When simulating target seekers, there is a great need for computationally efficient, target models. This report considers a study of radar target modelling based on Inverse Synthetic Aperture Radar (ISAR) measurements of generic aircraft. The results underlie future modelling of full-size air targets. A method is developed for two-dimensional modelling of aspect-dependent target scattering. The approach taken is to generate point-scatterer models of two targets, where each point scatterer is defined according to its position and radar cross section (RCS), estimated from ISAR images. The scattered energy contributions from all point scatterers are summed to simulate a radar return signal. To validate the models, the modelled radar target centre is compared to the true radar target centre, which is determined from ISAR images. The method is presented to be promising for modelling air targets with large, persistent radar cross section.

By analyzing ISAR images, the characteristics of military platforms with respect to radar visibility can be evaluated. The method, which is based on the Discrete-Time Fourier Transform (DTFT), that is currently used to calculate the ISAR images requires large computations efforts. This thesis investigates the possibility to replace the DTFT with the Fast Fourier Transform (FFT). Such a replacement is not trivial since the DTFT is able to compute a contribution anywhere along the spatial axis while the FFT delivers output data at fixed sampling, which requires subsequent interpolation. The interpolation leads to a difference in the ISAR image compared to the ISAR image obtained by DTFT. On the other hand, the FFT is much faster. In this quality-and-time trade-off, the objective is to minimize the error while keeping high computational efficiency. The FFT-approach is evaluated by studying execution time and image error when generating ISAR images for an aircraft model in a controlled environment. The FFT method shows good results. The execution speed is increased significantly without any visible differences in the ISAR images. The speed-up- factor depends on different parameters: image size, degree of zero-padding when calculating the FFT and the number of frequencies in the input data.

A Bussgang based blind deconvolution algorithm called self-correcting multi-channel Bussgang (SCMB) blind deconvolution algorithm was proposed. Unlike the original Bussgang blind deconvolution algorithm where the probability density function (pdf) of the signal being recovered is assumed to be completely known, the proposed SCMB blind deconvolution algorithm relaxes this restriction by parameterized the pdf with a Gaussian mixture model and expectation maximization (EM) algorithm, an iterative maximum likelihood approach, is employed to estimate the parameter side by side with the estimation of the equalization filters of the original Bussgang blind deconvolution algorithm. A feedback loop is also designed to compensate the effect of the parameter estimation error on the estimation of the equalization filters. Application of the SCMB blind deconvolution framework for binary image restoration, multi-pass synthetic aperture radar (SAR) autofocus and inverse synthetic aperture radar (ISAR) autofocus are exploited with great results.

<p>When simulating target seekers, there is a great need for computationally efficient, target models. This report considers a study of radar target modelling based on Inverse Synthetic Aperture Radar (ISAR) measurements of generic aircraft. The results underlie future modelling of full-size air targets. </p><p>A method is developed for two-dimensional modelling of aspect-dependent target scattering. The approach taken is to generate point-scatterer models of two targets, where each point scatterer is defined according to its position and radar cross section (RCS), estimated from ISAR images. The scattered energy contributions from all point scatterers are summed to simulate a radar return signal. To validate the models, the modelled radar target centre is compared to the true radar target centre, which is determined from ISAR images. </p><p>The method is presented to be promising for modelling air targets with large, persistent radar cross section.</p>

Diss.--Juristische Fakultät--Universität Regensburg, 2000. / Bibliogr. p. 206-223.

Synthetic aperture radar (SAR) is an imaging technique based on the radio reflectivity of the target being imaged. SAR instruments offer many advantages over optical imaging due to the ability to form coherent images in inclement weather, at night, and through ground cover. High resolution is achieved in azimuth through a synthesized aperture much larger than the physical antenna of the imaging device. Consequently, proper focusing requires accurate information about the relative motion between the antenna phase center and the scene. Any unknown target velocity, acceleration, rotation, or vibration will introduce errors in the image. This work addresses a novel method of focusing a moving target in a SAR image through the estimation of various motion parameters. The target azimuth position is determined through monopulse radar, at which point range velocity and acceleration are estimated across a series of overlapping sub-apertures. Cross-range velocity is then estimated through a search to optimize an image quality metric such as entropy or contrast. A final focused image is then generated based on this velocity vector. Methods of extending this work for a single phase center system are considered. This technique is demonstrated with real radar data from an experimental system, and the performance of this technique is compared both subjectively and with a variety of image metrics to the MITRE keystone technique. Finally, extensions to this current line of research are considered. / text

No description available.

