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Parameter estimation with GNSS-reflectometry and GNSS synthetic aperture techniques / Miguel Angel Ribot Sanfelix (2018)  

Public Titre : Parameter estimation with GNSS-reflectometry and GNSS synthetic aperture techniques Type de document : Thèse/HDR Auteurs : Miguel Angel Ribot Sanfelix, Auteur ; Pierre-André Farine, Directeur de thèse ; Cyril Botteron, Directeur de thèse Editeur : Lausanne : Ecole Polytechnique Fédérale de Lausanne EPFL Année de publication : 2018 Importance : 187 p. Format : 21 x 30 cm Note générale : bibliographie Thèse présentée à l'Ecole Polytechnique Fédérale de Lausanne pour l'obtention du grade de Docteur ès Sciences Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal [Termes IGN] classification par maximum de vraisemblance [Termes IGN] correction du trajet multiple [Termes IGN] erreur de positionnement [Termes IGN] filtre de Kalman [Termes IGN] interférence [Termes IGN] ligne de visée [Termes IGN] phase [Termes IGN] récepteur GNSS [Termes IGN] réflectométrie par GNSS [Termes IGN] signal GNSS [Termes IGN] signal GPS Résumé : (auteur) Aside from intentional interference, multipath is the most significant error source for Global Navigation Satellite Systems (GNSS) receivers in many operational scenarios. In this thesis, we study the multipath estimation from two different perspectives: to retrieve useful information from it using GNSS-Reflectometry (GNSS-R) techniques; and to mitigate its effects or to estimate its direction-of-arrival (DOA) as well as the line-of-sight (LOS) signal’s using synthetic aperture (SA) processing. The first part of the thesis focuses on precision bounds for GNSS-R techniques for groundbased receivers, in scenarios where a single antenna simultaneously receives the LOS signal and a specular reflection. First, we derive the Cramér-Rao bound (CRB) of the receiver’s height and the reflection coefficient, with the latter depending on the surface’s electrical properties. More specifically, we propose a CRB derivation applicable to GNSS-R techniques that make use of the phase information and long observation times, such as the interference pattern technique (IPT). The derivation is based on the parameter transformation of the Fisher information matrix. We study the dependence of the computed CRB on the scenario and the receiver bandwidth. The CRB results for the simulated scenarios are consistent with the precision reported for many GNSS-R techniques used in these scenarios. The proposed CRB is meant to benchmark and compare new and existing techniques. Besides the derived CRB, we propose an algorithm to obtain the maximum-likelihood (ML) estimator of the parameters of interest with the IPT: the segmented ML estimator (SML). The SML transforms a complex multivariate optimization problem into multiple simpler ones by dividing the parameter search space taking advantage of the cost function’s particular structure. The SML is validated with simulated signal and asymptotically cross-validates the CRB results. The second part of the thesis is devoted to the study of the SA processing of GNSS signals. The goal is to estimate the DOA of the signals received, and mitigate errors in the navigation solution caused by interfering signals, such as multipath. We start by deriving the CRB for the SA context, as a function of the antenna trajectory. This CRB considers the effect of the antenna complex gain, and we show in simulations that it is possible to achieve meaningful DOA estimation only by changing the antenna’s orientation. We continue by proposing a development framework built upon a signal tracking architecture integrating SA processing. Before any SA processing, it is necessary to estimate and compensate any carrier phase contribution not related to the antenna motion. To do so, we propose two new sequential techniques based on the extended Kalman filter (EKF). Also, we develop an open-loop version of the proposed SA tracking architecture, more robust than its closed-loop counterpart. Finally, we validate the proposed architecture and SA-based techniques with synthetic GPS signals at first, and then with real signals, recorded using an antenna mounted on a mechanical rotating arm. The obtained results validate the implemented techniques and show how the proposed SA architecture can ultimately mitigate the position bias error observed in environments with severe multipath interference. Note de contenu : 1- Introduction 2- GNSS-Reflectomery and Synthetic Aperture Processing: An Overview 3- Parameter Estimation in GNSS-Reflectometry Scenarios with Coherent Reflection 4- Spatial Filtering of GNSS Signals with Synthetic Aperture Processing 5- Conclusions Numéro de notice : 25793 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Thèse étrangère Note de thèse : Thèse de Doctorat : Sciences : Lausanne : 2018 En ligne : https://infoscience.epfl.ch/record/253111?ln=fr Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95019

U-SBAS: A universal multi-SBAS standard to ensure compatibility, interoperability and interchangeability / Mohamed Sahmoudi (2010)  

Public Titre : U-SBAS: A universal multi-SBAS standard to ensure compatibility, interoperability and interchangeability Type de document : Article/Communication Auteurs : Mohamed Sahmoudi, Auteur ; Jean-Luc Issler, Auteur ; Felix Perozans, Auteur ; Youssef Tawk, Auteur ; Aleksandar Jovanovic, Auteur ; Cyril Botteron, Auteur ; Pierre-André Farine, Auteur ; Landry René, Auteur ; Véronique Dehant, Auteur ; Alessandro Caporali, Auteur ; Serge Reboul, Auteur ; Pascal Willis , Auteur Editeur : New York : Institute of Electrical and Electronics Engineers IEEE Année de publication : 2010 Conférence : NAVITEC 2010, 5th ESA Workshop on Satellite Navigation Technologies and European Workshop on GNSS Signals and Signal Processing 08/12/2010 10/12/2010 Noordwijk Pays-Bas Proceedings IEEE Importance : 18 p. Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] interopérabilité [Termes IGN] standard [Termes IGN] système d'extension Résumé : (auteur) Several regional augmentation GNSS systems (like SBAS) are already fully operational and other are under development with new frequencies and signals on the way. Therefore, it becomes imperative to guarantee for all GNSS users the compatibility, interoperability and interchangeability between all these systems. The goal is to ensure that the user's multi-mode receiver can choose and mix signals from different GNSS and SBAS systems to achieve more availability, accuracy and robustness. Attaining that objective will require agreements on frequency plans and signal designs, as well as other details including means to ensure interoperability of system times and geodetic reference systems. This paper suggests a Universal-SBAS (U-SBAS) standard, compatible with all the existing and planned regional GNSS systems (and their evolutions) in the world, like IRNSS, QZSS, PCW, BEIDOU-1, WAAS, EGNOS, SDCM, GAGAN, MSAS. The proposed worldwide multimodal U-SBAS standard carries additional channels (signals and messages) to cover the non-aeronautical specific Safety-of-Life (SoL) services, and also High Precision Positioning Services (HPPS), Position Velocity Time (PVT), authentication services, safety services, scientific application services, High Precision Timing Services (HPTS), etc. U-SBAS is designed to be fully interoperable with the current SBAS standards and to allow significant performance and service improvements in operational, scientific and/or security areas. Finally usage examples of the proposed standard are given for different types of applications such as science, aviation, precise point positioning, timing, security, robust positioning, maritime and reflectometry. Numéro de notice : C2010-074 Affiliation des auteurs : LAREG+Ext (1991-2011) Thématique : POSITIONNEMENT Nature : Communication nature-HAL : ComAvecCL&ActesPubliésIntl DOI : 10.1109/NAVITEC.2010.5708076 En ligne : https://doi.org/10.1109/NAVITEC.2010.5708076 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102057