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1
Liu, Yuhang, Yu Shen, Lili Fan, Yonglin Tian, Yunfeng Ai, Bin Tian, Zhongmin Liu e Fei-Yue Wang. "Parallel Radars: From Digital Twins to Digital Intelligence for Smart Radar Systems". Sensors 22, n. 24 (16 dicembre 2022): 9930. http://dx.doi.org/10.3390/s22249930.
Testo completoAbstract (sommario):
Radar is widely employed in many applications, especially in autonomous driving. At present, radars are only designed as simple data collectors, and they are unable to meet new requirements for real-time and intelligent information processing as environmental complexity increases. It is inevitable that smart radar systems will need to be developed to deal with these challenges and digital twins in cyber-physical systems (CPS) have proven to be effective tools in many aspects. However, human involvement is closely related to radar technology and plays an important role in the operation and management of radars; thus, digital twins’ radars in CPS are insufficient to realize smart radar systems due to the inadequate consideration of human factors. ACP-based parallel intelligence in cyber-physical-social systems (CPSS) is used to construct a novel framework for smart radars, called Parallel Radars. A Parallel Radar consists of three main parts: a Descriptive Radar for constructing artificial radar systems in cyberspace, a Predictive Radar for conducting computational experiments with artificial systems, and a Prescriptive Radar for providing prescriptive control to both physical and artificial radars to complete parallel execution. To connect silos of data and protect data privacy, federated radars are proposed. Additionally, taking mines as an example, the application of Parallel Radars in autonomous driving is discussed in detail, and various experiments have been conducted to demonstrate the effectiveness of Parallel Radars.
2
Protat, Alain, Valentin Louf, Joshua Soderholm, Jordan Brook e William Ponsonby. "Three-way calibration checks using ground-based, ship-based, and spaceborne radars". Atmospheric Measurement Techniques 15, n. 4 (21 febbraio 2022): 915–26. http://dx.doi.org/10.5194/amt-15-915-2022.
Testo completoAbstract (sommario):
Abstract. This study uses ship-based weather radar observations collected from research vessel Investigator to evaluate the Australian weather radar network calibration monitoring technique that uses spaceborne radar observations from the NASA Global Precipitation Mission (GPM). Quantitative operational applications such as rainfall and hail nowcasting require a calibration accuracy of ±1 dB for radars of the Australian network covering capital cities. Seven ground-based radars along the western coast of Australia and the ship-based OceanPOL radar are first calibrated independently using GPM radar overpasses over a 3-month period. The calibration difference between the OceanPOL radar (used as a moving reference for the second step of the study) and each of the seven operational radars is then estimated using collocated, gridded, radar observations to quantify the accuracy of the GPM technique. For all seven radars the calibration difference with the ship radar lies within ±0.5 dB, therefore fulfilling the 1 dB requirement. This result validates the concept of using the GPM spaceborne radar observations to calibrate national weather radar networks (provided that the spaceborne radar maintains a high calibration accuracy). The analysis of the day-to-day and hourly variability of calibration differences between the OceanPOL and Darwin (Berrimah) radars also demonstrates that quantitative comparisons of gridded radar observations can accurately track daily and hourly calibration differences between pairs of operational radars with overlapping coverage (daily and hourly standard deviations of ∼ 0.3 and ∼ 1 dB, respectively).
3
Luong, David, Sreeraman Rajan e Bhashyam Balaji. "Quantum Monopulse Radar". Applied Computational Electromagnetics Society 35, n. 11 (5 febbraio 2021): 1430–32. http://dx.doi.org/10.47037/2020.aces.j.351184.
Testo completoAbstract (sommario):
We evaluate the feasibility of a quantum monopulse radar, focusing on quantum illumination (QI) radars and quantum two-mode squeezing (QTMS) radars. Based on their similarity with noise radar, for which monopulse operation is known to be possible, we find that QTMS radars can be adapted into monopulse radars, but QI radars cannot. We conclude that quantum monopulse radars are feasible.
4
Oh, Soo Young, Kyu Ho Cha, Hayoung Hong, Hongsoo Park e Sun K. Hong. "Measurement of Nonlinear RCS of Electronic Targets for Nonlinear Detection". Journal of Electromagnetic Engineering and Science 22, n. 4 (31 luglio 2022): 447–51. http://dx.doi.org/10.26866/jees.2022.4.r.108.
Testo completoAbstract (sommario):
The conventional radar technology is based on linear detection—i.e., the same transmit and receive frequencies are used. However, with linear radars, difficulties arise when detecting electronic objects with relatively small radar cross section (RCS). To overcome these limitations, a nonlinear radar that can detect nonlinear responses (i.e., harmonic and intermodulation) scattered by electronic devices due to nonlinear interaction can be utilized. Nonlinear radars require a different analysis from linear radars for analyzing RCS. In this paper, we present an experimental analysis of the nonlinear RCS of various electronic devices. Unlike linear radars, RCS in nonlinear radars is determined by the amount of nonlinear responses backscattered to the radar. Therefore, we derive a radar equation accustomed to harmonic radars that consists of nonlinear RCS. We then obtain and analyze the nonlinear RCS of various targets from the measured harmonic responses of the targets based on the nonlinear radar equation.
5
Lakshmanan, Valliappa, Travis Smith, Kurt Hondl, Gregory J. Stumpf e Arthur Witt. "A Real-Time, Three-Dimensional, Rapidly Updating, Heterogeneous Radar Merger Technique for Reflectivity, Velocity, and Derived Products". Weather and Forecasting 21, n. 5 (1 ottobre 2006): 802–23. http://dx.doi.org/10.1175/waf942.1.
Testo completoAbstract (sommario):
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.
6
Perelygin, B. V., e A. M. Luzbin. "Construction of a continuous radar field of a hydrometeorological monitoring system based on a geometric approach". Radiotekhnika, n. 191 (22 dicembre 2017): 173–80. http://dx.doi.org/10.30837/rt.2017.4.191.17.
Testo completoAbstract (sommario):
The concept of a continuous radar field generated by a system of meteorological radars is considered. To accommodate meteorological radars, it is proposed to apply a geometric approach, which consists in arranging meteorological radar stations at the vertices of various polygons and which greatly simplifies the construction of the required radar field. Quantitative indicators for estimating the quality of the radar field and the results of their calculations for various variants of constructing the radar field are proposed.
7
Johnston, Paul E., James R. Jordan, Allen B. White, David A. Carter, David M. Costa e Thomas E. Ayers. "The NOAA FM-CW Snow-Level Radar". Journal of Atmospheric and Oceanic Technology 34, n. 2 (febbraio 2017): 249–67. http://dx.doi.org/10.1175/jtech-d-16-0063.1.
Testo completoAbstract (sommario):
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.
8
BHAT, G. S., J. VIVEKANANDAN e D. PRADHAN. "Evolution of Radar Meteorology in India and the latest trends". MAUSAM 76, n. 1 (16 gennaio 2025): 55–64. https://doi.org/10.54302/mausam.v76i1.6497.