Submitted by Fabricia Fialho Reginato (fabriciar) on 2015-07-07T23:18:17Z No. of bitstreams: 1 MiriamFrosi.pdf: 727229 bytes, checksum: 5cbd9d89b48c8cb1dc375ce18100b6d7 (MD5) / Made available in DSpace on 2015-07-07T23:18:17Z (GMT). No. of bitstreams: 1 MiriamFrosi.pdf: 727229 bytes, checksum: 5cbd9d89b48c8cb1dc375ce18100b6d7 (MD5) Previous issue date: 2013-02-26 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Este estudo tem como objetivo avaliar o alinhamento dos currículos dos cursos de Ciências Contábeis ofertados em IES da Região Sul do Brasil à proposta de currículo mundial da ONU/UNCTAD/ISAR e à proposta de currículo do Conselho Federal de Contabilidade (CFC). A pesquisa é classificada como aplicada, qualitativa e quantitativa, descritiva e documental. A amostra é formada por 165 Instituições da Região Sul que oferecem cursos de Ciências Contábeis na modalidade presencial e que disponibilizaram seus currículos nas respectivas páginas eletrônicas. Os resultados indicam que há alinhamento entre os currículos das IES dos estados da Região Sul do Brasil ao currículo proposto pela ONU/UNCTAD/ISAR e ao currículo proposto pelo CFC. Os testes estatísticos comprovam que não há diferenças significativas entre as médias de alinhamento dos currículos das IES dos estados da Região Sul do Brasil em relação à proposta de currículo da ONU/UNCTAD/ISAR. Em relação à proposta de currículo do CFC, os testes indicam que as médias entre os cursos das IES dos estados do RS e PR tendem a ser iguais, enquanto as médias de RS e SC e SC e PR tendem a ser diferentes. Ao se comparar o comportamento do alinhamento nas IES com os conceitos dos cursos no ENADE, os resultados da análise revelam diferenças estatisticamente significativas entre os percentuais de alinhamento dos currículos à proposta da ONU/UNCTAD/ISAR dos cursos com conceitos 4 e 5 no ENADE, se comparados aos sem conceito, e pequena possibilidade de igualdade entre o alinhamento dos currículos dos cursos 4 e 5 comparados com os de conceitos 2 e 3. Em relação à proposta do CFC, os resultados da análise também revelam diferenças estatisticamente significativas entre os percentuais de alinhamento dos currículos dos cursos com conceitos 4 e 5 no ENADE, se comparados aos sem conceito e com conceito 2, e possibilidade de igualdade entre o alinhamento dos currículos dos cursos 4 e 5 comparados com os de conceito 3. / This study aims to evaluate the alignment of the Accountancy curricula offered by IES in Southern Brazil to the UN / UNCTAD / ISAR proposed global curriculum and the Federal Accounting Council (CFC) proposed curriculum. The research is classified as applied, qualitative and quantitative, descriptive and documentary. The sample is formed by 165 institutions from the Southern that offer courses in Accounting in the classroom and who provided their resumes on their homepages. The results indicate that there is alignment between the curricula of the 165 IES from the Southern States of Brazil to the curriculum proposed by the UN / UNCTAD / ISAR and the one proposed by the CFC. Statistical tests show that there are not significant differences between the mean alignment of IES curricula of the Southern States of Brazil in relation to the UN / UNCTAD / ISAR proposed curriculum. Regarding the proposed CFC curriculum, the tests indicate that the averages between courses of IES from the States of RS and PR tend to be the same as the means of the RS and SC and SC and PR tend to be different. When comparing the behavior of the alignment in IES with the concepts of the courses in ENADE (National Test of Student Performance), the analysis results show statistically significant differences between the percentage of the alignment to the curriculum proposed by the UN / UNCTAD / ISAR of the courses with concepts 4 and 5 in ENADE, compared to those without concept, and little possibility of equality between the alignment of course curricula 4 and 5 compared with the ones with concepts 2 and 3. Regarding the CFC proposal, analysis results also reveal statistically significant differences between the percentages of the alignment of course curricula with concepts 4 and 5 in ENADE, compared to the ones with no concept and the ones with concept 2, and the possibility of equality between the alignment of course curricula 4 and 5 compared with the ones with concept 3.

