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Literatura académica sobre el tema "Echos radar"

Autor: Grafiati

Publicado: 4 de junio de 2021

Última modificación: 1 de febrero de 2022

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Artículos de revistas sobre el tema "Echos radar"

Dyrud, L. P., K. Denney, S. Close, M. Oppenheim, J. Chau y L. Ray. "Meteor velocity determination with plasma physics". Atmospheric Chemistry and Physics 4, n.º 3 (3 de junio de 2004): 817–24. http://dx.doi.org/10.5194/acp-4-817-2004.

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Abstract. Understanding the global meteor flux at Earth requires the measurement of meteor velocities. While several radar methods exist for measuring meteor velocity, they may be biased by plasma reflection mechanisms. This paper presents a new method for deriving meteoroid velocity from the altitudinal extent of non-specular trails. This method employs our recent discoveries on meteor trail plasma instability. Dyrud et al. (2002) demonstrated that meteor trails are unstable over a limited altitude range, and that the precise altitudes of instability are dependent on the meteoroid that generated the trail. Since meteor trail instability results in field aligned irregularities (FAI) that allow for radar reflection, non-specular trail observations may be used to derive velocity. We use ALTAIR radar data of combined head echos and non-specular trails to test non-specular trail derived velocity against head echo velocities. Meteor velocities derived from non-specular trail altitudinal width match to within 5 km/s when compared with head echo range rates from the same meteor. We apply this technique to Piura radar observations of hundreds of non-specular trails to produce histograms of occurrence of meteor velocity based solely on this non-specular trails width criterion. The results from this study show that the most probable velocity of meteors seen by the Piura radar is near 50 km/s, which is comparable with modern head echo studies.

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Dyrud, L. P., K. Denney, S. Close, M. Oppenheim, L. Ray y J. Chau. "Meteor velocity determination with plasma physics". Atmospheric Chemistry and Physics Discussions 4, n.º 1 (27 de febrero de 2004): 1247–68. http://dx.doi.org/10.5194/acpd-4-1247-2004.

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Abstract. Understanding the global meteor flux at Earth requires the measurement of meteor velocities. While several radar methods exist for measuring meteor velocity, they may be biased by plasma reflection mechanisms. This paper presents a new method for deriving meteoroid velocity from the altitudinal extent of non-specular trails. This method employs our recent discoveries on meteor trail plasma instability. Dyrud et al. (2002) demonstrated that meteor trails are unstable over a limited altitude range, and that the precise altitudes of instability are dependent on the meteoroid velocity that generated the trail. Since meteor trail instability results in field aligned irregularities (FAI) that allow for radar reflection, non-specular trail observations may be used to derive velocity. We use ALTAIR radar data of combined head echos and non-specular trails to test non-specular trail derived velocity against head echo velocities. Meteor velocities derived from non-specular trail altitudinal width match to within 5 km/s when compared with head echo range rates from the same meteor. We apply this technique to Piura radar observations of hundreds of non-specular trails to produce histograms of occurrence of meteor velocity based solely on this non-specular trails width criterion. The results from this study show that the most probable velocity of meteors seen by the Piura radar is near 50 km/s which is comparable with modern head echo studies.

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Vierinen, J., M. S. Lehtinen y I. I. Virtanen. "Amplitude domain analysis of strong range and Doppler spread radar echos". Annales Geophysicae 26, n.º 8 (6 de agosto de 2008): 2419–26. http://dx.doi.org/10.5194/angeo-26-2419-2008.

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Abstract. We present a novel method for analyzing range and Doppler spread targets in the amplitude domain using linear statistical inversion. The result of the analysis is an estimate of the range dependent amplitude behaviour of the target backscatter during the time that the transmission passes the target. A meteor head echo and strong backscatter from artificially heated regions of the ionosphere are used to demonstrate this novel analysis method. Plans to apply amplitude-domain radar target estimation methods to more complicated noisy underdetermined targets are also briefly discussed.

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Ghezelbash, M., R. A. D. Fiori y A. V. Koustov. "Variations in the occurrence of SuperDARN F region echoes". Annales Geophysicae 32, n.º 2 (20 de febrero de 2014): 147–56. http://dx.doi.org/10.5194/angeo-32-147-2014.

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Abstract. The occurrence of F region ionospheric echoes observed by a number of SuperDARN HF radars is analyzed statistically in order to infer solar cycle, seasonal, and diurnal trends. The major focus is on Saskatoon radar data for 1994–2012. The distribution of the echo occurrence rate is presented in terms of month of observation and magnetic local time. Clear repetitive patterns are identified during periods of solar maximum and solar minimum. For years near solar maximum, echoes are most frequent near midnight during winter. For years near solar minimum, echoes occur more frequently near noon during winter, near dusk and dawn during equinoxes and near midnight during summer. Similar features are identified for the Hankasalmi and Prince George radars in the northern hemisphere and the Bruny Island TIGER radar in the southern hemisphere. Echo occurrence for the entire SuperDARN network demonstrates patterns similar to patterns in the echo occurrence for the Saskatoon radar and for other radars considered individually. In terms of the solar cycle, the occurrence rate of nightside echoes is shown to increase by a factor of at least 3 toward solar maximum while occurrence of the near-noon echoes does not significantly change with the exception of a clear depression during the declining phase of the solar cycle.