Testo completoAbstract (sommario):
Weather radar is an indispensable tool in the continuous monitoring and warning of extreme events including tropical cyclones and thunderstorms. The India Meteorological Department (IMD) has been operating radars since 1949. The evolution of radar meteorology in India may be divided into three broad phases, namely, the 1950s (phase-I), then up to the year 2000 (phase-II), and thereafter (phase-III). During phase-I, radars were imported and installed in cities to aid aircraft operations. Photographs of radar scopes were analysed to provide a broad understanding of temporal evolution and spatial extent of precipitating clouds in different parts of the country and seasons. During phase-II, storm warning (X-band) and cyclone warning (S-band) radars with more power and range were installed, and some of them were indigenous. Phase-III ushered in the era of digital Doppler weather radars in India. Interfacing between numerical models and radars started in phase-III including assimilation of radar winds and model verification. Installation and operation of weather radars outside IMD also started in phase-III. Important areas where more work needs to be done include a well-trained workforce in radar meteorology, radar calibration and data standardization, radar area coverage and networking, algorithms for quantitative precipitation estimation using polarimetric products, assimilation of radar products in numerical models, research on cloud physics and dynamics, applications of AI/ML in storm and severe weather nowcasting.
9
Wang, Dingyang, Sungwon Yoo e Sung Ho Cho. "Experimental Comparison of IR-UWB Radar and FMCW Radar for Vital Signs". Sensors 20, n. 22 (23 novembre 2020): 6695. http://dx.doi.org/10.3390/s20226695.
Testo completoAbstract (sommario):
In this paper, we compare the performances of impulse radio ultra-wideband (IR-UWB) and frequency modulation continuous wave (FMCW) radars in measuring noncontact vital signs such as respiration rate and heart rate. These two type radars have been widely used in various fields and have shown their applicability to extract vital signs in noncontact ways. IR-UWB radar can extract vital signs using distance information. On the other hand, FMCW radar requires phase information to estimate vital signs, and the result can be enhanced with Multi-input Multi-output (MIMO) antenna topologies. By using commercial radar chipsets, the operation of radars under different conditions and frequency bands will also affect the performance of vital sign detection capabilities. We compared the accuracy and signal-to-noise (SNR) ratios of IR-UWB and FMCW radars in various scenarios, such as distance, orientation, carotid pulse, harmonics, and obstacle penetration. In general, the IR-UWB radars offer a slightly better accuracy and higher SNR in comparison to FMCW radar. However, each radar system has its own unique advantages, with IR-UWB exhibiting fewer harmonics and a higher SNR, while FMCW can combine the results from each channel.
10
Vidal, Luis E., Ulises Román Concha, Justo Solís, José Piedra, Carlos Chávez, Dominga M. Cano e Juan C. Woolcott. "Implementation of a Transportable Radar Mode S of Monopulse Secondary Surveillance (MSSR-S) for the Peruvian Civil Aviation Surveillance". Telecom 4, n. 4 (3 ottobre 2023): 693–708. http://dx.doi.org/10.3390/telecom4040031.
Testo completoAbstract (sommario):
This article describes the process of implementing a transportable radar MSSR-S for Peruvian civil aviation (ACP) to minimize the operational impact in emergencies that affects air traffic without causing structural damage and restore data from the radar in a short time. In recent years, ACP has shown constant falls in the radars, causing radar data to be lost for long periods of time and putting air safety at risk due to the lack of maintenance and overlapping radar coverage of more than three radars. The deployment of the transportable radar in Mode S of Monopulse Secondary Surveillance (MSSR-S) has allowed for work that involves the prolonged stoppage of the radar to be carried out and provided coverage to eight more radars during maintenance and modernization, covering the areas without coverage in the Peruvian air space (EAP). For the implementation, this was divided into three SPRINTs using the SCRUM methodology; the first sprint refers to the equipment and radar coverage study, the second the implementation and service test phase, and the third the operational analysis phase with the eight modernized radars. As a result of the implementation and integration with the other ACP radar systems, they were able to operate together, providing highly reliable radar data, performing a continuous analysis of radar performance through the PASS software, complying with the thresholds established by ICAO and EuroControl, and guaranteeing that the systems operate under perfect conditions and with full coverage at all time.
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RAO, P. RAJESH, S. KALYANA SUNDARAM, S. B. THAMPI, R. SURESH e J. P. GUPTA. "An overview of first Doppler Weather Radar inducted in the cyclone detection network of India Meteorological Department". MAUSAM 55, n. 1 (19 gennaio 2022): 155–76. http://dx.doi.org/10.54302/mausam.v55i1.963.
Testo completoAbstract (sommario):
India Meteorological Department (IMD) maintains a wide network of radars for the detection and study of severe weather phenomena like cyclones, thunderstorms, gust front etc. and for deriving upper air wind profile. To keep pace with the fast developments in the field of weather radar technology, IMD is gradually replacing its conventional radars with digital radars, a few of them with Doppler capabilities. An S-band Doppler Weather Radar (DWR) has been inducted into India Meteorological Department’s (IMD) Cyclone Detection Radar (CDR) network recently at Chennai as a replacement to the outlived analogue S-band radar and is declared operational from 21 February 2002. Salient features, both hardware and software, of the radar are discussed in this article.
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Soumya, A., C. Krishna Mohan e Linga Reddy Cenkeramaddi. "Recent Advances in mmWave-Radar-Based Sensing, Its Applications, and Machine Learning Techniques: A Review". Sensors 23, n. 21 (1 novembre 2023): 8901. http://dx.doi.org/10.3390/s23218901.
Testo completoAbstract (sommario):
Human gesture detection, obstacle detection, collision avoidance, parking aids, automotive driving, medical, meteorological, industrial, agriculture, defense, space, and other relevant fields have all benefited from recent advancements in mmWave radar sensor technology. A mmWave radar has several advantages that set it apart from other types of sensors. A mmWave radar can operate in bright, dazzling, or no-light conditions. A mmWave radar has better antenna miniaturization than other traditional radars, and it has better range resolution. However, as more data sets have been made available, there has been a significant increase in the potential for incorporating radar data into different machine learning methods for various applications. This review focuses on key performance metrics in mmWave-radar-based sensing, detailed applications, and machine learning techniques used with mmWave radar for a variety of tasks. This article starts out with a discussion of the various working bands of mmWave radars, then moves on to various types of mmWave radars and their key specifications, mmWave radar data interpretation, vast applications in various domains, and, in the end, a discussion of machine learning algorithms applied with radar data for various applications. Our review serves as a practical reference for beginners developing mmWave-radar-based applications by utilizing machine learning techniques.
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Isom, Bradley, Robert Palmer, Redmond Kelley, John Meier, David Bodine, Mark Yeary, Boon-Leng Cheong, Yan Zhang, Tian-You Yu e Michael I. Biggerstaff. "The Atmospheric Imaging Radar: Simultaneous Volumetric Observations Using a Phased Array Weather Radar". Journal of Atmospheric and Oceanic Technology 30, n. 4 (1 aprile 2013): 655–75. http://dx.doi.org/10.1175/jtech-d-12-00063.1.
Testo completoAbstract (sommario):
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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Protat, A., D. Bouniol, E. J. O’Connor, H. Klein Baltink, J. Verlinde e K. Widener. "CloudSat as a Global Radar Calibrator". Journal of Atmospheric and Oceanic Technology 28, n. 3 (1 marzo 2011): 445–52. http://dx.doi.org/10.1175/2010jtecha1443.1.
