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Recent activities of the GGOS standing committee on Performance simulations and Architectural Trade-Offs (PLATO) / Benjamin Männel (2018)  

Public Titre : Recent activities of the GGOS standing committee on Performance simulations and Architectural Trade-Offs (PLATO) Type de document : Chapitre/Contribution Auteurs : Benjamin Männel, Auteur ; Daniela Thaller, Auteur ; Markus Rothacher, Auteur ; Johannes Böhm, Auteur ; Jurgen Müller, Auteur ; Susanne Glaser, Auteur ; Rolf Dach, Auteur ; Richard Biancale, Auteur ; Mathis Blossfeld, Auteur ; Alexander Kehm, Auteur ; Iván Herrera Pinzón, Auteur ; Franz Hofmann, Auteur ; Florian Andritsch, Auteur ; David Coulot , Auteur ; Arnaud Pollet , Auteur Editeur : Berlin, Heidelberg, Vienne, New York, ... : Springer Année de publication : 2018 Importance : pp 1 - 4 Langues : Anglais (eng) Résumé : (auteur) The Standing Committee on Performance Simulations and Architectural Trade-Offs (PLATO) was established by the Bureau of Networks and Observations of the Global Geodetic Observing System (GGOS) in order to support – by prior performance analysis – activities to reach the GGOS requirements for the accuracy and stability of the terrestrial reference frame. Based on available data sets and simulated observations for further stations and satellite missions the committee studies the impact of technique-specific improvements, new stations, and additional co-locations in space on reference frame products. Simulation studies carried out so far show the importance of the individual station performance and additional stations for satellite laser ranging, the perspectives for lunar laser ranging assuming additional stations and reflectors, and the significant impact of the new VGOS antennas. Significant progress is achieved in processing VLBI satellite tracking data. New insights in technique-specific error sources were derived based on real data from short baselines. Regarding co-location in space PLATO members confirmed that E-GRASP could fulfill the GGOS requirements with reaching a geocenter and scale accuracy and stability of 1 mm and 0.1 mm/year, respectively. Numéro de notice : H2018-006 Nature : Chapître / contribution nature-HAL : ChOuvrScient DOI : 10.1007/1345_2018_30 date de publication en ligne : 11/04/2018 En ligne : http://dx.doi.org/10.1007/1345_2018_30 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=90562

Ionospheric corrections for single-frequency tracking of GNSS satellites by VLBI based on co-located GNSS / Benjamin Männel in Journal of geodesy, vol 90 n° 2 (February 2016)  

Public [article]  inJournal of geodesy > vol 90 n° 2 (February 2016) . - pp 189-203 Titre : Ionospheric corrections for single-frequency tracking of GNSS satellites by VLBI based on co-located GNSS Type de document : Article/Communication Auteurs : Benjamin Männel, Auteur ; Markus Rothacher, Auteur Année de publication : 2016 Article en page(s) : pp 189-203 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes descripteurs IGN] co-positionnement [Termes descripteurs IGN] correction ionosphérique [Termes descripteurs IGN] positionnement par GNSS [Termes descripteurs IGN] positionnement par ITGB [Termes descripteurs IGN] poursuite de satellite [Termes descripteurs IGN] propagation ionosphérique Résumé : (auteur) Tracking L-band signals of GNSS satellites by radio telescopes became a new observation type in recent years and will be used to improve reference system realizations and links between Earth- and space-fixed frames. First successful test observations were done, with the drawback of being single-frequency only. In order to correct the ionospheric delay by using GNSS phase observations from co-located receivers, the L4R approach was developed. Based on residuals derived by a least-squares processing of the GNSS geometry-free linear combination corresponding corrections could be derived. As a first validation step L4R corrections were applied to GNSS L1 data analysis. Station coordinate repeatibilities at the 1-cm level were obtained for baselines of a few thousand kilometers. Comparing the derived delay corrections to VLBI ionospheric delays for quasars located in same directions, differences with a standard deviation of 2.2 TECU could be achieved. Numéro de notice : A2016-035 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern En ligne : http://link.springer.com/article/10.1007/s00190-015-0865-6/fulltext.html Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=79512 [article]

Co-location of geodetic observation techniques in space / Benjamin Männel (2016)  