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Ogawa, T., N. F. Arnold, S. Kirkwood, N. Nishitani y M. Lester. "Finland HF and Esrange MST radar observations of polar mesosphere summer echoes". Annales Geophysicae 21, n.º 4 (30 de abril de 2003): 1047–55. http://dx.doi.org/10.5194/angeo-21-1047-2003.

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Abstract. Peculiar near range echoes observed in summer with the SuperDARN HF radar in Finland are presented. The echoes were detected at four frequencies of 9, 11, 13 and 15 MHz at slant ranges of 105–250 km for about 100 min. Interferometer measurements indicate that the echoes are returned from 80–100 km altitudes with elevation angles of 20°–60°. Echo power (< 16 dB), Doppler velocity (between –30 and + 30 ms-1) and spectral width (< 60 ms-1) fluctuate with periods of several to 20 min, perhaps due to short–period atmospheric gravity waves. When the HF radar detected the echoes, a vertical incidence MST radar, located at Esrange in Sweden (650 km north of the HF radar site), observed polar mesosphere summer echoes (PMSE) at altitudes of 80–90 km. This fact suggests that the near range HF echoes are PMSE at HF band, although both radars did not probe a common volume. With increasing radar frequency, HF echo ranges are closer to the radar site and echo power becomes weaker. Possible mechanisms to explain these features are discussed.Key words. Meteorology and atmospheric dynamics (middle atmosphere dynamics; thermospheric dynamics; waves and tides; instruments and techniques)

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Foerster, Annette M., Michael M. Bell, Patrick A. Harr y Sarah C. Jones. "Observations of the Eyewall Structure of Typhoon Sinlaku (2008) during the Transformation Stage of Extratropical Transition". Monthly Weather Review 142, n.º 9 (septiembre de 2014): 3372–92. http://dx.doi.org/10.1175/mwr-d-13-00313.1.

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A unique dataset observing the life cycle of Typhoon Sinlaku was collected during The Observing System Research and Predictability Experiment (THORPEX) Pacific Asian Regional Campaign (T-PARC) in 2008. In this study observations of the transformation stage of the extratropical transition of Sinlaku are analyzed. Research flights with the Naval Research Laboratory P-3 and the U.S. Air Force WC-130 aircraft were conducted in the core region of Sinlaku. Data from the Electra Doppler Radar (ELDORA), dropsondes, aircraft flight level, and satellite atmospheric motion vectors were analyzed with the recently developed Spline Analysis at Mesoscale Utilizing Radar and Aircraft Instrumentation (SAMURAI) software with a 1-km horizontal- and 0.5-km vertical-node spacing. The SAMURAI analysis shows marked asymmetries in the structure of the core region in the radar reflectivity and three-dimensional wind field. The highest radar reflectivities were found in the left of shear semicircle, and maximum ascent was found in the downshear left quadrant. Initial radar echos were found slightly upstream of the downshear direction and downdrafts were primarily located in the upshear semicircle, suggesting that individual cells in Sinlaku’s eyewall formed in the downshear region, matured as they traveled downstream, and decayed in the upshear region. The observed structure is consistent with previous studies of tropical cyclones in vertical wind shear, suggesting that the eyewall convection is primarily shaped by increased vertical wind shear during step 2 of the transformation stage, as was hypothesized by Klein et al. A transition from active convection upwind to stratiform precipitation downwind is similar to that found in the principal rainband of more intense tropical cyclones.

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Martin, William J. y Alan Shapiro. "Discrimination of Bird and Insect Radar Echoes in Clear Air Using High-Resolution Radars". Journal of Atmospheric and Oceanic Technology 24, n.º 7 (1 de julio de 2007): 1215–30. http://dx.doi.org/10.1175/jtech2038.1.

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Abstract The source of clear-air reflectivity from operational and research meteorological radars has been a subject of much debate and study over the entire history of radar meteorology. Recent studies have suggested that bird migrations routinely contaminate wind profiles obtained at night, while historical studies have suggested insects as the main source of such nocturnal clear-air echoes. This study analyzes two cases of nocturnal clear-air return using data from operational Weather Surveillance Radar-1988 Doppler (WSR-88D) and X- and W-band research radars. The research radars have sufficient resolution to resolve the echo as point targets in some cases. By examining the radar cross section of the resolved point targets, and by determining the target density, it is found for both cases of nocturnal clear-air echoes that the targets are almost certainly insects. The analysis of the dependence of the echo strength on radar wavelength also supports this conclusion.

