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High-resolution geoid modeling using least squares modification of Stokes and Hotine formulas in Colorado / Mustafa Serkan Işık in Journal of geodesy, vol 95 n° 5 (May 2021)  

Public [article]  inJournal of geodesy > vol 95 n° 5 (May 2021) . - n° 49 Titre : High-resolution geoid modeling using least squares modification of Stokes and Hotine formulas in Colorado Type de document : Article/Communication Auteurs : Mustafa Serkan Işık, Auteur ; Bihter Erol, Auteur ; Serdar Erol, Auteur ; et al., Auteur Année de publication : 2021 Article en page(s) : n° 49 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] Colorado (Etats-Unis) [Termes IGN] correction [Termes IGN] géoïde local [Termes IGN] intégrale de Stokes [Termes IGN] levé gravimétrique [Termes IGN] matrice de covariance [Termes IGN] méthode des moindres carrés [Termes IGN] modèle de géopotentiel [Termes IGN] modèle mathématique [Termes IGN] montagne [Termes IGN] nivellement [Termes IGN] système de référence altimétrique Résumé : (auteur) The Colorado geoid experiment was initiated and organized as a joint study by the Joint Working Group (JWG) 2.2.2 (1-cm geoid experiment) of the International Association of Geodesy (IAG) in 2017, and different institutions and research groups contributed to this study. The aim of this experiment was to clarify the repeatability of gravity potential values as International Height Reference System (IHRS) coordinates from different geoid determination approaches carried out with the same input dataset. The dataset included the terrestrial and airborne gravity observations, a digital terrain model, the XGM2016 global geopotential model and GPS/leveling data for model validations belonging to a mountainous area of approximately 550 km × 730 km in Colorado, US. The dataset was provided by National Geodetic Survey (NGS) department. In this frame, this article aims providing a discussion on Colorado geoid modeling through individual experimental results obtained by Istanbul Technical University-Gravity Research Group (ITU-GRG). This contribution mainly focused on modeling the Colorado geoid using the least squares modifications of Stokes and Hotine integral formulas with additive corrections. The computations using each formula were carried out using ITU-GRG software, including the solution variants based on terrestrial-only, airborne-only and combined gravity datasets. Then, the calculated experimental geoid models were validated using historical and recently measured profile-based GPS/leveling datasets, and they were also compared with the official solutions submitted by different institutions for the “1-cm geoid experiment” of IAG JWG 2.2.2. For all validation results, the Hotine and Stokes integral formulas yielded similar performances in terms of geoid accuracy; however, the models computed using the combined data had better accuracy than those using the terrestrial-only and airborne-only solutions. The geoid model solutions using the combined data had an accuracy of 2.69 cm for the Hotine method and 2.87 cm for the Stokes method in the test results using GPS/leveling data of the GSVS17 (Geoid Slope Validation Survey 2017) profile. Airborne data from the Gravity for the Redefinition of the American Vertical Datum (GRAV-D) project contributed significantly towards improving the geoid model, especially in the mountainous parts of the area. Numéro de notice : A2021-311 Affiliation des auteurs : non IGN Thématique : MATHEMATIQUE/POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-021-01501-z Date de publication en ligne : 07/04/2021 En ligne : https://doi.org/10.1007/s00190-021-01501-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=97503 [article]

Multi-GNSS real-time precise clock estimation considering the correction of inter-satellite code biases / Liang Chen in GPS solutions, vol 25 n° 2 (April 2021)  

Public [article]  inGPS solutions > vol 25 n° 2 (April 2021) . - 17 p. Titre : Multi-GNSS real-time precise clock estimation considering the correction of inter-satellite code biases Type de document : Article/Communication Auteurs : Liang Chen, Auteur ; Min Li, Auteur ; Ying Zhao, Auteur ; et al., Auteur Année de publication : 2021 Article en page(s) : 17 p. Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] correction [Termes IGN] décalage d'horloge [Termes IGN] erreur systématique inter-systèmes [Termes IGN] phase [Termes IGN] positionnement par BeiDou [Termes IGN] positionnement par Galileo [Termes IGN] positionnement par GLONASS [Termes IGN] positionnement par GNSS [Termes IGN] positionnement par GPS [Termes IGN] récepteur GNSS [Termes IGN] temps réel Résumé : (Auteur) For reasons mostly related to chip shape distortions, global navigation satellite system (GNSS) observations are corrupted by receiver-dependent biases. These are often stable in the long term, though numerically different depending on the signal frequency, satellite system and receiver manufacturer. Based on the mixed-differenced model combining undifferenced pseudorange with epoch-differenced carrier phase observations, we present a multi-GNSS real-time precise clock estimation model considering correction of inter-satellite code biases (ISCBs). Pre-estimated receiver-dependent ISCB corrections are introduced to correct the inter-receiver, inter-satellite and inter-system biases largely. Then the number of estimated parameters is reduced to a manageable level for real-time estimation. Comparisons with post-processed data show that compared to undifferenced, epoch-differenced and non-bias-corrected mixed-differenced models, the proposed bias-corrected model can greatly reduce the precise clock offset systematic biases, especially for GLONASS and BeiDou. The test results show the root mean square data reductions are improved by up to 96% for GLONASS, 78% for BeiDou and 40% for GPS and Galileo. Numéro de notice : A2021-092 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s10291-020-01065-z Date de publication en ligne : 15/01/2021 En ligne : https://doi.org/10.1007/s10291-020-01065-z Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96883 [article]

