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Integrity investigation of global ionospheric TEC maps for high-precision positioning / Jiaojiao Zhao in Journal of geodesy, vol 95 n° 3 (March 2021)  

Public [article]  inJournal of geodesy > vol 95 n° 3 (March 2021) . - n° 35 Titre : Integrity investigation of global ionospheric TEC maps for high-precision positioning Type de document : Article/Communication Auteurs : Jiaojiao Zhao, Auteur ; Manuel Hernández-Pajares, Auteur ; Ningbo Wang, Auteur ; et al., Auteur Année de publication : 2021 Article en page(s) : n° 35 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] carte ionosphérique mondiale [Termes IGN] erreur moyenne quadratique [Termes IGN] International GNSS Service [Termes IGN] modèle ionosphérique [Termes IGN] modèle stochastique [Termes IGN] positionnement ponctuel précis [Termes IGN] tempête magnétique [Termes IGN] teneur totale en électrons Résumé : (auteur) Aside from the ionospheric total electron content (TEC) information, root-mean-square (RMS) maps are also provided as the standard deviations of the corresponding TEC errors in global ionospheric maps (GIMs). As the RMS maps are commonly used as the accuracy indicator of GIMs to optimize the stochastic model of precise point positioning algorithms, it is of crucial importance to investigate the reliability of RMS maps involved in GIMs of different Ionospheric Associated Analysis Centers (IAACs) of the International GNSS Service (IGS), i.e., the integrity of GIMs. We indirectly analyzed the reliability of RMS maps by comparing the actual error of the differential STEC (dSTEC) with the RMS of the dSTEC derived from the RMS maps. With this method, the integrity of seven rapid IGS GIMs (UQRG, CORG, JPRG, WHRG, EHRG, EMRG, and IGRG) and six final GIMs (UPCG, CODG, JPLG, WHUG, ESAG and IGSG) was examined under the maximum and minimum solar activity conditions as well as the geomagnetic storm period. The results reveal that the reliability of the RMS maps is significantly different for the GIMs from different IAACs. Among these GIMs, the values in the RMS maps of UQRG are large, which can be used as ionospheric protection level, while the RMS values in EHRG and ESAG are significantly lower than the realistic RMS. The rapid and final GIMs from CODE, JPL and WHU provide quite reasonable RMS maps. The bounding performance of RMS maps can be influenced by the location of the stations, while the influence of solar activity and the geomagnetic storm is not obvious. Numéro de notice : A2021-220 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-021-01487-8 Date de publication en ligne : 22/02/2021 En ligne : https://doi.org/10.1007/s00190-021-01487-8 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=97188 [article]

An examination of the Galileo NeQuick model: comparison with GPS and JASON TEC / Ningbo Wang in GPS solutions, vol 21 n° 2 (April 2017)  

Public [article]  inGPS solutions > vol 21 n° 2 (April 2017) . - pp 605 – 615 Titre : An examination of the Galileo NeQuick model: comparison with GPS and JASON TEC Type de document : Article/Communication Auteurs : Ningbo Wang, Auteur ; Yunbin Yuan, Auteur ; Zishen Li, Auteur ; et al., Auteur Année de publication : 2017 Article en page(s) : pp 605 – 615 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] analyse comparative [Termes IGN] modèle ionosphérique [Termes IGN] retard ionosphèrique [Termes IGN] teneur totale en électrons [Termes IGN] test de performance Résumé : (auteur) We evaluate the performance of Galileo broadcast NeQuick model by comparing it with GPS broadcast Klobuchar and the original NeQuick2 models. The broadcast coefficients of Galileo NeQuick model are computed from 23 globally distributed tracking stations of the International GNSS Service (IGS), by ingesting the Global Positioning System (GPS)-derived ionospheric total electron content (TEC) into the original NeQuick2 model. The accuracy of the three ionospheric models is evaluated over both the continental and oceanic regions for the year 2013. In continental regions, ionospheric TEC derived from 34 IGS stations is used as references for comparison. In oceanic regions, where the IGS stations are sparse, high-quality vertical TEC sources provided by JASON-1&2 altimeters are used as references. The evaluation results show that in continental regions, GPS broadcast Klobuchar and the original and broadcast NeQuick can mitigate the ionospheric delay by 56.8, 63.3 and 72.4 %, respectively. In oceanic regions, the three models can correct for 51.1, 61.2 and 68.6 % of the ionospheric delay. Galileo broadcast NeQuick model outperforms Klobuchar by 15.6 and 17.5 % over the continental and oceanic regions, respectively, for the test period. The broadcast NeQuick model can provide accurate ionospheric error corrections when Galileo begins full operational capability. Numéro de notice : A2017-213 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10291-016-0553-x En ligne : http://dx.doi.org/10.1007/s10291-016-0553-x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=85085 [article]

