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Termes IGN > sciences naturelles > physique > optique > optique physique > radiométrie > rayonnement électromagnétique > propagation ionosphérique
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Evaluating the impact of higher-order ionospheric corrections on multi-GNSS ultra-rapid orbit determination / Xinghan Chen in Journal of geodesy, vol 93 n° 9 (September 2019)
[article]
Titre : Evaluating the impact of higher-order ionospheric corrections on multi-GNSS ultra-rapid orbit determination Type de document : Article/Communication Auteurs : Xinghan Chen, Auteur ; Maorong Ge, Auteur ; Haroldo Antonio Marques, Auteur ; Harald Schuh, Auteur Année de publication : 2019 Article en page(s) : pp 1347 - 1365 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal
[Termes IGN] correction ionosphérique
[Termes IGN] orbitographie par GNSS
[Termes IGN] positionnement ponctuel précis
[Termes IGN] retard ionosphèrique
[Termes IGN] temps réelRésumé : (Auteur) The correction of higher-order ionospheric (HOI) delays remaining in the dual-frequency ionosphere-free combined observations is suggested after the confirmation of its impact on precise Global Navigation Satellite System (GNSS) data processing. However, in the precise orbit determination (POD) for generating ultra-rapid orbits, the higher-order corrections are not always considered most likely because a RT ionospheric model needed for calculating the higher-order corrections is hardly available or the HOI impact is believed rather small compared to the accuracy of the predicted orbit. With the increasing requirement on the positioning performances from various applications, providing more accurate and reliable ultra-rapid orbits becomes an essential task of the real-time GNSS precise positioning services. In this contribution, the temporal–spatial characteristics of HOI effects on GNSS observables are investigated thoroughly using data collected from International GNSS Service (IGS) global ground stations and fluctuations of the higher-order delays up to several centimeters are detected during periods of high ionospheric activity. Hereafter, we evaluate the HOI effects on the multi-GNSS POD based on a network with globally distributed IGS stations. Results show that owing to the applied HOI corrections, the agreement of overlapping orbits can be improved significantly for all satellites and especially in radial direction. The three-dimensional RMS values of the overlapping differences are reduced from 1.6, 2.0, 4.6 and 1.7 to 1.0, 1.1, 3.4, and 1.5 cm for GPS, GALILEO, BDS, and GLONASS, respectively. Furthermore, the orbit improvement is also confirmed by the satellite laser ranging (SLR) observations over a 2-month time period where the STD of SLR residuals is reduced by HOI corrections from 6.4 to 5.3 cm for the BDS-IGSO satellites. Numéro de notice : A2019-504 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-019-01249-7 Date de publication en ligne : 23/03/2019 En ligne : https://doi.org/10.1007/s00190-019-01249-7 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93786
in Journal of geodesy > vol 93 n° 9 (September 2019) . - pp 1347 - 1365[article]Consistency and analysis of ionospheric observables obtained from three precise point positioning models / Yan Xiang in Journal of geodesy, vol 93 n° 8 (August 2019)
[article]
Titre : Consistency and analysis of ionospheric observables obtained from three precise point positioning models Type de document : Article/Communication Auteurs : Yan Xiang, Auteur ; Yang Gao, Auteur ; Junbo Shi, Auteur ; Chaoqian Xu, Auteur Année de publication : 2019 Article en page(s) : pp 1161–1170 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] analyse comparative
[Termes IGN] cohérence géométrique
[Termes IGN] erreur de positionnement
[Termes IGN] erreur en altitude
[Termes IGN] erreur systématique
[Termes IGN] mesurage de phase
[Termes IGN] modèle ionosphérique
[Termes IGN] positionnement différentiel
[Termes IGN] positionnement ponctuel précis
[Termes IGN] propagation ionosphériqueRésumé : (auteur) Ionospheric observables based on Global Navigation Satellite System can be obtained by a variety of approaches. The most widely used one is the geometry-free combination of carrier-phase smoothed code measurements. This method, however, introduces leveling errors that substantially degrade the performance of ionospheric modeling and bias estimation. To reduce leveling errors, precise point positioning (PPP) model is preferred for obtaining the ionospheric observables. We aim to investigate whether the ionospheric observables obtained from three different PPP models are consistent and how the PPP-based ionospheric observables relates to the smoothed code