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Study on GPS–PPP precision for short observation sessions / Stefano Gandolfi in GPS solutions, vol 21 n° 3 (July 2017)  

Public [article]  inGPS solutions > vol 21 n° 3 (July 2017) . - pp 887 – 896 Titre : Study on GPS–PPP precision for short observation sessions Type de document : Article/Communication Auteurs : Stefano Gandolfi, Auteur ; Luca Tavasci, Auteur ; Luca Poluzzi, Auteur Année de publication : 2017 Article en page(s) : pp 887 – 896 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes IGN] coordonnées géodésiques [Termes IGN] Europe (géographie politique) [Termes IGN] GIPSY-OASIS [Termes IGN] positionnement ponctuel précis [Termes IGN] positionnement statique [Termes IGN] résolution d'ambiguïté [Termes IGN] station GNSS Résumé : (auteur) Precise point positioning is increasingly being used in geodetic applications that in many cases are based on static 24-hour RINEX files. Since there are many applications where sub-centimeter position accuracy is not required and users wish to use a single receiver and not be dependent on differential correction, we will evaluate PPP performance for static positioning with 12-, 6-, 3-, 1- and ½-h observations. We have, therefore, considered a dataset for the year 2013 from 14 European GNSS stations. The data were analyzed using GIPSY-OASIS II software package and evaluated in terms of repeatability of the coordinates and of coherence with the formal error indicated for each PPP solution. Particular attention was paid to solutions showing large discrepancies in coordinates. The test shows that PPP precision for the 24-h files is below 5 mm, but decreases slightly for the 12-, 6- and 3-h observation sets. For the 1-h and the ½-h RINEX files, precision is within 5 and 10 cm, respectively. The analysis is completed with a discussion on the impact of the ambiguity resolution that shows how it significantly improves only the easting component and moreover has a higher influence on the formal error rather than on the solutions. Lastly, the study contains an investigation into the reliability of the formal error associated with the PPP solutions. We show that the formal error can be used to identify incorrect solutions, but is not suitable to represent the real accuracy. For that reason, we propose to use the formal error given for the float solutions even for the ones with fixed ambiguities. Numéro de notice : A2017-440 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10291-016-0575-4 En ligne : https://doi.org/10.1007/s10291-016-0575-4 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=86356 [article]

Improved PPP performance in regional networks / Stefano Gandolfi in GPS solutions, vol 20 n° 3 (July 2016)  

Public [article]  inGPS solutions > vol 20 n° 3 (July 2016) . - pp 485 - 497 Titre : Improved PPP performance in regional networks Type de document : Article/Communication Auteurs : Stefano Gandolfi, Auteur ; Luca Tavasci, Auteur ; Luca Poluzzi, Auteur Année de publication : 2016 Article en page(s) : pp 485 - 497 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes IGN] GIPSY-OASIS [Termes IGN] International Terrestrial Reference System [Termes IGN] positionnement ponctuel précis [Termes IGN] réseau géodésique local [Termes IGN] série temporelle [Termes IGN] transformation de Helmert Résumé : (Auteur) It has been demonstrated that precise point positioning (PPP) is a powerful tool in geodetic and geodynamic applications. As is known, it provides solutions in the reference system of the satellite orbits. We focuses on the strategy to transform PPP solutions into the International Terrestrial Reference System (ITRS) by applying a set of local Helmert transformation parameters obtained from a regional network rather than using global parameters. In order to carry out this test, a regional network composed of 14 stations was analyzed using GIPSY-OASIS II software, over a period of 6 years. Two solutions differently aligned to the ITRS were compared in terms of accuracy, scattering, frequency content and local movements. One solution is aligned to IGb08 through the X-files provided by JPL, while the other is aligned to the European reference frame densification of IGb08 using customized regional X-files. Therefore, both are updated realizations of the ITRS. The test shows that a regional, instead of a global, alignment to the ITRS can significantly improve the repeatability of the solutions. A small improvement can also be found in terms of agreement with the regional densification of IGb08. The analysis of the signal content in the differently aligned time series allowed some differences to be found, in terms of both frequency and magnitude. These differences are mainly due to an evident common signal that is defined for the whole area and which is removed when using regional alignment. Finally, residual scattering was calculated after removing the modeled signals from each time series, which results in a scatter being significantly smaller for the regional solution than for the global solution. In order to obtain these results, the choice of the reference stations is a major question and therefore discussed in detail. Numéro de notice : A2016-633 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10291-015-0459-z En ligne : http://dx.doi.org/10.1007/s10291-015-0459-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81836 [article]