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The mixed-receiver BeiDou inter-satellite-type bias and its impact on RTK positioning / Nandakumaran Nadarajah in GPS solutions, vol 19 n° 3 (July 2015)  

Public [article]  inGPS solutions > vol 19 n° 3 (July 2015) . - pp 357 - 368 Titre : The mixed-receiver BeiDou inter-satellite-type bias and its impact on RTK positioning Type de document : Article/Communication Auteurs : Nandakumaran Nadarajah, Auteur ; Peter J.G. Teunissen, Auteur ; Jean-Marie Sleewaegen, Auteur ; Oliver Montenbruck, Auteur Année de publication : 2015 Article en page(s) : pp 357 - 368 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes IGN] erreur systématique [Termes IGN] positionnement cinématique en temps réel [Termes IGN] récepteur mixte [Termes IGN] récepteur monofréquence [Termes IGN] résolution d'ambiguïté [Termes IGN] signal BeiDou Résumé : (Auteur) The inter-satellite-type bias (ISTB) is a receiver-dependent hardware delay/bias between different satellite types. Our recent research revealed the existence of nonzero mixed-receiver phase ISTBs for the Chinese BeiDou system. Triggered by this finding, global navigation satellite system receiver manufactures, who are in the early stage of BeiDou-enabled receiver developments, are working toward a mutually consistent measurement extraction procedure. We analyze the long-term stability and current status of the mixed-receiver ISTBs, as well as study their impact on BeiDou stand-alone real-time kinematic (RTK) positioning. Our results confirm that a recent update in one of the receiver types has aligned it with one of the other receiver types. However, since not all receiver types are aligned yet, nonzero mixed-receiver ISTBs are shown to be still present. Analyses of BeiDou stand-alone RTK positioning using mixed-receiver types demonstrate that ISTBs could seriously affect the integer ambiguity resolution performance and that a priori correction for these biases will dramatically improve the success rate. Our analyses using real data from three different receiver types also demonstrate the long-term stability of the ISTBs, thus showing that such a priori calibration is indeed possible. Numéro de notice : A2015-460 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10291-014-0392-6 Date de publication en ligne : 28/06/2014 En ligne : https://doi.org/10.1007/s10291-014-0392-6 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=77130 [article]

Reduction of PPP convergence period through pseudorange multipath and noise mitigation / Garrett Seepersad in GPS solutions, vol 19 n° 3 (July 2015)  

Public [article]  inGPS solutions > vol 19 n° 3 (July 2015) . - pp 369 - 379 Titre : Reduction of PPP convergence period through pseudorange multipath and noise mitigation Type de document : Article/Communication Auteurs : Garrett Seepersad, Auteur ; Sunil Bisnath, Auteur Année de publication : 2015 Article en page(s) : pp 369 - 379 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes IGN] bruit atmosphérique [Termes IGN] correction du trajet multiple [Termes IGN] filtrage du bruit [Termes IGN] mesurage de pseudo-distance [Termes IGN] positionnement ponctuel précis [Termes IGN] trajet multiple Résumé : (auteur) Pseudorange multipath and pseudorange noise are the largest remaining unmanaged error sources in PPP. It is proposed that by reducing the effects of multipath and noise on the pseudorange observable, accurate estimates of carrier phase float ambiguities will be attained sooner, thus reducing the initial convergence period of PPP. Given the problem, this study seeks to improve mitigation of the pseudorange errors. The well-known multipath linear combination is used in two distinct ways: (1) to directly correct the raw pseudorange observables and (2) to stochastically de-weight the pseudorange observables. The improvements in the solution were calculated with respect to the conventional GPS PPP float solution, where the raw pseudorange observables were not modified or stochastically de-weighted. Corrections to the observables were made using the multipath linear combination from data obtained from the previous and same day. Minimal improvements were noted using the multipath observable from the previous day. Using the multipath observable from the same day was possible in real-time and post-processing modes, showing an improvement in the rate of convergence for 48 and 57 % of the data, respectively. An improvement in the rate of convergence for 34 % of the data was observed when the pseudorange measurements were stochastically de-weighted using the multipath observable. Datasets with no improvements from directly correcting the raw pseudorange observables (43 %) or stochastically de-weighting the pseudorange observables (66 %) presented similar quality of results as the conventional PPP solution. Numéro de notice : A2015-461 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10291-014-03 Date de publication en ligne : 01/08/2014 En ligne : https://doi.org/10.1007/s10291-014-0395-3 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=77136 [article]

Using ionospheric corrections from the space-based augmentation systems for low earth orbiting satellites / Jeongrae Kim in GPS solutions, vol 19 n° 3 (July 2015)  