SBAS-aided GPS positioning with an extended ionosphere map at the boundaries of WAAS service area / Mingyu Kim in Remote sensing, vol 13 n° 1 (January-1 2021)  

Public [article]  inRemote sensing > vol 13 n° 1 (January-1 2021) . - n° 151 Titre : SBAS-aided GPS positioning with an extended ionosphere map at the boundaries of WAAS service area Type de document : Article/Communication Auteurs : Mingyu Kim, Auteur ; Jeongrae Kim, Auteur Année de publication : 2021 Article en page(s) : n° 151 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes IGN] correction [Termes IGN] correction ionosphérique [Termes IGN] décalage d'horloge [Termes IGN] GPS assisté pour la navigation (technologies) [Termes IGN] orbite [Termes IGN] positionnement par GNSS [Termes IGN] retard ionosphèrique [Termes IGN] Wide Area Augmentation System Résumé : (auteur) Space-based augmentation system (SBAS) provides correction information for improving the global navigation satellite system (GNSS) positioning accuracy in real-time, which includes satellite orbit/clock and ionospheric delay corrections. At SBAS service area boundaries, the correction is not fully available to GNSS users and only a partial correction is available, mostly satellite orbit/clock information. By using the geospatial correlation property of the ionosphere delay information, the ionosphere correction coverage can be extended by a spatial extrapolation algorithm. This paper proposes extending SBAS ionosphere correction coverage by using a biharmonic spline extrapolation algorithm. The wide area augmentation system (WAAS) ionosphere map is extended and its ionospheric delay error is compared with the GPS Klobuchar model. The mean ionosphere error reduction at low latitude is 52.3%. The positioning accuracy of the extended ionosphere correction method is compared with the accuracy of the conventional SBAS positioning method when only a partial set of SBAS corrections are available. The mean positioning error reduction is 44.8%, and the positioning accuracy improvement is significant at low latitude. Numéro de notice : A2021-075 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.3390/rs13010151 Date de publication en ligne : 05/01/2021 En ligne : https://doi.org/10.3390/rs13010151 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96813 [article]

Evolution of orbit and clock quality for real-time multi-GNSS solutions / Kamil Kazmierski in GPS solutions, Vol 24 n° 4 (October 2020)  

Public [article]  inGPS solutions > Vol 24 n° 4 (October 2020) . - 12 p. Titre : Evolution of orbit and clock quality for real-time multi-GNSS solutions Type de document : Article/Communication Auteurs : Kamil Kazmierski, Auteur ; Radoslaw Zajdel, Auteur ; Krzysztof Sosnica, Auteur Année de publication : 2020 Article en page(s) : 12 p. Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] correction [Termes IGN] erreur systématique [Termes IGN] horloge atomique [Termes IGN] orbitographie par GNSS [Termes IGN] positionnement par GNSS [Termes IGN] positionnement ponctuel précis [Termes IGN] précision du positionnement [Termes IGN] synchronisation [Termes IGN] télémétrie laser sur satellite [Termes IGN] temps réel Résumé : (auteur) High-quality satellite orbits and clocks are necessary for multi-GNSS precise point positioning and timing. In undifferenced GNSS solutions, the quality of orbit and clock products significantly influences the resulting position accuracy; therefore, for precise positioning in real time, the corrections for orbits and clocks are generated and distributed to users. In this research, we assess the quality and the availability of real-time CNES orbits and clocks for GPS, GLONASS, Galileo, and BeiDou-2 separated by satellite blocks and types, as well as the product quality changes over time. We calculate the signal-in-space ranging error (SISRE) as the main orbit and clock quality indicator. Moreover, we employ independent orbit validation based on satellite laser ranging. We found that the most accurate orbits are currently available for GPS. However, Galileo utmost stable atomic clocks compensate for systematic errors in Galileo orbits. As a result, the SISRE for Galileo is lower than that for GPS, equaling 1.6 and 2.3 cm for Galileo and GPS, respectively. The GLONASS satellites, despite the high quality of their orbits, are characterized by poor quality of clocks, and together with BeiDou-2 in medium and geosynchronous inclined orbits, are characterized by SISRE of 4–6 cm. BeiDou-2 in geostationary orbits is characterized by large orbital errors and the lowest availability of real-time orbit and clock corrections due to a large number of satellite maneuvers. The quality of GNSS orbit and clock corrections changes over time and depends on satellite type, block, orbit characteristics, onboard atomic clock, and the sun elevation above the orbital plane. Numéro de notice : A2020-520 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s10291-020-01026-6 Date de publication en ligne : 28/08/2020 En ligne : https://doi.org/10.1007/s10291-020-01026-6 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95687 [article]