method. The paper begins by formulating the ionospheric observables. We then explain the statistical evaluation methods used for analyzing the bias terms derived from these methods and assessing the leveling errors from the carrier-phase smoothed code method. Numerical analysis is then conducted to compare the bias terms in the ionospheric observables and evaluate the leveling errors. The ionospheric observables based on the three PPP models show strong consistency. Compared to leveling errors in the carrier-phase smoothed code method, the leveling errors using the uncombined PPP model are significantly reduced up to five times. Numéro de notice : A2019-384 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-019-01233-1 Date de publication en ligne : 12/02/2019 En ligne : https://doi.org/10.1007/s00190-019-01233-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93463
in Journal of geodesy > vol 93 n° 8 (August 2019) . - pp 1161–1170[article]Processing of GNSS constellations and ground station networks using the raw observation approach / Sebastian Strasser in Journal of geodesy, vol 93 n°7 (July 2019)
[article]
Titre : Processing of GNSS constellations and ground station networks using the raw observation approach Type de document : Article/Communication Auteurs : Sebastian Strasser, Auteur ; Torsten Mayer-Gürr, Auteur ; Norbert Zehentner, Auteur Année de publication : 2019 Article en page(s) : pp 1045 - 1057 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] analyse diachronique
[Termes IGN] antenne GNSS
[Termes IGN] constellation GNSS
[Termes IGN] données GPS
[Termes IGN] erreur systématique
[Termes IGN] étalonnage d'instrument
[Termes IGN] Global Orbitography Navigation Satellite System
[Termes IGN] horloge du satellite
[Termes IGN] orbitographie
[Termes IGN] position
[Termes IGN] repère de référence
[Termes IGN] retard ionosphèrique
[Termes IGN] station GNSS
[Termes IGN] station GPSRésumé : (auteur) This article describes the raw observation approach as implemented at Graz University of Technology to determine GNSS products like satellite orbits, clocks, and station positions. To assess the performance of the approach, 15 years (2003–2017) of observations from a network of 245 globally distributed IGS stations to the GPS constellation were processed on a daily basis using the IGS14 reference frame and antenna calibrations. The resulting products are evaluated against those determined by IGS analysis centers. Orbit fit quality relative to the IGS combination is comparable to the best-fitting solutions used for evaluation. Starting from early 2017, when the IGS switched to IGS14, the determined orbits fit better to the IGS combination than any other considered solution. Midnight discontinuities show good internal orbit consistency and no noticeable satellite block-dependency. Satellite clocks are comparable to the considered IGS analysis center solutions. Station positions differ from the IGS combination on a similar level to the solutions they were evaluated against. The temporal repeatability of station positions is slightly better than that of the IGS combination. The quality of resulting GNSS products confirms that the raw observation approach is well suited for the task of determining satellite orbits, clocks, and station positions. It provides an alternative to well-established approaches used by IGS analysis centers and simplifies the introduction of additional observables from new and modernized GNSS. Numéro de notice : A2019-358 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-018-1223-2 Date de publication en ligne : 13/12/2018 En ligne : https://doi.org/10.1007/s00190-018-1223-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93426
in Journal of geodesy > vol 93 n°7 (July 2019) . - pp 1045 - 1057[article]Helmert-VCE-aided fast-WTLS approach for global ionospheric VTEC modelling using data from GNSS, satellite altimetry and radio occultation / Andong Hu in Journal of geodesy, vol 93 n°6 (June 2019)
[article]
Titre : Helmert-VCE-aided fast-WTLS approach for global ionospheric VTEC modelling using data from GNSS, satellite altimetry and radio occultation Type de document : Article/Communication Auteurs : Andong Hu, Auteur ; Zishen Li, Auteur ; Brett Anthony Carter, Auteur ; et al., Auteur Année de publication : 2019 Article en page(s) : pp 877 - 888 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] carte ionosphérique mondiale
[Termes IGN] données altimétriques
[Termes IGN] données GNSS
[Termes IGN] méthode des moindres carrés
[Termes IGN] modèle ionosphérique
[Termes IGN] occultation du signal
[Termes IGN] pondération
[Termes IGN] retard ionosphèrique
[Termes IGN] teneur verticale totale en électrons