Estimation and analysis of Galileo differential code biases / Min Li in Journal of geodesy, vol 91 n° 3 (March 2017)  

Public [article]  inJournal of geodesy > vol 91 n° 3 (March 2017) . - pp 279 - 293 Titre : Estimation and analysis of Galileo differential code biases Type de document : Article/Communication Auteurs : Min Li, Auteur ; Yunbin Yuan, Auteur ; Ningbo Wang, Auteur ; et al., Auteur Année de publication : 2017 Article en page(s) : pp 279 - 293 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] analyse comparative [Termes IGN] combinaison au niveau des observations [Termes IGN] constellation Galileo [Termes IGN] données Galileo [Termes IGN] données GPS [Termes IGN] erreur systématique [Termes IGN] estimation statistique [Termes IGN] Galileo en mode différentiel [Termes IGN] mesurage de pseudo-distance [Termes IGN] récepteur bifréquence [Termes IGN] récepteur GNSS [Termes IGN] signal Galileo Mots-clés libres : Multi-GNSS Experiment (MGEX) Résumé : (Auteur) When sensing the Earth’s ionosphere using dual-frequency pseudorange observations of global navigation satellite systems (GNSS), the satellite and receiver differential code biases (DCBs) account for one of the main sources of error. For the Galileo system, limited knowledge is available about the determination and characteristic analysis of the satellite and receiver DCBs. To better understand the characteristics of satellite and receiver DCBs of Galileo, the IGGDCB (IGG, Institute of Geodesy and Geophysics, Wuhan, China) method is extended to estimate the satellite and receiver DCBs of Galileo, with the combined use of GPS and Galileo observations. The experimental data were collected from the Multi-GNSS Experiment network, covering the period of 2013–2015. The stability of both Galileo satellite and receiver DCBs over a time period of 36 months was thereby analyzed for the current state of the Galileo system. Good agreement of Galileo satellite DCBs is found between the IGGDCB-based DCB estimates and those from the German Aerospace Center (DLR), at the level of 0.22 ns. Moreover, high-level stability of the Galileo satellite DCB estimates is obtained over the selected time span (less than 0.25 ns in terms of standard deviation) by both IGGDCB and DLR algorithms. The Galileo receiver DCB estimates are also relatively stable for the case in which the receiver hardware device stays unchanged. It can also be concluded that the receiver DCB estimates are rather sensitive to the change of the firmware version and that the receiver antenna type has no great impact on receiver DCBs. Numéro de notice : A2017-066 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-016-0962-1 En ligne : http://dx.doi.org/10.1007/s00190-016-0962-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=84294 [article]

Determination of differential code biases with multi-GNSS observations / Ningbo Wang in Journal of geodesy, vol 90 n° 3 (March 2016)  

