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A new ambiguity resolution method for LEO precise orbit determination / Xingyu Zhou in Journal of geodesy, vol 96 n° 7 (July 2022)  

Public [article]  inJournal of geodesy > vol 96 n° 7 (July 2022) . - n° 49 Titre : A new ambiguity resolution method for LEO precise orbit determination Type de document : Article/Communication Auteurs : Xingyu Zhou, Auteur ; Hua Chen, Auteur ; Weiping Jiang, Auteur ; et al., Auteur Année de publication : 2022 Article en page(s) : n° 49 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Techniques orbitales [Termes IGN] orbite basse [Termes IGN] orbitographie [Termes IGN] récepteur GNSS [Termes IGN] résolution d'ambiguïté Résumé : (auteur) Ambiguity resolution (AR) is an effective approach to improve the orbit accuracy of the low Earth orbit satellites using the Global Navigation Satellite System (GNSS). The most commonly used single-difference (SD) AR requires prior knowledge of the GNSS hardware biases, while the potential unavailability of the bias products may hinder the AR process for users. The track-to-track (T2T) AR can work as an alternative without the GNSS bias products, but the performance may be degraded by the receiver hardware biases. To provide a better alternative in this condition, a new AR method called SD T2T (SDT2T) is proposed in this study, where the GNSS and receiver biases can be greatly eliminated without external knowledge. The performance of the SD AR, SDT2T AR, and T2T AR methods are assessed based on the gravity recovery and climate experiment follow on and SWARM data. The results show that the improvements contributed by the SDT2T AR are comparable to the SD AR. The multiple iterations required by the T2T AR can be avoided by the SDT2T AR, and the accuracy of the T2T AR can be further improved with the preprocessed ambiguities of the SDT2T AR. Considering the efficiency and stable performance, the SDT2T AR is recommended as the preferred alternative single-receiver AR method in the absence of the GNSS hardware bias products. Numéro de notice : A2022-590 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-022-01629-6 Date de publication en ligne : 15/07/2022 En ligne : https://doi.org/10.1007/s00190-022-01629-6 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101272 [article]

A new global grid model for the determination of atmospheric weighted mean temperature in GPS precipitable water vapor / Liangke Huang in Journal of geodesy, vol 93 n° 2 (February 2019)  

Public [article]  inJournal of geodesy > vol 93 n° 2 (February 2019) . - pp 159 - 176 Titre : A new global grid model for the determination of atmospheric weighted mean temperature in GPS precipitable water vapor Type de document : Article/Communication Auteurs : Liangke Huang, Auteur ; Weiping Jiang, Auteur ; Lilong Liu, Auteur ; Hua Chen, Auteur ; Shirong Ye, Auteur Année de publication : 2019 Article en page(s) : pp 159 - 176 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] coordonnées GPS [Termes IGN] données météorologiques [Termes IGN] erreur moyenne quadratique [Termes IGN] Global Geodetic Observing System [Termes IGN] modèle de géopotentiel [Termes IGN] prévision météorologique [Termes IGN] radiosondage [Termes IGN] régression linéaire [Termes IGN] retard troposphérique zénithal [Termes IGN] vapeur d'eau Résumé : (auteur) In ground-based global positioning system (GPS) meteorology, atmospheric weighted mean temperature, Tm, plays a very important role in the progress of retrieving precipitable water vapor (PWV) from the zenith wet delay of the GPS. Generally, most of the existing Tm models only take either latitude or altitude into account in modeling. However, a great number of studies have shown that Tm is highly correlated with both latitude and altitude. In this study, a new global grid empirical Tm model, named as GGTm, was established by a sliding window algorithm using global gridded Tm data over an 8-year period from 2007 to 2014 provided by TU Vienna, where both latitude and altitude variations are considered in modeling. And the performance of GGTm was assessed by comparing with the Bevis formula and the GPT2w model, where the high-precision global gridded Tm data as provided by TU Vienna and the radiosonde data from 2015 are used as reference values. The results show the significant performance of the new GGTm model against other models when compared with gridded Tm data and radiosonde data, especially in the areas with great undulating terrain. Additionally, GGTm has the global mean RMSPWV and RMSPWV/PWV values of 0.26 mm and 1.28%, respectively. The GGTm model, fed only by the day of the year and the station coordinates, could provide a reliable and accurate Tm value, which shows the possible potential application in real-time GPS meteorology, especially for the application of low-latitude areas and western China. Numéro de notice : A2019-077 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-018-1148-9 Date de publication en ligne : 15/05/2018 En ligne : https://doi.org/10.1007/s00190-018-1148-9 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92191 [article]

GPS-derived geocenter motion from the IGS second reprocessing campaign / Liansheng Deng in Earth, Planets and Space, vol 71 (2019)  

