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GPS real-time precise point positioning for aerial triangulation / Junbo Shi in GPS solutions, vol 21 n° 2 (April 2017)  

Public [article]  inGPS solutions > vol 21 n° 2 (April 2017) . - pp 405 – 414 Titre : GPS real-time precise point positioning for aerial triangulation Type de document : Article/Communication Auteurs : Junbo Shi, Auteur ; Xiuxiao Yuan, Auteur ; Yang Cai, Auteur ; Gaojing Wang, Auteur Année de publication : 2017 Article en page(s) : pp 405 – 414 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes descripteurs IGN] aérotriangulation [Termes descripteurs IGN] antenne [Termes descripteurs IGN] coordonnées GNSS [Termes descripteurs IGN] point de vérification [Termes descripteurs IGN] positionnement cinématique en temps réel [Termes descripteurs IGN] positionnement ponctuel précis Résumé : (auteur) We extend the application of real-time kinematic PPP to aerial triangulation using GPS to determine coordinates of the antenna installed on the airplane, using real-time satellite products from IGS and the CNES Analysis Center. In order to verify the performance of real-time kinematic PPP for aerial triangulation, three tests with varying aerial and ground conditions are assessed. Numerical results show that real-time kinematic PPP using IGS real-time products of 5-cm orbit accuracy and 0.1- to 0.3-ns clock precision can provide comparable accuracy for aerial photogrammetric mapping at the scale of 1:1000 as does post-mission kinematic PPP using IGS final products. Millimeter-to-centimeter-level differences and centimeter-to-2-decimeter differences are identified for horizontal and vertical coordinates of ground check points, respectively, in the three tests. The comparison between real-time IGS and CNES products for GPS positioning and aerial triangulation unveils that real-time products with a better clock precision can result in better performance of GPS real-time kinematic PPP as applied to aerial triangulation. Numéro de notice : A2017-248 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article En ligne : http://dx.doi.org/10.1007/s10291-016-0532-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=85055 [article]

Instantaneous estimation of attitude from GNSS / Hendy Fitrian Suhandri (2017) 

