Centre de documentation
scientifique

Accuracy assessment of the GPS-TEC calibration constants by means of a simulation technique / Jacques Conte in Journal of geodesy, vol 85 n° 10 (October 2011)  

Public [article]  inJournal of geodesy > vol 85 n° 10 (October 2011) . - pp 707 - 714 Titre : Accuracy assessment of the GPS-TEC calibration constants by means of a simulation technique Type de document : Article/Communication Auteurs : Jacques Conte, Auteur ; F. Azpilicueta, Auteur ; C. Brunini, Auteur Année de publication : 2011 Article en page(s) : pp 707 - 714 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] analyse diachronique [Termes IGN] GPS en mode différentiel [Termes IGN] ionosphère [Termes IGN] propagation ionosphérique [Termes IGN] rayonnement solaire [Termes IGN] teneur totale en électrons [Termes IGN] variation saisonnière Résumé : (Auteur) During the last 2 decades, Global Positioning System (GPS) measurements have become a very important data-source for ionospheric studies. However, it is not a direct and easy task to obtain accurate ionospheric information from these measurements because it is necessary to perform a careful estimation of the calibration constants affecting the GPS observations, the so-called differential code biases (DCBs). In this paper, the most common approximations used in several GPS calibration methods, e.g. the La Plata Ionospheric Model (LPIM), are applied to a set of specially computed synthetic slant Total Electron Content datasets to assess the accuracy of the DCB estimation in a global scale scenario. These synthetic datasets were generated using a modified version of the NeQuick model, and have two important features: they show a realistic temporal and spatial behavior and all a-priori DCBs are set to zero by construction. Then, after the application of the calibration method the deviations from zero of the estimated DCBs are direct indicators of the accuracy of the method. To evaluate the effect of the solar activity radiation level the analysis was performed for years 2001 (high solar activity) and 2006 (low solar activity). To take into account seasonal changes of the ionosphere behavior, the analysis was repeated for three consecutive days close to each equinox and solstice of every year. Then, a data package comprising 24 days from approximately 200 IGS permanent stations was processed. In order to avoid unwanted geomagnetic storms effects, the selected days correspond to periods of quiet geomagnetic conditions. The most important results of this work are: i) the estimated DCBs can be affected by errors around +8 TECu for high solar activity and +3 TECu for low solar activity; and ii) DCB errors present a systematic behavior depending on the modip coordinate, that is more evident for the positive modip region. Numéro de notice : A2011-435 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-011-0477-8 Date de publication en ligne : 15/05/2011 En ligne : https://doi.org/10.1007/s00190-011-0477-8 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31213 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-2011101	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Simulation study of the influence of the ionospheric layer height in the thin layer ionospheric model / C. Brunini in Journal of geodesy, vol 85 n° 9 (September 2011)  

Public [article]  inJournal of geodesy > vol 85 n° 9 (September 2011) . - pp 637 - 645 Titre : Simulation study of the influence of the ionospheric layer height in the thin layer ionospheric model Type de document : Article/Communication Auteurs : C. Brunini, Auteur ; E. Camilion, Auteur ; F. Azpilicueta, Auteur Année de publication : 2011 Article en page(s) : pp 637 - 645 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] altitude [Termes IGN] données GNSS [Termes IGN] erreur systématique [Termes IGN] modèle ionosphérique [Termes IGN] propagation ionosphérique [Termes IGN] simulation [Termes IGN] teneur totale en électrons [Termes IGN] variation saisonnière Résumé : (Auteur) This work aims to contribute to the understanding of the influence of the ionospheric layer height (ILH) on the thin layer ionospheric model (TLIM) used to retrieve ionospheric information from the GNSS observations. Particular attention is paid to the errors caused on the estimation of the vertical total electron content (vTEC) and the GNSS satellites and receivers inter-frequency biases (IFB), by the use of an inappropriate ILH. The work relies upon numerical simulations performed with an empirical model of the Earth’s ionosphere: the model is used to create realistic but controlled ionospheric scenarios and the errors are evaluated after recovering those scenarios with the TLIM. The error assessment is performed in the Central and the northern part of the South American continents, a region where large errors are expected due to the combined actions of the Appleton Anomaly of the ionosphere and the South-Atlantic anomaly of the geomagnetic field. According to this study, there does not exist a unique ILH that cancels the vTEC error for the whole region under consideration. The ILH that cancels the regional mean vTEC error varies with the solar activity and season. The latitude-dependent conversion error propagates to the parameters of the model used to represent the latitudinal variation on the vTEC on the ionospheric layer, and to the IFB, when these values are simultaneously estimated from the observed sTEC. Besides, the ILH that cancels the regional mean vTEC error is different from the one that cancels the IFB error and the difference between both ILH varies with the solar activity and season. Numéro de notice : A2011-377 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-011-0470-2 Date de publication en ligne : 19/04/2011 En ligne : https://doi.org/10.1007/s00190-011-0470-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31156 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-2011091	RAB	Revue	Centre de documentation	En réserve L003	Disponible

