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Dependency of geodynamic parameters on the GNSS constellation / Stefano Scaramuzza in Journal of geodesy, vol 92 n° 1 (January 2018)  

Public [article]  inJournal of geodesy > vol 92 n° 1 (January 2018) . - pp 93 - 104 Titre : Dependency of geodynamic parameters on the GNSS constellation Type de document : Article/Communication Auteurs : Stefano Scaramuzza, Auteur ; Rolf Dach, Auteur ; Gerhard Beutler, Auteur ; Daniel Arnold, Auteur ; Andreja Sušnik, Auteur ; Adrian Jäggi, Auteur Année de publication : 2018 Article en page(s) : pp 93 - 104 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] constellation GLONASS [Termes IGN] constellation GPS [Termes IGN] géocentre [Termes IGN] mouvement du pôle [Termes IGN] orbite [Termes IGN] série temporelle Résumé : (Auteur) Significant differences in time series of geodynamic parameters determined with different Global Navigation Satellite Systems (GNSS) exist and are only partially explained. We study whether the different number of orbital planes within a particular GNSS contributes to the observed differences by analyzing time series of geocenter coordinates (GCCs) and pole coordinates estimated from several real and virtual GNSS constellations: GPS, GLONASS, a combined GPS/GLONASS constellation, and two virtual GPS sub-systems, which are obtained by splitting up the original GPS constellation into two groups of three orbital planes each. The computed constellation-specific GCCs and pole coordinates are analyzed for systematic differences, and their spectral behavior and formal errors are inspected. We show that the number of orbital planes barely influences the geocenter estimates. GLONASS’ larger inclination and formal errors of the orbits seem to be the main reason for the initially observed differences. A smaller number of orbital planes may lead, however, to degradations in the estimates of the pole coordinates. A clear signal at three cycles per year is visible in the spectra of the differences between our estimates of the pole coordinates and the corresponding IERS 08 C04 values. Combinations of two 3-plane systems, even with similar ascending nodes, reduce this signal. The understanding of the relation between the satellite constellations and the resulting geodynamic parameters is important, because the GNSS currently under development, such as the European Galileo and the medium Earth orbit constellation of the Chinese BeiDou system, also consist of only three orbital planes. Numéro de notice : A2018-012 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-017-1047-5 En ligne : https://doi.org/10.1007/s00190-017-1047-5 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89055 [article]

CODE’s new ultra-rapid orbit and ERP products for the IGS / Simon Lutz in GPS solutions, vol 20 n° 2 (April 2016)  

Public [article]  inGPS solutions > vol 20 n° 2 (April 2016) . - pp 239 - 250 Titre : CODE’s new ultra-rapid orbit and ERP products for the IGS Type de document : Article/Communication Auteurs : Simon Lutz, Auteur ; Gerhard Beutler, Auteur ; Stefan Schaer, Auteur ; Rolf Dach, Auteur ; Adrian Jäggi, Auteur Année de publication : 2016 Article en page(s) : pp 239 - 250 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] Bernese [Termes IGN] international GPS service for geodynamics [Termes IGN] orbite [Termes IGN] rotation de la Terre Résumé : (Auteur) The International GNSS Service (IGS) issues four sets of so-called ultra-rapid products per day, which are based on the contributions of the IGS Analysis Centers. The traditional (“old”) ultra-rapid orbit and earth rotation parameters (ERP) solution of the Center for Orbit Determination in Europe (CODE) was based on the output of three consecutive 3-day long-arc rapid solutions. Information from the IERS Bulletin A was required to generate the predicted part of the old CODE ultra-rapid product. The current (“new”) product, activated in November 2013, is based on the output of exactly one multi-day solution. A priori information from the IERS Bulletin A is no longer required for generating and predicting the orbits and ERPs. This article discusses the transition from the old to the new CODE ultra-rapid orbit and ERP products and the associated improvement in reliability and performance. All solutions used in this article were generated with the development version of the Bernese GNSS Software. The package was slightly extended to meet the needs of the new CODE ultra-rapid generation. Numéro de notice : A2016-613 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10291-014-0432-2 En ligne : http://dx.doi.org/10.1007/s10291-014-0432-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81813 [article]

Impact of the arc length on GNSS analysis results / Simon Lutz in Journal of geodesy, vol 90 n° 4 (April 2016)  

