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Modeling tropospheric wet delays with dense and sparse network configurations for PPP-RTK / Paulo S. de Oliveira in GPS solutions, vol 21 n° 1 (January 2017)  

Public [article]  inGPS solutions > vol 21 n° 1 (January 2017) . - pp 237 - 250 Titre : Modeling tropospheric wet delays with dense and sparse network configurations for PPP-RTK Type de document : Article/Communication Auteurs : Paulo S. de Oliveira, Auteur ; Laurent Morel, Auteur ; François Fund, Auteur ; Romain Legros, Auteur ; et al., Auteur Année de publication : 2017 Article en page(s) : pp 237 - 250 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes descripteurs IGN] France d'outre-mer [Termes descripteurs IGN] orbite précise [Termes descripteurs IGN] Orphéon [Termes descripteurs IGN] positionnement cinématique en temps réel [Termes descripteurs IGN] positionnement par GLONASS [Termes descripteurs IGN] positionnement par GNSS [Termes descripteurs IGN] positionnement par GPS [Termes descripteurs IGN] positionnement ponctuel précis [Termes descripteurs IGN] récepteur bifréquence [Termes descripteurs IGN] réseau géodésique clairsemé [Termes descripteurs IGN] réseau géodésique dense [Termes descripteurs IGN] retard troposphérique [Termes descripteurs IGN] retard troposphérique zénithal Résumé : (Auteur) Precise Point Positioning (PPP) is a well-known technique of positioning by Global Navigation Satellite Systems (GNSS) that provides accurate solutions. With the availability of real-time precise orbit and clock products provided by the International GNSS Service (IGS) and by individual analysis centers such as Centre National d’Etudes Spatiales through the IGS Real-Time Project, PPP in real time is achievable. With such orbit and clock products and using dual-frequency receivers, first-order ionospheric effects can be eliminated by the ionospheric-free combination. Concerning the tropospheric delays, the Zenith Hydrostatic Delays can be quite well modeled, although the Zenith Wet Delays (ZWDs) have to be estimated because they cannot be mitigated by, for instance, observable combinations. However, adding ZWD estimates in PPP processing increases the time to achieve accurate positions. In order to reduce this convergence time, we (1) model the behavior of troposphere over France using ZWD estimates at Orphéon GNSS reference network stations and (2) send the modeling parameters to the GNSS users to be introduced as a priori ZWDs, with an appropriate uncertainty. At the user level, float PPP-RTK is achieved; that is, GNSS data are performed in kinematic mode and ambiguities are kept float. The quality of the modeling is assessed by comparison with tropospheric products published by Institut National de l’Information Géographique et Forestière. Finally, the improvements in terms of required time to achieve 10-cm accuracy for the rover position (simulated float PPP-RTK) are quantified and discussed. Results for 68 % quantiles of absolute errors convergence show that gains for GPS-only positioning with ZWDs derived from the assessed tropospheric modeling are about: 1 % (East), 20 % (North), and 5 % (Up). Since ZWD estimation is correlated with satellite geometry, we also investigated the positioning when processing GPS + GLONASS data, which increases significantly the number of available satellites. The improvements achieved by adding tropospheric corrections in this case are about: 2 % (East), 5 % (North), and 13 % (Up). Finally, a reduction in the number of reference stations by using a sparser network configuration to perform the tropospheric modeling does not degrade the generated tropospheric corrections, and similar performances are achieved. Numéro de notice : A2017-017 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article En ligne : http://dx.doi.org/10.1007/s10291-016-0518-0 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=83948 [article]

Improved ambiguity resolution for URTK with dynamic atmosphere constraints / Weiming Tang in Journal of geodesy, vol 90 n° 12 (December 2016)  