Public [article]  inJournal of geodesy > vol 90 n° 3 (March 2016) . - pp 209 - 228 Titre : Determination of differential code biases with multi-GNSS observations Type de document : Article/Communication Auteurs : Ningbo Wang, Auteur ; Yunbin Yuan, Auteur ; Zishen Li, Auteur ; et al., Auteur Année de publication : 2016 Article en page(s) : pp 209 - 228 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] code GNSS [Termes IGN] erreur systématique [Termes IGN] estimation de précision [Termes IGN] retard ionosphèrique [Termes IGN] teneur totale en électrons [Vedettes matières IGN] Traitement de données GNSS Résumé : (auteur) In order to better understand the differential code biases (DCBs) of global navigation satellite system, the IGGDCB method is extended to estimate the intra- and inter-frequency biases of the global positioning system (GPS), GLONASS, BeiDou navigation satellite system (BDS), and Galileo based on observations collected by the multi-GNSS experiment (MGEX) of the international GNSS service (IGS). In the approach of IGGDCB, the local ionospheric total electronic content is modeled with generalized triangular series (GTS) function rather than using a global ionosphere model or a priori ionospheric information. The DCB estimated by the IGGDCB method is compared with the DCB products from the Center for Orbit Determination in Europe (CODE) and German Aerospace Center (DLR), as well as the broadcast timing group delay (TGD) parameters over a 2-year span (2013 and 2014). The results indicate that GPS and GLONASS intra-frequency biases obtained in this work show the same precision levels as those estimated by DLR (about 0.1 and 0.2–0.4 ns for the two constellations, respectively, with respect to the products of CODE). The precision levels of IGGDCB-based inter-frequency biases estimated over the 24-month period are about 0.29 ns for GPS, 0.56 ns for GLONASS, 0.36 ns for BDS, and 0.24 ns for Galileo, respectively. Here, the accuracies of GPS and GLONASS biases are assessed relative to the products of CODE, while those of BDS and Galileo are compared with the estimates of DLR. In addition, the monthly stability indices of IGGDCB-based DCBs are 0.11 (GPS), 0.18 (GLONASS), 0.17 (BDS), and 0.14 (Galileo) ns for the individual constellation. Numéro de notice : A2016-246 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-015-0867-4 Date de publication en ligne : 11/11/2015 En ligne : https://doi.org/10.1007/s00190-015-0867-4 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=80752 [article]

SHPTS: towards a new method for generating precise global ionospheric TEC map based on spherical harmonic and generalized trigonometric series functions / Zishen Li in Journal of geodesy, vol 89 n° 4 (April 2015)  

Public [article]  inJournal of geodesy > vol 89 n° 4 (April 2015) . - pp 333 - 345 Titre : SHPTS: towards a new method for generating precise global ionospheric TEC map based on spherical harmonic and generalized trigonometric series functions Type de document : Article/Communication Auteurs : Zishen Li, Auteur ; Yunbin Yuan, Auteur ; Ningbo Wang, Auteur ; et al., Auteur Année de publication : 2015 Article en page(s) : pp 333 - 345 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] données DORIS [Termes IGN] données Topex-Poseidon [Termes IGN] fonction harmonique [Termes IGN] harmonique sphérique [Termes IGN] modèle ionosphérique [Termes IGN] série de Fourier [Termes IGN] signal GNSS [Termes IGN] teneur totale en électrons [Termes IGN] trigonométrie sphérique Résumé : (auteur) To take maximum advantage of the increasing Global Navigation Satellite Systems (GNSS) data to improve the accuracy and resolution of global ionospheric TEC map (GIM), an approach, named Spherical Harmonic plus generalized Trigonometric Series functions (SHPTS), is proposed by integrating the spherical harmonic and the generalized trigonometric series functions on global and local scales, respectively. The SHPTS-based GIM from January 1st, 2001 to December 31st, 2011 (about one solar cycle) is validated by the ionospheric TEC from raw global GPS data, the GIM released by the current Ionospheric Associate Analysis Center (IAAC), the TOPEX/Poseidon satellite and the DORIS. The present results show that the SHPTS-based GIM over the area where no real data are available has the same accuracy level (approximately 2–6 TECu) to that released by the current IAAC. However, the ionospheric TEC in the SHPTS-based GIM over the area covered by real data is more accurate (approximately 1.5 TECu) than that of the GIM (approximately 3.0 TECu) released by the current IAAC. The external accuracy of the SHPTS-based GIM validated by the TOPEX/Poseidon and DORIS is approximately 2.5–5.5 and 1.5–4.5 TECu, respectively. In particular, the SHPTS-based GIM is the best or almost the best ranked, along with those of JPL and UPC, when they are compared with TOPEX/Poseidon measurements, and the best (in addition to UPC) when they are validated with DORIS data. With the increase in the number of GNSS satellites and contributing stations, the performance of the SHPTS-based GIM can be further improved. The SHPTS-based GIM routinely calculated using global GPS, GLONASS and BDS data will be found at the website http://​www.​gipp.​org.​cn. Numéro de notice : A2015-341 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-014-0778-9 Date de publication en ligne : 02/12/2014 En ligne : https://doi.org/10.1007/s00190-014-0778-9 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=76710 [article]