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GNSS three carrier ambiguity resolution using ionosphere-reduced virtual signals / Y. Feng in Journal of geodesy, vol 82 n° 12 (December 2008)  

Public [article]  inJournal of geodesy > vol 82 n° 12 (December 2008) Titre : GNSS three carrier ambiguity resolution using ionosphere-reduced virtual signals Type de document : Article/Communication Auteurs : Y. Feng, Auteur Année de publication : 2008 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] ambiguïté entière [Termes IGN] correction ionosphérique [Termes IGN] phase GNSS [Termes IGN] positionnement cinématique en temps réel [Termes IGN] positionnement par GNSS [Termes IGN] résolution d'ambiguïté [Termes IGN] signal GNSS [Termes IGN] traitement du signal Résumé : (Auteur) This paper presents a general modeling strategy for ambiguity resolution (AR) and position estimation (PE) using three or more phase-based ranging signals from a global navigation satellite system (GNSS). The proposed strategy will identify three best “virtual” signals to allow for more reliable AR under certain observational conditions characterized by ionospheric and tropospheric delay variability, level of phase noise and orbit accuracy. The selected virtual signals suffer from minimal or relatively low ionospheric effects, and thus are known as ionosphere-reduced virtual signals. As a result, the ionospheric parameters in the geometry-based observational models can be eliminated for long baselines, typically those of length tens to hundreds of kilometres. The proposed modeling comprises three major steps. Step 1 is the geometry-free determination of the extra-widelane (EWL) formed between the two closest L-band carrier measurements, directly from the two corresponding code measurements. Step 2 forms the second EWL signal and resolves the integer ambiguity with a geometry-based estimator alone or together with the first EWL. This is followed by a procedure to correct for the first-order ionospheric delay using the two ambiguity-fixed widelane (WL) signals derived from the integer-fixed EWL signals. Step 3 finds an independent narrow-lane (NL) signal, which is used together with a refined WL to resolve NL ambiguity with geometry-based integer estimation and search algorithms. As a result, the above two AR processes performed with WL/NL and EWL/WL signals respectively, either in sequence or in parallel, can support real time kinematic (RTK) positioning over baselines of tens to hundreds of kilometres, thus enabling centimetre-to-decimetre positioning at the local, regional and even global scales in the future. Copyright Springer Numéro de notice : A2008-469 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-008-0209-x En ligne : https://doi.org/10.1007/s00190-008-0209-x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29538 [article]

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The impact of errors in polar motion and nutation on UT1 determinations from VLBI Intensive observations / Axel Nothnagel in Journal of geodesy, vol 82 n° 12 (December 2008)  

Public [article]  inJournal of geodesy > vol 82 n° 12 (December 2008) . - pp 863 - 869 Titre : The impact of errors in polar motion and nutation on UT1 determinations from VLBI Intensive observations Type de document : Article/Communication Auteurs : Axel Nothnagel, Auteur ; D. Schnell, Auteur Année de publication : 2008 Article en page(s) : pp 863 - 869 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] compensation [Termes IGN] données ITGB [Termes IGN] écart type [Termes IGN] erreur systématique [Termes IGN] mouvement du pôle [Termes IGN] nutation [Termes IGN] temps universel Résumé : (Auteur) The earth’s phase of rotation, expressed as Universal Time UT1, is the most variable component of the earth’s rotation. Continuous monitoring of this quantity is realised through daily single-baseline VLBI observations which are interleaved with VLBI network observations. The accuracy of these single-baseline observations is established mainly through statistically determined standard deviations of the adjustment process although the results of these measurements are prone to systematic errors. The two major effects are caused by inaccuracies in the polar motion and nutation angles introduced as a priori values which propagate into the UT1 results. In this paper, we analyse the transfer of these components into UT1 depending on the two VLBI baselines being used for short duration UT1 monitoring. We develop transfer functions of the errors in polar motion and nutation into the UT1 estimates. Maximum values reach 30 [?s per milliarcsecond] which is quite large considering that observations of nutation offsets w.r.t. the state-of-the-art nutation model show deviations of as much as one milliarcsecond. Copyright Springer Numéro de notice : A2008-470 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-008-0212-2 En ligne : https://doi.org/10.1007/s00190-008-0212-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29539 [article]