Public [article]  inJournal of geodesy > vol 90 n° 12 (December 2016) . - pp 1359 - 1369 Titre : Improved ambiguity resolution for URTK with dynamic atmosphere constraints Type de document : Article/Communication Auteurs : Weiming Tang, Auteur ; Wenjian Liu, Auteur ; Xuan Zou, Auteur ; et al., Auteur Année de publication : 2016 Article en page(s) : pp 1359 - 1369 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes descripteurs IGN] correction ionosphérique [Termes descripteurs IGN] effet atmosphérique [Termes descripteurs IGN] positionnement cinématique en temps réel [Termes descripteurs IGN] précision du positionnement [Termes descripteurs IGN] résidu [Termes descripteurs IGN] résolution d'ambiguïté Résumé : (Auteur) Raw observation processing method with prior knowledge of ionospheric delay could strengthen the ambiguity resolution (AR), but it does not make full use of the relatively longer wavelength of wide-lane (WL) observation. Furthermore, the accuracy of calculated atmospheric delays from the regional augmentation information has quite different in quality, while the atmospheric constraint used in the current methods is usually set to an empirical value. A proper constraint, which matches the accuracy of calculated atmospheric delays, can most effectively compensate the residual systematic biases caused by large inter-station distances. Therefore, the standard deviation of the residual atmospheric parameters should be fine-tuned. This paper presents an atmosphere-constrained AR method for undifferenced network RTK (URTK) rover, whose ambiguities are sequentially fixed according to their wavelengths. Furthermore, this research systematically analyzes the residual atmospheric error and finds that it mainly varies along the positional relationship between the rover and the chosen reference stations. More importantly, its ionospheric part of certain location will also be cyclically influenced every day. Therefore, the standard deviation of residual ionospheric error can be modeled by a daily repeated cosine or other functions with the help of data one day before, and applied by rovers as pseudo-observation. With the data collected at 29 stations from a continuously operating reference station network in Guangdong Province (GDCORS) in China, the efficiency of the proposed approach is confirmed by improving the success and error rates of AR for 10-20 % compared to that of the WL-L1-IF one, as well as making much better positioning accuracy. Numéro de notice : A2016-807 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-016-0928-3 En ligne : http://dx.doi.org/10.1007/s00190-016-0928-3 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=82595 [article]

Single-frequency, dual-GNSS versus dual-frequency, single-GNSS: a low-cost and high-grade receivers GPS-BDS RTK analysis / Robert Odolinski in Journal of geodesy, vol 90 n° 11 (November 2016)  

Public [article]  inJournal of geodesy > vol 90 n° 11 (November 2016) . - pp 1255 - 1278 Titre : Single-frequency, dual-GNSS versus dual-frequency, single-GNSS: a low-cost and high-grade receivers GPS-BDS RTK analysis Type de document : Article/Communication Auteurs : Robert Odolinski, Auteur ; Peter J.G. Teunissen, Auteur Année de publication : 2016 Article en page(s) : pp 1255 - 1278 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes descripteurs IGN] analyse comparative [Termes descripteurs IGN] données BeiDou [Termes descripteurs IGN] fréquence multiple [Termes descripteurs IGN] positionnement cinématique en temps réel [Termes descripteurs IGN] positionnement par GNSS [Termes descripteurs IGN] récepteur BeiDou [Termes descripteurs IGN] récepteur GNSS [Termes descripteurs IGN] récepteur monofréquence Résumé : (Auteur) The concept of single-frequency, dual-system (SF-DS) real-time kinematic (RTK) positioning has become feasible since, for instance, the Chinese BeiDou Navigation Satellite System (BDS) has become operational in the Asia-Pacific region. The goal of the present contribution is to investigate the single-epoch RTK performance of such a dual-system and compare it to a dual-frequency, single-system (DF-SS). As the SF-DS we investigate the L1 GPS + B1 BDS model, and for DF-SS we take L1, L2 GPS and B1, B2 BDS, respectively. Two different locations in the Asia-Pacific region are analysed with varying visibility of the BDS constellation, namely Perth in Australia and Dunedin in New Zealand. To emphasize the benefits of such a model we also look into using low-cost ublox single-frequency receivers and compare such SF-DS RTK performance to that of a DF-SS, based on much more expensive survey-grade receivers. In this contribution a formal and empirical analysis is given. It will be shown that with the SF-DS higher elevation cut-off angles than the conventional 10∘ or 15∘ can be used. The experiment with low-cost receivers for the SF-DS reveals (for the first time) that it has the potential to achieve comparable ambiguity resolution performance to that of a DF-SS (L1, L2 GPS), based on the survey-grade receivers. Numéro de notice : A2016-801 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-016-0921-x En ligne : http://dx.doi.org/10.1007/s00190-016-0921-x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=82584 [article]

Centimeter positioning for UAVs and mass-market applications / Cécile Mongrédien in GPS world, vol 27 n° 10 (October 2016)

