Th. doct.-ing.--Géophys. et sci. spatiales--Toulouse 3, 1982. N°: 791.

Modern military acquisition and tracking RADARs are required to operate against aircraft and missiles specifically designed to have minimal radar cross section (RCS) and which fly at very low level to take maximum advantage of terrain screening. A model for predicting system performance is necessary for a range of terrain types in varying precipitation and seasonal cultural conditions. While the main degradation is from surface clutter and denial of sightline due to terrain and other local obstructions, several other factors such as multipath propagation, deliberate jamming and even operator performance contribute to the total model. The possibility that some radars may track obscured targets, however briefly, by using the diffraction path, is of particular interest. Although this report critically examines each of the contributory factors in order to select optimum values for inclusion in an overall computer prediction model; a new surface clutter model is specifically developed for sloped terrain using actual clutter measurements. The model is validated by comparison with an extensive survey of worldwide clutter results from both published and unpublished sources. Certain constraints have been necessary to restrict the study to a manageable size, while meeting the requirements of the sponsors. Attention is therefore focussed upon performance prediction for typical mobile tracking radar systems designed for operation against small RCS low level targets flying overland.

Dans le cadre de la détection radar en environnement gaussien comme non-gaussien, de nombreux détecteurs ont été développés en se basant sur des modèles de fouillis précis et des estimateurs de matrices adaptés à ces modèles. Les modèles gaussiens, simples d’utilisation, montrent rapidement leurs limites face à la réalité physique et laissent ainsi place aux SIRP, processus aléatoires sphériquement invariants qui rendent compte beaucoup plus fidèlement de la non-gaussianité du fouillis. Les détecteurs adaptés à ces environnements sont alors construits sur la base d’un estimateur de la matrice de covariance adapté. Or, dans de nombreuses applications, cette matrice de covariance présente une structure particulière dite persymétrique. L’objet de cette thèse est donc d’exploiter cette structure particulière de la matrice de covariance du fouillis afin d’en diminuer l’erreur d’estimation. Par cette exploitation, deux nouveaux estimateurs de la matrice ont été déterminés pour les environnements gaussiens et non-gaussiens. Ces détecteurs nommés PAMF et GLRT-PFP, ont été caractérisés statistiquement et une validation des travaux théoriques a été menée sur des données opérationnelles tant gaussiennes que non-gaussiennes. Une application de la persymétrie a également été effectuée dans le cadre des algorithmes spatio-temporels (STAP) ainsi que sur des algorithmes dits "à rang réduit". Les résultats probants en détection obtenus sur tous ces types de données confirment donc l’intérêt de la technique étudiée. Enfin, un élargissement de la structure persymétrique a été étudié par l’extension des détecteurs aux matrices dites de Toeplitz. Ces matrices obtenues dans le cas de traitements spatio-temporels présentent une structuration plus riche encore que la persymétrie et permettent d’envisager des développements futurs intéressants en vue de l’amélioration des performances des détecteurs. Les premiers résultats sont présentés pour conclure ce travail de thèse. / This thesis deals with Radar detection in Gaussian and non-Gaussian noise. In this context, the clutter covariance matrix commonly exhibits a particular persymmetric structure. This structure is exploited into a particular matrix transformation to provide two new covariance matrices estimates for Gaussian and non-gaussian noise. We use then this particular linear transformation in order to develop and to study the statistical property of the two new detectors based on these estimates for both Gaussian and non-Gaussian environments. The improvement in terms of detection performances of these new detectors is shown through a lots of simulations and validation on operational data, for both Gaussian and non- Gaussian noise. Moreover this exploitation is extended to space-time adaptive processing and reduced rank technical. All the results confirm then the high interest of taking into account this particular structure in radar detection process compared to classical detection schemes. The case of Toeplitz matrices is also studied. The Toeplitz matrices are a particular class of structured matrices obtain with space-time processing which theoretically allows to improve the performance of detectors based on this matrix assumption. In this context, some preliminary results are presented in order to conclude this thesis.