Testo completoAbstract (sommario):
Abstract The calibration of the CloudSat spaceborne cloud radar has been thoroughly assessed using very accurate internal link budgets before launch, comparisons with predicted ocean surface backscatter at 94 GHz, direct comparisons with airborne cloud radars, and statistical comparisons with ground-based cloud radars at different locations of the world. It is believed that the calibration of CloudSat is accurate to within 0.5–1 dB. In the present paper it is shown that an approach similar to that used for the statistical comparisons with ground-based radars can now be adopted the other way around to calibrate other ground-based or airborne radars against CloudSat and/or to detect anomalies in long time series of ground-based radar measurements, provided that the calibration of CloudSat is followed up closely (which is the case). The power of using CloudSat as a global radar calibrator is demonstrated using the Atmospheric Radiation Measurement cloud radar data taken at Barrow, Alaska, the cloud radar data from the Cabauw site, Netherlands, and airborne Doppler cloud radar measurements taken along the CloudSat track in the Arctic by the Radar System Airborne (RASTA) cloud radar installed in the French ATR-42 aircraft for the first time. It is found that the Barrow radar data in 2008 are calibrated too high by 9.8 dB, while the Cabauw radar data in 2008 are calibrated too low by 8.0 dB. The calibration of the RASTA airborne cloud radar using direct comparisons with CloudSat agrees well with the expected gains and losses resulting from the change in configuration that required verification of the RASTA calibration.
15
Худов, Г. В., Сальман Рашід Оваід, В. М. Ліщенко e В. О. Тютюнник. "Methods of signal processing in a multiradar system of the same type of two-coordinated surveillance radars". Системи обробки інформації, n. 3(162), (30 settembre 2020): 65–72. http://dx.doi.org/10.30748/soi.2020.162.07.
Testo completoAbstract (sommario):
The subject of research in the paper is the problem of developing methods of signal processing in a multiradar system of the same type of two-coordinate surveillance radars with mechanical rotation. The aim of the paper is to improve the quality of detection of air objects by combining the same type of two-coordinate radars in a multi-radar system. It is proposed to combine the existing surveillance radar stations into a spatially spaced coherent multi-radar system. The synthesis of optimal detectors of coherent and incoherent signals is carried out. The characteristics of detection of air objects in a multi-radar system with compatible signal receiving have been evaluated. The obtained results: the addition of the second radar, regardless of the degree of signal coherence, showed the greatest efficiency in the gain in terms of signal / noise, the optimal number of radars in the multi-radar system is not more than four. The expected signal / noise threshold gain in a system of four radars can be up to eighteen decibels for a system with coherent signals and up to eleven decibels for a system with incoherent signals. The using of more than four radars is impractical.
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Seflek, Ibrahim, Yunus Emre Acar e Ercan Yaldiz. "Small Motion Detection and Non-Contact Vital Signs Monitoring with Continuous Wave Doppler Radars". Elektronika ir Elektrotechnika 26, n. 3 (27 giugno 2020): 54–60. http://dx.doi.org/10.5755/j01.eie.26.3.25810.
Testo completoAbstract (sommario):
Radars have become devices that one can come across in any environment at any moment. This means that they enter to all areas of life and even in the field of medicine and will be used more intensively in the future. Especially, the attention has been drawn to that they are suitable for the non-contact vital signs monitoring. In this study, two radar structures operating at 24 GHz (Radar 1) and 2.4 GHz (Radar 2) frequencies are used. Radar 1 structure is created on a printed circuit board (PCB), whereas Radar 2 is obtained by combining discrete components. The 8.5 mm movement performed with the aid of a test mechanism is detected by two radars with percentage errors (PEs) of 2.58% and 6.23%, respectively. For the 0.25 Hz vibration frequency, the error is the same for both radars and is 2.4 %. In measurements taken from a healthy human subject, Radar 1 finds a respiration rate with 1.85 % of PE and heart beat rate with 6.17 % of PE. In Radar 2, these values are 2.35 % and 8.24 %, respectively. From the measurement results, it is seen that the resolution of Radar 1 is better than that of Radar 2. The results also indicate that small motion detection and vital signs monitoring are carried out successfully.
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Junyent, Francesc, e V. Chandrasekar. "Theory and Characterization of Weather Radar Networks". Journal of Atmospheric and Oceanic Technology 26, n. 3 (1 marzo 2009): 474–91. http://dx.doi.org/10.1175/2008jtecha1099.1.
Testo completoAbstract (sommario):
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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Snyder, Jeffrey C., e Howard B. Bluestein. "Some Considerations for the Use of High-Resolution Mobile Radar Data in Tornado Intensity Determination". Weather and Forecasting 29, n. 4 (22 luglio 2014): 799–827. http://dx.doi.org/10.1175/waf-d-14-00026.1.
Testo completoAbstract (sommario):
Abstract The increasing number of mobile Doppler radars used in field campaigns across the central United States has led to an increasing number of high-resolution radar datasets of strong tornadoes. There are more than a few instances in which the radar-measured radial velocities substantially exceed the estimated wind speeds associated with the enhanced Fujita (EF) scale rating assigned to a particular tornado. It is imperative, however, to understand what the radar data represent if one wants to compare radar observations to damage-based EF-scale estimates. A violent tornado observed by the rapid-scan, X-band, polarimetric mobile radar (RaXPol) on 31 May 2013 contained radar-relative radial velocities exceeding 135 m s−1 in rural areas essentially devoid of structures from which damage ratings can be made. This case, along with others, serves as an excellent example of some of the complications that arise when comparing radar-estimated velocities with the criteria established in the EF scale. In addition, it is shown that data from polarimetric radars should reduce the variance of radar-relative radial velocity estimates within the debris field compared to data from single-polarization radars. Polarimetric radars can also be used to retrieve differential velocity, large magnitudes of which are spatially associated with large spectrum widths inside the polarimetric tornado debris signature in several datasets of intense tornadoes sampled by RaXPol.
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Mahmood, Dalia A. "Estimation of Dual Polarization Weather Radar Variables". Al-Mustansiriyah Journal of Science 28, n. 2 (11 aprile 2018): 1. http://dx.doi.org/10.23851/mjs.v28i2.492.
Testo completoAbstract (sommario):
Dual polarization weather radar has now become a widely used as instrument in meteorological offices around the world because of its capability in distinguishing different precipitation type and in improving the accuracy of quantitative precipitation estimation. The aim of this work is to estimate the polarimetry radar variables for radars of different frequency bands and study their behavior with rainfall rates.
Calculations of polarimetry radar variables were made on the basis of several assumptions. The results showed that factors at horizontal and vertical polarization, ZH,V, ranges between 20 dBz respectively, and more than 55 dBz for light rain and extreme heavy rain respectively, and radar reflectivity factor at horizontal ZH is greater than radar reflectivity factor at vertical ZV for all rainfall rates. The differential reflectivity, ZDR, also increases with increasing rainfall rates since it is the difference between ZH and Zv.
Calculations of specific differential attenuation indicated that X band radars are seriously atten-uated by rain and C band radars are less affected by rain. The specific differential attenuation, S band radars is very small. In addition to this feature, the results showed that the differential phase shift between return signals of horizontal and vertical polarizations for S band radars is much less than those for C and X band radars, and also, the results showed that the co-polarization correlation coefficient for S band the radars is much higher than those of C and X bands.
In order to investigate the accuracy of the calculated polarimetric weather radar variables per-formed in this research, real radar measurements were used for this purpose. Results indicated that the range of values for calculated polarimetric radar variables are very consistent with range of values for measured variables
20
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.
