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Undifferenced zenith tropospheric modeling and its application in fast ambiguity recovery for long-range network RTK reference stations / Dezhong Chen in GPS solutions, vol 23 n° 1 (January 2019)  

Public [article]  inGPS solutions > vol 23 n° 1 (January 2019) Titre : Undifferenced zenith tropospheric modeling and its application in fast ambiguity recovery for long-range network RTK reference stations Type de document : Article/Communication Auteurs : Dezhong Chen, Auteur ; Shirong Ye, Auteur ; Caijun Xu, Auteur ; et al., Auteur Année de publication : 2019 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] Continuously Operating Reference Station network [Termes IGN] correction troposphérique [Termes IGN] positionnement cinématique en temps réel [Termes IGN] propagation troposphérique [Termes IGN] résidu [Termes IGN] résolution d'ambiguïté [Termes IGN] station de référence [Termes IGN] station permanente Résumé : (Auteur) A large number of continuously operating reference station (CORS) networks have been established around the world to support various high-precision navigation and positioning applications. However, the presence of significant tropospheric delays makes rapid ambiguity recovery for long inter-station baselines of network real-time kinematic (RTK) systems a major challenge. Since tropospheric delays are strongly temporally correlated over short periods, we propose an undifferenced (UD) zenith tropospheric prediction model to effectively correct tropospheric errors on the subsequent epoch measurements. Using 2-h sessions of the independent baselines in a CORS network, the ambiguities are easily and reliably resolved with the conventional ionospheric-free combination method. The derived double-differenced (DD), ionospheric-free residuals are then converted to UD residuals for each satellite and all stations. The UD residuals and the corresponding wet coefficients of each satellite are used to construct the zenith tropospheric model. The model is reconstructed every 5 min for each station. The slant tropospheric errors of observations within this period can be predicted using the established models. Seven independent baselines with an average length of 97 km are used to test the ambiguity recovery performance of the proposed method. The experimental results show that the proposed tropospheric prediction model can efficiently reduce the effects of slant tropospheric errors and improve the float solution of ambiguities. The average initialization time with the proposed method is less than 111.5 s, which is a 45% improvement with respect to the conventional approach. The proposed method was shown to be effective for fast ambiguity recovery of long-range baselines between reference stations. Numéro de notice : A2019-051 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s10291-018-0815-x Date de publication en ligne : 02/01/2019 En ligne : https://doi.org/10.1007/s10291-018-0815-x Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92078 [article]

A geometry-free and ionosphere-free multipath mitigation method for BDS three-frequency ambiguity resolution / Dezhong Chen in Journal of geodesy, vol 90 n° 8 (August 2016)  

Public [article]  inJournal of geodesy > vol 90 n° 8 (August 2016) . - pp 703 – 714 Titre : A geometry-free and ionosphere-free multipath mitigation method for BDS three-frequency ambiguity resolution Type de document : Article/Communication Auteurs : Dezhong Chen, Auteur ; Shirong Ye, Auteur ; Jingchao Xia, Auteur ; et al., Auteur Année de publication : 2016 Article en page(s) : pp 703 – 714 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] correction du trajet multiple [Termes IGN] erreur systématique [Termes IGN] positionnement par BeiDou [Termes IGN] résolution d'ambiguïté [Termes IGN] signal BeiDou [Termes IGN] station de référence [Termes IGN] trajet multiple [Termes IGN] troposphère Résumé : (auteur) Because of the unknown systematic errors and special satellite constellations in the Beidou system (BDS), it is difficult to quickly and reliably determine the ambiguity over long-range baselines in continuously operating reference station (CORS) network. This study seeks to improve the effectiveness and reliability of BDS ambiguity resolution (AR) by combining the geometry-free and ionosphere-free (GFIF) combination and multipath mitigation algorithm. The GFIF combination composed with three-frequency signals is free of distance-dependent errors and can be used to determine the narrow lane ambiguity. The presence of multipath errors means that not all ambiguities can be correctly achieved by rounding the averaged GFIF ambiguity series. A multipath model of the single-differenced (SD) GFIF combination from the previous period is established for each individual satellite. This model is subtracted from the SD GFIF combination for the current day to remove the effects of multipath errors. Using three triangle networks with lengths of approximately 120, 80 and 50 km, we demonstrate that the proposed method improves the AR performance. The ambiguity averaged first fixing time is typically less than 1801 s for inclined geosynchronous orbit (IGSO) and medium earth orbit (MEO) satellites and less than 2007 s for the ∼42∘ elevation geostationary earth orbit (GEO) C02 satellite. However, it is more time consuming for the low-elevation GEO satellites C04 (∼18∘) and C05 (∼28∘). Kalman filtering is used to estimate the troposphere delays and two unfixed ambiguities by employing the ionosphere-free observations of all ambiguity-fixed/unfixed satellites. The experimental results show that only tens of seconds are required for AR in around 90 km baselines. Numéro de notice : A2016-503 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-016-0903-z En ligne : http://dx.doi.org/10.1007/s00190-016-0903-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81527 [article]