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Czaplewski, Krzysztof y 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.º 16 (4 de agosto de 2021): 3066. http://dx.doi.org/10.3390/rs13163066.

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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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Cifelli, R., S. W. Nesbitt, S. A. Rutledge, W. A. Petersen y S. Yuter. "Radar Characteristics of Precipitation Features in the EPIC and TEPPS Regions of the East Pacific". Monthly Weather Review 135, n.º 4 (1 de abril de 2007): 1576–95. http://dx.doi.org/10.1175/mwr3340.1.

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Abstract Ship-based radar data are used to compare the structure of precipitation features in two regions of the east Pacific where recent field campaigns were conducted: the East Pacific Investigation of Climate Processes in the Coupled Ocean–Atmosphere System (EPIC-2001; 10°N, 95°W) in September 2001 and the Tropical Eastern Pacific Process Study (TEPPS; 8°N, 125°W) in August 1997. Corresponding July–September 1998–2004 Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) data are also used to provide context for the field campaign data. An objective technique is developed to identify precipitation features in the ship and TRMM PR data and to develop statistics on horizontal and vertical structure and precipitation characteristics. Precipitation features were segregated into mesoscale convective system (MCS) and sub-MCS categories, based on a contiguous area threshold of 1000 km2 (these features were required to have at least one convective pixel), as well as an “other” (NC) category. Comparison of the satellite and field campaign data showed that the two datasets were in good agreement for both regions with respect to MCS features. Specifically, both the satellite and ship radar data showed that approximately 80% of the rainfall volume in both regions was contributed by MCS features, similar to results from other observational datasets. EPIC and TEPPS MCSs had similar area distributions but EPIC MCSs tended to be more vertically developed and rain heavier than their TEPPS counterparts. In contrast to MCSs, smaller features (NCs and sub-MCSs) sampled by the ship radar in both regions showed important differences compared with the PR climatology. In the EPIC field campaign, a large number of small (<100 km2), shallow (radar echo tops below the melting level) NCs and sub-MCSs were sampled. A persistent dry layer above 800 mb during undisturbed periods in EPIC may have been responsible for the high occurrence of these features. Also, during the TEPPS campaign, sub-MCSs were larger and deeper with respect to the TRMM climatology, which may have been due to the higher than average SSTs during 1997–98 when TEPPS was conducted. Despite these differences, it was found that for sizes greater than about 100 km2, EPIC precipitation features had 30-dBZ echos at higher altitudes and also had higher rain rates than similar sized TEPPS features. These results suggest that ice processes play a more important role in rainfall production in EPIC compared with TEPPS.

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Kastinen, Daniel y Johan Kero. "Probabilistic analysis of ambiguities in radar echo direction of arrival from meteors". Atmospheric Measurement Techniques 13, n.º 12 (16 de diciembre de 2020): 6813–35. http://dx.doi.org/10.5194/amt-13-6813-2020.

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Abstract. Meteors and hard targets produce coherent radar echoes. If measured with an interferometric radar system, these echoes can be used to determine the position of the target through finding the direction of arrival (DOA) of the incoming echo onto the radar. Depending on the spatial configuration of radar-receiving antennas and their individual gain patterns, there may be an ambiguity problem when determining the DOA of an echo. Radars that are theoretically ambiguity-free are known to still have ambiguities that depend on the total radar signal-to-noise ratio (SNR). In this study, we investigate robust methods which are easy to implement to determine the effect of ambiguities on any hard target DOA determination by interferometric radar systems. We apply these methods specifically to simulate four different radar systems measuring meteor head and trail echoes, using the multiple signal classification (MUSIC) DOA determination algorithm. The four radar systems are the Middle And Upper Atmosphere (MU) radar in Japan, a generic Jones 2.5λ specular meteor trail radar configuration, the Middle Atmosphere Alomar Radar System (MAARSY) radar in Norway and the Program of the Antarctic Syowa Mesosphere Stratosphere Troposphere Incoherent Scatter (PANSY) radar in the Antarctic. We also examined a slightly perturbed Jones 2.5λ configuration used as a meteor trail echo receiver for the PANSY radar. All the results are derived from simulations, and their purpose is to grant understanding of the behaviour of DOA determination. General results are as follows: there may be a region of SNRs where ambiguities are relevant; Monte Carlo simulation determines this region and if it exists; the MUSIC function peak value is directly correlated with the ambiguous region; a Bayesian method is presented that may be able to analyse echoes from this region; the DOA of echoes with SNRs larger than this region are perfectly determined; the DOA of echoes with SNRs smaller than this region completely fail to be determined; the location of this region is shifted based on the total SNR versus the channel SNR in the direction of the target; and asymmetric subgroups can cause ambiguities, even for ambiguity-free radars. For a DOA located at the zenith, the end of the ambiguous region is located at 17 dB SNR for the MU radar and 3 dB SNR for the PANSY radar. The Jones radars are usually used to measure specular trail echoes far from zenith. The ambiguous region for a DOA at 75.5∘ elevation and 0∘ azimuth ends at 12 dB SNR. Using the Bayesian method, it may be possible to analyse echoes down to 4 dB SNR for the Jones configuration when given enough data points from the same target. The PANSY meteor trail echo receiver did not deviate significantly from the generic Jones configuration. The MAARSY radar could not resolve arbitrary DOAs sufficiently well enough to determine a stable region. However, if the DOA search is restricted to 70∘ elevation or above by assumption, stable DOA determination occurs above 15 dB SNR.