Public Titre : Instantaneous estimation of attitude from GNSS Type de document : Thèse/HDR Auteurs : Hendy Fitrian Suhandri, Auteur ; Alfred Kleusberg, Directeur de thèse ; Hasanuddin Zainal Abidin, Directeur de thèse Editeur : Stuttgart : University of Stuttgart Année de publication : 2017 Importance : 143 p. Format : 21 x 30 cm Note générale : Bibliographie thesis accepted by the Faculty of Aerospace Engineering and Geodesy of the University of Stuttgart in partial fulfilment of the requirements for the degree of Doctor of Engineering Sciences (Dr.-Ing.) Langues : Anglais (eng) Descripteur : [Termes descripteurs IGN] ambiguïté entière [Termes descripteurs IGN] angle d'Euler [Termes descripteurs IGN] double différence [Termes descripteurs IGN] filtre de Kalman [Termes descripteurs IGN] méthode des moindres carrés [Termes descripteurs IGN] modèle stochastique [Termes descripteurs IGN] orientation de véhicule [Termes descripteurs IGN] positionnement cinématique [Termes descripteurs IGN] positionnement par GNSS [Termes descripteurs IGN] récepteur GNSS [Termes descripteurs IGN] simple différence [Vedettes matières IGN] Traitement de données GNSS Résumé : (auteur) The use of the Global Navigation Satellite System (GNSS) is widely spread from position determination to attitude determination of a platform in space. This system offers time invariant estimation position. Another thing that can be an advantage is that the flexibility to operate the GNSS receiver variants, from the low-cost until the high-performance GNSS receivers. In terms of attitude determination application at least three receivers are required to determine three spatial axes, where the cost-effective GNSS attitude determination systems can be constructed with today’s receiver technology. At the moment, however, algorithms are lacking which are fast and efficient enough to estimate the position angles without delay. For this reason, the present work deals with the development of algorithms for the attitude determination in space of a platform under the help of the "GNSS" Global Positioning System (GPS). The investigation through this work is classified into three sequential parts: The first part is the estimation of the optimal configuration of baseline array as well as the estimation of the integer ambiguity of carrier phase differences. The estimated integer ambiguity is then used to estimate the high precision baseline coordinates. The second part is to estimate the attitude of the platform in space by means of quaternion using batch process, and the last part is to improve the algorithm using a recursive algorithm for the kinematic application purpose. The precise attitude determination about three spatial axes is possible if at least three GNSS receivers with fixed baselines are used in particular array configurations. Assuming that the basic lengths of the baselines are known a priori, the attitude angles can be calculated via the combination of carrier phase and pseudorange observations. Since the carrier of the GPS signal is propagated in short-wave form, the measured phase differences are ambiguous. The multiples of the GPS signal phases together with the baseline lengths are therefore estimated and improved in a first step with the aid of the a priori baseline lengths information. The multiple-baseline float solution estimation method is used. However, the approach does not provide optimal results. Therefore, an alternative algorithm for the float solution is presented, which estimates the float solution by using the socalled the gradient based iterative method of the least-squares. It shows that method is able to give convergent estimate parameter. It is also shown here that the proposed method outperforms the conventional iterative least-squares in terms of iteration number and computational time. For instantaneous applications, the Least-squares AMBiguity Decorrelation Adjustment (LAMBDA) method is not optimal for fixing the integer multiples of the carrier phase differences for several baseline lengths. In addition, this method requires a high computational effort as soon as a larger number of baseline lines enter into the calculation. An improvement in this work is utilising the partial LAMBDA method, which only uses a subset of the integer multiples to be determined. This algorithm improves the determination of integer multiples and precise calculation of the baseline lengths. The advantages of this algorithm are discussed, and it is empirically demonstrated that the ambiguities are better resolved. Furthermore, the estimation of the attitude angles with the aid of quaternions is theoretically improved and analysed. Two processing strategies are investigated: the least-squares method and the Kalman Filter (KF) method. For the static case, the least-squares is applied and tested. Simulations show that the developed gradient based iterative method of the least-squares provides better estimates than the conventional adjustment methods. It is also shown that the number of iterations required is less and the computational time is reduced. This algorithm is not useful for kinematic applications where a fast sequence of results is required. A modified Extended Kalman Filter (EKF)-Like algorithm is used for kinematic applications. Experiments show that with this algorithm more stable quaternions can be calculated with fewer outliers than when they are determined by the least-squares method. All newly developed algorithms are theoretically analysed and subjected to extensive simulations and experimental kinematic tests in the field. Note de contenu : Introduction 1 - General mathematical model of GNSS positioning 2 - Multi-baseline GNSS estimation method 3 - GNSS based attitude determination 4 - Recursive attitude determination 5 - Experimental result of static and kinematic tests 6 - Summary, conclusion and future work suggestion Numéro de notice : 21574 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse étrangère Note de thèse : Doctor thesis : Engineering sciences : Stuttgart : 2017 Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=90576

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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]

Better GNSS navigation and spoofing detection with chip scale-atomic clocks / Thomas Krawinkel in GPS world, vol 27 n° 10 (October 2016)

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

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

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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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Kinematic interpolation of movement data / Jed A. Long in International journal of geographical information science IJGIS, vol 30 n° 5-6 (May - June 2016)  

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GNSS navigation and positioning for the GEOHALO experiment in Italy / Kaifei He in GPS solutions, vol 20 n° 2 (April 2016)  

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Towards sustainable mobility behavior: research challenges for location-aware information and communication technology / Paul Weiser in Geoinformatica [en ligne], vol 20 n° 2 (April - June 2016)  

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Potential of GPS common clock single-differences for deformation monitoring / Steffen Schön in Journal of applied geodesy, vol 10 n° 1 (March 2016)  

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