Public [article]  inEarth, Planets and Space > vol 71 (2019) . - n° 74 Titre : GPS-derived geocenter motion from the IGS second reprocessing campaign Type de document : Article/Communication Auteurs : Liansheng Deng, Auteur ; Zhao Li, Auteur ; Na Wei, Auteur ; Yifang Ma , Auteur ; Hua Chen, Auteur Année de publication : 2019 Article en page(s) : n° 74 Note générale : bibloigraphie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] campagne d'observations [Termes IGN] mouvement du géocentre [Termes IGN] télémétrie laser sur satellite Résumé : (auteur) GPS data processing methods and theories are under continuous refinement in the past 30 years. Using the latest products is supposed to provide more stable and reliable geocenter estimates. In this paper, geocenter estimates from deformation inversion approach with new observations of IGS second data reprocessing campaign (IG2) are investigated. Results indicate that our IG2-derived geocenter motion estimates agree well with solutions from network approach for SLR. The truncated degree 5 exhibits the highest consistency between GPS-inverted geocenter estimates and the SLR results in both annual amplitudes and phases. Then, the GPS-derived geocenter motions are compared with results from other different approaches. We find that except for a discrepancy in the annual phase estimates of Z component, geocenter motions predicted with the IG2 data are in line with those based on other techniques. In addition, the effects of the translational parameters and the comparison with the IGS first data reprocessing campaign (IG1)-estimated geocenter motions are investigated, and results demonstrate that the translation parameters should be estimated when inversing the geocenter motion with the newly IG2 solutions and the advantage of the IG2 data reprocessing over the previous IG1 efforts. Finally, we address the impacts of post-seismic effects and the missing ocean data on the IG2-derived solutions. After removing the stations affected by large earthquakes, the amplitudes of Y component become higher, but the annual phases of the Y component become far away from the SLR solutions. Comparisons of the equivalent water height from the IG2-estimated coefficients and the solutions from the estimation of the circulation and climate of the ocean indicate that the differences between the two types of solutions vary with different truncated degrees, and the consistency is getting worse and worse with the truncated degree grows. Further researches still need to be done to invert surface mass variation coefficients from various combinations of GPS observations, ocean models and other datasets. Numéro de notice : A2019-669 Affiliation des auteurs : Géodésie+Ext (mi2018-2019) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1186/s40623-019-1054-2 Date de publication en ligne : 05/07/2019 En ligne : https://doi.org/10.1186/s40623-019-1054-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=99940 [article]

Study of the effects on GPS coordinate time series caused by higher-order ionospheric corrections calculated using the DIPOLE model / Liansheng Deng in Geodesy and Geodynamics, vol 8 n° 2 (March 2017)  

Public [article]  inGeodesy and Geodynamics > vol 8 n° 2 (March 2017) . - pp 111 - 119 Titre : Study of the effects on GPS coordinate time series caused by higher-order ionospheric corrections calculated using the DIPOLE model Type de document : Article/Communication Auteurs : Liansheng Deng, Auteur ; Weiping Jiang, Auteur ; Hua Chen, Auteur ; Zhaohan Zhu, Auteur ; Wen Zhao, Auteur Année de publication : 2017 Article en page(s) : pp 111 - 119 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] amplitude [Termes IGN] bruit blanc [Termes IGN] bruit rose [Termes IGN] champ géomagnétique [Termes IGN] correction ionosphérique [Termes IGN] GAMIT [Termes IGN] GLOBK [Termes IGN] International Geomagnetic Reference Field [Termes IGN] série temporelle [Vedettes matières IGN] Traitement de données GNSS Résumé : (auteur) As one of the main error sources in high-precision Global Positioning System (GPS) data processing, higher-order ionospheric (HOI) delays cause significant effects on coordinate time series that cannot be ignored in analyses of long time series. Typically two geomagnetic models, DIPOLE model and International Geomagnetic Reference Field (IGRF) model, are used for calculating HOI corrections. This paper investigates the effects of HOI correction caused by the DIPOLE model on coordinate time series. GPS data from 104 globally distributed International GNSS Service (IGS) stations spanning from January, 1999 to December, 2003 were reprocessed following up-to-date processing strategies utilizing GAMIT and GLOBK software. Two coordinate time series solutions before and after applying HOI corrections using the DIPOLE model were derived for studying the effects in terms of seasonal variations and noise amplitudes. The results show that after applying the HOI corrections calculated with DIPOLE, the noise amplitudes of the coordinate time series increased, especially in the north and east directions, and the increased amplitudes of the flicker noise were larger than those of the white noise. Furthermore, spurious periodic signals that were probably introduced by the HOI corrections from the DIPOLE model were also found. Moreover, an apparent increase was confirmed for the power spectra of most of the stations, especially in the north direction, and the amplitudes of both the annual and semi-annual signals also increased in the north and east directions. It can be inferred that the quality of the external data sources such as the geomagnetic model might be the key factors that lead to the above results. The results also suggest that we should be very careful when the DIPOLE model is used for HOI corrections. Numéro de notice : A2017-235 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1016/j.geog.2017.01.004 En ligne : https://doi.org/10.1016/j.geog.2017.01.004 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=85167 [article]