[Termes IGN] varianceRésumé : (auteur) Vertical total electron content (VTEC) global ionospheric maps (GIM) are commonly used to correct the ionospheric delay of global navigation satellite system (GNSS) signals for single-frequency positioning and other ionospheric studies. The measurements observed by inhomogeneously distributed ground reference stations are the only data used to generate the GIMs. Thus the accuracy of the GIMs over ocean and polar regions is relatively poor due to the lack of measurements over these regions. In this study, space-borne VTECs obtained from ocean-altimetry and GNSS radio occultation measurements are incorporated into the modelling process. Since the three types of VTEC data have different qualities, the weight for each type of data is determined using the Helmert-variance component estimation (Helmert-VCE) method. In addition, unlike the traditional weighted least squares (WLS) estimation method in which the design matrix of observation equations is fixed, in this study, the design matrix, especially those elements in design matrix that are derived from the coordinates of either tangent point or ionospheric pierce point, are considered to be inaccurate. Thus they are adjusted together with the unknown coefficient parameters of the fitting model using the fast-weighted total least squares (fast-WTLS) technique. The proposed approach, named Helmert-WTLS, was tested using the data in the period of day of year (DOY) 217–224, 2016 and validated using GIMs produced by the research team for ionosphere and precise positioning based on BDS/GNSS (GIPP) at the Academy of Opto-Electronics, Chinese Academy of Sciences (CAS). Comparison results showed that the GIMs (with a 2 h temporal resolution) generated using the new approach can improve the determination of ionospheric TEC by 0.28 TEC units (TECU) over those from the Helmert-VCE-aided WLS approach (w.r.t CAS references, respectively) and by 1.61 TECU better than those from WLS, in terms of the mean of all root-mean-squares errors of all 2 h time slots in the 8-day testing period. In addition, in comparison with out-of-sample Jason-3 observations, results from the proposed method also outperformed Helmert-VCE-aided WLS, CAS and CODE models by 1.5, 2.4 and 2.4 TECU, respectively. Numéro de notice : A2019-352 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-018-1210-7 Date de publication en ligne : 14/11/2018 En ligne : https://doi.org/10.1007/s00190-018-1210-7 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93398
in Journal of geodesy > vol 93 n°6 (June 2019) . - pp 877 - 888[article]Seasonal pattern in time series of variances of GPS residual errors Anova estimates / Darko Anđić in Geodetski vestnik, vol 63 n° 2 (June - August 2019)
[article]
Titre : Seasonal pattern in time series of variances of GPS residual errors Anova estimates Type de document : Article/Communication Auteurs : Darko Anđić, Auteur Année de publication : 2019 Article en page(s) : pp 260 - 271 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] double différence
[Termes IGN] positionnement par GPS
[Termes IGN] propagation ionosphérique
[Termes IGN] propagation troposphérique
[Termes IGN] rayonnement solaire
[Termes IGN] résidu
[Termes IGN] série temporelle
[Termes IGN] variance
[Termes IGN] variation saisonnièreRésumé : (auteur) In this paper, which represents a continuation of the previous author's work, an inconstancy of GPS residual error ANOVA estimates and their variances are presented. For the purpose of the analysis, fixed solutions for all of the three coordinates, e (eastwards), n (northwards) and u (upwards), obtained by using ionosphere-free (L0) linear combination of double-difference phase observations in the processing of GPS data, were employed. The aim of the research was to consider the behaviour of variances of GPS residual error ANOVA estimates in time because there has not been any paper dealing with that issue so far. Herein, it turned out a seasonal pattern in related time series was present. In addition, it was concluded there was a difference in ANOVA estimate extreme values obtained when one considered daily data subsets compared to those obtained in the approach considering monthly data of the fixed solutions. GPS data collected at ending stations of a baseline of 40 km in length within a four-year period, involving the lowest and increased solar activity, were used in calculations. Numéro de notice : A2019-405 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.15292/geodetski-vestnik.2019.02.260-271 En ligne : http://dx.doi.org/10.15292/geodetski-vestnik.2019.02.260-271 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93509
in Geodetski vestnik > vol 63 n° 2 (June - August 2019) . - pp 260 - 271[article]Réservation
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