorology 6, nr 4 (1.08.2005): 532–49. http://dx.doi.org/10.1175/jhm433.1.

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Abstract Nowcasting precipitation is a key element in the anticipation of floods in warning systems. In this framework, weather radars are very useful because of the high resolution of their measurements both in time and space. The aim of this study is to assess the performance of a recently proposed nowcasting technique (S-PROG) from a hydrological point of view in a Mediterranean environment. S-PROG is based on the advection of weather radar fields according to the motion field derived with an algorithm based on tracking radar echoes by correlation (TREC), and it has the ability of filtering out the most unpredictable scales of these fields as the forecasting time increases. Validation of this nowcasting technique was done from two different perspectives: (i) comparing forecasted precipitation fields against radar measurements, and (ii) by means of a distributed rainfall runoff model, comparing hydrographs simulated with a hydrological model using rainfall fields forecasted by S-PROG against hydrographs generated with the model using the entire series of radar measurements. In both cases, results obtained by a simpler nowcasting technique are used as a reference to evaluate improvements. Validation showed that precipitation fields forecasted with S-PROG seem to be better than fields forecasted using simpler techniques. Additionally, hydrological validation led the authors to point out that the use of radar-based nowcasting techniques allows the anticipation window in which flow estimates are forecasted with enough quality to be sensibly extended.

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Nanding, Nergui, Miguel Angel Rico-Ramirez i Dawei Han. "Comparison of different radar-raingauge rainfall merging techniques". Journal of Hydroinformatics 17, nr 3 (3.01.2015): 422–45. http://dx.doi.org/10.2166/hydro.2015.001.

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The improvement of precipitation estimation with the use of radar-raingauge rainfall merging techniques is influenced by several factors, such as topography, storm types, raingauge network density for adjustment, data quality and the rainfall accumulation time. However, the influence of the raingauge network configuration on the performance of radar-raingauge merging methods is often ignored. The aim of this study is to compare and evaluate the performance of different radar-raingauge merging methods on various densities of raingauge network and raingauge network configurations. The analysis of the effect of the raingauge network density shows that the performance of Kriging merging methods increases with the increase of raingauge network density. The results also showed that the influence of raingauge network configuration on the spatial distribution of precipitation of the merged products is relatively smaller for the Kriging with radar-based error correction (KRE) and Kriging with external drift (KED) methods than for the ordinary Kriging method. This indicates that the inclusion of radar data in the KRE and KED methods helps to maintain the spatial distribution of precipitation on an hourly timescale. According to the statistical performance indicators and visual inspection of the merged rainfall fields, the KED outperforms the other radar-raingauge merging techniques, regardless of raingauge network density and configuration.

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Zheng, Zexin, Wei Li i Kun Zou. "Airborne Radar Anti-Jamming Waveform Design Based on Deep Reinforcement Learning". Sensors 22, nr 22 (10.11.2022): 8689. http://dx.doi.org/10.3390/s22228689.

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Airborne radars are susceptible to a large number of clutter, noise and variable jamming signals in the real environment, especially when faced with active main lobe jamming, as the waveform shortcut technology in the traditional regime can no longer meet the actual battlefield radar anti-jamming requirements. Therefore, it is necessary to study anti-main-lobe jamming techniques for airborne radars in complex environments to improve their battlefield survivability. In this paper, we propose an airborne radar waveform design method based on a deep reinforcement learning (DRL) algorithm under clutter and jamming conditions, after previous research on reinforcement-learning (RL)-based airborne radar anti-jamming waveform design methods that have improved the anti-jamming performance of airborne radars. The method uses a Markov decision process (MDP) to describe the complex operating environment of airborne radars, calculates the value of the radar anti-jamming waveform strategy under various jamming states using deep neural networks and designs the optimal anti-jamming waveform strategy for airborne radars based on the duelling double deep Q network (D3QN) algorithm. In addition, the method uses an iterative transformation method (ITM) to generate the time domain signals of the optimal waveform strategy. Simulation results show that the airborne radar waveform designed based on the deep reinforcement learning algorithm proposed in this paper improves the signal-to-jamming plus noise ratio (SJNR) by 2.08 dB and 3.03 dB, and target detection probability by 26.79% and 44.25%, respectively, compared with the waveform designed based on the reinforcement learning algorithm and the conventional linear frequency modulation (LFM) signal at a radar transmit power of 5 W. The airborne radar waveform design method proposed in this paper helps airborne radars to enhance anti-jamming performance in complex environments while further improving target detection performance.

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LIU, ZHONG, XIAOHUA ZHU, WEN HU i FEI JIANG. "PRINCIPLES OF CHAOTIC SIGNAL RADAR". International Journal of Bifurcation and Chaos 17, nr 05 (maj 2007): 1735–39. http://dx.doi.org/10.1142/s0218127407018038.

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The noise-like chaotic signal can be generated with very simple nonlinear circuits, and has broad bandwidth and aperiodic properties. These characteristics have drawn considerable attention in the radar community. In the past, the chaotic signal or its modulated version serves as a transmitting signal, and the traditional correlation-type receiver is used for processing. In this sense, the chaotic signal acts as a radar waveform in the noise signal radar, and hence the performance advantages are not distinct. Here, we present a scheme for processing chaotic radar signals. We find a simple relation between the target parameters (range and velocity) and the system parameters of chaos-generating system. With this relation, the measurement of the target parameters is transformed into estimation of the system parameters from the radar return signals. Equipped with high resolution parameter estimation techniques, the proposed principles provide a way to develop high resolution noise signal radars.