La reconnaissance automatique de cibles non coopératives est d’une grande importance dans divers domaines. C’est le cas pour les applications en environnement incertain aérien et maritime. Il s’avère donc nécessaire d’introduire des méthodes originales pour le traitement et l’identification des cibles radar. C’est dans ce contexte que s’inscrit notre travail. La méthodologie proposée est fondée sur le processus d’extraction de connaissance à partir de données (ECD) pour l’élaboration d’une chaine complète de reconnaissance à partir des images radar en essayant d’optimiser chaque étape de cette chaine de traitement. Les expérimentations réalisées pour constituer une base de données d’images ISAR ont été effectuées dans la chambre anéchoïque de l’ENSTA de Bretagne. Ce dispositif de mesures utilisé a l’avantage de disposer d’une maîtrise de la qualité des données représentants les entrées dans le processus de reconnaissance (ECD). Nous avons ainsi étudié les étapes composites de ce processus de l’acquisition jusqu’à l’interprétation et l’évaluation de résultats de reconnaissance. En particulier, nous nous sommes concentrés sur l’étape centrale dédiée à la fouille de données considérée comme le cœur du processus développé. Cette étape est composée de deux phases principales : une porte sur la classification et l’autre sur la fusion des résultats des classifieurs, cette dernière est nommée fusion décisionnelle. Dans ce cadre, nous avons montré que cette dernière phase joue un rôle important dans l’amélioration des résultats pour la prise de décision tout en prenant en compte les imperfections liées aux données radar, notamment l’incertitude et l’imprécision. Les résultats obtenus en utilisant d’une part les différentes techniques de classification (kppv, SVM et PMC), et d’autre part celles de de fusion décisionnelle (Bayes, vote, théorie de croyance, fusion floue) font l’objet d’une étude analytique et comparative en termes de performances. / The automatic recognition of non-cooperative targets is very important in various fields. This is the case for applications in aviation and maritime uncertain environment. Therefore, it’s necessary to introduce innovative methods for radar targets treatment and identification.The proposed methodology is based on the Knowledge Discovery from Data process (KDD) for a complete chain development of radar images recognition by trying to optimize every step of the processing chain.The experimental system used is based on an ISAR image acquisition system in the anechoic chamber of ENSTA Bretagne. This system has allowed controlling the quality of the entries in the recognition process (KDD). We studied the stages of the composite system from acquisition to interpretation and evaluation of results. We focused on the center stage; data mining considered as the heart of the system. This step is composed of two main phases: classification and the results of classifiers combination called decisional fusion. We have shown that this last phase improves results for decision making by taking into account the imperfections related to radar data, including uncertainty and imprecision.The results across different classification techniques as a first step (kNN, SVM and MCP) and decision fusion in a second time (Bayes, majority vote, belief theory, fuzzy fusion) are subject of an analytical and comparative study in terms of performance.

In this thesis, Inverse Synthtetic Aperture Radar image reconstruction techniques, named as Range Doppler, Back Projection, Polar Formatting, Multiple Signal Classification (MUSIC) and Time Frequency techniques are analysed and compared using simulations. Time Frequency techniques investigated in this thesis are Short Time Fourier Transform, Wigner-Ville Distribution, Smoothed Wigner-Ville Distribution and Choi-Williams Distribution. First, some fundamental concepts of ISAR, such as resolution, range profile, time dependent Doppler frequency are given. A data simulator is designed and implemented for the purpose of providing configurable input to ISAR signal processing algorithms for a given ISAR target geometry. Estimation of target rotational velocity is explained with the help of three methods, namely Grid Search, WVD Slope and Radon Wigner-Hough Transform. Then, theoretical background of image formation algorithms is discussed. MATLAB simulations for each algorithm are implemented with several configurations in order to visualize and analyse the results. Finally, processing algorithms are compared to discuss the advantages and disadvantages.