GPS slant total electron content accuracy using the single layer model under different geomagnetic regions and ionospheric conditions / C. Brunini in Journal of geodesy, vol 84 n° 5 (May 2010)  

Public [article]  inJournal of geodesy > vol 84 n° 5 (May 2010) . - pp 293 - 304 Titre : GPS slant total electron content accuracy using the single layer model under different geomagnetic regions and ionospheric conditions Type de document : Article/Communication Auteurs : C. Brunini, Auteur ; F. Azpilicueta, Auteur Année de publication : 2010 Article en page(s) : pp 293 - 304 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] erreur systématique [Termes IGN] ionosphère [Termes IGN] positionnement par GPS [Termes IGN] teneur totale en électrons [Termes IGN] traitement de données GNSS Résumé : (Auteur) The use of observations from the Global Positioning System (GPS) has significantly impacted the study of the ionosphere. As it is widely known, dual-frequency GPS observations can provide very precise estimation of the slant Total Electron Content (sTEC—the linear integral of the electron density along a ray-path) and that the precision level is bounded by the carrier-phase noise and multi-path effects on both frequencies. Despite its precision, GPS sTEC estimations can be systematically affected by errors in the estimation of the satellites and receivers by Inter-Frequency Biases (IFB) that are simultaneously determined with the sTEC. Thus, the ultimate accuracy of the GPS sTEC estimation is determined by the errors with which the IFBs are estimated. This contribution attempts to assess the accuracy of IFBs estimation techniques based on the single layer model for different ionospheric regions (low, mid and high magnetic latitude); different seasons (summer and winter solstices and spring and autumn equinoxes); different solar activity levels (high and low); and different geomagnetic conditions (quiet and very disturbed). The followed strategy relies upon the generation of a synthetic data set free of IFB, multi-path, measurement noise and of any other error source. Therefore, when a data set with such properties is used as the input of the IFB estimation algorithms, any deviation from zero on the estimated IFBs should be taken as indications of the errors introduced by the estimation technique. The truthfulness of this assessment work is warranted by the fact that the synthetic data sets resemble, as realistically as possible, the different conditions that may happen in the real ionosphere. The results of this work show that during the high solar activity period the accuracy for the estimated sTEC is approximately of 110 TECu for the low geomagnetic region and of 12.2 TECu for the mid-latitude. During low solar activity the accuracy can be assumed to be in the order of 12 TECu. For the geomagnetic high-disturbed period, the results show that the accuracy is degraded for those stations located over the region where the storm has the strongest impact, but for those stations over regions where the storm has a moderate effect, the accuracy is comparable to that obtained in the quiet period. Numéro de notice : A2010-182 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-010-0367-5 Date de publication en ligne : 29/01/2010 En ligne : https://doi.org/10.1007/s00190-010-0367-5 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30377 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-2010051	SL	Revue	Centre de documentation	Revues en salle	Disponible

Accuracy assessment of the GPS-based slant total electron content / C. Brunini in Journal of geodesy, vol 83 n° 8 (August 2009)  