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Hibbins, R. E., i M. J. Jarvis. "A long-term comparison of wind and tide measurements in the upper mesosphere recorded with an imaging Doppler interferometer and SuperDARN radar at Halley, Antarctica". Atmospheric Chemistry and Physics Discussions 7, nr 3 (16.05.2007): 6573–601. http://dx.doi.org/10.5194/acpd-7-6573-2007.

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Abstract. Data from a co-located imaging Doppler interferometer and SuperDARN radar recorded since 1996 have been analysed in a consistent manner to determine daily mean winds and tides in the upper mesosphere. By comparing only days when both techniques were recording good quality data it is shown that the SuperDARN radar winds and tides correlate best with the IDI height bin 90–95 km. On timescales of one hour the winds derived from each technique correlate poorly, whereas the daily mean winds are in much better agreement suggesting that the two radars are sensitive to different parts of the gravity wave spectrum. Regression analysis reveals that the observed SuperDARN daily mean meridional wind strength is approximately 65% that recorded by the IDI while the zonal winds are of similar magnitude, in good quantitative agreement with previous studies which have shown contamination to SuperDARN-derived winds due to the significant back lobe of the radar radiation pattern. Climatologically the two techniques observe similar monthly mean winds with the SuperDARN meridional winds suppressed compared to the IDI which tends to record winds more poleward and eastward than those derived by the SuperDARN radar during the summer months, and to be slightly more equatorward during the winter. The 12-h tidal amplitude and phase in both the zonal and meridional components derived from both techniques are in excellent agreement, whereas the 24-h tides are seen much more strongly in the SuperDARN radar, especially in wintertime, with poor phase agreement. Long term comparison of the two techniques reveals a tendency for the IDI meridional winds to be more poleward during solar maximum especially during summer time; an effect which is not reproduced in the meridional winds derived from the SuperDARN radar. These results are discussed in the context of previous studies to independently determine the veracity of each technique.

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Yin, Mingye, Bo Feng i Yanbing Li. "Mitigation of Millimeter-Wave Radar Mutual Interference Using Spectrum Sub-Band Analysis and Synthesis". Remote Sensing 15, nr 13 (21.06.2023): 3210. http://dx.doi.org/10.3390/rs15133210.

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Millimeter-wave radars are widely used in automotive radars because of their all-weather and all-day operation capability. However, as more and more radar sensors are used, the possibility of mutual interference between radars increases dramatically. Severe interference increases the noise level, affects target detection performance, and can lead to missed detection and wrong detection. In this study, a novel solution to the problem of mutual radar interference is introduced. The method is based on the analysis and synthesis of spectrum sub-bands. Specifically, the received radar signal is partitioned into sub-bands, after which interference mitigation is carried out in each sub-band. Finally, the signals are reconstructed to obtain interference-free data. The effectiveness of this approach is evaluated using both a simulated multi-target scenario and a real-life experimental environment. The results demonstrate that the proposed method outperforms existing techniques in terms of interference mitigation while exhibiting rapid processing speeds.

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Noskov, Alexey, Joerg Bendix i Nicolas Friess. "A Review of Insect Monitoring Approaches with Special Reference to Radar Techniques". Sensors 21, nr 4 (20.02.2021): 1474. http://dx.doi.org/10.3390/s21041474.

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Drastic declines in insect populations are a vital concern worldwide. Despite widespread insect monitoring, the significant gaps in the literature must be addressed. Future monitoring techniques must be systematic and global. Advanced technologies and computer solutions are needed. We provide here a review of relevant works to show the high potential for solving the aforementioned problems. Major historical and modern methods of insect monitoring are considered. All major radar solutions are carefully reviewed. Insect monitoring with radar is a well established technique, but it is still a fast-growing topic. The paper provides an updated classification of insect radar sets. Three main groups of insect radar solutions are distinguished: scanning, vertical-looking, and harmonic. Pulsed radar sets are utilized for all three groups, while frequency-modulated continuous-wave (FMCW) systems are applied only for vertical-looking and harmonic insect radar solutions. This work proves the high potential of radar entomology based on the growing research interest, along with the emerging novel setups, compact devices, and data processing approaches. The review exposes promising insect monitoring solutions using compact radar instruments. The proposed compact and resource-effective setups can be very beneficial for systematic insect monitoring.

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Davies, J. A., T. K. Yeoman, M. Lester i S. E. Milan. "<i>Letter to the Editor:</i> A comparison of F-region ion velocity observations from the EISCAT Svalbard and VHF radars with irregularity drift velocity measurements from the CUTLASS Finland HF radar". Annales Geophysicae 18, nr 5 (31.05.2000): 589–94. http://dx.doi.org/10.1007/s00585-000-0589-6.

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Abstract. During August 1998, the UK EISCAT special programme SP-UK-CSUB, which combines operation of both the mainland VHF and Svalbard UHF incoherent scatter radars, was run for several hours around magnetic midnight on four consecutive days. The CUTLASS Finland HF coherent scatter radar was, at these times, operating in a discretionary mode, sounding on all 16 beams, one at high-time resolution. This study presents a comparison of the velocities measured by coherent and incoherent techniques during the SP-UK-CSUB experiments. Agreement, particularly between the ion velocities measured by the EISCAT Svalbard radar and irregularity drift measurements by the Finland radar, is remarkable, thereby validating the scientific integrity of both data sets. This work highlights the substantive contribution to our understanding of the solar-terrestrial environment which can be made by use in concert of incoherent and HF coherent scatter radars.Key words: Ionosphere (ionospheric irregularities; plasma convection; instruments and techniques)

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