Public [article]  inJournal of geodesy > vol 90 n° 4 (April 2016) . - pp 365 - 378 Titre : Impact of the arc length on GNSS analysis results Type de document : Article/Communication Auteurs : Simon Lutz, Auteur ; Michael Meindl, Auteur ; Peter Steigenberger, Auteur ; Gerhard Beutler, Auteur ; Krzysztof Sosnica, Auteur ; Stefan Schaer, Auteur ; Rolf Dach, Auteur ; Daniel Arnold, Auteur ; Daniela Thaller, Auteur ; Adrian Jäggi, Auteur Année de publication : 2016 Article en page(s) : pp 365 - 378 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] géocentre [Termes IGN] mouvement du pôle [Termes IGN] orientation de la Terre [Vedettes matières IGN] Traitement de données GNSS Résumé : (auteur) Homogeneously reprocessed combined GPS/GLONASS 1- and 3-day solutions from 1994 to 2013, generated by the Center for Orbit Determination in Europe (CODE) in the frame of the second reprocessing campaign REPRO-2 of the International GNSS Service, as well as GPS- and GLONASS-only 1- and 3-day solutions for the years 2009 to 2011 are analyzed to assess the impact of the arc length on the estimated Earth Orientation Parameters (EOP, namely polar motion and length of day), on the geocenter, and on the orbits. The conventional CODE 3-day solutions assume continuity of orbits, polar motion components, and of other parameters at the day boundaries. An experimental 3-day solution, which assumes continuity of the orbits, but independence from day to day for all other parameters, as well as a non-overlapping 3-day solution, is included into our analysis. The time series of EOPs, geocenter coordinates, and orbit misclosures, are analyzed. The long-arc solutions were found to be superior to the 1-day solutions: the RMS values of EOP and geocenter series are typically reduced between 10 and 40 %, except for the polar motion rates, where RMS reductions by factors of 2–3 with respect to the 1-day solutions are achieved for the overlapping and the non-overlapping 3-day solutions. In the low-frequency part of the spectrum, the reduction is even more important. The better performance of the orbits of 3-day solutions with respect to 1-day solutions is also confirmed by the validation with satellite laser ranging. Numéro de notice : A2016-250 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-015-0878-1 Date de publication en ligne : 24/12/2015 En ligne : https://doi.org/10.1007/s00190-015-0878-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=80758 [article]

CODE’s new solar radiation pressure model for GNSS orbit determination / Daniel Arnold in Journal of geodesy, vol 89 n° 8 (August 2015)  

Public [article]  inJournal of geodesy > vol 89 n° 8 (August 2015) . - pp 775 - 791 Titre : CODE’s new solar radiation pressure model for GNSS orbit determination Type de document : Article/Communication Auteurs : Daniel Arnold, Auteur ; Michael Meindl, Auteur ; Gerhard Beutler, Auteur ; et al., Auteur Année de publication : 2015 Article en page(s) : pp 775 - 791 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Technologies spatiales [Termes IGN] géocentre [Termes IGN] International GNSS Service [Termes IGN] modèle d'orbite [Termes IGN] orbitographie [Termes IGN] rayonnement solaire [Termes IGN] récepteur GLONASS [Termes IGN] récepteur GPS [Termes IGN] rotation de la Terre Résumé : (auteur) The Empirical CODE Orbit Model (ECOM) of the Center for Orbit Determination in Europe (CODE), which was developed in the early 1990s, is widely used in the International GNSS Service (IGS) community. For a rather long time, spurious spectral lines are known to exist in geophysical parameters, in particular in the Earth Rotation Parameters (ERPs) and in the estimated geocenter coordinates, which could recently be attributed to the ECOM. These effects grew creepingly with the increasing influence of the GLONASS system in recent years in the CODE analysis, which is based on a rigorous combination of GPS and GLONASS since May 2003. In a first step we show that the problems associated with the ECOM are to the largest extent caused by the GLONASS, which was reaching full deployment by the end of 2011. GPS-only, GLONASS-only, and combined GPS/GLONASS solutions using the observations in the years 2009–2011 of a global network of 92 combined GPS/GLONASS receivers were analyzed for this purpose. In a second step we review direct solar radiation pressure (SRP) models for GNSS satellites. We demonstrate that only even-order short-period harmonic perturbations acting along the direction Sun-satellite occur for GPS and GLONASS satellites, and only odd-order perturbations acting along the direction perpendicular to both, the vector Sun-satellite and the spacecraft’s solar panel axis. Based on this insight we assess in the third step the performance of four candidate orbit models for the future ECOM. The geocenter coordinates, the ERP differences w. r. t. the IERS 08 C04 series of ERPs, the misclosures for the midnight epochs of the daily orbital arcs, and scale parameters of Helmert transformations for station coordinates serve as quality criteria. The old and updated ECOM are validated in addition with satellite laser ranging (SLR) observations and by comparing the orbits to those of the IGS and other analysis centers. Based on all tests, we present a new extended ECOM which substantially reduces the spurious signals in the geocenter coordinate z (by about a factor of 2–6), reduces the orbit misclosures at the day boundaries by about 10 %, slightly improves the consistency of the estimated ERPs with those of the IERS 08 C04 Earth rotation series, and substantially reduces the systematics in the SLR validation of the GNSS orbits. Numéro de notice : A2015-376 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-015-0814-4 Date de publication en ligne : 12/05/2015 En ligne : https://doi.org/10.1007/s00190-015-0814-4 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=76854 [article]

