14 research outputs found

    Processeurs SAR Basés sur des Détecteurs de Sous-Espaces

    Get PDF
    Classical SAR Imagery algorithms or SAR processors are all based on the isotropic point model. When detecting Man Made Targets (MMT), this assumption shows its limitation because of the directive behavior of these kind of targets: this model does not take into account their physical properties. The basic idea of this thesis is that we shall be able to develop more efficient SAR processors for the detection of MMT, provided that we adopt a more suited description for these targets. A natural way to model these MMT is to consider them as sets of canonical elements with unknown orientation. If the signal backscattered by the canonical element, whatever its orientation, belongs to a low dimensional subspace, it is then possible to develop a SAR processor based on subspace detectors matched to the canonical element. This processor is called Subspace Signal Detector SAR (SSDSAR) algorithm. When the MMT is embedded in a medium, where specific scatterers create interferences, one can model the electromagnetic response of these scatterers to clear them from the SAR image. Once again, if the set of signals backscattered by the element used to model the scatterer, whatever its orientation, belongs to a low dimensional subspace, a SAR processor based on subspace detectors can be developed. This processor is called Signal or Interference Subspace Detector SAR (SISDSAR) algorithm. Different ways to implement SSDSAR and SISDSAR are presented. Theoretical performances of the two new algorithms are studied in details. Finally, we apply these two processors to simulated and real data.Les algorithmes classiques d'imagerie SAR sont tous basés sur le modèle du point isotrope. Lors de la détection de cibles manufacturées (Man-Made Targets ou MMT), cette hypothèse montre ses limites en raison de la diffusion directive de ce genre de cibles: ce modèle ne tient pas compte de leurs propriétés physiques. L'idée de base de cette thèse est que nous serons en mesure de développer des processeurs SAR plus efficaces pour la détection du MMT, à condition que nous adoptions une description plus adaptée à ces objectifs. Une façon naturelle de modéliser ces MMT est de les considérer comme des ensembles d'éléments canoniques avec orientation inconnue. Si le signal rétrodiffusé par l'élément canonique, quelle que soit son orientation, appartient à un sous-espace de faible dimension, il est alors possible d'élaborer un processeur SAR sur la base de détecteurs de sous-espaces adaptés à l'élément canonique. Cet algorithme est appelé processeur SAR basé sur un Détecteur de Sous Espaces Signaux (SSDSAR). Lorsque le MMT est intégré dans un milieu où les diffuseurs spécifiques créent des interférences, on peut modéliser la réponse électromagnétique de ces diffuseurs pour les faire disparaître de l'image SAR. Encore une fois, si l'ensemble des signaux rétrodiffusés par l'élément utilisé pour modéliser le diffuseur, quelle que soit son orientation, appartient à un sous-espace de dimension faible, un processeur SAR basé sur des détecteurs subspatiales peut être développé. Ce processeur est appelé processeur SAR basé sur des Détecteurs de Sous Espaces Signaux ou Interférences (SISDSAR). Différentes façons de mettre en œuvre SSDSAR et SISDSAR sont présentées. Les performances théoriques des deux nouveaux algorithmes sont étudiées en détail. Enfin, nous appliquons ces deux processeurs à des données réelles et simulées

    Signal Processing for Non-Gaussian Statistics: Clutter Distribution Identification and Adaptive Threshold Estimation

    Get PDF
    We examine the problem of determining a decision threshold for the binary hypothesis test that naturally arises when a radar system must decide if there is a target present in a range cell under test. Modern radar systems require predictable, low, constant rates of false alarm (i.e. when unwanted noise and clutter returns are mistaken for a target). Measured clutter returns have often been fitted to heavy tailed, non-Gaussian distributions. The heavy tails on these distributions cause an unacceptable rise in the number of false alarms. We use the class of spherically invariant random vectors (SIRVs) to model clutter returns. SIRVs arise from a phenomenological consideration of the radar sensing problem, and include both the Gaussian distribution and most commonly reported non-Gaussian clutter distributions (e.g. K distribution, Weibull distribution). We propose an extension of a prior technique called the Ozturk algorithm. The Ozturk algorithm generates a graphical library of points corresponding to known SIRV distributions. These points are generated from linked vectors whose magnitude is derived from the order statistics of the SIRV distributions. Measured data is then compared to the library and a distribution is chosen that best approximates the measured data. Our extension introduces a framework of weighting functions and examines both a distribution classification technique as well as a method of determining an adaptive threshold in data that may or may not belong to a known distribution. The extensions are then compared to neural networking techniques. Special attention is paid to producing a robust, adaptive estimation of the detection threshold. Finally, divergence measures of SIRVs are examined