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Más fuentes

Tesis sobre el tema "Echos radar"

Luce, Hubert. "Interpretation des echos radar st vhf a l'aide de mesures a haute resolution de la temperature". Toulon, 1996. http://www.theses.fr/1996TOUL0004.

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L'origine du renforcement des echos radar vhf (30-300 mhz) st (stratosphere-troposphere) en incidence verticale par rapport a l'oblique est toujours sujet a controverses. En effet, plusieurs mecanismes ont ete proposes tels que la reflexion partielle sur des couches stables horizontalement stratifiees ou la diffusion par la turbulence anisotrope. La campagne rasci-ba90 (aire sur l'adour, france, 1990) realisee conjointement par le laboratoire de sondages electromagnetiques de l'environnement terrestre (l. S. E. E. T), le service d'aeronomie du c. N. R. S de verrieres le buisson et le departement d'astrophysique de nice (u. N. S. A) a permis de reunir des donnees ballon complementaires a celles des radars vhf provence 45 mhz et insu meteo 72. 5 mhz. Les mesures de temperature a haute resolution verticale (20 cm) ont revele la presence de feuillets, gradients positifs intenses de temperature confines sur de faibles epaisseurs (quelques metres) jusque dans la stratosphere moyenne (27 km au moins) et coexistant avec des fluctuations turbulentes aux memes echelles. Il est montre, d'une part, que le modele de reflexion partielle applique a ces feuillets de temperature est suffisant pour reproduire l'essentiel des caracteristiques des echos en incidence verticale et, d'autre part, que le modele de diffusion par la turbulence isotrope est satisfaisant pour reproduire les profils de puissance recue en incidence oblique (15 du zenith). Bien que la validation des modeles passe par une description encore plus complete des structures atmospheriques aux petites echelles, ces etudes ont apporte des resultats decisifs sur l'interpretation des echos radar vhf

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LE, HELLARD DANIEL. "Modelisation des echos de sol radar en eclairement rasant, de 1 ghz a 10 ghz, a partir d'un modele numerique de terrain". Rennes 1, 1997. http://www.theses.fr/1997REN10025.

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Cette these est consacree a la modelisation et la simulation du fouillis de sol en eclairement rasant, dans les bandes de frequence l (1 ghz) a x (10 ghz). Apres une synthese des modeles de fouillis existants, nous procedons a l'analyse de mesures de fouillis de sol. Cette analyse montre que, en eclairement rasant, les echos de fouillis proviennent principalement du sursol. Nous developpons ensuite un modele de fouillis de sol base sur une distribution verticale de reflecteurs elementaires. Ce modele est mis en uvre dans un logiciel de generation de cartes de reflectivite de fouillis de sol a partir d'un modele numerique de terrain. L'analyse des parametres statistiques de la reflectivite simulee et la correlation de cartes d'echos simules avec les cartes de fouillis enregistrees par un radar nous permettent de valider le modele propose.

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Belhadj, Zied. "Apport de la polarisation multifréquence pour la classification en télédétection radar". Nantes, 1995. http://www.theses.fr/1995NANT2056.