Public [article]  inJournal of geodesy > vol 83 n° 8 (August 2009) . - pp 773 - 785 Titre : Accuracy assessment of the GPS-based slant total electron content Type de document : Article/Communication Auteurs : C. Brunini, Auteur ; F. Azpilicueta, Auteur Année de publication : 2009 Article en page(s) : pp 773 - 785 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] calibrage [Termes IGN] erreur systématique [Termes IGN] étalonnage d'instrument [Termes IGN] ionosphère [Termes IGN] positionnement par GPS [Termes IGN] teneur totale en électrons Résumé : (Auteur) The main scope of this research is to assess the ultimate accuracy that can be achieved for the slant total electron content (sTEC) estimated from dual-frequency global positioning system (GPS) observations which depends, primarily, on the calibration of the inter-frequency biases (IFB). Two different calibration approaches are analyzed: the so-called satellite-by-satellite one, which involves levelling the carrier-phase to the code-delay GPS observations and then the IFB estimation; and the so-called arc-by-arc one, which avoids the use of code-delay observations but requires the estimation of arc-dependent biases. Two strategies are used for the analysis: the first one compares calibrated sTEC from two co-located GPS receivers that serve to assess the levelling errors; and the second one, assesses the model error using synthetic data free of calibration error, produced with a specially developed technique. The results show that the arc-by-arc calibration technique performs better than the satellite-by-satellite one for mid-latitudes, while the opposite happens for low-latitudes. Copyright Springer Numéro de notice : A2009-326 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-008-0296-8 En ligne : https://doi.org/10.1007/s00190-008-0296-8 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29956 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-09071	SL	Revue	Centre de documentation	Revues en salle	Disponible

Calibration errors on experimental slant total electron content (TEC) determined with GPS / L. Ciraolo in Journal of geodesy, vol 81 n° 2 (February 2007)  

Public [article]  inJournal of geodesy > vol 81 n° 2 (February 2007) . - pp 111 - 120 Titre : Calibration errors on experimental slant total electron content (TEC) determined with GPS Type de document : Article/Communication Auteurs : L. Ciraolo, Auteur ; F. Azpilicueta, Auteur ; C. Brunini, Auteur ; et al., Auteur Année de publication : 2007 Article en page(s) : pp 111 - 120 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] correction ionosphérique [Termes IGN] erreur systématique [Termes IGN] phase GPS [Termes IGN] positionnement par GPS [Termes IGN] propagation ionosphérique [Termes IGN] teneur totale en électrons [Termes IGN] trajet multiple Résumé : (Auteur) The Global Positioning System (GPS) has become a powerful tool for ionospheric studies. In addition, ionospheric corrections are necessary for the augmentation systems required for Global Navigation Satellite Systems (GNSS) use. Dual-frequency carrier-phase and code-delay GPS observations are combined to obtain ionospheric observables related to the slant total electron content (sTEC) along the satellite-receiver line-of-sight (LoS). This observable is affected by inter-frequency biases [IFB; often called differential code biases (DCB)] due to the transmitting and the receiving hardware. These biases must be estimated and eliminated from the data in order to calibrate the experimental sTEC obtained from GPS observations. Based on the analysis of single differences of the ionospheric observations obtained from pairs of co-located dual-frequency GPS receivers, this research addresses two major issues: (1) assessing the errors translated from the code-delay to the carrier-phase ionospheric observable by the so-called levelling process, applied to reduce carrier-phase ambiguities from the data; and (2) assessing the short-term stability of receiver IFB. The conclusions achieved are: (1) the levelled carrier-phase ionospheric observable is affected by a systematic error, produced by code-delay multi-path through the levelling procedure; and (2) receiver IFB may experience significant changes during 1 day. The magnitude of both effects depends on the receiver/antenna configuration. Levelling errors found in this research vary from 1.4 total electron content units (TECU) to 5.3 TECU. In addition, intra-day vaiations of code-delay receiver IFB ranging from 1.4 to 8.8 TECU were detected. Copyright Springer Numéro de notice : A2007-047 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-006-0093-1 En ligne : https://doi.org/10.1007/s00190-006-0093-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28412 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-07021	RAB	Revue	Centre de documentation	En réserve L003	Disponible
266-07022	RAB	Revue	Centre de documentation	En réserve L003	Disponible