    Polarimetric Synthetic Aperture Radar

    Get PDF
    This open access book focuses on the practical application of electromagnetic polarimetry principles in Earth remote sensing with an educational purpose. In the last decade, the operations from fully polarimetric synthetic aperture radar such as the Japanese ALOS/PalSAR, the Canadian Radarsat-2 and the German TerraSAR-X and their easy data access for scientific use have developed further the research and data applications at L,C and X band. As a consequence, the wider distribution of polarimetric data sets across the remote sensing community boosted activity and development in polarimetric SAR applications, also in view of future missions. Numerous experiments with real data from spaceborne platforms are shown, with the aim of giving an up-to-date and complete treatment of the unique benefits of fully polarimetric synthetic aperture radar data in five different domains: forest, agriculture, cryosphere, urban and oceans

    Integrated Applications of Geo-Information in Environmental Monitoring

    Get PDF
    This book focuses on fundamental and applied research on geo-information technology, notably optical and radar remote sensing and algorithm improvements, and their applications in environmental monitoring. This Special Issue presents ten high-quality research papers covering up-to-date research in land cover change and desertification analyses, geo-disaster risk and damage evaluation, mining area restoration assessments, the improvement and development of algorithms, and coastal environmental monitoring and object targeting. The purpose of this Special Issue is to promote exchanges, communications and share the research outcomes of scientists worldwide and to bridge the gap between scientific research and its applications for advancing and improving society

    Polarimetric Synthetic Aperture Radar, Principles and Application

    Get PDF
    Demonstrates the benefits of the usage of fully polarimetric synthetic aperture radar data in applications of Earth remote sensing, with educational and development purposes. Includes numerous up-to-date examples with real data from spaceborne platforms and possibility to use a software to support lecture practicals. Reviews theoretical principles in an intuitive way for each application topic. Covers in depth five application domains (forests, agriculture, cryosphere, urban, and oceans), with reference also to hazard monitorin

    Abstracts on Radio Direction Finding (1899 - 1995)

    Get PDF
    The files on this record represent the various databases that originally composed the CD-ROM issue of "Abstracts on Radio Direction Finding" database, which is now part of the Dudley Knox Library's Abstracts and Selected Full Text Documents on Radio Direction Finding (1899 - 1995) Collection. (See Calhoun record https://calhoun.nps.edu/handle/10945/57364 for further information on this collection and the bibliography). Due to issues of technological obsolescence preventing current and future audiences from accessing the bibliography, DKL exported and converted into the three files on this record the various databases contained in the CD-ROM. The contents of these files are: 1) RDFA_CompleteBibliography_xls.zip [RDFA_CompleteBibliography.xls: Metadata for the complete bibliography, in Excel 97-2003 Workbook format; RDFA_Glossary.xls: Glossary of terms, in Excel 97-2003 Workbookformat; RDFA_Biographies.xls: Biographies of leading figures, in Excel 97-2003 Workbook format]; 2) RDFA_CompleteBibliography_csv.zip [RDFA_CompleteBibliography.TXT: Metadata for the complete bibliography, in CSV format; RDFA_Glossary.TXT: Glossary of terms, in CSV format; RDFA_Biographies.TXT: Biographies of leading figures, in CSV format]; 3) RDFA_CompleteBibliography.pdf: A human readable display of the bibliographic data, as a means of double-checking any possible deviations due to conversion

    Data bases and data base systems related to NASA's aerospace program. A bibliography with indexes

    Get PDF
    This bibliography lists 1778 reports, articles, and other documents introduced into the NASA scientific and technical information system, 1975 through 1980

    Naval Postgraduate School Catalog 2015

    Get PDF
    Approved for public release; distribution is unlimited

    Naval Postgraduate School Catalog 2016

    Get PDF
    Approved for public release; distribution is unlimited

    Naval Postgraduate School Academic Catalog - September 2021

    Get PDF
    corecore