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Le but du travail réalisé dans cette thèse est l'étude des informations acquises par un capteur polarimétrique multifréquence. L'objectif vise d'une part la modélisation statistique d'échos radar et d'autre part la discrimination et la classification polarimétrique multifréquence. La distinction fine entre les couverts à divers stades de croissance illustre l'apport spécifique de la polarimétrie multifréquence. Des images multipolarisées, multifréquences acquises en 1989 par le système ROS de la Nasa/JPL concernant la forêt des Landes ont été exploitées dans laquelle les diverses sections différent par leurs paramètres intrinsèques (biomasse, hauteur, âge, densité,). La modélisation polarimétrique d'échos radar consiste à trouver les lois de distribution décrivant au mieux les amplitudes absolues, les rapports d'amplitude et les différences de phase. La distribution K s'est révélée être la mieux adaptée pour décrire les amplitudes absolues des données aussi bien monovues que multivues. La méthode dite Bootstrap minimisant, voire éliminant l'interdépendance des données, a été introduite afin d'améliorer la confiance du test d'adéquation confirmant le choix de la distribution K. Un nouveau discriminateur fréquentiel, issu de la distribution k et étroitement lié à l'hétérogénéité du couvert, a été développé. La non symétrie azimutale, classiquement négligée, a été mise en évidence par une représentation équi-amplitude des signatures polarimétriques. L'algorithme de classification de Van Zyl et celui de décomposition de Freeman ont été exploités pour classifier les terrains. De plus, un algorithme de classification de pixels vérifiant la non symétrie azimutale a été développé permettant d'introduire une nouvelle classe la non symétrie azimutale pour une interprétation plus réaliste des terrains. Une extension des algorithmes de Novak concernant la réduction du speckle, a été proposée et appliquée sur des données réelles et sur des données synthétisées, en utilisant la propriété de non symétrie azimutale. Le travail de thèse réalisé représente une contribution non seulement à l'évaluation de l'apport de la polarimétrie multifréquence, mais aussi au développement des méthodes d'analyse et de traitement de données en télédétection radar.

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NAKAMURA, Kenji, Shinsuke SATOH, Fumie A. FURUZAWA y Haruya MINDA. "Bird Migration Echoes Observed by Polarimetric Radar". Institute of Electronics, Information and Communication Engineers, 2008. http://hdl.handle.net/2237/15008.

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Dorfman, Seth E. "Intense spreading of radar echoes from ionospheric plasmas". Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/32897.

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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, 2005.
Includes bibliographical references (leaf 41).
On December 25, 2004, a large-scale ionospheric plasma bubble was observed over Arecibo Observatory in Puerto Rico, inducing significant range spreading on ionograms. This phenomena may be explained by means of the E x B instability and gravitational Rayleigh-Taylor instability. A derivation of the dispersion relations for X and O mode waves transmitted from an ionosonde and an analysis of the collisional Rayleigh-Taylor instability leading to an expression for the growth rate are presented as background information. Ray tracing code developed by Nathan Dalrymple, a previous graduate student of Professor Min-Chang Lee, is extended, first to draw refractive index surfaces to illustrate a key principle in ray tracing and later to simulate range spreading due to depleted ionospheric ducts [1]. Data from Arecibo incoherent scatter radar and Arecibo's CADI digisonde is examined showing strong evidence for the development of a plasma bubble following a rise in the plasma layer and the appearance of a horizontal density gradient. In one portion of the ionosphere, this gradient is found to be at an angle of approximately 70 degrees to the Earth's magnetic field, a favorable condition for the excitation of the Rayleigh-Taylor instability over Arecibo.
by Seth E. Dorfman.
S.B.

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Vásquez, Rubén Dario Léon. "Processador da razão de verossimilhança aplicado a sinais de radar". Instituto Tecnológico de Aeronáutica, 1992. http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=1812.

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A deteção de um alvo em radar com processadores da razão de verossimilhança é analisada. Duas teorias {Haykin-Metford e Farina-Russo-Scannapieco} para a determinação do logaritmo da razão de verossimilhança, são analisadas e comparadas. É mostrado teoricamente e através de simulações que a teoria de Farina et.alli. é um caso particular da de Haykin-Metford quando os processos "clutter" e Sinal Alvo são gaussianos coloridos. Quando esses processos possuem funções densidade de probabilidade diferentes da gaussiana, é mostrado que a teoria de Haykin é mais geral que a de Farina et. alli. Considerando ainda os processos "clutter" e Sinal Alvo gaussianos, é proposta uma aproximação para a determinação do chamado processo de inovações. Mostra-se que a nova estrutura apresenta pequenas perdas relativas ao ótimo mas com custo computacional menor. No caso em que o Sinal Alvo é conhecido a-priori e o "cIutter" é um processo Weibull com parâmetro de forma conhecido, é proposta uma estrutura com predição linear. Mostra-se que esta nova estrutura apresenta pequenas perdas relativasàquela com predição homomórfica, mas com custo computacional menor, além de não ser necessário o conhecimento do parâmetro de forma do "clutter" Weibull. Ainda para esse caso, é também proposto um processador que utiliza as idéias básicas dos processadores CF AR. Mostra-se que este processador apresenta um melhor desempenho que os anteriores. Finalmente, uma forma de se determinar as chamadas variâncias das inovações é proposta e testada com sucesso utilizando dados reais de radar.

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Dean, Timothy J. Physical Environmental &amp Mathematical Sciences Australian Defence Force Academy UNSW. "Development and evaluation of automated radar systems for monitoring and characterising echoes from insect targets". Awarded by:University of New South Wales - Australian Defence Force Academy. School of Physical, Environmental and Mathematical Sciences, 2007. http://handle.unsw.edu.au/1959.4/38667.