Testo completoAbstract (sommario):
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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Frech, Michael, Cornelius Hald, Maximilian Schaper, Bertram Lange e Benjamin Rohrdantz. "Assessing and mitigating the radar–radar interference in the German C-band weather radar network". Atmospheric Measurement Techniques 16, n. 2 (20 gennaio 2023): 295–309. http://dx.doi.org/10.5194/amt-16-295-2023.
Testo completoAbstract (sommario):
Abstract. The national German weather radar network operates in C-band between 5.6 and 5.65 GHz. In a radar network, individual transmit frequencies have to be chosen such that radar–radar-induced interferences are avoided. In a unique experiment the Hohenpeißenberg research radar and five operational systems from the radar network were used to characterize radar–radar-induced interferences as a function of the radar frequency. The results allow assessment of the possibility of adding additional C-band radars with magnetron transmitters into the existing network. Based on the experiment, at least a 15 MHz separation of the nominal radar frequency is needed to avoid a radar–radar interference. The most efficient mitigation of radar–radar interference is achieved by the “Radar Tango”, which refers to the synchronized scanning of all radar systems in the network. Based on those results, additional C-band radar systems can be added to the German weather radar network if a further improvement of the radar coverage is needed.
22
Pfitzenmaier, Lukas, Alessandro Battaglia e Pavlos Kollias. "The Impact of the Radar-Sampling Volume on Multiwavelength Spaceborne Radar Measurements Using Airborne Radar Observations". Remote Sensing 11, n. 19 (28 settembre 2019): 2263. http://dx.doi.org/10.3390/rs11192263.
Testo completoAbstract (sommario):
Multiwavelength radar observations have demonstrated great potential in improving microphysical retrievals of cloud properties especially in ice and snow precipitation systems. Advancements in spaceborne radar technology have already fostered the launch in 2014 of the first multiwavelength radar system in space, while several future spaceborne multiwavelength radar concepts are under consideration. However, due to antenna size limitations, the sampling volume of spaceborne radars is considerably larger than those achieved by surface- and airborne-based radars. Here, the impact of these large sampling volumes in the information content of the Dual-Wavelength Ratio estimates at Ka-W, Ku-Ka is investigated. High-resolution airborne multiwavelength radar observations during the Olympic Mountain Experiment (OLYMPEx) are used to perform retrievals of ice/snow characteristic particle size, such as mass-weighted particle diameter. To mimic the different satellite sampling volumes, a moving average is applied to the airborne measurements. The radar-observed variables (reflectivity and dual-wavelength ratios) and retrieved microphysical properties at the coarser resolution are compared against those at the original resolution. Our analysis indicates that future Ka-W spaceborne radar missions should take into account the impact of the radar resolution volume on the retrieval of microphysical properties and avoid footprints larger than 2–3 km.
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Maahn, Maximilian, Fabian Hoffmann, Matthew D. Shupe, Gijs de Boer, Sergey Y. Matrosov e Edward P. Luke. "Can liquid cloud microphysical processes be used for vertically pointing cloud radar calibration?" Atmospheric Measurement Techniques 12, n. 6 (13 giugno 2019): 3151–71. http://dx.doi.org/10.5194/amt-12-3151-2019.
Testo completoAbstract (sommario):
Abstract. Cloud radars are unique instruments for observing cloud processes, but uncertainties in radar calibration have frequently limited data quality. Thus far, no single robust method exists for assessing the calibration of past cloud radar data sets. Here, we investigate whether observations of microphysical processes in liquid clouds such as the transition of cloud droplets to drizzle drops can be used to calibrate cloud radars. Specifically, we study the relationships between the radar reflectivity factor and three variables not affected by absolute radar calibration: the skewness of the radar Doppler spectrum (γ), the radar mean Doppler velocity (W), and the liquid water path (LWP). For each relation, we evaluate the potential for radar calibration. For γ and W, we use box model simulations to determine typical radar reflectivity values for reference points. We apply the new methods to observations at the Atmospheric Radiation Measurement (ARM) sites North Slope of Alaska (NSA) and Oliktok Point (OLI) in 2016 using two 35 GHz Ka-band ARM Zenith Radars (KAZR). For periods with a sufficient number of liquid cloud observations, we find that liquid cloud processes are robust enough for cloud radar calibration, with the LWP-based method performing best. We estimate that, in 2016, the radar reflectivity at NSA was about 1±1 dB too low but stable. For OLI, we identify serious problems with maintaining an accurate calibration including a sudden decrease of 5 to 7 dB in June 2016.
24
Perelygin, B. V. "Ensuring stability of radar field when creating hydrometeorological monitoring system". Radiotekhnika, n. 192 (30 marzo 2018): 21–27. http://dx.doi.org/10.30837/rt.2018.1.192.03.
Testo completoAbstract (sommario):
Based on the model of the radar field formed by a group of meteorological radars, the radar field characteristics are calculated for different radar location variants based on a geometric approach. A failure of a part of the radar is simulated for each of the field construction variants and the degree of stability of the continuous radar field is quantitatively assessed upon the failure of a part of the radar. Recommendations are given on the construction of a systematically stable radar field.
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Ryzhkov, Alexander, Pengfei Zhang, Petar Bukovčić, Jian Zhang e Stephen Cocks. "Polarimetric Radar Quantitative Precipitation Estimation". Remote Sensing 14, n. 7 (31 marzo 2022): 1695. http://dx.doi.org/10.3390/rs14071695.
Testo completoAbstract (sommario):
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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Morales, Carlos Augusto, e Wando Celso Amorim. "METODOLOGIA PARA INTEGRAÇÃO DE UMA REDE DE RADARES METEOROLÓGICOS: APLICAÇÃO PARA O ESTADO DE SÃO PAULO". Ciência e Natura 38, n. 2 (31 maggio 2016): 1036. http://dx.doi.org/10.5902/2179460x17328.
Testo completoAbstract (sommario):
This study presents two procedures to integrate three weather radars in the State of São Paulo that can be extended to any other radar network. The methology consists of a radar calibration procedure followed by the integratio. The radar calibration is based on the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) coincident measurements. In this procedure, it was found that both Salesópolis and Presidente Prudent weather radars were over-estimating the radar refletivity fator (Z) by +6.0 and +4.4 dBZ respectively, while Bauru radar was under-estimating by -4.3 dBZ. Upon the calibration, the 3 weather radars were integrated by employing the constant altitude plan position indicator (CAPPIs) and the iluminated volume projected in a 3D space. In the CAPPI procedure, only the distance from the radar was used to weight the measurements, while for the volumetric methodology we employed the contribution of the ilumilated volume fraction that intercepted the integrated volume. Based on these two approaches it was found that the CAPPI integration presented under estimation for Z < 29 dBZ and super-estimation above, while the Volumetric method understimate almost constant at 0,5 dBZ.
27
Lengfeld, Katharina, Marco Clemens, Claire Merker, Hans Münster e Felix Ament. "A Simple Method for Attenuation Correction in Local X-Band Radar Measurements Using C-Band Radar Data". Journal of Atmospheric and Oceanic Technology 33, n. 11 (novembre 2016): 2315–29. http://dx.doi.org/10.1175/jtech-d-15-0091.1.
