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BDS-3 precise orbit and clock solution at Wuhan University: status and improvement / Jing Guo in Journal of geodesy, vol 97 n° 2 (February 2023)
[article]
Titre : BDS-3 precise orbit and clock solution at Wuhan University: status and improvement Type de document : Article/Communication Auteurs : Jing Guo, Auteur ; Guo Chen, Auteur ; Xiaolong Xu, Auteur ; et al., Auteur Année de publication : 2023 Article en page(s) : n° 15 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Techniques orbitales
[Termes IGN] horloge du satellite
[Termes IGN] orbite précise
[Termes IGN] orbitographie
[Termes IGN] positionnement par BeiDou
[Termes IGN] rayonnement solaire
[Termes IGN] signal BeiDouRésumé : (auteur) With the rapid deployment of the third-generation satellites of the BeiDou Navigation Satellite System (BDS-3), Wuhan University (WHU) has incorporated BDS-3 satellites to its routine Multi-GNSS analysis since Day of Year 1, 2019. This article summarizes the processing strategy and presents the validation results of the WHU BDS-3 orbit and clock solutions submitted to the International GNSS Service Multi-GNSS Experiment in 2019. Although more than 200 stations with B1I and B3I signals tracking capability can be used for BDS-3 precise orbit determination, the number of tracking stations for different satellites diverges greatly; in general, more stations track those launched early and less those deployed late. The validations with orbit boundary misclosures, orbit differences with respect to BDS-3 products of GeoForschungsZentrum (GFZ) and Satellite Laser Ranging (SLR) residuals show that the orbits are affected by the number of tracking stations and the deficiency of dynamic models. To overcome the latter, an a priori solar radiation pressure (SRP) model has been proposed considering the Earth albedo and antenna thrust. The SLR validation shows that the new SRP model significantly improves the orbit from 5 to 7 cm to about 3 to 4 cm by reducing the Sun-elongation-angle-dependent errors of the BDS-3 orbits. Besides, the clock products have been compared with those of GFZ, and the root-mean-square (RMS) of clock linear fit is also analyzed. Noticeable different quality has been shown for Rubidium Atomic Frequency Standard and Passive Hydrogen Maser (PHM) clocks. The Sun-elevation-angle-dependent patterns are identified in PHM clocks, and the RMS of clock linear fit of PHM clocks can be reduced with improved dynamic modeling, particularly in eclipse seasons. Numéro de notice : A2023-131 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-023-01705-5 En ligne : https://doi.org/10.1007/s00190-023-01705-5 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102674
in Journal of geodesy > vol 97 n° 2 (February 2023) . - n° 15[article]Coastal GNSS-R phase altimetry based on the combination of L1 and L5 signals under high sea states / Yunqiao He in Journal of geodesy, vol 97 n° 2 (February 2023)
[article]
Titre : Coastal GNSS-R phase altimetry based on the combination of L1 and L5 signals under high sea states Type de document : Article/Communication Auteurs : Yunqiao He, Auteur ; Fan Gao, Auteur ; Tianhe Xu, Auteur ; et al., Auteur Année de publication : 2023 Article en page(s) : n° 19 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] diffusion de Rayleigh
[Termes IGN] hauteurs de mer
[Termes IGN] niveau de la mer
[Termes IGN] phase GNSS
[Termes IGN] précision altimétrique
[Termes IGN] Quasi-Zenith Satellite System
[Termes IGN] rapport signal sur bruit
[Termes IGN] récepteur bifréquence
[Termes IGN] réflectométrie par GNSS
[Termes IGN] signal GNSS
[Vedettes matières IGN] AltimétrieRésumé : (auteur) High-precision sea surface heights retrieved from the Global Navigation Satellite System Reflectometry (GNSS-R) measurements will be valuable in the fields of geodesy and oceanography studies. Due to the short wavelengths and low power of GNSS signals, the continuously tracked carrier phase measurements of reflected signals are usually unavailable for sea surfaces with big roughness, varying over space and time. In coastal conditions, persisting spatial coherence assumption can be made within the antenna coverage when the waves are not greatly breaking. To deal with temporal incoherence, we propose an improved algorithm to extract the combined interferometric phase difference measurements between direct and reflected signals under high sea states. After initial tracking the direct signals, dual-frequency observations are combined in the complex domain and the resulting interferometric signal is refined through open-loop tracking with 60-s coherent integration before the phase difference measurements are extracted, without tracking their respective carrier phase measurements in advance. In order to verify our method, a coastal experiment under different sea conditions was conducted and raw intermediate frequency data were collected. The raw data were then processed by a GNSS-R software-defined receiver to compute the path delay measurements of Quasi-Zenith Satellite System signals, which had good visibility during our experiment. For high sea states, that is, when the Rayleigh criterion is not fulfilled for the individual wavelengths, the phase delay measurements of L1 and L5 were random over time, while phase delay can still be well recovered for their combination. Also, the phase delay combination can be well extracted with a higher elevation angle than the previous studies. Finally, the altimetry solutions derived from the carrier phase delay measurements combination were compared with the in situ observations from a 26-GHz radar altimeter. The results show that centimeter-level altimetry accuracy using the combined measurements of L1 and L5 can be achieved under high sea states. Numéro de notice : A2023-132 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-023-01712-6 Date de publication en ligne : 27/03/2023 En ligne : https://doi.org/10.1007/s00190-023-01712-6 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102675