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This thesis describes the construction of a mobile Insect Monitoring Radars (IMR) and investigations of: the reliability of IMRs for observing insect migration in inland Australia; possible biases in IMR migration estimates; the relation between an insect???s size and its radar properties; radar discrimination between insect species; the effect of weather on the migrations of Australian plague locusts and of moths; the scale of these migrations; and here IMRs are best located. The principles of entomological radar design, and the main features of insect migration in inland Australia, are reviewed. The main procedures used in the study are: calculation of radar performance and of insect radar cross sections (RCSs); reanalysis of a laboratory RCS dataset; statistical analysis of a fouryear dataset of IMR and weather observations; and a field campaign using both two existing fixed IMRs and the new mobile unit. Statistical techniques used include correlation, multiple regression, discriminant analysis, and principal components analysis. The original results of this work include design details of the mobile IMR, extension of radar performance calculations to IMRs and evaluation of flight speed biases, a holistic approach to IMR design, the relation of insect RCS magnitudes and polarization patterns to morphological variables, an estimate of the accuracy of the retrieved parameters, evaluations of three approaches (oneparameter, theory-based, and a novel two-stage method) to target identification, and verification of inferred target identities using results from nearby light traps. Possible sites for future IMRs are identified. The major conclusions are that: a mobile IMR can be built with a performance equal to that of a fixed IMR but at half the cost; significant biases in the signal processing results arise from insect speed; locusts and moths can be distinguished if all RCS parameters are used; IMRs can be designed to match particular requirements; weather has a significant effect on insect migration, the best single predictor of insect numbers being temperature; moonlight has no effect; the spatial correlation of migration properties falls to 50% at a separation of 300 km; and migrating insects can be carried by the wind for 500 km in a single night

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Duncan, Mike R. (Mike Ross). "The universal multifractal nature of radar echo fluctuations". Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41364.

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The intensity returns obtained by a radar from precipitation are well known to fluctuate violently in space and time. We present a systematic study of the resolution dependence time series with overlapping time resolutions spanning 10 orders of magnitude (0.77 ms to 4 months), of the fluctuating radar echo from precipitation. The results undermine the current assumptions of homogeneity of rainfield at scales smaller than the radar resolution, due to Marshall and Hitschfeld (1953), by showing that the only length scales identifiable in the time series are those of the radar pulse volume, the wavelength, and a very small inner scale of the order of millimeters. An analysis of the multiscaling nature of the time series of echo fluctuations reveals multiscaling behaviour at scales down to the resolution or pulse volume scale. Since there are no a priori scales in the rainfield we proceed to model the fluctuating radar echo by assuming a multiscaling model of rainfield variability which extends to sub-resolution scales. A systematic analysis of the statistical behaviour of computed reflectivities from this variability gives a full statistical description of reflectivity originating from multiscaling variability, and solves the scalar multifractal radar observer's problem. Computation of time series of reflectivities from a time-space representation of this variability reveals quantitative and qualitative behaviours consistent with those of observed echo fluctuation time series. We conclude that a multiscaling model of the rainfield which extends to the smallest scales of the rainfield is consistent with observation.

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Nordström, Per. "Anomalous Meteor Head Echoes Detected by the MU Radar". Thesis, Luleå tekniska universitet, Rymdteknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-79101.

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This study have identified and analysed anomalous meteor head echos detected by the MU Radar, as well as reproduced an interference anomaly through simulation with the use of an existing analysis pipeline. The parameters used to detect anomalies were High Start Altitude [HSAA], High Radar Cross Section [HRCSA] and High Eccentricity [HEA]. A cut-off of the head echo signal were the cause of the HSAA’s. Trail echos misclassified as head echoes and low agreement with the multiple emitter location and signal parameter estimation (MUSIC) method gave rise to the HRCSA’s. The majority of the HEA’s were given a falsely high eccentric- ity due to high beam angle and trail echos detection. Three found HEA’s showed a small possibility of having an hyperbolic orbit. Additionally, a simulation was made which concluded that signal interference will occur between two echos if the range is the same to the radar.

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Georgiev, Krasin. "Biologically inspired processing of radar and sonar target echoes". Thesis, Cranfield University, 2017. http://dspace.lib.cranfield.ac.uk/handle/1826/12692.

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Modern radar and sonar systems rely on active sensing to accomplish a variety of tasks, including detection and classification of targets, accurate localization and tracking, autonomous navigation and collision avoidance. Bats have relied on active sensing for over 50 million years and their echolocation system provides remarkable perceptual and navigational performance that are of envy to synthetic systems. The aim of this study is to investigate the mechanisms bats use to process echo acoustic signals and investigate if there are lessons that can be learned and ultimately applied to radar systems. The basic principles of the bat auditory system processing are studied and applied to radio frequencies. A baseband derivative of the Spectrogram Correlation and Transformation (SCAT) model of the bat auditory system, called Baseband SCAT (BSCT), has been developed. The BSCT receiver is designed for processing radio-frequency signals and to allow an analytical treatment of the expected performance. Simulations and experiments have been carried out to confirm that the outputs of interest of both models are “equivalent”. The response of the BSCT to two closely spaced targets is studied and it is shown that the problem of measuring the relative distance between two targets is converted to a problem of measuring the range to a single target. Nearly double improvement in the resolution between two close scatterers is achieved with respect to the matched filter. The robustness of the algorithm has been demonstrated through laboratory measurements using ultrasound and radio frequencies (RF). Pairs of spheres, flat plates and vertical rods were used as targets to represent two main reflectors.

