Descripteur
Documents disponibles dans cette catégorie (1607)
Ajouter le résultat dans votre panier
Visionner les documents numériques
Affiner la recherche Interroger des sources externes
Etendre la recherche sur niveau(x) vers le bas
Kindred spirits : laser ranging to GNSS satellites / Urs Hugentobler in GPS world, vol 28 n° 5 (May 2017)
[article]
Titre : Kindred spirits : laser ranging to GNSS satellites Type de document : Article/Communication Auteurs : Urs Hugentobler, Auteur Année de publication : 2017 Article en page(s) : pp 42 - 48 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] constellation Galileo
[Termes IGN] erreur systématique
[Termes IGN] positionnement par GNSS
[Termes IGN] rétroréflecteur
[Termes IGN] télémétrie laser sur satelliteRésumé : (Auteur) Satellite laser ranging or SLR has been an indispensable independent tool for validating the precise orbits determined for GNSS satellites using microwave pseudorange and carrierphase observations for several decades. SLR has allowed researchers to identify several orbit-modeling issues. Adding albedo radiation pressure and antenna thrust, among other effects, into the GPS orbit model allowed them to eliminate the observed bias between microwave- and SLR-derived orbits. For the first Galileo satellites launched, SLR residuals indicated severe orbit modeling issues caused by the different shape of Galileo satellite bodies compared to those of GPS. In the future, all GNSS satellites will be equipped with laser retroreflectors, a big challenge for researchers concerning tracking scenarios and observation planning to make economic use of the ground equipment. In this article, we will take a brief look at the history of laser ranging to navigation satellites, how that ranging has improved the accuracy of the orbits of those satellites, and what the future portends for this important contribution to space geodesy. Numéro de notice : A2017-293 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=85329
in GPS world > vol 28 n° 5 (May 2017) . - pp 42 - 48[article]GPS, Galileo, QZSS and IRNSS differential ISBs: estimation and application / Dennis Odijk in GPS solutions, vol 21 n° 2 (April 2017)
[article]
Titre : GPS, Galileo, QZSS and IRNSS differential ISBs: estimation and application Type de document : Article/Communication Auteurs : Dennis Odijk, Auteur ; Nandakumaran Nadarajah, Auteur ; Safoora Zaminpardaz, Auteur ; Peter J.G. Teunissen, Auteur Année de publication : 2017 Article en page(s) : pp 439 – 450 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] base géodésique
[Termes IGN] constellation GNSS
[Termes IGN] données GNSS
[Termes IGN] erreur systématique inter-systèmes
[Termes IGN] positionnement cinématique en temps réel
[Termes IGN] positionnement différentiel
[Termes IGN] positionnement par GNSS
[Termes IGN] résolution d'ambiguïtéRésumé : (auteur) Knowledge of inter-system biases (ISBs) is essential to combine observations of multiple global and regional navigation satellite systems (GNSS/RNSS) in an optimal way. Earlier studies based on GPS, Galileo, BDS and QZSS have demonstrated that the performance of multi-GNSS real-time kinematic positioning is improved when the differential ISBs (DISBs) corresponding to signals of different constellations but transmitted at identical frequencies can be calibrated, such that only one common pivot satellite is sufficient for inter-system ambiguity resolution at that particular frequency. Recently, many new GNSS satellites have been launched. At the beginning of 2016, there were 12 Galileo IOV/FOC satellites and 12 GPS Block IIF satellites in orbit, while the Indian Regional Navigation Satellite System (IRNSS) had five satellites launched of which four are operational. More launches are scheduled for the coming years. As a continuation of the earlier studies, we analyze the magnitude and stability of the DISBs corresponding to these new satellites. For IRNSS this article presents for the first time DISBs with respect to the L5/E5a signals of GPS, Galileo and QZSS for a mixed-receiver baseline. It is furthermore demonstrated that single-frequency (L5/E5a) ambiguity resolution is tremendously improved when the multi-GNSS observations are all differenced with respect to a common pivot satellite, compared to classical differencing for which a pivot satellite is selected for each constellation. Numéro de notice : A2017-214 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10291-016-0536-y En ligne : http://dx.doi.org/10.1007/s10291-016-0536-y Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=85084
in GPS solutions > vol 21 n° 2 (April 2017) . - pp 439 – 450[article]Integrating uncertainty propagation in GNSS radio occultation retrieval: From bending angle to dry-air atmospheric profiles / Jakob Schwarz in Earth and space science, vol 4 n° 4 (April 2017)