The impact of common versus separate estimation of orbit parameters on GRACE gravity field solutions / U. Meyer in Journal of geodesy, vol 89 n° 7 (July 2015)  

Public [article]  inJournal of geodesy > vol 89 n° 7 (July 2015) . - pp 685 - 696 Titre : The impact of common versus separate estimation of orbit parameters on GRACE gravity field solutions Type de document : Article/Communication Auteurs : U. Meyer, Auteur ; Adrian Jäggi, Auteur ; Gerhard Beutler, Auteur ; Heike Bock, Auteur Année de publication : 2015 Article en page(s) : pp 685 - 696 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] données GRACE [Termes IGN] élément orbital [Termes IGN] orbitographie [Termes IGN] paramètre de temps [Termes IGN] propagation du signal [Termes IGN] traitement du signal Résumé : (auteur) Gravity field parameters are usually determined from observations of the GRACE satellite mission together with arc-specific parameters in a generalized orbit determination process. When separating the estimation of gravity field parameters from the determination of the satellites’ orbits, correlations between orbit parameters and gravity field coefficients are ignored and the latter parameters are biased towards the a priori force model. We are thus confronted with a kind of hidden regularization. To decipher the underlying mechanisms, the Celestial Mechanics Approach is complemented by tools to modify the impact of the pseudo-stochastic arc-specific parameters on the normal equations level and to efficiently generate ensembles of solutions. By introducing a time variable a priori model and solving for hourly pseudo-stochastic accelerations, a significant reduction of noisy striping in the monthly solutions can be achieved. Setting up more frequent pseudo-stochastic parameters results in a further reduction of the noise, but also in a notable damping of the observed geophysical signals. To quantify the effect of the a priori model on the monthly solutions, the process of fixing the orbit parameters is replaced by an equivalent introduction of special pseudo-observations, i.e., by explicit regularization. The contribution of the thereby introduced a priori information is determined by a contribution analysis. The presented mechanism is valid universally. It may be used to separate any subset of parameters by pseudo-observations of a special design and to quantify the damage imposed on the solution. Numéro de notice : A2015-354 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-015-0807-3 Date de publication en ligne : 29/03/2015 En ligne : https://doi.org/10.1007/s00190-015-0807-3 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=76777 [article]

Impact of loading displacements on SLR-derived parameters and on the consistency between GNSS and SLR results / Krzysztof Sosnica in Journal of geodesy, vol 87 n° 8 (August 2013)  

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Evaluation of the impact of atmospheric pressure loading modeling on GNSS data analysis / Rolf Dach in Journal of geodesy, vol 85 n° 2 (February 2011)  

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Rapid static positioning using GPS and GLONASS / Gerhard Beutler in Bulletin of geodesy and geomatics BGG, vol 69 n° 2 - 3 (December 2010)

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The celestial mechanics approach: application to data of the GRACE mission / Gerhard Beutler in Journal of geodesy, vol 84 n° 11 (November 2010)  

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The celestial mechanics approach : theoretical foundations / Gerhard Beutler in Journal of geodesy, vol 84 n° 10 (October 2010)  

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The International Global navigation satellite systems Service (IGS): development and achievements / Gerhard Beutler in Journal of geodesy, vol 83 n° 3-4 (March - April 2009)  

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IGEX, International GLONASS Experiment : scientific objectives and preparation / Pascal Willis in Advances in space research, vol 23 n° 4 (01/10/1999)  

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Progress report 1998, commission 8, international Coordination of Space Techniques for Geodesy and geodynamics (CSTG) [of the] international association of geodesy (IAG) / Gerhard Beutler (1999)

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Reprocessing of about 15 months of global IGS data using improved orbit model / Serge Botton (01/04/1997)

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Report on the activities of the sub-commission on precise satellite microwave systems / Gerhard Beutler in CSTG bulletin, n° 13 ([01/01/1997])

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