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The AUSGeoid09 model of the Australian Height Datum / Will E. Featherstone in Journal of geodesy, vol 85 n° 3 (March 2011)  

Public [article]  inJournal of geodesy > vol 85 n° 3 (March 2011) . - pp 133 - 150 Titre : The AUSGeoid09 model of the Australian Height Datum Type de document : Article/Communication Auteurs : Will E. Featherstone, Auteur ; J.F. Kirby, Auteur ; C. Hirt, Auteur ; M. Filmer, Auteur ; et al., Auteur Année de publication : 2011 Article en page(s) : pp 133 - 150 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes IGN] Australian Height Datum [Termes IGN] Australie [Termes IGN] géoïde local [Termes IGN] positionnement par GNSS Résumé : (Auteur) AUSGeoid09 is the new Australia-wide gravimetric quasigeoid model that has been a posteriori fitted to the Australian Height Datum (AHD) so as to provide a product that is practically useful for the more direct determination of AHD heights from Global Navigation Satellite Systems (GNSS). This approach is necessary because the AHD is predominantly a third-order vertical datum that contains a ~1 m north-south tilt and ~0.5 m regional distortions with respect to the quasigeoid, meaning that GNSS-gravimetric-quasigeoid and AHD heights are inconsistent. Because the AHD remains the official vertical datum in Australia, it is necessary to provide GNSS users with effective means of recovering AHD heights. The gravimetric component of the quasigeoid model was computed using a hybrid of the remove-compute-restore technique with a degree-40 deterministically modified kernel over a one-degree spherical cap, which is superior to the remove-compute-restore technique alone in Australia (with or without a cap). This is because the modified kernel and cap combine to filter long-wavelength errors from the terrestrial gravity anomalies. The zero-tide EGM2008 global gravitational model to degree 2,190 was used as the reference field. Other input data are ~1.4 million land gravity anomalies from Geoscience Australia, 1' x ' DNSC2008GRA altimeter-derived gravity anomalies offshore, the 9"x 9" GEODATA-DEM9S Australian digital elevation model, and a readjustment of Australian National Levelling Network (ANLN) constrained to the CARS2006 mean dynamic ocean topography model. To determine the numerical integration parameters for the modified kernel, the gravimetric component of AUSGeoid09 was compared with 911 GNSS-observed ellipsoidal heights at benchmarks. The standard deviation of fit to the GNSS-AHD heights is + 222 mm, which dropped to + 134 mm for the readjusted GNSS-ANLN heights showing that careful consideration now needs to be given to the quality of the levelling data used to assess gravimetric quasigeoid models. The publicly released version of AUSGeoid09 also includes a geometric component that models the difference between the gravimetric quasigeoid and the zero surface of the AHD at 6,794 benchmarks. This a posteriori fitting used least-squares collocation (LSC) in cross-validation mode to determine a correlation length of 75 km for the analytical covariance function, whereas the noise was taken from the estimated standard deviation of the GNSS ellipsoidal heights. After this LSC surface fitting, the standard deviation of fit reduced to + 30 mm, one-third of which is attributable to the uncertainty in the GNSS ellipsoidal heights. Numéro de notice : A2011-163 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-010-0422-2 Date de publication en ligne : 19/11/2010 En ligne : https://doi.org/10.1007/s00190-010-0422-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30941 [article]

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266-2011031	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Regional reference network augmented precise point positioning for instantaneous ambiguity resolution / X. Li in Journal of geodesy, vol 85 n° 3 (March 2011)  

Public [article]  inJournal of geodesy > vol 85 n° 3 (March 2011) . - pp 151 - 158 Titre : Regional reference network augmented precise point positioning for instantaneous ambiguity resolution Type de document : Article/Communication Auteurs : X. Li, Auteur ; X. Zhang, Auteur ; M. Ge, Auteur Année de publication : 2011 Article en page(s) : pp 151 - 158 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] ambiguïté entière [Termes IGN] positionnement cinématique en temps réel [Termes IGN] positionnement ponctuel précis [Termes IGN] réseau géodésique local [Termes IGN] résolution d'ambiguïté Résumé : (Auteur) Integer ambiguity fixing can significantly shorten the initialization time and improve the accuracy of precise point positioning (PPP), but it still takes approximate 15 min of time to achieve reliable integer ambiguity solutions. In this contribution, we present a new strategy to augment PPP estimation with a regional reference network, so that instantaneous ambiguity fixing is achievable for users within the network coverage. In the proposed method, precise zero-differenced atmospheric delays are derived from the PPP fixed solution of the reference stations, which are disseminated to, and interpolated at user stations to correct for L1, L2 phase observations or their combinations. With the corrected observations, instantaneous ambiguity resolution can be carried out within the user PPP software, thus achieving the position solutions equivalent to the network real-time kinematic positioning (NRTK). The strategy is validated experimentally. The derived atmospheric delays and the interpolated corrections are investigated. The ambiguity fixing performance and the resulted position accuracy are assessed. The validation confirms that the new strategy can provide comparable service with NRTK. Therefore, with this new processing strategy, it is possible to integrate PPP and NRTK into a seamless positioning service, which can provide an accuracy of about 10 cm anywhere, and upgrade to a few centimeters within a regional network. Numéro de notice : A2011-164 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-010-0424-0 Date de publication en ligne : 23/11/2010 En ligne : https://doi.org/10.1007/s00190-010-0424-0 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30942 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-2011031	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Potentialities of multifrequency ionospheric correction in Global Navigation Satellite Systems / B. Kim in Journal of geodesy, vol 85 n° 3 (March 2011)  

Public [article]  inJournal of geodesy > vol 85 n° 3 (March 2011) . - pp 159 - 169 Titre : Potentialities of multifrequency ionospheric correction in Global Navigation Satellite Systems Type de document : Article/Communication Auteurs : B. Kim, Auteur ; M. Tinin, Auteur Année de publication : 2011 Article en page(s) : pp 159 - 169 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] correction ionosphérique [Termes IGN] diffraction [Termes IGN] propagation du signal [Termes IGN] récepteur bifréquence [Termes IGN] récepteur GNSS [Termes IGN] résidu [Termes IGN] traitement de données GNSS [Termes IGN] variance Résumé : (Auteur) The first-order ionospheric error is reduced in the dual-frequency Global Navigation Satellite Systems (GNSS). In this paper, the possibility of eliminating ionospheric higher-order errors in the multifrequency GNSS is explored. Since the second-order error associated with the geomagnetic field effect on the refractive index can be eliminated in dual-frequency measurements, we explore the possibility of eliminating third-order errors in triple-frequency GNSS in view of phase scintillations. A connection between the possibility of improving the multifrequency GNSS accuracy and diffraction effects in radio signal propagation through the randomly inhomogeneous ionosphere is shown. The numerical simulation has revealed that the systematic, residual ionospheric error is considerably reduced when we pass on from dual-frequency to triple-frequency measurements. The change in the residual error variance during such a transition depends however on the relationship between the inner scale of the turbulent spectrum of ionospheric irregularities and the Fresnel radius. Given the inner scale larger than the Fresnel radius, not only the systematic error, but also the standard deviation reduces when we pass on from dual-frequency to triple-frequency measurements. Otherwise, when the Fresnel radius exceeds the inner scale, the variance increases with increasing number of frequencies in use. Numéro de notice : A2011-165 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-010-0425-z Date de publication en ligne : 27/11/2010 En ligne : https://doi.org/10.1007/s00190-010-0425-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30943 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-2011031	RAB	Revue	Centre de documentation	En réserve L003	Disponible