Testo completoAbstract (sommario):
AbstractThis paper presents a novel, simple method to correct reflectivity measurements of weather radars that operate in attenuation-influenced frequency bands using observations from less attenuated radar systems. In recent years radar systems operating in the X-band frequency range have been developed to provide precipitation fields for areas of special interest in high temporal (≤1 min) and spatial (≤250 m) resolution in complement to nationwide radar networks. However, X-band radars are highly influenced by attenuation. C- and S-band radars typically have coarser resolution (250 m–1 km and 5 min) but are less affected by attenuation.Correcting for attenuation effects in simple (non-Doppler) single-polarized X-band radars remains challenging and is often dependent on restriction parameters, for example, those derived from mountain returns. Therefore, these algorithms are applicable only in limited areas. The method proposed here uses measurements from C-band radars and hence can be applied in all regions covered by nationwide C- (or S-) band radar networks. First, a single scan of X-band radar measurements is used exemplary to identify advantages and disadvantages of the novel algorithm compared to a standard single radar algorithm. The performance of the correction algorithms in different types of precipitation is examined in nine case studies. The proposed method provides very promising results for each type of precipitation. Additionally, it is evaluated in a 5-month comparison with Micro Rain Radar (MRR) observations. The bias between uncorrected X-band radar and MRR data is nearly eliminated by the attenuation correction algorithm, and the RMSE is reduced by 20% while the correlation of ~0.9 between both systems remains nearly constant.
28
Berngardt, Oleg, Vladimir Kurkin, Dmitriy Kushnarev, Konstantin Grkovich, Roman Fedorov, Andrey Orlov e Vitaliy Harchenko. "ISTP SB RAS decameter radars". Solar-Terrestrial Physics 6, n. 2 (27 giugno 2020): 63–73. http://dx.doi.org/10.12737/stp-62202006.
Testo completoAbstract (sommario):
Under the project National Heliogeophysical Complex of the Russian Academy of Sciences, it is planned to create several coherent decameter radars. ISTP SB RAS developed a network of coherent decameter radars well before the start of financing this project. This has provided extensive experience in operating such radars, has enabled us to identify their technological problems, which should be solved when creating radars of own design, and to develop a project of radars with broader capabilities for diagnostics of the ionosphere as compared to existing radars of similar types. The paper analyzes the existing EKB ISTP SB RAS radar, reviews its technological problems, and proposes the structure of a new radar of SECIRA type. We report the results of prototyping of elements of the SECIRA radar, which demonstrate the possibility of its implementation. We discuss the potential applicability of the radar to ionospheric studies on the territory of the Russian Federation, in particular in high-latitude regions.
29
Berngardt, Oleg, Vladimir Kurkin, Dmitriy Kushnarev, Konstantin Grkovich, Roman Fedorov, Andrey Orlov e Vitaliy Harchenko. "ISTP SB RAS decameter radars". Solnechno-Zemnaya Fizika 6, n. 2 (27 giugno 2020): 79–92. http://dx.doi.org/10.12737/szf-62202006.
Testo completoAbstract (sommario):
Under the project National Heliogeophysical Complex of the Russian Academy of Sciences, it is planned to create several coherent decameter radars. ISTP SB RAS developed a network of coherent decameter radars well before the start of financing this project. This has provided extensive experience in operating such radars, has enabled us to identify their technological problems, which should be solved when creating radars of own design, and to develop a project of radars with broader capabilities for diagnostics of the ionosphere as compared to existing radars of similar types. The paper analyzes the existing EKB ISTP SB RAS radar, reviews its technological problems, and proposes the structure of a new radar of SECIRA type. We report the results of prototyping of elements of the SECIRA radar, which demonstrate the possibility of its implementation. We discuss the potential applicability of the radar to ionospheric studies on the territory of the Russian Federation, in particular in high-latitude regions.
30
Sabaria, Sabaria, e Syahfrizal Tahcfulloh. "Range and Velocity Resolution of Linear- Frequency-Modulated Signals on Subarray-Mimo Radar". Jurnal ELTIKOM 7, n. 2 (2 febbraio 2024): 200–209. http://dx.doi.org/10.31961/eltikom.v7i2.940.
Testo completoAbstract (sommario):
The most important radar system performance is determining the range-velocity of the detected target. This performance is obtained from processing an ambiguity-function (AF) between signals from target reflections and radar radiation signals. Selection of the appropriate waveform transmitted by the radar is a key factor in supporting high resolution radar performance in the AF. There are many waveforms that have been studied in radar systems, especially for multi-antenna radars, i.e., subarray-MIMO (SMIMO) radar which can form phased array (PA) and MIMO radars simultaneously, in the form of linear-frequency-modulated (LFM) signals. In this paper, we examine the use of LFM waveforms combined with SMIMO radar to produce plots of three-dimensional AF as a function of time delay and Doppler shift. The results of the comparison with the Hadamard signal determine the effectiveness of the observed AF performance on parameters such as magnitude, range-velocity resolution, peak sidelobe level ratio, and integrated sidelobe ratio by taking into account the factors of the number of Tx antennas on the PA radar and the number of Tx subarrays on the MIMO radar. The evaluation results of the SMIMO radar configuration (M = 6) with the number of Tx-Rx antenna elements the being 8 provide the best mainlobe magnitude, sidelobe magnitude, range resolution, velocity resolution, PSLR, and ISLR of AF LFM signals compared to conventional radars are 235.2dB, 7.54dB, 37.5m, 75km/s, 29.89dB, and 29.8dB, respectively. Meanwhile, the LFM signal is far superior to the Hadamard signal which has PSLR and ISLR 1.16dB and -3.36dB, respectively.
31
Dolan, Brenda A., e Steven A. Rutledge. "An Integrated Display and Analysis Methodology for Multivariable Radar Data". Journal of Applied Meteorology and Climatology 46, n. 8 (1 agosto 2007): 1196–213. http://dx.doi.org/10.1175/jam2524.1.
Testo completoAbstract (sommario):
Abstract Polarimetric Doppler radars provide valuable information about the kinematic and microphysical structure of storms. However, in-depth analysis using radar products, such as Doppler-derived wind vectors and hydrometeor identification, has been difficult to achieve in (near) real time, mainly because of the large volumes of data generated by these radars, lack of quick access to these data, and the challenge of applying quality-control measures in real time. This study focuses on modifying and automating several radar-analysis and quality-control algorithms currently used in postprocessing and merging the resulting data from several radars into an integrated analysis and display in (near) real time. Although the method was developed for a specific network of four Doppler radars: two Weather Surveillance Radar-1988 Doppler (WSR-88D) radars (KFTG and KCYS) and two Colorado State University (CSU) research radars [Pawnee and CSU–University of Chicago–Illinois State Water Survey (CSU–CHILL)], the software is easily adaptable to any radar platform or network of radars. The software includes code to synthesize radial velocities to obtain three-dimensional wind vectors and includes algorithms for automatic quality control of the raw polarimetric data, hydrometeor identification, and rainfall rate. The software was successfully tested during the summers of 2004 and 2005 at the CSU–CHILL radar facility, ingesting data from the four-radar network. The display software allows users the ability to view mosaics of reflectivity, wind vectors, and rain rates, to zoom in and out of radar features easily, to create vertical cross sections, to contour data, and to archive data in real time. Despite the lag time of approximately 10 min, the software proved invaluable for diagnosing areas of intense rainfall, hail, strong updrafts, and other features such as mesocyclones and convergence lines. A case study is presented to demonstrate the utility of the software.
32
Saltikoff, Elena, Mikko Kurri, Hidde Leijnse, Sergio Barbosa e Kjetil Stiansen. "Maintenance Keeps Radars Running". Bulletin of the American Meteorological Society 98, n. 9 (1 settembre 2017): 1833–40. http://dx.doi.org/10.1175/bams-d-16-0095.1.