Exemplaires(2)

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266-08112	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Polar motion modeling, analysis, and prediction with time dependent harmonic coefficients / Huseyin Baki Iz in Journal of geodesy, vol 82 n° 12 (December 2008)  

Public [article]  inJournal of geodesy > vol 82 n° 12 (December 2008) . - pp 871 - 881 Titre : Polar motion modeling, analysis, and prediction with time dependent harmonic coefficients Type de document : Article/Communication Auteurs : Huseyin Baki Iz, Auteur Année de publication : 2008 Article en page(s) : pp 871 - 881 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] modèle de simulation [Termes IGN] mouvement du pôle [Termes IGN] série temporelle [Termes IGN] terme de Chandler Résumé : (Auteur) A time dependent amplitude model was proposed for the analysis and prediction of polar motion time series. The formulation was implemented to analyze part of the new combined solution, EOP (IERS) C 04, daily polar motion time series of 14 years length using a statistical model with first order autoregressive disturbances. A new solution approach, where the serial correlations of the disturbances are eliminated by sequentially differencing the measurements, was used to estimate the model parameters using weighted least squares. The new model parsimoniously represents the 14-year time series with 0.5 mas rms fit, close to the reported 0.1 mas observed pole position precisions for the x and y components. The model can also predict 6 months into the future with less than 4 mas rms prediction error for both polar motion components, and down to sub mas for one-step ahead prediction as validated using a set of daily time series data that are not used in the estimation. Copyright Springer Numéro de notice : A2008-471 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-008-0215-z En ligne : https://doi.org/10.1007/s00190-008-0215-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29540 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-08111	RAB	Revue	Centre de documentation	En réserve L003	Disponible
266-08112	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Assessing the accuracy of predicted ocean tide loading displacement values / Nigel Penna in Journal of geodesy, vol 82 n° 12 (December 2008)  

Public [article]  inJournal of geodesy > vol 82 n° 12 (December 2008) . - pp 893 - 907 Titre : Assessing the accuracy of predicted ocean tide loading displacement values Type de document : Article/Communication Auteurs : Nigel Penna, Auteur ; M. Bos, Auteur ; Trevor Baker, Auteur ; H. Scherneck, Auteur Année de publication : 2008 Article en page(s) : pp 893 - 907 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] interpolation bilinéaire [Termes IGN] marée océanique [Termes IGN] positionnement par GPS [Termes IGN] surcharge océanique Résumé : (Auteur) The accuracy of ocean tide loading (OTL) displacement values has long been assumed to be dominated by errors in the ocean tide models used, with errors due to the convolution scheme used considered very small (2–5%). However, this paper shows that much larger convolution errors can arise at sites within approximately 150 km of the coastline, depending on the method used to refine the discrete regularly spaced grid cells of the ocean tide model to better fit the coastline closest to the site of interest. If the local water mass redistribution approach is implemented, as used in the OLFG/OLMPP software recommended in the IERS 2003 conventions, OTL height displacement errors of up to around 20% can arise, depending on the ocean tide model used. Bilinear interpolation only, as used in the SPOTL and CARGA softwares for example, is shown from extensive global and regional comparisons of OTL displacement values derived from the different methods and softwares to be more appropriate. This is verified using GPS observations. The coastal refinement approach used in the OLFG/OLMPP software was therefore changed in August 2007 to use bilinear interpolation only. It is shown that with this change, OTL displacement values computed using OLFG/OLMPP, SPOTL and CARGA invariably agree to the millimetre level for coastal sites, and better than 0.2 mm for sites more than about 150 km inland. Copyright Springer Numéro de notice : A2008-472 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-008-0220-2 En ligne : https://doi.org/10.1007/s00190-008-0220-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29541 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-08111	RAB	Revue	Centre de documentation	En réserve L003	Disponible
266-08112	RAB	Revue	Centre de documentation	En réserve L003	Disponible

