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Laser ranging data analysis for a colocation campaign of French Transportable Laser Ranging System (FTLRS) in Tahiti / Xiaoni Wang in Journal of geodesy, vol 89 n° 1 (January 2015)  

Public [article]  inJournal of geodesy > vol 89 n° 1 (January 2015) . - pp 1 - 11 Titre : Laser ranging data analysis for a colocation campaign of French Transportable Laser Ranging System (FTLRS) in Tahiti Type de document : Article/Communication Auteurs : Xiaoni Wang, Auteur ; Pascal Bonnefond, Auteur ; Pierre Exertier, Auteur ; David Coulot , Auteur ; Richard Biancale, Auteur ; Jean-Michel Lemoine, Auteur ; Jean-Claude Poyard, Auteur ; Clément Courde, Auteur ; Jean-Pierre Barriot, Auteur ; François Barlier, Auteur Année de publication : 2015 Article en page(s) : pp 1 - 11 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes IGN] analyse comparative [Termes IGN] co-positionnement [Termes IGN] données DORIS [Termes IGN] données GPS [Termes IGN] données Lageos [Termes IGN] données Starlette [Termes IGN] données TLS (télémétrie) [Termes IGN] International Terrestrial Reference Frame [Termes IGN] point de liaison (géodésie) [Termes IGN] Tahiti [Termes IGN] télémétrie laser transportable Résumé : (auteur) Tahiti is a unique geodetic site located in the south Pacific Ocean where few observatories exist nearby. The American mobile station MOBLAS-8 was installed in Tahiti in 1998, and GPS and DORIS systems were also deployed in its vicinity in order to develop this site into one of the fundamental colocated sites of the International Terrestrial Reference Frame. In order to make a new estimate of the colocation differences between the different techniques, a campaign of the French Transportable Laser Ranging System (FTLRS) was conducted in Tahiti between April and October 2011. The FTLRS was deployed close to the existing equipment. Observations for LAGEOS 1, LAGEOS 2 and Starlette were studied, and the solutions to the local ties between FTLRS, MOBLAS-8, DORIS and GPS were evaluated. Our results of the geodetic local-ties between laser stations and GPS agree well with the measurements made by the Institut National de l’Information Géographique et Forestière (IGN) during the campaign, with differences less than 2 mm in the vertical direction. The laser station range biases as a function of satellites are also presented, −3 (±2) mm for MOBLAS-8 and 3 (±3) mm for FTLRS, respectively. In addition, we investigated the role of time bias (ranging from a few hundreds of nanoseconds to one microsecond) given by the Time Transfer by Laser Link experiment, which shows a limited impact on the present SLR analysis. We also compared the coordinates of the three available techniques at Tahiti, i.e., laser, GPS and DORIS. We found the accuracy of laser solutions still needs to be improved, so that the SLR at Tahiti could contribute more effectively to the tracking of satellites and thus to the international reference frame. This study is useful in evaluating the SLR and other space techniques in order to prepare the deployment of new equipment in Tahiti in the near future. Numéro de notice : A2015-230 Affiliation des auteurs : IGN+Ext (2012-2019) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-014-0755-3 En ligne : https://doi.org/10.1007/s00190-014-0755-3 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=76064 [article]

Retrieving three-dimensional displacement fields of mining areas from a single InSAR pair / Zhi Wei Li in Journal of geodesy, vol 89 n° 1 (January 2015)  

