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Visualization of GNSS multipath effects and its potential application in IGS data processing / Weiming Tang in Journal of geodesy, vol 95 n° 9 (September 2021)  

Public [article]  inJournal of geodesy > vol 95 n° 9 (September 2021) . - n° 103 Titre : Visualization of GNSS multipath effects and its potential application in IGS data processing Type de document : Article/Communication Auteurs : Weiming Tang, Auteur ; Yawei Wang, Auteur ; Xuan Zou, Auteur ; et al., Auteur Année de publication : 2021 Article en page(s) : n° 103 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] grille [Termes IGN] interférence [Termes IGN] international GPS service for geodynamics [Termes IGN] modèle d'erreur [Termes IGN] phase [Termes IGN] positionnement cinématique [Termes IGN] qualité des données [Termes IGN] trajet multiple [Vedettes matières IGN] Traitement de données GNSS Résumé : (auteur) A modified multipath error mitigation method using the multi-point hemispherical grid model (MHGM) is proposed, and the influence of changes in the observation environments of IGS stations on their data quality is evaluated. The multipath error models of different satellite pairs for different observation periods can be established using the integrated multi-GNSS data in the proposed method. The test under deliberate high multipath environment reveals that this method can effectively estimate the GNSS multipath error, detect and present the orientation of the interference sources around the station. The RMS of residuals and the kinematic positioning accuracy on day 237 of 2018 are improved by 68% and 61%, respectively. Compared with the empirical site model (ESM), which can also visualize the effects of the multipath, the RMS of residuals when applying the MHGM is improved by 20%. The test with IGS historical observations shows that MHGM can effectively reflect the influence of changing multipath interference around stations on carrier phase observations, with an average improvement of 25% in the RMS of carrier phase residuals in the extrapolated 9-day validations over the past 18 years. The results of a kinematic positioning experiment in 2019 generally coincide with the RMS statistic results of carrier phase residuals as well. The MHGM demonstrates distinct potential in the influence evaluation of changes for the multipath interference around the stations on their observation quality. Numéro de notice : A2021-625 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-021-01559-9 Date de publication en ligne : 28/08/2021 En ligne : https://doi.org/10.1007/s00190-021-01559-9 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=98249 [article]

Improved ambiguity resolution for URTK with dynamic atmosphere constraints / Weiming Tang in Journal of geodesy, vol 90 n° 12 (December 2016)  

Public [article]  inJournal of geodesy > vol 90 n° 12 (December 2016) . - pp 1359 - 1369 Titre : Improved ambiguity resolution for URTK with dynamic atmosphere constraints Type de document : Article/Communication Auteurs : Weiming Tang, Auteur ; Wenjian Liu, Auteur ; Xuan Zou, Auteur ; et al., Auteur Année de publication : 2016 Article en page(s) : pp 1359 - 1369 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes IGN] correction ionosphérique [Termes IGN] effet atmosphérique [Termes IGN] positionnement cinématique en temps réel [Termes IGN] précision du positionnement [Termes IGN] résidu [Termes IGN] résolution d'ambiguïté Résumé : (Auteur) Raw observation processing method with prior knowledge of ionospheric delay could strengthen the ambiguity resolution (AR), but it does not make full use of the relatively longer wavelength of wide-lane (WL) observation. Furthermore, the accuracy of calculated atmospheric delays from the regional augmentation information has quite different in quality, while the atmospheric constraint used in the current methods is usually set to an empirical value. A proper constraint, which matches the accuracy of calculated atmospheric delays, can most effectively compensate the residual systematic biases caused by large inter-station distances. Therefore, the standard deviation of the residual atmospheric parameters should be fine-tuned. This paper presents an atmosphere-constrained AR method for undifferenced network RTK (URTK) rover, whose ambiguities are sequentially fixed according to their wavelengths. Furthermore, this research systematically analyzes the residual atmospheric error and finds that it mainly varies along the positional relationship between the rover and the chosen reference stations. More importantly, its ionospheric part of certain location will also be cyclically influenced every day. Therefore, the standard deviation of residual ionospheric error can be modeled by a daily repeated cosine or other functions with the help of data one day before, and applied by rovers as pseudo-observation. With the data collected at 29 stations from a continuously operating reference station network in Guangdong Province (GDCORS) in China, the efficiency of the proposed approach is confirmed by improving the success and error rates of AR for 10-20 % compared to that of the WL-L1-IF one, as well as making much better positioning accuracy. Numéro de notice : A2016-807 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-016-0928-3 En ligne : http://dx.doi.org/10.1007/s00190-016-0928-3 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=82595 [article]

Instantaneous ambiguity resolution for URTK and its seamless transition with PPP-AR / Xuan Zou in GPS solutions, vol 19 n° 4 (october 2015)  

Public [article]  inGPS solutions > vol 19 n° 4 (october 2015) . - pp 559 - 567 Titre : Instantaneous ambiguity resolution for URTK and its seamless transition with PPP-AR Type de document : Article/Communication Auteurs : Xuan Zou, Auteur ; Weiming Tang, Auteur ; Chuang Shi, Auteur ; Jingnan Liu, Auteur Année de publication : 2015 Article en page(s) : pp 559 - 567 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes IGN] positionnement cinématique en temps réel [Termes IGN] positionnement ponctuel précis [Termes IGN] résolution d'ambiguïté [Termes IGN] système d'extension [Termes IGN] véhicule automobile Résumé : (auteur) We extend the current Undifferenced network RTK (URTK) approaches by additionally using P1/CA augmentation information from reference stations. P1/CA augmentation information can shorten the convergence time and help to fix the ionosphere-free combination ambiguities in several epochs. Instantaneous and centimeter-level positioning solutions can be achieved for rovers within the coverage of regional reference network. Also, we develop an approach for seamless transition between URTK and precise point positioning with ambiguity resolution (PPP-AR) and present a new scheme to provide URTK service. Therefore, a service for a large number of rovers can be easily realized in real-time data communication for ambiguity fixing. In addition, the period when augmentation information from a particular reference station is not available can be bridged with the help of PPP-AR. Rovers can experience more operational time with fewer interruptions, which are difficult tasks for current URTK and Network Real-Time Kinematic services. More importantly, with this new scheme, URTK and PPP-AR services can be integrated into a unique PPP-AR system. The obtained convergence time only depends on whether or not the rover is receiving the regional augmentation information. Numéro de notice : A2015-465 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10291-014-0411-7 Date de publication en ligne : 14/10/2014 En ligne : https://doi.org/10.1007/s10291-014-0411-7 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=77152 [article]