Testo completoAbstract (sommario):
Abstract Weather radars provide us with colorful images of storms, their development, and their movement, but from time to time the radars fail and we are left without data. To minimize these disruptions, owners of weather radars carry out preventive maintenance. The European radar project Operational Programme for the Exchange of Weather Radar Information (OPERA) conducted a survey among technicians from 21 countries on their experiences of maintenance. Regular maintenance frequency varies widely from as frequent as weekly to as infrequent as 6 months. Results show that the primary causes of missing data are not the failure of radar components and software or lack of maintenance but rather issues with the electricity supplies or telecommunications. Where issues are with the radars themselves, they are most commonly with the transmitter or the antenna controllers. Faults can be repaired quickly, but, if certain parts are required or the site is very remote, a radar can be out of service for weeks or even months. Failures of electricity or communications may also lead to lengthy periods of unavailability. As an example there is a story from Norway where wintertime thunderstorms severely damaged a radar at a very remote location. Annual operative costs of a radar are typically on the order of 5%–10% of the radar purchase price. During the lifetime of a system (typically 10–20 years) the operator can hence pay as much for the running costs as for the hardware purchase. It is extremely important to take infrastructure, maintenance, and monitoring into account when purchasing a new radar.
33
Cha, Kyuho, Sooyoung Oh, Hayoung Hong, Hongsoo Park e Sun K. Hong. "Detection of Electronic Devices Using FMCW Nonlinear Radar". Sensors 22, n. 16 (15 agosto 2022): 6086. http://dx.doi.org/10.3390/s22166086.
Testo completoAbstract (sommario):
Nonlinear radars can be utilized to detect electronic devices, which are difficult to detect with conventional radars due to their small radar cross sections (RCS). Since the receiver in a nonlinear radar is designed to only receive harmonic or intermodulated echoes from electronic devices, it is able to separate electronic devices from non-electronic scatters (clutter) by rejecting their echoes at fundamental frequencies. This paper presents a harmonic-based nonlinear radar scheme utilizing frequency-modulated continuous-wave (FMCW) signals for the detection of various electronic devices at short range. Using a laboratory experiment setup for FMCW radar at S-band for Tx (C-band for Rx), measurements are carried out to detect electronic devices of various sizes. The results show that the detection of small electronic devices is possible with nonlinear FMCW radar when appropriate system parameters are selected. Furthermore, we also discuss the maximum detectable range estimation for electronic targets using the radar range equation for FMCW nonlinear radar.
34
Ľoncová, Jana, e Ján Ochodnický. "Adaptive Algorithms in Radar Signal Processing". Science & Military 19, n. 1 (2024): 15–25. http://dx.doi.org/10.52651/sam.a.2024.1.15-25.
Testo completoAbstract (sommario):
The development of modern technologies has fundamentally transformed the field of radar signal and data processing. With the use of advanced algorithms and computational power, radars are now capable of extracting crucial information from received signals, facilitating improved target identification and tracking. This article presents some of the advanced technologies employed in radar signal and data processing and their impact on adaptability of radar systems. It traces the evolution of radar technology from old systems to the present, emphasizing the benefits of adaptive radar signal processing, which includes algorithms such as adaptive beamforming, Space-Time Adaptive Processing, and the integration of Machine Learning and Artificial Intelligence. In conclusion, challenges, and future prospects in the field of radar systems are discussed, with a focus on the potential integration of Artificial Intelligence methods, Cognitive radars, and Multiple Input Multiple Output technologies. Despite technical obstacles, opportunities emerge to enhance the performance of radar systems and achieve new levels of efficiency.
35
Fall, Veronica M., Qing Cao e Yang Hong. "Intercomparison of Vertical Structure of Storms Revealed by Ground-Based (NMQ) and Spaceborne Radars (CloudSat-CPR and TRMM-PR)". Scientific World Journal 2013 (2013): 1–8. http://dx.doi.org/10.1155/2013/270726.
Testo completoAbstract (sommario):
Spaceborne radars provide great opportunities to investigate the vertical structure of clouds and precipitation. Two typical spaceborne radars for such a study are the W-band Cloud Profiling Radar (CPR) and Ku-band Precipitation Radar (PR), which are onboard NASA’s CloudSat and TRMM satellites, respectively. Compared to S-band ground-based radars, they have distinct scattering characteristics for different hydrometeors in clouds and precipitation. The combination of spaceborne and ground-based radar observations can help in the identification of hydrometeors and improve the radar-based quantitative precipitation estimation (QPE). This study analyzes the vertical structure of the 18 January, 2009 storm using data from the CloudSat CPR, TRMM PR, and a NEXRAD-based National Mosaic and Multisensor QPE (NMQ) system. Microphysics above, within, and below the melting layer are studied through an intercomparison of multifrequency measurements. Hydrometeors’ type and their radar scattering characteristics are analyzed. Additionally, the study of the vertical profile of reflectivity (VPR) reveals the brightband properties in the cold-season precipitation and its effect on the radar-based QPE. In all, the joint analysis of spaceborne and ground-based radar data increases the understanding of the vertical structure of storm systems and provides a good insight into the microphysical modeling for weather forecasts.
36
Ahmed, Shahzad, Karam Dad Kallu, Sarfaraz Ahmed e Sung Ho Cho. "Hand Gestures Recognition Using Radar Sensors for Human-Computer-Interaction: A Review". Remote Sensing 13, n. 3 (2 febbraio 2021): 527. http://dx.doi.org/10.3390/rs13030527.
Testo completoAbstract (sommario):
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.
37
Gourley, Jonathan J., David P. Jorgensen, Sergey Y. Matrosov e Zachary L. Flamig. "Evaluation of Incremental Improvements to Quantitative Precipitation Estimates in Complex Terrain". Journal of Hydrometeorology 10, n. 6 (1 dicembre 2009): 1507–20. http://dx.doi.org/10.1175/2009jhm1125.1.
Testo completoAbstract (sommario):
Abstract Advanced remote sensing and in situ observing systems employed during the Hydrometeorological Testbed experiment on the American River basin near Sacramento, California, provided a unique opportunity to evaluate correction procedures applied to gap-filling, experimental radar precipitation products in complex terrain. The evaluation highlighted improvements in hourly radar rainfall estimation due to optimizing the parameters in the reflectivity-to-rainfall (Z–R) relation, correcting for the range dependence in estimating R due to the vertical variability in Z in snow and melting-layer regions, and improving low-altitude radar coverage by merging rainfall estimates from two research radars operating at different frequencies and polarization states. This evaluation revealed that although the rainfall product from research radars provided the smallest bias relative to gauge estimates, in terms of the root-mean-square error (with the bias removed) and Pearson correlation coefficient it did not outperform the product from a nearby operational radar that used optimized Z–R relations and was corrected for range dependence. This result was attributed to better low-altitude radar coverage with the operational radar over the upper part of the basin. In these regions, the data from the X-band research radar were not available and the C-band research radar was forced to use higher-elevation angles as a result of nearby terrain and tree blockages, which yielded greater uncertainty in surface rainfall estimates. This study highlights the challenges in siting experimental radars in complex terrain. Last, the corrections developed for research radar products were adapted and applied to an operational radar, thus providing a simple transfer of research findings to operational rainfall products yielding significantly improved skill.
