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Auteur Kamal Ahmed |
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Comparative analysis of multi-constellation GNSS single-frequency precise point positioning / Mahmoud Abd Rabbou in Survey review, vol 50 n° 361 (July 2018)
[article]
Titre : Comparative analysis of multi-constellation GNSS single-frequency precise point positioning Type de document : Article/Communication Auteurs : Mahmoud Abd Rabbou, Auteur ; Adel El-Shazly, Auteur ; Kamal Ahmed, Auteur Année de publication : 2018 Article en page(s) : pp 373 - 382 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement
[Termes IGN] analyse comparative
[Termes IGN] positionnement par BeiDou
[Termes IGN] positionnement par Galileo
[Termes IGN] positionnement par GLONASS
[Termes IGN] positionnement par GPS
[Termes IGN] positionnement ponctuel précis
[Termes IGN] récepteur GNSS
[Termes IGN] récepteur monofréquenceRésumé : (Auteur) We develop new single-frequency PPP models, which combine the observations of the current GNSS constellations, including GPS, GLONASS, Galileo and BeiDou. Four single-frequency GNSS PPP models are developed, namely, the undifferenced single-frequency GNSS PPP model, the undifferenced ionosphere-free (IF) code and phase model known as quasi-phase model, the between-satellite-single-difference model (BSSD) and the between-satellite-single-difference ionosphere-free (BSSDIF) model. The IGS final precise products are used to account for the orbital and clock errors. For both undifferenced and BSSD models, the IGS final global ionospheric maps (GIM) model is used to correct the ionospheric delay. The GNSS inter-system biases are treated as additional unknowns in the estimation process for the undifferenced models, while a loosely coupled technique is used for the BSSD models. Various GNSS combinations are considered in the assessment for each PPP model, including GPS/GLONASS, GPS/Galileo, GPS/BeiDou and quad-constellation GNSS observations. It is shown that the multi-GNSS observations enhance the PPP solution accuracy in comparison with the GPS-only solution. Furthermore, the use of IF-PPP technique enhances the positioning accuracy by 25, 20, 24, 20 and 19% compared with the GIM-based PPP model for the GPS-only, GPS/GLONASS, GPS/Galileo, GPS/BeiDou and quad-GNSS combinations, respectively, for 1 h of GNSS data processing. In addition, an average of 15% positioning accuracy improvement can be obtained when the BSSD techniques are used compared with the undifferenced techniques. However, for 6 h of processing, comparable positioning accuracy can be obtained from all four single-frequency models. Numéro de notice : A2018-445 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/00396265.2017.1296628 Date de publication en ligne : 13/03/2017 En ligne : https://doi.org/10.1080/00396265.2017.1296628 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91030
in Survey review > vol 50 n° 361 (July 2018) . - pp 373 - 382[article]Effect of occupation time on the horizontal accuracy of a mapping-grade GNSS receiver under dense forest canopy / Robert J. McGaughey in Photogrammetric Engineering & Remote Sensing, PERS, vol 83 n° 12 (December 2017)
[article]
Titre : Effect of occupation time on the horizontal accuracy of a mapping-grade GNSS receiver under dense forest canopy Type de document : Article/Communication Auteurs : Robert J. McGaughey, Auteur ; Kamal Ahmed, Auteur ; Hans-Erik Andersen, Auteur ; Stephen E. Reutebuch, Auteur Année de publication : 2017 Article en page(s) : PP 861 - 868 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] analyse comparative
[Termes IGN] densité de la végétation
[Termes IGN] Etats-Unis
[Termes IGN] forêt
[Termes IGN] inventaire forestier (techniques et méthodes)
[Termes IGN] inventaire forestier étranger (données)
[Termes IGN] lever topographique
[Termes IGN] récepteur bifréquence
[Termes IGN] récepteur GPS
[Vedettes matières IGN] Inventaire forestierRésumé : (Auteur) A mapping-grade dual frequency GNSS receiver was tested under dense forest canopy to determine the effect of occupation time on horizontal accuracy. The U.S. Forest Service Forest Inventory and Analysis unit in the Pacific Northwest has been using 32 of these units to collect over 7,000 plot locations since 2013. In this study, one-hour GNSS static occupations were collected at 33 ground-surveyed positions with Trimble GeoXH6000 mapping-grade and Javad Triumph1 survey-grade receivers. Rover files were differentially post-processed and horizontal accuracy of each post-processed position was computed. Results indicated that 1.85 m accuracy (n = 990) could be achieved with the GeoXH6000 receiver with 15-minute occupations; however, maximum horizontal error was 7.01 m. Increasing occupation time to 20 minutes did not result in a significant improvement in accuracy. No correlation was found between the horizontal precision of a post-processed position reported by the postprocessing software and the field-measured horizontal accuracy of the positions. Numéro de notice : A2017-805 Affiliation des auteurs : non IGN Thématique : FORET/POSITIONNEMENT Nature : Article DOI : 10.14358/PERS.83.12.861 En ligne : https://doi.org/10.14358/PERS.83.12.861 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89166
in Photogrammetric Engineering & Remote Sensing, PERS > vol 83 n° 12 (December 2017) . - PP 861 - 868[article]