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scientifique

Uncertainty in radar emitter classification and clustering / Guillaume Revillon (2019)  

Public Titre : Uncertainty in radar emitter classification and clustering Titre original : Gestion des incertitudes en identification des modes radar Type de document : Thèse/HDR Auteurs : Guillaume Revillon, Auteur ; Charles Soussen, Directeur de thèse ; A. Mohammad-Djafari, Directeur de thèse Editeur : Paris-Orsay : Université de Paris 11 Paris-Sud Centre d'Orsay Année de publication : 2019 Importance : 181 p. Format : 21 x 30 cm Note générale : bibliographie Thèse de Doctorat de l’Université Paris-Saclay préparée à l’Université Paris-Sud Sciences et Technologies de l’Information et de la Communication (STIC) Spécialité : Traitement du signal et des images Langues : Français (fre) Descripteur : [Vedettes matières IGN] Traitement du signal [Termes IGN] approximation [Termes IGN] détection du signal [Termes IGN] écho radar [Termes IGN] émetteur [Termes IGN] estimation bayesienne [Termes IGN] inférence statistique [Termes IGN] modèle de mélange multilinéaire [Termes IGN] modulation du signal [Termes IGN] probabilités [Termes IGN] valeur aberrante Index. décimale : THESE Thèses et HDR Résumé : (auteur) In Electronic Warfare, radar signals identification is a supreme asset for decision making in military tactical situations. By providing information about the presence of threats, classification and clustering of radar signals have a significant role ensuring that countermeasures against enemies are well-chosen and enabling detection of unknown radar signals to update databases. Most of the time, Electronic Support Measures systems receive mixtures of signals from different radar emitters in the electromagnetic environment. Hence a radar signal, described by a pulse-to-pulse modulation pattern, is often partially observed due to missing measurements and measurement errors. The identification process relies on statistical analysis of basic measurable parameters of a radar signal which constitute both quantitative and qualitative data. Many general and practical approaches based on data fusion and machine learning have been developed and traditionally proceed to feature extraction, dimensionality reduction and classification or clustering. However, these algorithms cannot handle missing data and imputation methods are required to generate data to use them. Hence, the main objective of this work is to define a classification/clustering framework that handles both outliers and missing values for any types of data. Here, an approach based on mixture models is developed since mixture models provide a mathematically based, flexible and meaningful framework for the wide variety of classification and clustering requirements. The proposed approach focuses on the introduction of latent variables that give us the possibility to handle sensitivity of the model to outliers and to allow a less restrictive modelling of missing data. A Bayesian treatment is adopted for model learning, supervised classification and clustering and inference is processed through a variational Bayesian approximation since the joint posterior distribution of latent variables and parameters is untractable. Some numerical experiments on synthetic and real data show that the proposed method provides more accurate results than standard algorithms. Note de contenu : Introduction 1- State of the art and the selected approach 2- Continuous data 3- Mixed data 4- Temporal evolution data 5- Conclusion and perspectives Numéro de notice : 25703 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Thèse française Note de thèse : Thèse de Doctorat : Traitement du signal et des images : Paris 11 : 2019 Organisme de stage : Thales, GPI nature-HAL : Thèse DOI : sans Date de publication en ligne : 02/09/2019 En ligne : https://hal.science/tel-02275817 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94829

Geodetic VLBI with an artificial radio source on the Moon : a simulation study / Grzegorz Klopotek in Journal of geodesy, vol 92 n° 5 (May 2018)  

Public [article]  inJournal of geodesy > vol 92 n° 5 (May 2018) . - pp 457 – 469 Titre : Geodetic VLBI with an artificial radio source on the Moon : a simulation study Type de document : Article/Communication Auteurs : Grzegorz Klopotek, Auteur ; Thomas Hobiger, Auteur ; Rüdiger Haas, Auteur Année de publication : 2018 Article en page(s) : pp 457 – 469 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] C++ [Termes IGN] émetteur [Termes IGN] interférométrie à très grande base [Termes IGN] Lune [Termes IGN] méthode de Monte-Carlo [Termes IGN] modèle de simulation [Termes IGN] modèle stochastique [Termes IGN] simulation Résumé : (Auteur) We perform extensive simulations in order to assess the accuracy with which the position of a radio transmitter on the surface of the Moon can be determined by geodetic VLBI. We study how the quality and quantity of geodetic VLBI observations influence these position estimates and investigate how observations of such near-field objects affect classical geodetic parameters like VLBI station coordinates and Earth rotation parameters. Our studies are based on today’s global geodetic VLBI schedules as well as on those designed for the next-generation geodetic VLBI system. We use Monte Carlo simulations including realistic stochastic models of troposphere, station clocks, and observational noise. Our results indicate that it is possible to position a radio transmitter on the Moon using today’s geodetic VLBI with a two-dimensional horizontal accuracy of better than one meter. Moreover, we show that the next-generation geodetic VLBI has the potential to improve the two-dimensional accuracy to better than 5 cm. Thus, our results lay the base for novel observing concepts to improve both lunar research and geodetic VLBI. Numéro de notice : A2018-149 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-017-1072-4 Date de publication en ligne : 27/10/2017 En ligne : https://doi.org/10.1007/s00190-017-1072-4 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89760 [article]