[article]
Titre : Integrating uncertainty propagation in GNSS radio occultation retrieval: From bending angle to dry-air atmospheric profiles Type de document : Article/Communication Auteurs : Jakob Schwarz, Auteur ; Gottfried Kirchengast, Auteur ; Marc Schwaerz, Auteur Année de publication : 2017 Article en page(s) : pp 200 - 228 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] covariance
[Termes IGN] données GNSS
[Termes IGN] incertitude géométrique
[Termes IGN] méthode de Monte-Carlo
[Termes IGN] occultation du signal
[Termes IGN] positionnement par GNSS
[Termes IGN] température en altitude
[Termes IGN] vapeur d'eau
[Vedettes matières IGN] Traitement de données GNSSRésumé : (auteur) Global Navigation Satellite Systems (GNSS) Radio Occultation (RO) observations, globally available as a continuous record since 2001, are highly accurate and long-term stable data records. Essential climate variables for the thermodynamic state of the free atmosphere, such as temperature and tropospheric water vapor profiles (involving background information), can be derived from these records, which consequentially have the potential to serve as climate benchmark data. In order to exploit this potential, atmospheric profile retrievals need to be very accurate and the remaining uncertainties need to be quantified and traced throughout the retrieval chain. The new Reference Occultation Processing System at the Wegener Center aims to deliver such an accurate retrieval chain with integrated uncertainty propagation. Here we introduce and demonstrate the algorithms implemented for uncertainty propagation from RO bending angle profiles to dry-air variables (pressure and temperature), for estimated random and systematic uncertainties, and for coestimates of observation-to-background weighting ratio profiles. We estimated systematic uncertainty profiles with the same operators as used for the basic profiles retrieval. The random uncertainty propagation was integrated by a covariance propagation approach and validated using Monte-Carlo ensemble methods. We present the results of the validation and demonstrate how the algorithm performs for individual simulated RO events and for ensembles of real RO events. We also compare the new results from the integrated uncertainty propagation to previous ones from empirical error analyses for RO-retrieved atmospheric profiles. We find that the new uncertainty estimation chain shows robust performance and is in good agreement with previous comparable results. Numéro de notice : A2017-269 Affiliation des auteurs : non IGN Thématique : INFORMATIQUE/MATHEMATIQUE/POSITIONNEMENT Nature : Article DOI : 10.1002/2016EA000234 En ligne : https://doi.org/10.1002/2016EA000234 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=85294
in Earth and space science > vol 4 n° 4 (April 2017) . - pp 200 - 228[article]Rapid initialization of real-time PPP by resolving undifferenced GPS and GLONASS ambiguities simultaneously / Jianghui Geng in Journal of geodesy, vol 91 n° 4 (April 2017)
[article]
Titre : Rapid initialization of real-time PPP by resolving undifferenced GPS and GLONASS ambiguities simultaneously Type de document : Article/Communication Auteurs : Jianghui Geng, Auteur ; Chuang Shi, Auteur Année de publication : 2017 Article en page(s) : pp 361 - 374 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] Allemagne
[Termes IGN] positionnement par GLONASS
[Termes IGN] positionnement par GPS
[Termes IGN] positionnement ponctuel précis
[Termes IGN] récepteur bifréquence
[Termes IGN] résolution d'ambiguïté
[Termes IGN] temps réelRésumé : (auteur) Rapid initialization of real-time precise point positioning (PPP) has constantly been a difficult problem. Recent efforts through multi-GNSS and multi-frequency data, though beneficial indeed, have not proved sufficiently effective in reducing the initialization periods to far less than 10 min. Though this goal can be easily reached by introducing ionosphere corrections as accurate as a few centimeters, a dense reference network is required which is impractical for wide-area applications. Leveraging the latest development of GLONASS PPP ambiguity resolution (PPP-AR) technique, we propose a composite strategy, where simultaneous GPS and GLONASS dual-frequency PPP-AR is carried out, and herein, the reliability of partial AR improves dramatically. We used 14 days of data from a German network and divided them into hourly data to test this strategy. We found that the initialization periods were shortened drastically from over 25 min when only GPS data were processed to about 6 min when GPS and GLONASS PPP-AR were accomplished simultaneously. More encouragingly, over 50% of real-time PPP solutions could be initialized successfully within 5 min through our strategy, in contrast to only 4% when only GPS data were used. We expect that our strategy can provide a promising route to overcoming the difficulty of achieving PPP initializations within a few minutes. Numéro de notice : A2017-105 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-016-0969-7 En ligne : http://dx.doi.org/10.1007/s00190-016-0969-7 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=84495