Public Titre : Co-location of geodetic observation techniques in space Type de document : Thèse/HDR Auteurs : Benjamin Männel, Auteur Editeur : Zurich : Schweizerischen Geodatischen Kommission / Commission Géodésique Suisse Année de publication : 2016 Autre Editeur : Zurich : Eidgenossische Technische Hochschule ETH - Ecole Polytechnique Fédérale de Zurich EPFZ Collection : Geodätisch-Geophysikalische Arbeiten in der Schweiz, ISSN 0257-1722 num. 97 Importance : 200 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-908440-43-7 Note générale : bibliographie A thesis submitted to attain the degree of Doctor of Sciences of ETH Zurich (Eidg. Technische Hochschule Zürich) Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes descripteurs IGN] antenne GPS [Termes descripteurs IGN] Bernese [Termes descripteurs IGN] centre de phase [Termes descripteurs IGN] co-positionnement [Termes descripteurs IGN] données GRACE [Termes descripteurs IGN] géocentre [Termes descripteurs IGN] interférométrie à très grande base [Termes descripteurs IGN] International Terrestrial Reference System [Termes descripteurs IGN] orbite basse [Termes descripteurs IGN] orbitographie [Termes descripteurs IGN] positionnement par GPS [Termes descripteurs IGN] poursuite de satellite [Termes descripteurs IGN] propagation ionosphérique [Termes descripteurs IGN] repère de référence [Termes descripteurs IGN] système international de référence céleste Index. décimale : 30.60 Géodésie spatiale Résumé : (auteur) This thesis describes the combination of geodetic observation techniques on-board satellites. This socalled co-location in space provides a considerable potential regarding the improvements needed to realize a long-term accurate and stable terrestrial reference frame. The space ties (i.e., the offset vectors between the on-board sensors) introduces new geometrical connections between sensors of dfferent space geodetic techniques. This space ties can be provided easily to each fundamental site via space geodetic observations. Consequently, co-location in space allows to assess technique-specific error sources as systematic effects can be addressed either to a certain station or to a certain technique. Moreover, the additional introduced orbit dynamics improve the estimation of several geodetic parameters. Within this thesis the following core topics concerning co-location in space are discussed: orbit determination, the combination of ground and space GNSS observations, and VLBI Earth-orbiting satellite tracking. Highly accurate orbit determination is the prerequisite for a suitable co-location in space. Based on the Earth observation satellite missions GRACE, GOCE, and OSTM/Jason-2 orbit determination and the impact of modeling non gravitational perturbations is studied. The overall reached orbit accuracies are at the level of a few centimeters. The combination of ground and space-geodetic GNSS observations is studied based on the GPS observations derived by 53 ground stations and the four LEOs (low Earth orbiter). Adding one LEO to the ground-only processing decreases the formal errors of weekly geocenter estimates by around 20% which is eight times more than expected due to the increased number of observations. This shows the considerable potential of the combination of ground and LEO data. Comparing the derived geocenter time series against results from satellite laser ranging (SLR) shows a good agreement for annual amplitudes, whereas the annual phases shows considerable discrepancies in the x- and the z-component. Geocenter coordinates derived from surface load density coeficients estimated in a long-term solution show a better agreement to SLR solutions but without a significant impact of additional LEOs. Using the gravitational constraint GPS satellite antenna phase center offsets were estimated based on ground and LEO observations. The results show a significant benefit for the horizontal offsets as the introduced LEOs help to dissolve limiting correlations. Concerning single-frequency VLBI satellite tracking the L4R method is introduced to derive ionosphere delay corrections based on co-located GNSS observations. A 1 cm daily station coordinate repeatability is achieved in a single-frequency GNSS processing while introducing the L4R corrections. Differences to ionospheric delays derived from VLBI observations show also a good agreement. As VLBI satellite tracking is currently in an experimental stage Monte-Carlo simulations were performed for eight different satellite orbit types. For a GNSS constellation tracking, station coordinate repeatabilities are at the level of 0.7 and 1.2 cm for a regional and a global network, respectively. Station coordinate repeatabilities of around 1 cm were derived for simulated VLBI observation to a fictitious LEO with an altitude of 2000 km. The station coordinates estimated from simulated observations to E-GRIP and E-GRASP/Eratosthenes show larger uncertainties. Based on the results suggestions for future action items regarding co-location in space were formulated. The most important recommendations are, that the combination of ground- and space GNSS observations provides a considerable benefit for the determination of several parameters and that ionosphere delay corrections should be derived from co-located GNSS observations. Note de contenu : 1- Motivation and Introduction 2- Geodetic Observation Techniques in a Nutshell 3- Reference Systems and the Combination and Co-location of Space Geodetic Techniques 4- Investigations on GPS-based Precise Orbit Determination for Low Earth Orbiters 5- Investigations on the Combined Processing of Ground- and Space-based GPS Observations 6- Investigations on VLBI Satellite Tracking 7- Conclusions and Outlook Numéro de notice : 21987 Thématique : POSITIONNEMENT Nature : Thèse étrangère Note de thèse : PhD : Sciences : ETH Zurich : 2016 DOI : 10.3929/ethz-a-010811791 En ligne : https://www.research-collection.ethz.ch/handle/20.500.11850/125751 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91982

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