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Tese (doutorado)—Universidade de Brasília, Programa de Pós-Graduação em Geociências Aplicada. 2012. / Submitted by Jaqueline Ferreira de Souza (jaquefs.braz@gmail.com) on 2012-06-19T12:23:43Z No. of bitstreams: 1 2012_NiloSergiodeOliveiraAndrade.pdf: 7929994 bytes, checksum: af5ba1ebf0007444df194577d780d741 (MD5) / Approved for entry into archive by Jaqueline Ferreira de Souza(jaquefs.braz@gmail.com) on 2012-06-19T12:24:11Z (GMT) No. of bitstreams: 1 2012_NiloSergiodeOliveiraAndrade.pdf: 7929994 bytes, checksum: af5ba1ebf0007444df194577d780d741 (MD5) / Made available in DSpace on 2012-06-19T12:24:11Z (GMT). No. of bitstreams: 1 2012_NiloSergiodeOliveiraAndrade.pdf: 7929994 bytes, checksum: af5ba1ebf0007444df194577d780d741 (MD5) / A extração de informações a partir de imagens de radares de abertura sintética (SAR) tem sido uma promissora área de pesquisa por muitos anos. A fim de obter resultados confiáveis medidas de parâmetros múltiplos são, geralmente, necessárias. Dados multi-temporais, multi-freqüência e multi-polarizados têm sido sugeridos e utilizados para as aplicações de Sensoriamento Remoto. Enquanto os métodos que se utilizam de dados multi-temporais e de multi-freqüência são amplamente utilizados e razoavelmente bem documentados, o uso da polarimetria SAR é uma abordagem relativamente nova que conduz a algumas vantagens quando comparada às metodologias convencionais. Isto se deve ao fato de se gerar diretamente a partir dos dados brutos os atributos necessários para síntese de imagens em amplitude e fase. As características destas imagens é a possibilidade, por exemplo, de sua utilização em classificadores voltados à seleção de alvos. Este estudo contribui para um melhor entendimento da teoria de dados polarimétricos de Radar e para o desenvolvimento de um software piloto para síntese, processamento e classificação das imagens em linguagem de alto nível, em ambiente IDL, utilizando-se de dados brutos coletados com o sensor SAR da aeronave R99. _______________________________________________________________________________________ ABSTRACT / The extraction of information from Synthetic Aperture Radar (SAR) data has been a promising area of research for many years. In order to achieve reliable results, multi parameter measurements are generally necessary. Multi-temporal, multi-frequency and multi-polarization data have been suggested and used for remote sensing applications. While multi-temporal and multi-frequency approaches are widely used and fairly well documented, SAR polarimetry is a relatively new approach, which yields some advantages over the conventional methods due the fact that the raw data can be used to generate the necessary attributes for image synthesis in amplitude; and phase. From these new images raise the possibility to use their peculiar charactheristcs into target classifiers. This study contributes to a better understanding of the theory of Radar polarimetric data, as well as to the development of a pilot software for synthesis, processing and classification of images in a high-level language using IDL environment, by utilizing raw data collected by the SAR sensor installed on R99 aircrafts.

Dissertação (mestrado)—Universidade de Brasília, Instituto de Geociências, 2009. / Submitted by Allan Wanick Motta (allan_wanick@hotmail.com) on 2010-03-15T17:37:18Z No. of bitstreams: 1 2009_ElaineMarradosSantos.pdf: 5054960 bytes, checksum: 05b807c07bfb99f6249d1d65c615ab4b (MD5) / Approved for entry into archive by Carolina Campos(carolinacamposmaia@gmail.com) on 2010-04-09T14:11:07Z (GMT) No. of bitstreams: 1 2009_ElaineMarradosSantos.pdf: 5054960 bytes, checksum: 05b807c07bfb99f6249d1d65c615ab4b (MD5) / Made available in DSpace on 2010-04-09T14:11:07Z (GMT). No. of bitstreams: 1 2009_ElaineMarradosSantos.pdf: 5054960 bytes, checksum: 05b807c07bfb99f6249d1d65c615ab4b (MD5) Previous issue date: 2009 / Mapas de cobertura de terras são importantes fontes de dados para monitoramentos ambientais, preservação da biodiversidade, zoneamentos sócio-econômico e ambiental e monitoramento de mudanças climáticas locais e globais, dentre outras atividades. No Distrito Federal (DF), os mapeamentos de cobertura de terras têm sido realizados com base em imagens ópticas. No entanto, imagens de radar constituem-se em uma alternativa viável às imagens ópticas, pois independem das condições de iluminação solar, podem atravessar nuvens e fumaças e podem detectar diferenças nas estruturas da vegetação. O objetivo deste estudo é analisar o potencial das imagens de radar adquiridas pelo satélite ALOS PALSAR para o mapeamento de cobertura de terras. Uma imagem de 25 de abril de 2007 (banda L, polarizações HH, HV e VV, final da estação chuvosa) de parte do DF foi convertida para coeficientes de retroespalhamento (s°) e processada por meio da técnica de segmentação por crescimento de regiões. Valores de s° foram analisados estatisticamente por meio de cluster analysis. Os segmentos foram convertidos para o formato shape e mapeados visualmente na tela do monitor de computador, com suporte de um pacote de programas de sistema de informações geográficas, em uma escala de mapeamento compatível com 1:100.000. As seguintes classes temáticas foram consideradas: Áreas Urbanas consolidadas, Áreas Urbanas em consolidação, Culturas Agrícolas, Pastagens Cultivadas, Reflorestamento, Campos, Cerrado Típico, Matas de Galeria, Matas Indiscriminadas e Reservatórios. A exatidão de mapeamento, fornecido pelo índice kappa e calculado a partir da verificação de 86 pontos em campo, foi de 0,69. _______________________________________________________________________________ ABSTRACT / Land cover maps are important source of data for environmental monitoring, biodiversity conservation, social, economic and environmental zonning, and local and global climatic changes, among other activities. In the Federal District of Brazil (FD), land cover mappings have been obtained from optical images. However, radar data are valuable alternative for the optical remote sensing since they are independent of solar illumination, can penetrate clouds and smokes and can depict differences in canopy structures. The goal of this study is to analyze the potential of ALOS PALSAR radar data for land cover mapping. A scene covering part of FD, obtained in April 25th, 2007 (L-band, HH, HV and VV polarizations, end of wet season) was converted into backscattering coefficients (s°) and processed through the image segmentation technique by growing region. Values of s° were analyzed with the support of cluster analysis. The segments were converted into shape format and mapped visually in the computer screen using a geographical information system software package, in a 1:100,000 mapping scale. The following thematic classes were considered: consolidated urban areas, urban areas in consolidation, croplands, planted pasturelands, reforestations, grasslands, shrub Cerrado, gallery forests, indiscriminated forests and reservoirs. The accuracy of the final map, provided by the kappa index and obtained from 86 field checking points, was 0.69.