in Journal of geodesy > vol 91 n° 4 (April 2017) . - pp 361 - 374[article]Evaluation of quad-constellation GNSS precise point positioning in Egypt / Emad El Manaily in Artificial satellites, vol 52 n° 1 (March 2017)
[article]
Titre : Evaluation of quad-constellation GNSS precise point positioning in Egypt Type de document : Article/Communication Auteurs : Emad El Manaily, Auteur ; Mahmoud Abd Rabbou, Auteur ; Adel El-Shazly, Auteur ; Moustafa Baraka, Auteur Année de publication : 2017 Article en page(s) : pp 9 - Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] Alexandrie
[Termes IGN] Assouan
[Termes IGN] Le Caire
[Termes IGN] positionnement par BeiDou
[Termes IGN] positionnement par Galileo
[Termes IGN] positionnement par GNSS
[Termes IGN] positionnement ponctuel précis
[Termes IGN] zone urbaineRésumé : (auteur) Commonly, relative GPS positioning technique is used in Egypt for precise positioning applications. However, the requirement of a reference station is usually problematic for some applications as it limits the operational range of the system and increases the system cost and complexity. On the other hand, the single point positioning is traditionally used for low accuracy applications such as land vehicle navigation with positioning accuracy up to 10 meters in some scenarios which caused navigation problems especially in downtown areas. Recently, high positioning accuracy can be obtained through Precise Point Positioning (PPP) technique in which only once GNSS receiver is used. However, the major drawback of PPP is the long convergence time to reach to the surveying grade accuracy compared to the existing relative techniques. Moreover, the PPP accuracy is significantly degraded due to shortage in satellite availability in urban areas. To overcome these limitations, the quad constellation GNSS systems namely GPS, GLONASS, Galileo and BeiDou can be combined to increase the satellite availability and enhance the satellite geometry which in turn reduces the convergence time. In Egypt, at the moment, the signals of both Galileo and BeiDou could be logged with limited number of satellites up to four and six satellites for both Systems respectively. In this paper, we investigated the performance of the Quad-GNSS positioning in both dual- and single-frequency ionosphere free PPP modes for both high accurate and low cost navigation application, respectively. The performance of the developed PPP models will be investigated through GNSS data sets collected at three Egyptian cities namely, Cairo, Alexandria and Aswan. Numéro de notice : A2017-268 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1515/arsa-2017-0002 En ligne : https://doi.org/10.1515/arsa-2017-0002 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=85292
in Artificial satellites > vol 52 n° 1 (March 2017) . - pp 9 -[article]Adaptive time-variant adjustment for the positioning errors of a mobile mapping platform in GNSS-hostile areas / Jiawei Han in Survey review, vol 49 n° 352 (March 2017)PermalinkAirborne Lidar/INS/GNSS : algorithm uses fuzzy controlled Scale Invariant Feature Transform (SIFT) / Haowei Xu in GPS world, vol 28 n° 3 (March 2017)PermalinkEstimation and analysis of Galileo differential code biases / Min Li in Journal of geodesy, vol 91 n° 3 (March 2017)PermalinkPermalinkGeodetic monitoring of subrosion-induced subsidence processes in urban areas / Tobias Kersten in Journal of applied geodesy, vol 11 n° 1 (March 2017)PermalinkMulti-GNSS precise point positioning (MGPPP) using raw observations / Teng Liu in Journal of geodesy, vol 91 n° 3 (March 2017)PermalinkPerformance analysis of precise point positioning using multi-constellation GNSS : GPS, GLONASS, Galileo and BeiDou / Mahmoud Abd Rabbou in Survey review, vol 49 n° 352 (March 2017)PermalinkReference satellite selection method for GNSS high-precision relative positioning / Xiao Gao in Geodesy and Geodynamics, vol 8 n° 2 (March 2017)PermalinkShipborne over- and under-water integrated mobile mapping system and its seamless integration of point clouds / Bo Shi in Marine geodesy, vol 40 n° 2-3 (March - June 2017)PermalinkSurveillance de santé structurale des ouvrages d’art incluant les systèmes de positionnement par satellites / Camille Favre in XYZ, n° 150 (mars - mai 2017)Permalink