Public [article]  inGPS solutions > vol 19 n° 3 (July 2015) . - pp 423 - 431 Titre : Using ionospheric corrections from the space-based augmentation systems for low earth orbiting satellites Type de document : Article/Communication Auteurs : Jeongrae Kim, Auteur ; Young Jae, Auteur Année de publication : 2015 Article en page(s) : pp 423 - 431 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Technologies spatiales [Termes IGN] correction ionosphérique [Termes IGN] données GRACE [Termes IGN] European Geostationary Navigation Overlay Service [Termes IGN] orbite basse [Termes IGN] orbitographie [Termes IGN] signal GPS [Termes IGN] système d'extension spatial [Termes IGN] teneur totale en électrons [Termes IGN] Wide Area Augmentation System Résumé : (auteur) For low earth orbit satellite global positioning systems (GPS) receivers, ionospheric delay corrections from space-based augmentation system (SBAS) can be considered for real-time use. Due to the different total electron contents between ground and low altitude orbits, a scaling factor is required to adjust the ionospheric corrections. After an analysis of the scale factor determination with GPS data from the NASA/DLR gravity recovery and climate experiment satellite is conducted, evaluations of WAAS, MSAS, and EGNOS ionospheric correction accuracies are performed. In terms of the ionospheric correction error in 2012, SBAS outperforms GPS broadcast with the reduction of 42 %. This SBAS ionospheric correction accuracy shows a high level of correlation with solar flux F10.7. Numéro de notice : A2015-462 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10291-014-0402-8 Date de publication en ligne : 22/08/2014 En ligne : https://doi.org/10.1007/s10291-014-0402-8 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=77138 [article]

GBAS ionospheric threat model assessment for category I operation in the Korean region / Minchan Kim in GPS solutions, vol 19 n° 3 (July 2015)  

Public [article]  inGPS solutions > vol 19 n° 3 (July 2015) . - pp 443 - 456 Titre : GBAS ionospheric threat model assessment for category I operation in the Korean region Type de document : Article/Communication Auteurs : Minchan Kim, Auteur ; Yunjung Choi, Auteur ; Hyang-Sig Jun, Auteur ; Jiyun Lee, Auteur Année de publication : 2015 Article en page(s) : pp 443 - 456 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] Corée du sud [Termes IGN] gradient ionosphèrique [Termes IGN] perturbation ionosphérique [Termes IGN] système d'extension au sol Résumé : (auteur) During extreme ionospheric storms, anomalous ionospheric gradients can become high enough to affect Global Navigation Satellite Systems (GNSS) Ground-Based Augmentation Systems (GBAS) and to threaten the safety of GBAS users. An ionospheric anomaly threat model for the Conterminous United States (CONUS) was developed based on extreme ionospheric gradients observed in CONUS during the last solar maximum period (2000–2004). However, in order to understand and mitigate ionosphere threats occurring in different geographical regions, ionospheric anomaly threat models have to be established for the relevant regions. To allow the certification of a GBAS ground facility in South Korea, a Korean ionospheric anomaly threat model must be determined. We describe the method of data analysis that was used to estimate ionospheric spatial gradients. Estimates of anomalous gradients in the Korean region were used to define and build an ionospheric anomaly threat model for this region. All gradient estimates obtained using Korean GNSS reference network data for potential ionospheric storm dates from 2000 to 2004 were included in this threat space. The maximum spatial gradient within this threat space is 160 mm of delay per km of user separation, which falls well within the bounds of the current ionospheric threat model for CONUS. We also provide a detailed examination of the two largest ionospheric spatial gradient events observed in this study, which occurred on November 10, 2004, and November 6, 2001, respectively. Numéro de notice : A2015-463 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10291-014-0404-6 En ligne : https://doi.org/10.1007/s10291-014-0404-6 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=77144 [article]

Development of an improved empirical model for slant delays in the troposphere (GPT2w) / Johannes Böhm in GPS solutions, vol 19 n° 3 (July 2015)    

Public [article]  inGPS solutions > vol 19 n° 3 (July 2015) . - pp 433 - 441 Titre : Development of an improved empirical model for slant delays in the troposphere (GPT2w) Type de document : Article/Communication Auteurs : Johannes Böhm , Auteur ; Gregor Möller, Auteur ; Michael Schindelegger, Auteur ; Grégory Pain, Auteur ; Robert Weber, Auteur Année de publication : 2015 Article en page(s) : pp 433 - 441 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] coordonnées GNSS [Termes IGN] erreur systématique [Termes IGN] modèle empirique [Termes IGN] retard troposphérique [Termes IGN] station permanente [Termes IGN] teneur en vapeur d'eau Résumé : (Auteur) Global pressure and temperature 2 wet (GPT2w) is an empirical troposphere delay model providing the mean values plus annual and semiannual amplitudes of pressure, temperature and its lapse rate, water vapor pressure and its decrease factor, weighted mean temperature, as well as hydrostatic and wet mapping function coefficients of the Vienna mapping function 1. All climatological parameters have been derived consistently from monthly mean pressure level data of ERA-Interim fields (European Centre for Medium-Range Weather Forecasts Re-Analysis) with a horizontal resolution of 1°, and the model is suitable to calculate slant hydrostatic and wet delays down to 3° elevation at sites in the vicinity of the earth surface using the date and approximate station coordinates as input. The wet delay estimation builds upon gridded values of the water vapor pressure, the weighted mean temperature, and the water vapor decrease factor, with the latter being tuned to ray-traced zenith wet delays. Comparisons with zenith delays at 341 globally distributed global navigation satellite systems stations show that the mean bias over all stations is below 1 mm and the mean standard deviation is about 3.6 cm. The GPT2w model with the gridded input file is provided at. Numéro de notice : A2015--112 Affiliation des auteurs : ENSG+Ext (2012-2019) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s10291-014-0403-7 Date de publication en ligne : 26/08/2014 En ligne : https://doi.org/10.1007/s10291-014-0403-7 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=90646 [article]

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