On the explicit determination of stability constants for linearized geodetic boundary value problems / Fernando Sanso in Journal of geodesy, vol 82 n° 12 (December 2008)  

Public [article]  inJournal of geodesy > vol 82 n° 12 (December 2008) . - pp 909 - 916 Titre : On the explicit determination of stability constants for linearized geodetic boundary value problems Type de document : Article/Communication Auteurs : Fernando Sanso, Auteur ; Giovanna Venuti, Auteur Année de publication : 2008 Article en page(s) : pp 909 - 916 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] champ de pesanteur terrestre [Termes IGN] problème des valeurs limites Résumé : (Auteur) The theory of GBVPs provide the basis to the approximate methods used to compute global gravity models. A standard approximation procedure is least squares, which implicitly assumes that data, e.g. gravity disturbance and gravity anomaly, are given functions in L 2(S). We know that solutions in these cases exist, but uniqueness (and coerciveness which implies stability of the numerical solutions) is the real problem. Conditions of uniqueness for the linearized fixed boundary and Molodensky problems are studied in detail. They depend on the geometry of the boundary; however, the case of linearized fixed boundary BVP puts practically no constraint on the surface S, while the linearized Molodensky BVP requires the previous knowledge of very low harmonics, for instance up to degree 25, if we want the telluroid to be free to have inclinations up to 60°. Copyright Springer Numéro de notice : A2008-473 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-008-0221-1 En ligne : https://doi.org/10.1007/s00190-008-0221-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29542 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-08111	RAB	Revue	Centre de documentation	En réserve L003	Disponible
266-08112	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Variations in the accuracy of gravity recovery due to ground track variability: GRACE, CHAMP, and GOCE / J. Klokocnik in Journal of geodesy, vol 82 n° 12 (December 2008)  

Public [article]  inJournal of geodesy > vol 82 n° 12 (December 2008) . - pp 917 - 927 Titre : Variations in the accuracy of gravity recovery due to ground track variability: GRACE, CHAMP, and GOCE Type de document : Article/Communication Auteurs : J. Klokocnik, Auteur ; C.A. Wagner, Auteur ; J. Kostelecky, Auteur ; et al., Auteur Année de publication : 2008 Article en page(s) : pp 917 - 927 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] champ de pesanteur terrestre [Termes IGN] GOCE [Termes IGN] GRACE [Termes IGN] orbite [Termes IGN] poursuite de satellite [Termes IGN] précision des mesures [Termes IGN] résonance Résumé : (Auteur) Following an earlier recognition of degraded monthly geopotential recovery from GRACE (Gravity Recovery And Climate Experiment) due to prolonged passage through a short repeat (low order resonant) orbit, we extend these insights also to CHAMP (CHAllenging Minisatellite Payload) and GOCE (Gravity field and steady state Ocean Circulation Explorer). We show wide track-density variations over time for these orbits in both latitude and longitude, and estimate that geopotential recovery will be as widely affected as well within all these regimes, with lesser track density leading to poorer recoveries. We then use recent models of atmospheric density to estimate the future orbit of GRACE and warn of degraded performance as other low order resonances are encountered in GRACE’s free fall. Finally implications for the GOCE orbit are discussed. Copyright Springer Numéro de notice : A2008-474 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-008-0222-0 En ligne : https://doi.org/10.1007/s00190-008-0222-0 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29543 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-08111	RAB	Revue	Centre de documentation	En réserve L003	Disponible
266-08112	RAB	Revue	Centre de documentation	En réserve L003	Disponible