An offshore real-time precise point positioning technique based on a single set of BeiDou short-message communication devices / Zhixi Nie in Journal of geodesy, vol 94 n° 9 (September 2020)  

Public [article]  inJournal of geodesy > vol 94 n° 9 (September 2020) . - n° 78 Titre : An offshore real-time precise point positioning technique based on a single set of BeiDou short-message communication devices Type de document : Article/Communication Auteurs : Zhixi Nie, Auteur ; Boyang Wang, Auteur ; Zhenjie Wang, Auteur ; Kaifei He, Auteur Année de publication : 2020 Article en page(s) : n° 78 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes IGN] correction [Termes IGN] horloge du satellite [Termes IGN] international GPS service for geodynamics [Termes IGN] positionnement par GNSS [Termes IGN] positionnement ponctuel précis [Termes IGN] temps réel Résumé : (auteur) Real-time precise point positioning (PPP) based on open-access real-time service (RTS) of the international GNSS service (IGS) has attracted increasing attention in recent years. For offshore applications, the receiving of RTS corrections becomes a major obstacle due to lack of internet-based infrastructures. Short-message communication (SMC) is a particular technique of BeiDou navigation satellite system (BDS), which can provide bidirectional communication between users in a cost-effective way. However, the limited bandwidth and frequency of BDS SMC make it impossible to directly broadcast IGS RTS corrections with BDS SMC. An offshore real-time PPP technique is proposed based on IGS RTS corrections with a single set of BDS SMC devices for communication. RTS orbit corrections in the along-track, cross-track and radial directions, the clock correction and the code bias correction of each satellite are together converted into an equivalent range correction on the basis of user approximate position and will-be-used code observation types. The range corrections within 1 min are fitted into a first-order polynomial. Only the range and range-rate corrections at the reference time are broadcast with BDS SMC. In addition, different from broadcasting corrections of all satellites in the IGS RTS, corrections of only visible satellites are encoded into a BDS SMC correction message to further reduce the data size. The encoding strategy of BDS SMC correction message and a detailed procedure of the offshore real-time PPP technique are presented. The land-simulated and offshore experiment results show that the proposed technique can meet the demands of high-precision offshore applications. Numéro de notice : A2020-543 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-020-01411-6 Date de publication en ligne : 08/08/2020 En ligne : https://doi.org/10.1007/s00190-020-01411-6 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95745 [article]

A two-step approach for the correction of rolling shutter distortion in UAV photogrammetry / Yilin Zhou in ISPRS Journal of photogrammetry and remote sensing, vol 160 (February 2020)  

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On the detectability of mis-modeled biases in the network-derived positioning corrections and their user impact / Amir Khodabandeh in GPS solutions, vol 23 n° 3 (July 2019)  

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A posteriori bias correction of three models used for environmental reporting / Bogdan M. Strimbu in Forestry, an international journal of forest research, vol 91 n° 1 (January 2018)  

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Correction des tendances marégraphiques long terme avec du GPS / Alvaro Santamaria Gomez in Bulletin d'information scientifique et technique de l'IGN, n° 77 (avril 2011) 

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EGNOS gets to work / F. Boullete in GPS world, vol 22 n° 2 (February 2011)

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Sources d'erreurs et combinaisons linéaires des trois fréquences du système Galiléo pour le positionnement différentiel / L. Tabti in Bulletin des sciences géographiques, n° 22 (octobre 2008)

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Adjusting for long term anomalous trends in NOAA's Global Vegetation Index datasets / L. Jiang in IEEE Transactions on geoscience and remote sensing, vol 46 n° 2 (February 2008)  

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A novel method for automating the checking and correction of digital elevation models using orthophographs / A. Georgopoulos in Photogrammetric record, vol 18 n° 102 (June - August 2003)  

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True orthophoto generation of built-up areas using multi-view images / J.Y. Rau in Photogrammetric Engineering & Remote Sensing, PERS, vol 68 n° 6 (June 2002)

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Mapping Dilution of Precision (MDOP) and map-matched GPS / Geoffrey Blewitt in International journal of geographical information science IJGIS, vol 16 n° 1 (january 2002)  

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