in Journal of geodesy > vol 97 n° 2 (February 2023) . - n° 19[article]Undifferenced and uncombined GNSS time and frequency transfer with integer ambiguity resolution / Xiaolong Mi in Journal of geodesy, vol 97 n° 2 (February 2023)
[article]
Titre : Undifferenced and uncombined GNSS time and frequency transfer with integer ambiguity resolution Type de document : Article/Communication Auteurs : Xiaolong Mi, Auteur ; Baocheng Zhang, Auteur ; Ahmed El-Mowafy, Auteur ; et al., Auteur Année de publication : 2023 Article en page(s) : n° 13 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] ambiguïté entière
[Termes IGN] modèle ionosphérique
[Termes IGN] positionnement cinématique en temps réel
[Termes IGN] positionnement ponctuel précis
[Termes IGN] résolution d'ambiguïté
[Termes IGN] retard ionosphèrique
[Termes IGN] temps-fréquenceRésumé : (auteur) Precise point positioning (PPP) has been a competitive global navigation satellite system (GNSS) technique for time and frequency transfer. However, the classical PPP is usually based on the ionosphere-free combination of dual-frequency observations, which has limited flexibility in the multi-frequency scenario. More importantly, the unknown integer ambiguities are not restored to the integer nature, making the advantage of high-precision carrier phase observations underutilized. In this contribution, using the undifferenced and uncombined (UDUC) observations, we derive the time and frequency transfer model suitable for multi-constellation and multi-frequency scenarios. Notably, in short- and medium-baseline time and frequency transfer, the ionosphere-fixed and ionosphere-weighted UDUC models are derived, respectively, by making full use of the single-differenced (SD) ionospheric constraints. The proposed model can be applied to short-, medium- and long-baseline time and frequency transfer. The ambiguities are solved in a double-differenced (DD) form and can thus be restored to integers. To verify the feasibility of the model, GPS data from several time laboratories were collected, and the performance of the time and frequency transfer were analyzed with different baseline lengths. The results showed that the ionosphere-fixed and ionosphere-weighted UDUC models with integer ambiguity resolution could improve the frequency stability by 25–60% and 9–30% at an averaging time of several tens of seconds to 1 day for short- and medium-baseline, respectively. Concerning the long-baseline, the UDUC model is 10–25% more stable than PPP for averaging time below a few thousands second and over 1 day. Numéro de notice : A2022-613 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-022-01689-8 Date de publication en ligne : 06/02/2023 En ligne : https://doi.org/10.1007/s00190-022-01689-8 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102677
in Journal of geodesy > vol 97 n° 2 (February 2023) . - n° 13[article]Autonomous coordinate establishment of local reference frames for ground-based positioning systems without known points / Tengfei Wang in Journal of geodesy, vol 97 n° 1 (January 2023)
[article]
Titre : Autonomous coordinate establishment of local reference frames for ground-based positioning systems without known points Type de document : Article/Communication Auteurs : Tengfei Wang, Auteur ; Zheng Yao, Auteur ; Mingquan Lu, Auteur Année de publication : 2023 Article en page(s) : n° 4 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement
[Termes IGN] ambiguïté entière
[Termes IGN] auto-étalonnage
[Termes IGN] mesurage de phase
[Termes IGN] positionnement cinématique en temps réel
[Termes IGN] positionnement par GNSS
[Termes IGN] pseudolite
[Termes IGN] récepteur
[Termes IGN] signal GPSRésumé : (auteur) Ground-based positioning systems (GBPSs) can serve as a supplement and backup to global navigation satellite systems. GBPSs are known for their low cost and high flexibility, but most of them have difficulty in achieving rapid deployment and operation, since the coordinates of transmitters rely on external precise measurements. Several existing self-calibration methods based on carrier phase measurements require known points of GBPS transmitters or receivers, which implies dependence on external measurements. This paper proposes an autonomous coordinate establishment (ACE) method without using known reference points for GBPSs. ACE utilizes a kinematic receiver to collect carrier phase measurements and employs a three-step procedure to establish a regional coordinate system. In the first step, ACE uses the properties of matrix structures to decouple generalized ambiguities and coordinates. Then, ACE obtains the rough estimation of the transmitter coordinates via multi-dimensional scaling in the second step. In the third step, ACE refines the estimate by solving a least squares problem which would be difficult to solve without the previous two steps. Numerical simulations and a real-world experiment show that the coordinate estimation of ACE can achieve decimeter to centimeter-level accuracy. The proposed method enables rapid deployment and operation for GBPSs. Numéro de notice : A2023-123 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-022-01687-w Date de publication en ligne : 04/01/2023 En ligne : https://doi.org/10.1007/s00190-022-01687-w Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102499