Modern radar systems / H. Meikle (2008)

Public Titre : Modern radar systems Type de document : Monographie Auteurs : H. Meikle, Auteur Mention d'édition : 2 Editeur : Londres, Washington : Artech House Année de publication : 2008 Importance : 701 p. Format : 22 x 29 cm ISBN/ISSN/EAN : 978-1-59693-242-5 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Télédétection [Termes IGN] antenne radar [Termes IGN] détecteur [Termes IGN] écho radar [Termes IGN] émetteur [Termes IGN] filtrage du signal [Termes IGN] géopositionnement [Termes IGN] hyperfréquence [Termes IGN] performance [Termes IGN] polarisation [Termes IGN] radar [Termes IGN] récepteur radar [Termes IGN] seuillage d'image [Termes IGN] télédétection en hyperfréquence [Termes IGN] traitement du signal [Termes IGN] transformation de Fourier [Termes IGN] transformation mathématique Index. décimale : 35.22 Télédétection en hyperfréquence - Traitement d'image radar Résumé : (Editeur) This revised and updated edition offers professionals complete and current coverage of the subject, including new material on critical aspects such as accuracy, resolution, and convolution and correlation. The book features more than 540 illustrations that offer a greater understanding of various waveforms, and other two- and three-dimensional functions, to help engineers more accurately analyze radar system performance. The effects of pulse shaping on transmitter stability and spectra are discussed - a topic that is becoming more and more important to today's engineers. Radar practitioners get a number of critical atmospheric models to help them with their challenging work. Each chapter ends with a performance section, showing the effect of that particular aspect on the complete radar system budget for range, accuracy, and stability. Note de contenu : Chapitre 1 - The radar and its ground environment Chapitre 2 - Usual and Unusual Concepts Chapitre 3 - Transmitters Chapitre 4 - Microwave waveguide and transmission line system Chapitre 5 - Antennas Chapitre 6 - Factors outside the radar : propagation, scattering and clutter Chapitre 7 - Receivers Chapitre 8 - Matched and matching filters Chapitre 9 - Detectors Chapitre 10 - Analogue-to-digital conversion Chapitre 11 - Signal processing Chapitre 12 - Threshold and detection Chapitre 13 - Determination of position Chapitre 14 - Performance Chapitre 15 - Transforms Annexes Numéro de notice : 20108 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Monographie Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=62917

Development of a dispersometer for the implementation into geodetic high-accuracy direction measurement systems / Burkhard Böckem (2001)  

