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Evolution of orbit and clock quality for real-time multi-GNSS solutions / Kamil Kazmierski in GPS solutions, Vol 24 n° 4 (October 2020)
[article]
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 réelRésumé : (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
in GPS solutions > Vol 24 n° 4 (October 2020) . - 12 p.[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)
[article]
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 réelRésumé : (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
in Journal of geodesy > vol 94 n° 9 (September 2020) . - n° 78[article]Evaluating the accuracy of ALS-based removal estimates against actual logging data / Ville Vähä-Konka in Annals of Forest Science, vol 77 n° 3 (September 2020)
[article]
Titre : Evaluating the accuracy of ALS-based removal estimates against actual logging data Type de document : Article/Communication Auteurs : Ville Vähä-Konka, Auteur ; Matti Maltamo, Auteur ; Timo Pukkala, Auteur ; Kalle Kärhä, Auteur Année de publication : 2020 Article en page(s) : 11 p. Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie
[Termes IGN] éclaircie (sylviculture)
[Termes IGN] fiabilité des données
[Termes IGN] Finlande
[Termes IGN] gestion forestière
[Termes IGN] inventaire forestier étranger (données)
[Termes IGN] récolte de bois
[Termes IGN] télédétection par lidar
[Termes IGN] télémètre laser aéroporté
[Termes IGN] volume en boisRésumé : (auteur) Key message: We examined the accuracy of the stand attribute data based on airborne laser scanning (ALS) provided by the Finnish Forest Centre. The precision of forest inventory data was compared for the first time with operative logging data measured by the harvester.
Context: Airborne laser scanning (ALS) is increasingly used together with models to predict the stand attributes of boreal forests. The information is updated by growth models. Information produced by remote sensing, model prediction, and growth simulation needs field verification. The data collected by harvesters on logging sites provide a means to evaluate and verify the accuracy of the ALS-based data.
Aims: This study investigated the accuracy of ALS-based forest inventory data provided by the Finnish Forest Centre at the stand level, using harvester data as the reference. Special interest was on timber assortment volumes where the quality reductions of sawlog are model predictions in ALS-based data and true realized reductions in the logging data.
Methods: We examined the accuracy of total volume and timber assortment volumes by comparing ALS-based data and operative logging data measured by a harvester. This was done both for clear cuttings and thinning sites. Accuracy of the identification of the dominant tree species of the stand was examined using the Kappa coefficient.
Results: In clear-felling sites, the total harvest removals based on ALS and model prediction had a RMSE% of 26.0%. In thinning, the corresponding difference in the total harvested removal was 42.4%. Compared to logged volume, ALS-based prediction overestimated sawlog removals in clear cuttings and underestimated pulpwood removals.
Conclusion: The study provided valuable information on the accuracy of ALS-based stand attribute data. Our results showed that ALS-based data need better methods to predict the technical quality of harvested trees, to avoid systematic overestimates of sawlog volume. We also found that the ALS-based estimates do not accurately predict the volume of trees removed in actual thinnings.Numéro de notice : A2020-592 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s13595-020-00985-7 Date de publication en ligne : 27/08/2020 En ligne : https://doi.org/10.1007/s13595-020-00985-7 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95927
in Annals of Forest Science > vol 77 n° 3 (September 2020) . - 11 p.[article]GipsyX/RTGx, a new tool set for space geodetic operations and research / Willy I. Bertiger in Advances in space research, vol 66 n° 3 (1 August 2020)
[article]
Titre : GipsyX/RTGx, a new tool set for space geodetic operations and research Type de document : Article/Communication Auteurs : Willy I. Bertiger, Auteur ; Yoaz E. Bar-Sever, Auteur ; A. Dorsey, Auteur ; Bruce J. Haines, Auteur ; N.R. Harvey, Auteur ; Dan Hemberger, Auteur ; Michael B. Heflin, Auteur ; Wenwen Lu, Auteur ; Mark Miller, Auteur ; Angelyn Moore, Auteur ; Dave Murphy, Auteur ; Paul Ries, Auteur ; L.J. Romans, Auteur ; Aurore E. Sibois, Auteur ; Ant Sibthorpe, Auteur ; Bela Szilagyi, Auteur ; Michele Vallisneri, Auteur ; Pascal Willis , Auteur Année de publication : 2020 Projets : 3-projet - voir note / Article en page(s) : pp 469 - 489 Note générale : bibliographie
The research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] données DORIS
[Termes IGN] données GNSS
[Termes IGN] données ITGB
[Termes IGN] données TLS (télémétrie)
[Termes IGN] filtre de Kalman
[Termes IGN] horloge atomique
[Termes IGN] horloge du satellite
[Termes IGN] logiciel d'orbitographie
[Termes IGN] positionnement ponctuel précis
[Termes IGN] série temporelle
[Termes IGN] temps réel
[Termes IGN] traitement de données GNSSRésumé : (auteur) GipsyX/RTGx is the Jet Propulsion Laboratory’s (JPL) next generation software package for positioning, navigation, timing, and Earth science using measurements from three geodetic techniques: Global Navigation Satellite Systems (GNSS), Satellite Laser Ranging (SLR), and Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS); with Very Long Baseline Interferometry (VLBI) under development. The software facilitates combined estimation of geodetic and geophysical parameters using a Kalman filter approach on real or simulated data in both post-processing and in real-time. The estimated parameters include station coordinates and velocities, satellite orbits and clocks, Earth orientation, ionospheric and tropospheric delays. The software is also capable of full realization of a dynamic terrestrial reference through analysis and combination of time series of ground station coordinates.