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Más fuentes

Libros sobre el tema "Echos radar"

Echo signal processing. Boston: Kluwer Academic Publishers, 2003.

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Bernard, Lovell. Echoes of war: The story of H2S radar. Bristol: Adam Hilger, 1991.

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Ricker, Dennis W. Echo Signal Processing. Boston, MA: Springer US, 2003.

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Echoes of war: The story of H S radar. Bristol, England: Hilger, 1991.

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Brown, C. S. Bed topography inferred from airborne radio-echo sounding of Columbia Glacier, Alaska. Washington: U.S. G.P.O., 1986.

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Macheret, I︠U︡ I︠A︡. Radiozondirovanie lednikov. Moskva: Nauchnyĭ mir, 2006.

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Macheret, I︠U︡ I︠A︡. Radiozondirovanie lednikov. Moskva: Nauchnyĭ mir, 2006.

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Simmonds, Ed. Echoes over the Pacific: An overview of allied air warning radar in the Pacific, from Pearl Harbor to the Philippines campaign. Banora Point, NSW: E.W. & E. Simmonds, 1995.

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Ber, Lovell Sir. Echoes of War: The Story of H2S Radar. Taylor & Francis, 1991.

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Ensco, inc. Applied Meteorology Unit. y United States. National Aeronautics and Space Administration. Scientific and Technical Information Program., eds. Report on the radar/PIREP cloud top discrepancy study: Under contract NAS10-96108. [Washington, D.C.]: National Aeronautics and Space Administration, Office of Management, Scientific and Technical Information Program, 1997.

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Capítulos de libros sobre el tema "Echos radar"

Ludloff, Albrecht. "Entdeckung konstanter und fluktuierender Echos im Rauschen". En Handbuch Radar und Radarsignalverarbeitung, 55–94. Wiesbaden: Vieweg+Teubner Verlag, 1993. http://dx.doi.org/10.1007/978-3-322-96329-1_3.

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Ludloff, Albrecht. "Entdeckung konstanter und fluktuierender Echos im Rauschen". En Praxiswissen Radar und Radarsignalverarbeitung, 55–94. Wiesbaden: Vieweg+Teubner Verlag, 1998. http://dx.doi.org/10.1007/978-3-663-12325-5_3.

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Ludloff, Albrecht. "Entdeckung konstanter und fluktuierender Echos im Rauschen". En Praxiswissen Radar und Radarsignalverarbeitung, 55–94. Wiesbaden: Vieweg+Teubner Verlag, 2002. http://dx.doi.org/10.1007/978-3-322-99555-1_3.

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Weik, Martin H. "radar echo". En Computer Science and Communications Dictionary, 1393. Boston, MA: Springer US, 2000. http://dx.doi.org/10.1007/1-4020-0613-6_15289.

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Wilcox, Calvin H. "Sonar and Radar Echo Structure". En Radar and Sonar, 169–228. New York, NY: Springer New York, 1991. http://dx.doi.org/10.1007/978-1-4684-7100-7_3.

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Ryzhkov, Alexander V. y Dusan S. Zrnic. "Polarimetric Classification of Radar Echo". En Springer Atmospheric Sciences, 309–72. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-05093-1_9.

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Ricker, Robert, Stefan Hendricks, Veit Helm y Rüdiger Gerdes. "Classification of CryoSat-2 Radar Echoes". En Towards an Interdisciplinary Approach in Earth System Science, 149–58. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-13865-7_17.

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Goddard, D. M. y B. J. Conway. "Experiments to reveal regions of frequent spurious radar echoes in COST-73 composites". En International Weather Radar Networking, 191–96. Dordrecht: Springer Netherlands, 1992. http://dx.doi.org/10.1007/978-94-011-2404-1_30.

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Sun, Zhaoping, Can Lai, Xia Chen y Haijiang Wang. "The Radar Echo Extrapolation Based on ConvLSTM". En Lecture Notes in Electrical Engineering, 1903–10. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-15-8411-4_250.

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Sodeikat, Ch. "Practical Applications of Ultrasonic-Echo and Impulse Radar". En Nondestructive Testing of Materials and Structures, 811–17. Dordrecht: Springer Netherlands, 2011. http://dx.doi.org/10.1007/978-94-007-0723-8_116.