Public Titre : Development of a dispersometer for the implementation into geodetic high-accuracy direction measurement systems Type de document : Thèse/HDR Auteurs : Burkhard Böckem, Auteur Editeur : Zurich : Institut für Geodäsie und Photogrammetrie IGP - ETH Année de publication : 2001 Collection : IGP Mitteilungen, ISSN 0252-9335 num. 73 Importance : 140 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-906467-33-7 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie [Termes IGN] effet atmosphérique [Termes IGN] émetteur [Termes IGN] impulsion laser [Termes IGN] mesurage électronique d'angles [Termes IGN] mesurage électronique de distances [Termes IGN] propagation du signal [Termes IGN] rayonnement électromagnétique [Termes IGN] récepteur bifréquence [Termes IGN] réfraction atmosphérique [Termes IGN] téléscope Index. décimale : 30.03 Instruments de géodésie Résumé : (Auteur) In the course of the progressive developments of sophisticated geodetic systems which offer a very high accuracy potential strategies for correcting atmosphere-related effects will become increasingly important. These atmosphere-related effects arise in a large span of time scales: systematic deviations caused by a quasi-stationary refractive index gradient environment, generally referred to as refraction in geodetic context, slowly transfer to stochastic deviations resulting from optical turbulence. Refraction corrected optical direction and angle measurements are required in numerous high-accuracy measurement applications. These applications include surveying tasks in connection with civil engineering projects, the alignment of particle accelerator facilities, surveying tasks in context within assembling processes in industrial environments, e.g. aircraft industry, tasks wherein surveying instruments provide the spatial guidance of large machines, etc. A dispersometer, based on the dual-wavelength method by utilizing atmospheric dispersion, constitutes a metrological solution to atmosphere-related effects. Another decisive advantage of a dispersometer is that the envisaged correction of atmosphere-related effects works integrally and is available in real time. The aim of this thesis was to develop this dispersometer to overcome atmospherically induced limitations in very high-accuracy direction and angle measurements. The dispersometer consists of two modules: the dual-wavelength transmitter and the detection system being composed of the dispersion telescope and a position sensitive detector. By applying the dual-wavelength method, the major .challenges in instrumental realization are the generation of coaxial single-mode emission at two spectrally optimized wavelengths and the achievement of optical position sensing accuracy in the order of a few nanometers. The development of the dispersometer is principally made possible by focussing on three key technologies: dual-wavelength generation by frequency conversion, optical fiber technology, and gap- technology. Within this work detailed studies of these three key technologies are performed. In this work it is demonstrated that a dual-wavelength laser by frequency conversion is clearly suited for the implementation in the dual-wavelength transmitter. Furthermore, a novel technique for achieving coaxial single-mode propagation at two spectrally wide-separated wavelengths by one single-mode fiber is established within this thesis. Due to the application of optical fiber technology it is now possible to couple both beams into one optical channel of a modem geodetic total station. In order to achieve optical position sensing with the accuracy of a few nanometers by using a short-focal-length receiving telescope, gap-technology by utilizing special segmented position sensitive detectors is applied. This thesis contains a complete treatment addressed to this technology. Within the course of dispersometer performance tests, difference position sensing accuracy of ó = 7.3 nm was achieved. Additionally, the existence of the position sensitive detector inherent dispersion was demonstrated. In combination with the dispersion of the receiving optics, the position sensitive detector inherent dispersion has to be considered for the measurement of the atmospheric dispersion induced displacement between both beams of different wavelengths. As a solution a self-calibration procedure which corrects the dispersion of the complete detection system is described. This self-calibration procedure which utilizes the impact of optical turbulence possesses the decisive advantages that it obviates the need of additional measurements and the dispersion correction can be computed and applied in real time. A substantial part of this thesis is devoted to dispersometer measurements. Two basic atmospheric conditions which are typical for industrial measurement tasks indoors were simulated. Additionally, a detailed study of the influence of the aperture diameter on the dispersometer measurements was performed. The optimal aperture diameter for the present instrumental layout and for the prevailing ambient conditions was 30 mm. For theodolite-like and smaller apertures it is confirmed that the accuracy of the refraction angle improves with the square root of the integration time. Due to dispersometer performance by using theodolite-like and possibly smaller apertures in combination with the self-calibration procedure, the implementation of a standard theodolite-telescope is proposed. In a moderately turbulent atmosphere the accuracy of the refraction angle for single- face telescope observation was found to be 0.2 µrad (0.01 mgon) after an integration time of 12 sand a sight length of 17 m. Summarizing the theoretical investigations, the key technologies involved in the instrumental development, and the experimental results, presented in this dissertation, it can be concluded that the realized dispersometer in combination with a theodolite is capable of the refraction corrected angular measurements, the influences of optical turbulence notwithstanding. The application of optical fiber technology and the envisaged implementation of a standard theodolite-telescope confirm the presumption that the realized dispersometer can be implemented into modem geodetic total stations. Improvements with respect to field-operativeness are expected by an industrial realization of the dispersometer and by implementing the dispersometer into modem geodetic total stations. The integration of blue laser diodes, when meeting the standards of nowadays infrared laser diodes, would significantly enhance efficiency and reduce overall costs. Due to the technologies presented within this thesis such an integration is clearly feasible. Numéro de notice : 14740 Affiliation des auteurs : non IGN Autre URL associée : http://dx.doi.org/10.3929/ethz-a-004176211 Thématique : POSITIONNEMENT Nature : Thèse étrangère DOI : 10.3929/ethz-a-004176211 En ligne : http://e-collection.library.ethz.ch/eserv/eth:24109/eth-24109-02.pdf Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=62684

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Code-barres	Cote	Support	Localisation	Section	Disponibilité
14740-01	30.03	Livre	Centre de documentation	En réserve M-103	Disponible

Télémétrie laser-satellite / F. Pierron (25/10/1983)

Public contenu dans Astrométrie, géodésie, mécanique céleste / Observatoire de l'université de Bordeaux (1983) Titre : Télémétrie laser-satellite Type de document : Article/Communication Auteurs : F. Pierron, Auteur ; J.L. Hatat, Auteur ; Maurice Laplanche, Auteur ; R. Futaully, Auteur Editeur : Bordeaux : Université de Bordeaux 1 Année de publication : 25/10/1983 Conférence : Colloque 1983, 5e colloque du GS-5, Astrométrie, géodésie, mécanique céleste 25/10/1983 27/10/1983 Paris France Importance : pp 149 - 153 Langues : Français (fre) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] chronométrie [Termes IGN] émetteur [Termes IGN] Grasse [Termes IGN] spécification de processus [Termes IGN] télémétrie laser sur satellite Numéro de notice : C1983-013 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Communication Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=65135

La télédétection en hydrographie / J. Bourgoin in Géomètre, vol 1983 n° 10 (octobre 1983)

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Physique et théorie du radar, 1. Tome 1 / J. Darricau (1973)

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Diodes et transistors / Gaston Fontaine (1969)

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Vibrations mécaniques, acoustique / Pierre Fleury (1968)

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Courants alternatifs, ondes hertziennes / Pierre Fleury (1967)

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Mesures en radiotechnique / E. Fromy (1963)

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Applications de la radioélectricité (2ème partie) / M. Decaux (1960)

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