Centre dedocumentation
scientifique

Reduction of ZTD outliers through improved GNSS data processing and screening strategies [Interactive discussion] / Katarzyna Stępniak in Atmospheric measurement techniques, vol 11 n° 3 (March 2018)  

Public [article]  inAtmospheric measurement techniques > vol 11 n° 3 (March 2018) . - pp 1347 - 1361 Titre : Reduction of ZTD outliers through improved GNSS data processing and screening strategies [Interactive discussion] Type de document : Article/Communication Auteurs : Katarzyna Stępniak, Auteur ; Olivier Bock , Auteur ; Pawel Wielgosz, Auteur Année de publication : 2018 Projets : 3-projet - voir note / Article en page(s) : pp 1347 - 1361 Note générale : Bibliographie This work has been supported by Polish National Science Centre grant no. UMO-2015/19/B/ST10/02758. The study was partially carried out during Short Term Scientific Mission (STSM) in the framework of ES1206 COST Action. Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes descripteurs IGN] Bernese [Termes descripteurs IGN] coordonnées GPS [Termes descripteurs IGN] double différence [Termes descripteurs IGN] erreur systématique [Termes descripteurs IGN] Pologne [Termes descripteurs IGN] réseau géodésique local [Termes descripteurs IGN] réseau géodésique permanent [Termes descripteurs IGN] retard troposphérique zénithal [Termes descripteurs IGN] série temporelle [Termes descripteurs IGN] valeur aberrante Résumé : (Auteur) Though Global Navigation Satellite System (GNSS) data processing has been significantly improved over the years, it is still commonly observed that zenith tropospheric delay (ZTD) estimates contain many outliers which are detrimental to meteorological and climatological applications. In this paper, we show that ZTD outliers in double-difference processing are mostly caused by sub-daily data gaps at reference stations, which cause disconnections of clusters of stations from the reference network and common mode biases due to the strong correlation between stations in short baselines. They can reach a few centimetres in ZTD and usually coincide with a jump in formal errors. The magnitude and sign of these biases are impossible to predict because they depend on different errors in the observations and on the geometry of the baselines. We elaborate and test a new baseline strategy which solves this problem and significantly reduces the number of outliers compared to the standard strategy commonly used for positioning (e.g. determination of national reference frame) in which the pre-defined network is composed of a skeleton of reference stations to which secondary stations are connected in a star-like structure. The new strategy is also shown to perform better than the widely used strategy maximizing the number of observations available in many GNSS programs. The reason is that observations are maximized before processing, whereas the final number of used observations can be dramatically lower because of data rejection (screening) during the processing. The study relies on the analysis of 1 year of GPS (Global Positioning System) data from a regional network of 136 GNSS stations processed using Bernese GNSS Software v.5.2. A post-processing screening procedure is also proposed to detect and remove a few outliers which may still remain due to short data gaps. It is based on a combination of range checks and outlier checks of ZTD and formal errors. The accuracy of the final screened GPS ZTD estimates is assessed by comparison to ERA-Interim reanalysis. Numéro de notice : A2018-065 Affiliation des auteurs : LaSTIG LAREG+Ext (2012-mi2018) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.5194/amt-11-1347-2018 date de publication en ligne : 08/03/2018 En ligne : http://dx.doi.org/10.5194/amt-11-1347-2018 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89407 [article]

Determining normal heights with the use of Precise Point Positioning / Grzegorz Krzan in Survey review, vol 49 n° 355 (October 2017)  

Public [article]  inSurvey review > vol 49 n° 355 (October 2017) . - pp 259 - 267 Titre : Determining normal heights with the use of Precise Point Positioning Type de document : Article/Communication Auteurs : Grzegorz Krzan, Auteur ; Karol Dawidowicz, Auteur ; Katarzyna Stępniak, Auteur Année de publication : 2017 Article en page(s) : pp 259 - 267 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Nivellement [Termes descripteurs IGN] altitude normale [Termes descripteurs IGN] Napeos [Termes descripteurs IGN] positionnement ponctuel précis [Termes descripteurs IGN] résolution d'ambiguïté Résumé : (Auteur) In this paper, the authors analysed the Precise Point Positioning (PPP) performance in determination of normal heights using observations from a test network consisting of ten sites. One-week observation interval was processed using standard PPP approach and Multi-Station PPP (MS-PPP) with ambiguity resolution using the NAvigation Package for Earth Observation Satellites v. 3.3.1 software. In post-processing corrections like the Earth rotation parameters, ocean loadings, antenna phase centre offsets and variations etc. needed to obtain the most accurate position were utilised. By processing the various lengths observing sessions (1 hour, 30 minutes, 15 minutes) the authors examined the degradation of the position determination precision with shortening the observation time. In the study both high-end receivers used most often at CORS, as well as commercial two-frequency receivers were utilised. Normal heights were obtained using PL–geoid–2011 model. The results of the research show that PPP is a viable alternative for Relative GNSS Positioning in the case of GNSS levelling. Numéro de notice : A2017-549 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1080/00396265.2016.1164939 En ligne : https://doi.org/10.1080/00396265.2016.1164939 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=86605 [article]

Application of the undifferenced GNSS precise positioning in determining coordinates in national reference frames / Grzegorz Krzan in Artificial satellites, vol 52 n° 3 (September 2017)  

Public [article]  inArtificial satellites > vol 52 n° 3 (September 2017) . - pp 49 - 69 Titre : Application of the undifferenced GNSS precise positioning in determining coordinates in national reference frames Type de document : Article/Communication Auteurs : Grzegorz Krzan, Auteur ; Katarzyna Stępniak, Auteur Année de publication : 2017 Article en page(s) : pp 49 - 69 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes descripteurs IGN] coordonnées géodésiques [Termes descripteurs IGN] Napeos [Termes descripteurs IGN] positionnement par GNSS [Termes descripteurs IGN] positionnement ponctuel précis [Termes descripteurs IGN] précision centimétrique [Termes descripteurs IGN] récepteur bifréquence [Termes descripteurs IGN] récepteur GPS [Termes descripteurs IGN] réseau permanent EUREF [Termes descripteurs IGN] système de référence géodésique [Termes descripteurs IGN] système de référence local Résumé : (Auteur) In high-accuracy positioning using GNSS, the most common solution is still relative positioning using double-difference observations of dual-frequency measurements. An increasingly popular alternative to relative positioning are undifferenced approaches, which are designed to make full use of modern satellite systems and signals. Positions referenced to global International Terrestrial Reference Frame (ITRF2008) obtained from Precise Point Positioning (PPP) or Undifferenced (UD) network solutions have to be transformed to national (regional) reference frame, which introduces additional bases related to the transformation process. In this paper, satellite observations from two test networks using different observation time series were processed. The first test concerns the positioning accuracy from processing one year of dual-frequency GPS observations from 14 EUREF Permanent Network (EPN) stations using NAPEOS 3.3.1 software. The results were transformed into a national reference frame (PL-ETRF2000) and compared to positions from an EPN cumulative solution, which was adopted as the true coordinates. Daily observations were processed using PPP and UD multi-station solutions to determine the final accuracy resulting from satellite positioning, the transformation to national coordinate systems and Eurasian intraplate plate velocities. The second numerical test involved similar processing strategies of post-processing carried out using different observation time series (30 min., 1 hour, 2 hours, daily) and different classes of GNSS receivers. The centimeter accuracy of results presented in the national coordinate system satisfies the requirements of many surveying and engineering applications. Numéro de notice : A2017-594 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1515/arsa-2017-0006 En ligne : https://doi.org/10.1515/arsa-2017-0006 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=86802 [article]