38
Zheng, Zexin, Wei Li e Kun Zou. "Airborne Radar Anti-Jamming Waveform Design Based on Deep Reinforcement Learning". Sensors 22, n. 22 (10 novembre 2022): 8689. http://dx.doi.org/10.3390/s22228689.
Testo completoAbstract (sommario):
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.
39
Caffa, Mattia, Francesco Biletta e Riccardo Maggiora. "Binary-Phase vs. Frequency Modulated Radar Measured Performances for Automotive Applications". Sensors 23, n. 11 (1 giugno 2023): 5271. http://dx.doi.org/10.3390/s23115271.
Testo completoAbstract (sommario):
Radars have been widely deployed in cars in recent years, for advanced driving assistance systems. The most popular and studied modulated waveform for automotive radar is the frequency-modulated continuous wave (FMCW), due to FMCW radar technology’s ease of implementation and low power consumption. However, FMCW radars have several limitations, such as low interference resilience, range-Doppler coupling, limited maximum velocity with time-division multiplexing (TDM), and high-range sidelobes that reduce high-contrast resolution (HCR). These issues can be tackled by adopting other modulated waveforms. The most interesting modulated waveform for automotive radar, which has been the focus of research in recent years, is the phase-modulated continuous wave (PMCW): this modulated waveform has a better HCR, allows large maximum velocity, permits interference mitigation, thanks to codes orthogonality, and eases integration of communication and sensing. Despite the growing interest in PMCW technology, and while simulations have been extensively performed to analyze and compare its performance to FMCW, there are still only limited real-world measured data available for automotive applications. In this paper, the realization of a 1 Tx/1 Rx binary PMCW radar, assembled with connectorized modules and an FPGA, is presented. Its captured data were compared to the captured data of an off-the-shelf system-on-chip (SoC) FMCW radar. The radar processing firmware of both radars were fully developed and optimized for the tests. The measured performances in real-world conditions showed that PMCW radars manifest better behavior than FMCW radars, regarding the above-mentioned issues. Our analysis demonstrates that PMCW radars can be successfully adopted by future automotive radars.
40
Briggs, J. N. "Specifications for Reflectors and Radar Target Enhancers to Aid Detection of Small Marine Radar Targets". Journal of Navigation 55, n. 1 (gennaio 2002): 23–38. http://dx.doi.org/10.1017/s0373463301001564.
Testo completoAbstract (sommario):
This paper considers the need for better detectability of small targets at sea using marine radars in the 3 and 9 GHz bands. The problems of using radar reflectors and radar target enhancers to improve radar cross section, particularly when clutter is present, are discussed in detail. The IMO carriage requirement and the lack of suitably robust specifications are highlighted, and a proposal is made for a standard family of radar reflectors to meet the requirement. Radar target enhancers are also considered together with how these and radar reflectors should be mounted for best effect.
41
Geiger, Martin, Christian Wegner, Winfried Mayer e Christian Waldschmidt. "A Wideband Dielectric Waveguide-Based 160-GHz Radar Target Generator". Sensors 19, n. 12 (22 giugno 2019): 2801. http://dx.doi.org/10.3390/s19122801.
Testo completoAbstract (sommario):
The increasing number of radar sensors in commercial and industrial products leads to a growing demand for system functionality tests. Conventional test procedures require expensive anechoic chambers to provide a defined test environment for radar sensors. In this paper, a compact and low cost dielectric waveguide radar target generator for level probing radars is presented. The radar target generator principle is based on a long dielectric waveguide as a one-target scenery. By manipulating the field distribution of the waveguide, a specific reflection of a radar target is generated. Two realistic scenarios for a tank level probing radar are investigated and suitable targets are designed with full wave simulations. Target distances from 13 cm to at least 9 m are realized with an extruded dielectric waveguide with dielectric losses of 2 dB/m at 160 GHz. Low loss (0.5 dB) and low reflection holders are used to fix the waveguide. Due to the dispersion of the dielectric waveguide, a detailed analysis of its impact on frequency-modulated continuous wave (FMCW) radars is given and compared to free-space propagation. The functionality of the radar target generator is verified with a 160-GHz FMCW radar prototype.
42
Ilcev, Dimov Stojce. "Introduction to Coastal HF Maritime Surveillance Radars". Polish Maritime Research 26, n. 3 (1 settembre 2019): 153–62. http://dx.doi.org/10.2478/pomr-2019-0056.
Testo completoAbstract (sommario):
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.
43
Vasiliev, Ivan, Sergey Saliy, Rollan Altynbekov, Gulshat Rysbayeva e Vladimir Echin. "Issue of VHF Continuous Emission Radars Coordinate Measurement Discrepancy". Journal of Physical Science 34, n. 3 (6 dicembre 2023): 37–52. http://dx.doi.org/10.21315/jps2023.34.3.3.
Testo completoAbstract (sommario):
The research delves into the significance of continuous emission radars of very high frequency (VHF) range in detecting small unmanned aircraft and marine targets for navigation safety. Recognising the need for improved radars and reduced coordinate measurement errors, the study aims to analyse discrepancies in azimuth and range determination in radars with fixed-phased antenna arrays. By developing effective tools with low computational complexity for target azimuth determination, the research seeks to enhance radar performance. Employing analytical, classification, functional, and statistical methods, the study comprehensively examines the peculiarities and differences of radars. It meticulously analyses coordinate measurement errors and investigates their causes. The impact of these discrepancies on radar performance and their relevance in various applications, particularly maritime navigation, is carefully evaluated. The findings emphasise the critical role of continuous emission radars in ensuring shipping safety and economic efficiency. The recommendations derived from the study offer valuable insights for improving radar effectiveness, addressing operational limitations, and enhancing overall functionality. By tackling coordinate measurement errors and providing accurate azimuth determination tools, this research contributes to advancing continuous emission radar technology and its practical applications. Through its findings and recommendations, the study aims to optimise radar performance, enhance navigation safety, and improve economic efficiency in diverse sectors.
44
Cao, Yu Peng, Yang Zhang, Jun Luo, Fu Sheng Jian, Xi Guo Dai, Zhu Qun Zhai, Xiao Ying Ma et al. "Simulation Detection Power of Shore-Based Radar under the Influence of Sea Clutter". Advanced Materials Research 1049-1050 (ottobre 2014): 1200–1204. http://dx.doi.org/10.4028/www.scientific.net/amr.1049-1050.1200.
Testo completoAbstract (sommario):
According to the principle of electromagnetic wave propagation and the model of radar multipath propagation, this paper established radar detection power model in natural space under the impact of sea clutter, and on condition that conducting simulations to study detection power of shore-based radars on different altitudes and different operating frequencies. Simulation results indicate that when the radar operating frequency is constant, with the erection height increases, the detection range will increase at the same time, while significantly reduced about blind region. When the radar erection height is constant, blind region is filled with radars working at C, S and X operating frequencies. The effect of blind filling is of great importance for adjacent bands. This paper provides theoretical reference analysis for radar detection power assessing and overall with a strong engineering application value.
45
Ogawa, T., S. Nozawa, M. Tsutsumi, N. F. Arnold, N. Nishitani, N. Sato e A. S. Yukimatu. "Arctic and Antarctic polar mesosphere summer echoes observed with oblique incidence HF radars: analysis using simultaneous MF and VHF radar data". Annales Geophysicae 22, n. 12 (22 dicembre 2004): 4049–59. http://dx.doi.org/10.5194/angeo-22-4049-2004.