Orientador : Helio Waldman / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Campinas / Made available in DSpace on 2018-07-14T02:58:25Z (GMT). No. of bitstreams: 1 Almeida_Celsode_M.pdf: 2422052 bytes, checksum: 8576b360b41a32d3dbd0205fa777acee (MD5) Previous issue date: 1983 / Resumo: Não informado / Abstract: Not informed / Mestrado / Mestre em Ciências

A detailed understanding of the relationship between altimetry measurement, especially significant wave height (SWH) measurement, and phase distortion is still unclear. Therefore, the objective of this Ph.D. study is first to outline this relationship by a simulation using a model that considers the errors from both the signal source and the power amplifier. The simulation results show the power amplifier influence is more significant than that of signal source in SWH estimation, and that the phase errors influence is worse for lower SWH conditions. It is recommended from the simulation that the group delay error of the whole transmitter link, after the chirp generator, should be well controlled to be under 0.5ns. In the payload design, Class-F is chosen as the amplifier operation mode due to its high efficiency and fewer harmonic frequency components. The difference between the operational principles of second and third harmonic peaking Class-F amplifiers have been illustrated by the simulation. Both of them can achieve high efficiency and high gain, however the third harmonic peaking Class-F is simpler to implement. Therefore it was chosen by the final design. In the simulation, a large signal STATZ model is set up, followed by the S-band Class-F amplifier design simulation and the implementation of third harmonic peaking Class-F amplifier. Based on this, an adaptive feedback group delay equalizer is proposed as a solution for the phase error compensation within the whole chirp signal swept bandwidth. A very simple but effective phase error detection and calculation circuit is designed, built and measured. The test branch results are very satisfying. Its small size and lower power consumption makes it very suitable for a compact microsatellite environment. In summary, the possibility of a medium resolution microsatellite borne radar altimeter for optimising shipping routes is investigated in this study. A 12 satellites constellation is proposed for achieving near real time altimetry broadcasting. The key payload design problems are identified in a thorough feasibility study: the restriction corresponding to these main problems is quantified via the SWH estimation simulation. A feedback linearization method is proposed as a promising solution for the compact microsatellite design with high power efficiency requirements, demonstrated by both simulation and hardware implementation results.

Dissertation submitted in fulfillment of the requirements for the Master's Diploma in Technology: Maritime Studies, Technikon Natal, 1999. / This study was intended to develop suitable software to emulate Marine Radar and other Electronic Navigation Systems found on Merchant,vessels. This equipment includes Radar with or without Automatic Radar Plotting facilities, Navstar Global Positioning Systems, Echo Sounders, Radio Direction Finder as well as Decca Navigator. Certain of these aids are required in the Radar Simulator Specifications [ref 1] to which the SAMSA - South African Maritime Safety Authority (formerly the South African Department of Transport) adheres. SAMSA is the authority which approves Maritime training and Simulators in South Africa in compliance with International standards as laid down by, IMO - International Maritime Organisation. / M