in Journal of geodesy > vol 97 n° 1 (January 2023) . - n° 4[article]Evaluation of GNSS-based volunteered geographic information for assessing visitor spatial distribution within protected areas: A case study of the Bavarian Forest National Park, Germany / Laura Horst in Applied Geography, vol 150 (January 2023)
[article]
Titre : Evaluation of GNSS-based volunteered geographic information for assessing visitor spatial distribution within protected areas: A case study of the Bavarian Forest National Park, Germany Type de document : Article/Communication Auteurs : Laura Horst, Auteur ; Karolina Taczanowska, Auteur ; Florian Porst, Auteur ; et al., Auteur Année de publication : 2023 Article en page(s) : n° 102825 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géomatique web
[Termes IGN] aire protégée
[Termes IGN] ArcGIS
[Termes IGN] Bavière (Allemagne)
[Termes IGN] distribution spatiale
[Termes IGN] données GNSS
[Termes IGN] données issues des réseaux sociaux
[Termes IGN] données localisées des bénévoles
[Termes IGN] géodatabase
[Termes IGN] parc naturel national
[Termes IGN] piétonRésumé : (auteur) Systematic monitoring of recreational use in vulnerable ecosystems is crucial to balance human needs and site capacities. Recently, publicly available digital data, including Global Navigation Satellite System-based Volunteered Geographic Information, gained attention as a potential resource depicting visitor movement. However, there is a need to critically assess its reliability for visitor monitoring across countries, regions and available databases. Our research evaluates the usability of GNSS-based VGI-data obtained from three common platforms: GPSies, Outdooractive, and Komoot for assessing the spatial distribution of hikers in the Bavarian Forest National Park. A total sample of 1742 GNSS-tracks uploaded between 2013 and 2018 were compared across data platforms. Additionally, available systematic field counts, carried out between 2013 and 2014 (11 Eco-Counter sensors), were compared to GNSS-based VGI data uploaded within the corresponding period. The comparisons at individual and collective levels (route lengths, kernel density, optimized hotspot analysis along with fishnet-based counts of GNSS-tracks) showed similarities between VGI data platforms. Data obtained from GPSies and Outdooractive displayed a higher correlation with each other than with those obtained from Komoot. Also, for GPSies, there was a significant positive correlation between VGI-data and field count data. Data sample of Outdooractive and Komoot within the specified spatio-temporal frame was too small to compare with available field count data. We highlight the necessity of systematic validation of GNSS-based VGI data resources, being complementary rather than the primary data source in visitor monitoring and recreation planning. Also, systematic long-term visitor monitoring using other methods is crucial to assess the validity of novel data resources, such as GNSS-based VGI. Numéro de notice : A2023-020 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1016/j.apgeog.2022.102825 Date de publication en ligne : 25/11/2023 En ligne : https://doi.org/10.1016/j.apgeog.2022.102825 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102220
in Applied Geography > vol 150 (January 2023) . - n° 102825[article]GENESIS: co-location of geodetic techniques in space / Pacôme Delva in Earth, Planets and Space, vol 75 n° 1 (2023)PermalinkImproving undifferenced precise satellite clock estimation with BDS-3 quad-frequency B1I/B3I/B1C/B2a observations for precise point positioning / Guoqiang Jiao in GPS solutions, vol 27 n° 1 (January 2023)PermalinkINS-assisted inter-system biases estimation and inter-system ambiguity resolution in a complex environment / Wenhao Zhao in GPS solutions, vol 27 n° 1 (January 2023)PermalinkMultipath mitigation for improving GPS narrow-lane uncalibrated phase delay estimation and speeding up PPP ambiguity resolution / Kai Zheng in Measurement, vol 206 (January 2023)PermalinkParameterisation of the GNSS troposphere tomography domain with optimisation of the nodes’ distribution / Estera Trzcina in Journal of geodesy, vol 97 n° 1 (January 2023)PermalinkPerformance tests of geodetic receivers with tilt sensors in obstructed environments using the NRTK GNSS technique / Puttipol Dumrongchai in Journal of applied geodesy, vol 17 n° 1 (January 2023)PermalinkPrecise orbit determination for BDS-3 GEO satellites enhanced by intersatellite links / Xiaojie Li in GPS solutions, vol 27 n° 1 (January 2023)PermalinkSpatiotemporal accuracy evaluation and errors analysis of global VTEC maps using a simulation technique / Jian Lin in GPS solutions, vol 27 n° 1 (January 2023)PermalinkWavelet-like denoising of GNSS data through machine learning. Application to the time series of the Campi Flegrei volcanic area (Southern Italy) / Rolando Carbonari in Geomatics, Natural Hazards and Risk, vol 14 n° 1 (2023)PermalinkDétermination de la déviation de la verticale sur le barrage de Plan d’Aval, sans aucune instrumentation spéciale, avec une précision de 0,4 mgon / Thomas Touzé in XYZ, n° 173 (décembre 2022)Permalink