Public [article]  inJournal of geodesy > vol 89 n° 1 (January 2015) . - pp 17 - 32 Titre : Retrieving three-dimensional displacement fields of mining areas from a single InSAR pair Type de document : Article/Communication Auteurs : Zhi Wei Li, Auteur ; Zefa Yang, Auteur ; Jian Jun Zhu, Auteur ; et al., Auteur Année de publication : 2015 Article en page(s) : pp 17 - 32 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes IGN] Chine [Termes IGN] déformation horizontale de la croute terrestre [Termes IGN] déformation verticale de la croute terrestre [Termes IGN] données localisées 3D [Termes IGN] image ALOS-PALSAR [Termes IGN] interféromètrie par radar à antenne synthétique [Termes IGN] lever souterrain [Termes IGN] mine de charbon [Termes IGN] positionnement par GPS [Termes IGN] subsidence [Termes IGN] surveillance géologique Résumé : (auteur) This paper presents a novel method for retrieving three-dimensional (3-D) displacement fields of mining areas from a single interferometric synthetic aperture radar (InSAR) pair. This method fully exploits the mechanism of mining subsidence, specifically the proportional relationship between the horizontal displacement and horizontal gradient of vertical displacements caused by underground mining. This method overcomes the limitations of conventional InSAR techniques that can only measure one-dimensional (1-D) deformation of mining area along the radar line-of-sight direction. The proposed method is first validated with simulated 3-D displacement fields, which are obtained by the FLAC3D software. The root mean square errors of the 3-D displacements retrieved by the proposed method are 13.7, 27.6 and 3.6 mm for the West–East, North–South, and Up–Down components, respectively. We then apply the proposed method to estimate the 3-D displacements of the Qianyingzi and the Xuzhou coal mines in China, respectively, each along with two Advanced Land Observing Satellite (ALOS) Phased Array Type L-band Synthetic Aperture Radar images. Results show that the estimated 3-D displacement is highly consistent with that of the field surveying. This demonstrates that the proposed method is an effective approach for retrieving 3-D mining displacement fields and will play an important role in mining-related hazard prevention and environment assessment under limited InSAR acquisitions. Numéro de notice : A2015-327 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-014-0757-1 Date de publication en ligne : 09/09/2014 En ligne : https://doi.org/10.1007/s00190-014-0757-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=76652 [article]

GOCE: assessment of GPS-only gravity field determination / Adrian Jäggi in Journal of geodesy, vol 89 n° 1 (January 2015)  

Public [article]  inJournal of geodesy > vol 89 n° 1 (January 2015) . - pp 33 - 48 Titre : GOCE: assessment of GPS-only gravity field determination Type de document : Article/Communication Auteurs : Adrian Jäggi, Auteur ; Heike Bock, Auteur ; U. Meyer, Auteur ; et al., Auteur Année de publication : 2015 Article en page(s) : pp 33 - 48 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] champ de pesanteur terrestre [Termes IGN] champ géomagnétique [Termes IGN] données GOCE [Termes IGN] données GPS [Termes IGN] erreur systématique [Termes IGN] ionosphère [Termes IGN] orbite précise [Termes IGN] positionnement cinématique Résumé : (auteur) The GOCE satellite was orbiting the Earth in a Sun-synchronous orbit at a very low altitude for more than 4 years. This low orbit and the availability of high-quality data make it worthwhile to assess the contribution of GOCE GPS data to the recovery of both the static and time-variable gravity fields. We use the kinematic positions of the official GOCE precise science orbit (PSO) product to perform gravity field determination using the Celestial Mechanics Approach. The generated gravity field solutions reveal severe systematic errors centered along the geomagnetic equator. Their size is significantly coupled with the ionospheric density and thus generally increasing over the mission period. The systematic errors may be traced back to the kinematic positions of the PSO product and eventually to the ionosphere-free GPS carrier phase observations used for orbit determination. As they cannot be explained by the current higher order ionospheric correction model recommended by the IERS Conventions 2010, an empirical approach is presented by discarding GPS data affected by large ionospheric changes. Such a measure yields a strong reduction of the systematic errors along the geomagnetic equator in the gravity field recovery, and only marginally reduces the set of useable kinematic positions by at maximum 6 % for severe ionosphere conditions. Eventually it is shown that GOCE gravity field solutions based on kinematic positions have a limited sensitivity to the largest annual signal related to land hydrology. Numéro de notice : A2015-328 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-014-0759-z Date de publication en ligne : 10/09/2014 En ligne : https://doi.org/10.1007/s00190-014-0759-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=76653 [article]

Accounting for Galileo–GPS inter-system biases in precise satellite positioning / Jacek Paziewski in Journal of geodesy, vol 89 n° 1 (January 2015)  