Testo completoAbstract (sommario):
Abstract. Polar mesosphere summer echoes (PMSEs) have been well studied using vertical incidence VHF radars at northern high-latitudes. In this paper, two PMSE events detected with the oblique incidence SuperDARN HF radars at Hankasalmi, Finland (62.3° N) and Syowa Station, Antarctica (69.0° S), are analyzed, together with simultaneous VHF and medium-frequency (MF) radar data. Altitude resolutions of the HF radars in the mesosphere and the lower thermosphere are too poor to know exact PMSE altitudes. However, a comparison of Doppler velocity from the HF radar and neutral wind velocity from the MF radar shows that PMSEs at the HF band appeared at altitudes within 80-90km, which are consistent with those from previous vertical incidence HF-VHF radar results. The HF-VHF PMSE occurrences exhibit a semidiurnal behavior, as observed by other researchers. It is found that in one event, PMSEs occurred when westward semidiurnal winds with large amplitude at 85-88km altitudes attained a maximum. When the HF-VHF PMSEs were observed at distances beyond 180km from MF radar sites, the MF radars detected no appreciable signatures of echo enhancement. Key words. Meteorology and atmospheric dynamics (middle atmosphere dynamics; thermospheric dynamics; waves and tides)
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RAO, P. RAJESH, R. C. SAXENA e S. K. BANERJEE. "Some aspects of accuracy of radar/satellite fixes of tropical cyclone over Bay of Bengal". MAUSAM 43, n. 4 (31 dicembre 2021): 379–84. http://dx.doi.org/10.54302/mausam.v43i4.3505.
Testo completoAbstract (sommario):
Consequent to installation of 10 cyclone detection radars and availability of INSAT observations availability of fixes* of cyclones by two or more radars and satellite has become a common feature during tracking of cyclones. Generally these fixes differ from each other to some extent. The paper presents a study of tracks of four cyclones in Bay of Bengal as determined by coastal radars and satellite. It is seen that satellite fix is generally closer to coast as compared to radar fix. Amongst radar fixes, the fix of radar closest to the storm may be considered as best fix of the system.
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Tahcfulloh, Syahfrizal, e Muttaqin Hardiwansyah. "Subarrays of phased-array antennas for multiple-input multiple-output radar applications". International Journal of Informatics and Communication Technology (IJ-ICT) 11, n. 3 (1 dicembre 2022): 218. http://dx.doi.org/10.11591/ijict.v11i3.pp218-228.
Testo completoAbstract (sommario):
The subarray MIMO radar (SMIMO) is a multiple-input multiple-output (MIMO) radar with elements in the form of a sub-array that acts as a phased array (PAR), so it combines at the same time the key advantage of the PAR radar, which is high directional gain to increase target range, and the key advantage of the MIMO radar, i.e., high diversity gains to increase the maximum number of detected targets. Different schemes for the number of antenna elements in the transceiver zones, such as uniform and/or variable, overlapped and non-overlapped, significantly determine the performance of radars as virtual arrays (VARs), maximum number of detected targets, accuracy of target angle, detection resolution, SNR detection, and detection probability. Performance is also compared with the PAR, the MIMO, and the phased MIMO radars (PMIMO). The SMIMO radar offers great versatility for radar applications, being able to adapt to different shapes of the multiple targets to be detected and their environment. For example, for a transmit-receive with an antenna element number, i.e., <em>M</em> = <em>N</em> = 8, the range of the number of detected targets for the SMIMO radar is flexible compared to the other radars. On the other hand, the proposed radar's signal-to-noise ratio (SNR) detection performance and detection probability (<em>K</em> = 5, <em>L</em> = 3) are both 1,999 and above 90%, which are better than other radars.
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Czaplewski, Krzysztof, e Sławomir Świerczyński. "A Method of Increasing the Accuracy of Radar Distance Measurement in VTS Systems for Vessels with Very Large Dimensions". Remote Sensing 13, n. 16 (4 agosto 2021): 3066. http://dx.doi.org/10.3390/rs13163066.
Testo completoAbstract (sommario):
The navigation information about a vessel’s position in the waters covered by the vessel traffic system operation is obtained through supervisory services, mainly from coastal navigation radars. Although today it is possible to simultaneously acquire data from many independent radars, the obtained radar image is inconsistent and consists of several echoes next to each other. This makes it difficult to establish which echo represents the monitored unit. Another problem is the method of determining radar distances, which significantly affect the quality of determining the observation position. Errors in radar distance may occur when determining the radar echoes from large vessels, where the position of the unit is not the same as the edge of the radar echo to which the observation is made. In this article, the authors present a method of improving the measured radar distance. The presented proposal was verified in navigation and maneuvering simulation conditions. It could support the process of determining the ship position in vessel traffic service (VTS) systems with increased accuracy.
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Bluestein, Howard B., Robert M. Rauber, Donald W. Burgess, Bruce Albrecht, Scott M. Ellis, Yvette P. Richardson, David P. Jorgensen et al. "Radar in Atmospheric Sciences and Related Research: Current Systems, Emerging Technology, and Future Needs". Bulletin of the American Meteorological Society 95, n. 12 (1 dicembre 2014): 1850–61. http://dx.doi.org/10.1175/bams-d-13-00079.1.
Testo completoAbstract (sommario):
To assist the National Science Foundation in meeting the needs of the community of scientists by providing them with the instrumentation and platforms necessary to conduct their research successfully, a meeting was held in late November 2012 with the purpose of defining the problems of the next generation that will require radar technologies and determining the suite of radars best suited to help solve these problems. This paper summarizes the outcome of the meeting: (i) Radars currently in use in the atmospheric sciences and in related research are reviewed. (ii) New and emerging radar technologies are described. (iii) Future needs and opportunities for radar support of high-priority research are discussed. The current radar technologies considered critical to answering the key and emerging scientific questions are examined. The emerging radar technologies that will be most helpful in answering the key scientific questions are identified. Finally, gaps in existing radar observing technologies are listed.
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Qi, Youcun, e Jian Zhang. "Correction of Radar QPE Errors Associated with Low and Partially Observed Brightband Layers". Journal of Hydrometeorology 14, n. 6 (22 novembre 2013): 1933–43. http://dx.doi.org/10.1175/jhm-d-13-040.1.
Testo completoAbstract (sommario):
Abstract The melting of aggregated snow/crystals often results in an enhancement of the reflectivity observed by weather radars, and this is commonly referenced as the bright band (BB). The locally high reflectivity often causes overestimation in radar quantitative precipitation estimates (QPE) if no appropriate correction is applied. When the melting layer is high, a complete BB layer profile (including top, peak, and bottom) can be observed by the ground radar, and a vertical profile of reflectivity (VPR) correction can be made to reduce the BB impact. When a melting layer is near the ground and the bottom part of the bright band cannot be observed by the ground radar, a VPR correction cannot be made directly from the Weather Surveillance Radar-1988 Doppler (WSR-88D) radar observations. This paper presents a new VPR correction method under this situation. From high-resolution precipitation profiler data, an empirical relationship between BB peak and BB bottom is developed. The empirical relationship is combined with the apparent BB peak observed by volume scan radars and the BB bottom is found. Radar QPEs are then corrected based on the estimated BB bottom. The new method was tested on 13 radars during seven low brightband events over different areas in the United States. It is shown to be effective in reducing the radar QPE overestimation under low brightband situations.