Public [article]  inGPS world > vol 27 n° 10 (October 2016) . - pp 24 - 33 Titre : Centimeter positioning for UAVs and mass-market applications Type de document : Article/Communication Auteurs : Cécile Mongrédien, Auteur ; Chris Hide, Auteur ; Peter Fairhurst, Auteur ; Daniel Ammann, Auteur Année de publication : 2016 Article en page(s) : pp 24 - 33 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes descripteurs IGN] analyse comparative [Termes descripteurs IGN] implémentation (informatique) [Termes descripteurs IGN] module d'extension [Termes descripteurs IGN] positionnement cinématique en temps réel [Termes descripteurs IGN] précision centimétrique [Termes descripteurs IGN] test de performance Résumé : (auteur) Emerging high-volume markets call for RTK technologies previously limited to niche markets by complexity and cost. This article disccusses design and implementation of a very precise RTK-based module solution while maintaining cost, size and power consumption as low as possible. Several tests under a range of signal environments benchmark the new module's performance against existing L1 RTK products. Numéro de notice : A2016-718 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=82208 [article]

Enabling innovation through geodetic technologies: a provincial perspective / Jason Bond in Geomatica [en ligne], vol 70 n° 3 (September 2016)  

Public [article]  inGeomatica [en ligne] > vol 70 n° 3 (September 2016) . - pp 181 - 186 Titre : Enabling innovation through geodetic technologies: a provincial perspective Type de document : Article/Communication Auteurs : Jason Bond, Auteur Année de publication : 2016 Article en page(s) : pp 181 - 186 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes descripteurs IGN] évolution technologique [Termes descripteurs IGN] positionnement cinématique en temps réel [Termes descripteurs IGN] positionnement différentiel [Termes descripteurs IGN] positionnement par GNSS [Termes descripteurs IGN] précision du positionnement Résumé : (auteur) Geodetic technologies enable the measurement of the size, shape and orientation of the Earth, as well as the variation of these parameters over time. Advances in geodetic technology over the past few decades, par ticularly relating to Global Navigation Satellite Systems (GNSS), have made access to real-time centimetre level positioning accuracy commonplace. As spatial position information becomes more critical to human and artificial intelligence decision-making processes, innovation has ensued to leverage that information. A review of key advances in geodetic technology is provided. Examples of innovations that leverage these technologies are presented. It is concluded that the role of geodetic infrastructure will become increasingly important as the backbone for other innovations and that jurisdictions investing resources in this area will be more likely to realize the potential economic benefits and operational efficiencies it create Numéro de notice : A2016-991 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article En ligne : http://dx.doi.org/10.5623/cig2016-303 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=83755 [article]

Evaluation d'une solution de positionnement ponctuel précis temps réel / Pierre Bosser in XYZ, n° 148 (septembre - novembre 2016)

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PPP-RTK and inter-system biases: the ISB look-up table as a means to support multi-system PPP-RTK / Amir Khodabandeh in Journal of geodesy, vol 90 n° 9 (September 2016)  

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Ground-based phase wind-up and its application in yaw angle determination / M. Cai in Journal of geodesy, vol 90 n° 8 (August 2016)  

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UAV- derived orthoimagery and topography: Comparing photogrammetric models processed with direct geo-referencing and ground control points / Chris H. Hugenholtz in Geomatica [en ligne], vol 70 n° 1 (March 2016)  

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On the estimability of parameters in undifferenced, uncombined GNSS network and PPP-RTK user models by means of S-system theory / Dennis Odijk in Journal of geodesy, vol 90 n° 1 (January 2016)  

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Le drone fait carrière / Michel Ravelet in Géomètre, n° 2131 (décembre 2015)

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Multi-GNSS as a combination of GPS, GLONASS and Beidou measurements carried out in real time / Zbigniew Siejka in Artificial satellites, vol 50 n° 4 (December 2015)  

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UAV real-time: Data use in a lightweight direct georeferencing system / Christian Eling in GPS world, vol 26 n° 11 (November 2015)  

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Instantaneous ambiguity resolution for URTK and its seamless transition with PPP-AR / Xuan Zou in GPS solutions, vol 19 n° 4 (october 2015)  

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Impacts of real-time satellite clock errors on GPS precise point positioning-based troposphere zenith delay estimation / Junbo Shi in Journal of geodesy, vol 89 n° 8 (August 2015)  

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