Public [article]  inJournal of geodesy > vol 89 n° 1 (January 2015) . - pp 81 - 93 Titre : Accounting for Galileo–GPS inter-system biases in precise satellite positioning Type de document : Article/Communication Auteurs : Jacek Paziewski, Auteur ; Pawel Wielgosz, Auteur Année de publication : 2015 Article en page(s) : pp 81 - 93 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] acquisition de données [Termes IGN] analyse comparative [Termes IGN] données GNSS [Termes IGN] double différence [Termes IGN] erreur systématique [Termes IGN] fusion de données [Termes IGN] positionnement différentiel [Termes IGN] signal Galileo [Termes IGN] signal GPS [Termes IGN] stabilité dans le temps Résumé : (auteur) Availability of two overlapping frequencies L1/E1 and L5/E5a of the signals transmitted by GPS and Galileo systems offers the possibility of tightly combining observations from both systems in a single observational model. A tightly combined observational model assumes a single reference satellite for all observations from both Galileo and GPS systems. However, when inter-system double-differenced observations are created, receiver inter-system bias is introduced. This study presents the results and the methodology for estimation and accounting for phase and code GPS-Galileo inter-system bias in precise relative positioning. The research investigates the size and temporal stability of the estimated bias for different receiver pairs as well as examines the influence of accounting for the inter-system bias on the user position solution. The obtained numerical results are based on four experiments carried out at different locations and time periods using both real and simulated GNSS data. Numéro de notice : A2015-329 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-014-0763-3 En ligne : https://doi.org/10.1007/s00190-014-0763-3 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=76654 [article]

Positioning configurations with the lowest GDOP and their classification / Shuqiang Xue in Journal of geodesy, vol 89 n° 1 (January 2015)  

Public [article]  inJournal of geodesy > vol 89 n° 1 (January 2015) . - pp 49 - 71 Titre : Positioning configurations with the lowest GDOP and their classification Type de document : Article/Communication Auteurs : Shuqiang Xue, Auteur ; Yuanxi Yang, Auteur Année de publication : 2015 Article en page(s) : pp 49 - 71 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] affaiblissement géométrique de la précision [Termes IGN] constellation GNSS [Termes IGN] équation linéaire [Termes IGN] erreur systématique [Termes IGN] optimisation (mathématiques) [Termes IGN] orbitographie [Termes IGN] polyèdre [Termes IGN] pseudolite Résumé : (auteur) The positioning configuration optimization is a basic problem in surveying, and the geometric dilution of precision (GDOP) is a key index to handle this problem. Simplex graphs as regular polygons and regular polyhedrons are the well-known configurations with the lowest GDOP. However, it has been proved that there are at most five kinds of regular polyhedrons. We analytically solve the GDOP minimization problem with arbitrary observational freedom to extend the current knowledge. The configuration optimization framework established is composed of the algebraic and geometric operators (including combination, reflection, collinear mapping, projection and three kinds of equivalence relations), basic properties to GDOP minimization (including continuity, combination invariant, reflection invariant, rotation invariant and collinear invariant) and the lowest GDOP configurations (including cones, regular polygons, regular polyhedrons, Descartes configuration, helical configuration and generalized Walker configuration, and their reflections and combinations). GDOP minimization criterion and D-maximization criterion both reduce to the same criterion matrices that the optimization becomes the problem for solving an underdetermined quadratic equation system. Making use of the concepts for solving underdetermined linear equation system, the concepts of base configuration (single classification) and general configuration (combined classification) are applied to the GDOP minimization to analytically solve the quadratic equation system. Firstly, the problems are divided into two subproblems by two kinds of GDOP to reveal the impact of the clock-offset on the configuration optimization, and it shows that the symmetry and uniformity play a key role in identifying the systematic errors. Then, the solution of the GDOP minimization is classified by the number of symmetry axes, that the base configurations with at least one symmetry axis and the general configurations without symmetry axis are categorized to be two large classifications. Complex configurations can be then generated by the combination and the reflection of those base configurations with simplex structure, and this indicates that completely solving the GDOP minimization needs to solve the simplex classifications primarily. Ultimately, constrained or unconstrained configuration optimization examples including GDOP distribution analysis, single-global satellite navigation system (GNSS) or multi-GNSS constellation design, configuration optimization of pseudolites and configuration design of buoys for underwater positioning are performed by employing the properties, lemmas, theorems and corollaries proposed. Numéro de notice : A2015-330 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-014-0760-6 Date de publication en ligne : 14/10/2014 En ligne : https://doi.org/10.1007/s00190-014-0760-6 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=76655 [article]