Applying lessons learned from its predecessors, GIPSY-OASIS and Real Time GIPSY (RTG), GipsyX/RTGx was re-designed from the ground up to offer improved precision, accuracy, usability, and operational flexibility. We present some key aspects of its new architecture, and describe some of its major applications, including Real-time orbit determination and ephemeris predictions in the U.S. Air Force Next Generation GPS Operational Control Segment (OCX), as well as in JPL’s Global Differential GPS (GDGPS) System, supporting User Range Error (URE) of
5 cm RMS; precision post-processing GNSS orbit determination, including JPL’s contributions to the International GNSS Service (IGS) with URE in the 2 cm RMS range; Precise point positioning (PPP) with ambiguity resolution, both statically and kinematically, for geodetic applications with 2 mm horizontal, and 6.5 mm vertical repeatability for static positioning; Operational orbit and clock determination for Low Earth Orbiting (LEO) satellites, such as NASA’s Gravity Recovery and Climate Experiment (GRACE) mission with GRACE relative clock alignment at the 20 ps level; calibration of radio occultation data from LEO satellites for weather forecasting and climate studies; Satellite Laser Ranging (SLR) to GNSS and LEO satellites, DORIS-based and multi-technique orbit determination for LEO; production of terrestrial reference frames and Earth rotation parameters in support of JPL’s contribution to the International Terrestrial Reference Frame (ITRF).Numéro de notice : A2020-575 Affiliation des auteurs : UMR IPGP-Géod+Ext (2020- ) Thématique : INFORMATIQUE/POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.asr.2020.04.015 Date de publication en ligne : 22/04/2020 En ligne : https://doi.org/10.1016/j.asr.2020.04.015 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96369
in Advances in space research > vol 66 n° 3 (1 August 2020) . - pp 469 - 489[article]History of laser scanning, part 2: the later phase of industrial and heritage applications / Adam P. Spring in Photogrammetric Engineering & Remote Sensing, PERS, vol 86 n° 8 (August 2020)
[article]
Titre : History of laser scanning, part 2: the later phase of industrial and heritage applications Type de document : Article/Communication Auteurs : Adam P. Spring, Auteur Année de publication : 2020 Article en page(s) : pp 479-501 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie
[Termes IGN] balayage laser
[Termes IGN] évolution technologique
[Termes IGN] histoire des sciences et techniques
[Termes IGN] instrument embarqué
[Termes IGN] télémètre laser
[Termes IGN] télémétrie laser terrestre
[Termes IGN] travaux de terrainRésumé : (Auteur) The second part of this article examines the transition of midrange terrestrial laser scanning (TLS)–from applied research to applied markets. It looks at the crossover of technologies; their connection to broader developments in computing and microelectronics; and changes made based on application. The shift from initial uses in on-board guidance systems and terrain mapping to tripod-based survey for as-built documentation is a main focus. Origins of terms like digital twin are identified and, for the first time, the earliest examples of cultural heritage (CH) based midrange TLS scans are shown and explained. Part two of this history of laser scanning is a comprehensive analysis upto the year 2020. Numéro de notice : A2020-435 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.14358/PERS.86.8.479 Date de publication en ligne : 01/08/2020 En ligne : https://doi.org/10.14358/PERS.86.8.479 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95703
in Photogrammetric Engineering & Remote Sensing, PERS > vol 86 n° 8 (August 2020) . - pp 479-501[article]Réservation
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