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Actas de conferencias sobre el tema "Echos radar"

Xiaofeng, Zhao, Huang Sixun y Sheng Zheng. "Refractivity Estimation from Radar Sea Echos". En 2009 Second International Conference on Information and Computing Science. IEEE, 2009. http://dx.doi.org/10.1109/icic.2009.290.

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Mahesh, V. S., K. Senthilkumaran y P. C. Jha. "3D Digitization of Sub Surface Features Using 3D GPR". En ASME 2011 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/detc2011-48044.

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Ground Penetrating Radars (GPR) finds its applications in civil engineering, archeology, earth sciences, military and environmental studies. This paper proposes a framework for using GPR as a digitizing technique that can make 3D digitization/measurement of the buried objects. Currently, the 3D radar volume data is acquired by dense subset of parallel 2D radar profiles. However, it results in a very large amount data and related processing time, and needs to be avoided due to the significant computer resources and processing time required to process the data. In order to achieve simplified and faster processing as well as to reduce memory requirements, it is often useful to convert the original image data to a more compact representation. The conversion removes as much of the redundant information as possible. Then the data is processed by removing noise initially and then eliminating undesired presence of ground surface echo. Further, propagation losses are compensated followed by segmentation and skeletonizing. However the accuracy of the 3D measurement depends upon number of parameters such as antenna design, scan paths, scan spacing and frequency which needs to be evaluated in detail. The framework presented in this paper would help to measure the buried objects accurately using 3D GPR.

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Misiurewicz, J. "Analysis of recorded helicopter echo". En Radar Systems (RADAR 97). IEE, 1997. http://dx.doi.org/10.1049/cp:19971715.

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Vetrov, V. I. "On possibility of radar angel-echoes study with Sodar and RASS techniques". En Radar Systems (RADAR 97). IEE, 1997. http://dx.doi.org/10.1049/cp:19971629.

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Zhang, Shunsheng y Juan Chen. "A echo simulation algorithm for natural scene". En 2008 International Conference on Radar (Radar 2008). IEEE, 2008. http://dx.doi.org/10.1109/radar.2008.4653968.

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Tanski, Grzegorz. "Software radar echo synthesizer". En SPIE Proceedings, editado por Ryszard S. Romaniuk. SPIE, 2004. http://dx.doi.org/10.1117/12.569047.

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Lin Wang, Wanjie Song y Zijing Zhang. "Impulse fuse echo recovery using compressive sensing". En IET International Conference on Radar Systems (Radar 2012). Institution of Engineering and Technology, 2012. http://dx.doi.org/10.1049/cp.2012.1733.

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Chen, Juan, Dazhi Zeng y Teng Long. "High precision radar echo modelling and simulation method". En 2008 International Conference on Radar (Radar 2008). IEEE, 2008. http://dx.doi.org/10.1109/radar.2008.4653969.

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Mathews, J. D. "Conjuring Radar Meteor Head-Echoes". En 2018 2nd URSI Atlantic Radio Science Meeting (AT-RASC). IEEE, 2018. http://dx.doi.org/10.23919/ursi-at-rasc.2018.8471509.

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Abdullah, R. S. A. Raja, N. L. Saleh, S. M. S. Ahmad, Asem A. Salah y N. E. Abdul Rashid. "Detection of Human Echo Locator Waveform Using Gammatone Filter Processing". En 2018 International Conference on Radar (RADAR). IEEE, 2018. http://dx.doi.org/10.1109/radar.2018.8557342.

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Informes sobre el tema "Echos radar"

Kohn, David. Echoes, April 1997, Number 18. Radar Program,. Fort Belvoir, VA: Defense Technical Information Center, abril de 1997. http://dx.doi.org/10.21236/ada325397.

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Doerry, Armin. Digital Signal Processing of Radar Pulse Echoes. Office of Scientific and Technical Information (OSTI), septiembre de 2020. http://dx.doi.org/10.2172/1663260.

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Borden, Brett y R. J. Dinger. Radar Inverse Scattering Using Statistical Estimation of the Echo Phase- Front Derivatives. Fort Belvoir, VA: Defense Technical Information Center, noviembre de 1986. http://dx.doi.org/10.21236/ada176598.

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Skolnik, Merrill I. Radar Information from the Partial Derivatives of the Echo Signal Phase from a Point Scatterer. Fort Belvoir, VA: Defense Technical Information Center, febrero de 1988. http://dx.doi.org/10.21236/ada193402.

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Nishitani, Nozomu, Mark Lester, Steve E. Milan, Tadahiko Ogawa y Natsuo Sato. Unusual Ionospheric Echoes with Velocity and Very Low Special Width Observed by the SuperDARN Radars in the Polar Cap During High Geomagnetic Activity. Fort Belvoir, VA: Defense Technical Information Center, febrero de 2004. http://dx.doi.org/10.21236/ada425045.

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