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Multi-GNSS Hybridization for Precise Positioning / Georgia Katsigianni (2019)  

Public Titre : Multi-GNSS Hybridization for Precise Positioning Type de document : Thèse/HDR Auteurs : Georgia Katsigianni, Auteur ; Félix Perosanz, Directeur de thèse ; Sylvain Loyer, Directeur de thèse Editeur : Toulouse : Université de Toulouse 3 Paul Sabatier Année de publication : 2019 Importance : 143 p. Format : 21 x 30 cm Note générale : Thèse en vue de l'obtention du Doctorat de l'Université de Toulouse 3 Paul Sabatier, Spécialité Sciences de la Terre et des Planètes Solides Langues : Anglais (eng) Descripteur : [Termes IGN] données Galileo [Termes IGN] données GPS [Termes IGN] orbitographie [Termes IGN] positionnement cinématique [Termes IGN] positionnement par GNSS [Termes IGN] positionnement ponctuel précis [Termes IGN] résolution d'ambiguïté [Vedettes matières IGN] Traitement de données GNSS Index. décimale : THESE Thèses et HDR Résumé : (auteur) GNSS are widely used for precise positioning applications of geosciences and especially space geodesy. So far, mainly the existing GPS was extensively used for scientific applications. With the arrival of the new European Galileo system it became imperative to include the new system in the studies and check the new capabilities that it will bring as a system alone and as combined together with the others in a Multi-GNSS processing. The CNES/CLS analysis center of the IGS is weekly calculating GNSS (GPS, GLONASS and Galileo) products that can be taken from any kind of user to perform precise positioning. A way to achieve the best accuracy possible is to resolve the unknown integer ambiguities of the phase measurements. Up until now, the CNES/CLS was performing ambiguity resolution to the GPS system using the zero-difference method. In this way they are able to deliver precise satellite orbits and precise clock products with phase fixed ambiguities. The goal of this work was to implement and validate if the method can be also applied for the Galileo system. The method applied from the CNES/CLS is consisting of two further steps. The first one is the resolution of the Wide-Lane ambiguities. The Galileo Wide-Lane satellite biases have been proven to be stable over long periods of time. In addition, there is homogeneity in the way they are observed from different types of receivers. These findings were used and the Wide-Lane biases were successfully resolved with nearly 100% success rate percentage. The second step of zero-difference method is the Narrow-Lane ambiguity resolution. This step was executed for the Galileo system together with the GPS system in a Multi-GNSS Precise Orbit Determination processing. Galileo ambiguity fixing success percentage is around 93%, nearly similar to the one of the GPS system. The integer property of the Galileo phase clocks is demonstrated. Both orbit overlaps and orbit validation using SLR validation methods showed that ambiguity resolution improves mainly in the normal and the along track direction. Galileo orbit overlaps in 3D RMS showed an improvement of around 50%, from around 7 cm to 3.5 cm. The results of this work were used by the CNES/CLS IGS AC that has announced the delivery of weekly Galileo precise orbits, clocks and Wide-Lane satellite biases. A new method is also introduced on how to compare ambiguity resolution results for a common overlapping period. This method is also used to speculate the agreement and the disagreement between two different daily solutions. Finally, it was examined the post-processed kinematic PPP and PPP-AR using Galileo-only, GPSonly and Multi-GNSS (GPS + Galileo) constellations. The interest was to validate the accuracy for each GNSS system individually but also of their combination. Results showed that Galileoonly positioning accuracy is nearly at the same level of accuracy as GPS-only. The use of Galileo system improves the performance of the GPS positioning giving mm level repeatability. The contribution of Galileo ameliorates the positioning accuracy around 30% in all directions(comparison GPS PPP-AR and Multi-GNSS PPP-AR). This proved that the Galileo constellation together with GPS will give improved precise positioning with respect to the current GPS-only. All these are indications that the Galileo system will contribute to precise positioning required by geoscience applications through a Multi-GNSS (GPS + Galileo) solution. Note de contenu : 1- Introduction 2- GNSS in science 3- GNSS measurements 4- Galileo Wide-Lane AR 5- Galileo Narrow-Lane AR 6- Precise Point Positioning 7- Conclusions and Suggestions Numéro de notice : 28511 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse française Note de thèse : Thèse de Doctorat : Sciences de la Terre et des Planètes Solides : Toulouse 3 : 2019 Organisme de stage : Geosciences Environnement Toulouse nature-HAL : Thèse DOI : sans En ligne : http://www.theses.fr/2019TOU30209 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=97142