Descripteur
Documents disponibles dans cette catégorie (325)
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
Acquisition of weak GPS signals using wavelet-based de-noising methods / Mohaddeseh Sharie in Survey review, vol 52 n° 375 (November 2020)
[article]
Titre : Acquisition of weak GPS signals using wavelet-based de-noising methods Type de document : Article/Communication Auteurs : Mohaddeseh Sharie, Auteur ; Mohammad-Reza Mosavi, Auteur ; Narjes Rahemi, Auteur Année de publication : 2020 Article en page(s) : pp 497 - 513 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal
[Termes IGN] atténuation du signal
[Termes IGN] filtrage du bruit
[Termes IGN] rapport signal sur bruit
[Termes IGN] récepteur GPS
[Termes IGN] seuillage
[Termes IGN] signal GPS
[Termes IGN] sous ensemble flou
[Termes IGN] transformation en ondelettesRésumé : (auteur) Various factors cause GPS signals to be weakened in their path from satellites to receiver. This phenomenon leads to some problems in the normal stages of the positioning process, including acquisition stage. The wavelet transform is one of the tools that have been employed in several methods to improve receiver’s sensitivity in confronting weak GPS signals. Choosing an appropriate threshold plays a key role in the performance of this de-noising method. This study presents two methods for selecting an appropriate threshold. In the first method, the threshold is determined based on the statistical information extracted from the signal. On the other hand, the threshold in the second method is determined by type II fuzzy sets. The results show that employment of these two methods increases SNR gain as well as the range of acquirable SNR which makes signals acquisition with minimum post-correlation SNR of −6.5dB in a GPS receiver possible. Numéro de notice : A2020-687 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/00396265.2019.1648718 Date de publication en ligne : 01/08/2020 En ligne : https://doi.org/10.1080/00396265.2019.1648718 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96220
in Survey review > vol 52 n° 375 (November 2020) . - pp 497 - 513[article]Ground-based remote sensing of forests exploiting GNSS signals / Leila Guerriero in IEEE Transactions on geoscience and remote sensing, vol 58 n° 10 (October 2020)
[article]
Titre : Ground-based remote sensing of forests exploiting GNSS signals Type de document : Article/Communication Auteurs : Leila Guerriero, Auteur ; Francisco Martin, Auteur ; Antonio Mollfulleda, Auteur Année de publication : 2020 Article en page(s) : pp 6844 - 6860 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection
[Termes IGN] atténuation du signal
[Termes IGN] bande L
[Termes IGN] bande P
[Termes IGN] biomasse aérienne
[Termes IGN] canopée
[Termes IGN] diamètre à hauteur de poitrine
[Termes IGN] Leaf Area Index
[Termes IGN] polarisation
[Termes IGN] Populus (genre)
[Termes IGN] réseau neuronal artificiel
[Termes IGN] signal GNSSRésumé : (auteur) The estimation of aboveground biomass is commonly recognized for global relevance because of the vegetation role in the carbon cycle. Both active and passive microwave sensors can significantly contribute to this goal because of their high sensitivity to water content and high penetration at lower frequencies (L-/P-bands). In particular, Global Navigation Satellite Systems (GNSSs) are recently receiving increasing interest as source of opportunity to be employed as illuminator for L-band remote sensing, since they could provide low-cost sensors for nondestructive forest biomass estimation over large areas. In this article, we suggest a method to extract forest information using the GNSS direct signals collected in clear sky and below the vegetation canopy at both circular polarizations. An experimental campaign, carried out in the framework of an European Space Agency (ESA) project, was conducted over three poplar forests with different biomass to verify the feasibility of this technique. The relationships between the GNSS measurements and the tree parameters were first assessed and then interpreted and supported by statistical analysis and a theoretical model. The signal collected under the canopy is affected by attenuation and depolarization with respect to the one collected in open air, and this article demonstrated that both direct line-of-sight propagation and volume scattering play a role in the signal magnitude and its fluctuation in time. Although the experimental data set is limited in size and environmental conditions, two inversion algorithms were also tested with the encouraging retrieval results. Numéro de notice : A2020-585 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2020.2976899 Date de publication en ligne : 23/03/2020 En ligne : https://doi.org/10.1109/TGRS.2020.2976899 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95913
in IEEE Transactions on geoscience and remote sensing > vol 58 n° 10 (October 2020) . - pp 6844 - 6860[article]Integer-estimable GLONASS FDMA model as applied to Kalman-filter-based short- to long-baseline RTK positioning / Pengyu Hou in GPS solutions, Vol 24 n° 4 (October 2020)
[article]
Titre : Integer-estimable GLONASS FDMA model as applied to Kalman-filter-based short- to long-baseline RTK positioning Type de document : Article/Communication Auteurs : Pengyu Hou, Auteur ; Baocheng Zhang, Auteur ; Teng Liu, Auteur Année de publication : 2020 Article en page(s) : 14 p. Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] compensation Lambda
[Termes IGN] données GLONASS
[Termes IGN] données GPS
[Termes IGN] filtre de Kalman
[Termes IGN] ionosphère
[Termes IGN] ligne de base
[Termes IGN] positionnement cinématique en temps réel
[Termes IGN] positionnement par GLONASS
[Termes IGN] résolution d'ambiguïté
[Termes IGN] signal GLONASSRésumé : (auteur) Fast ambiguity resolution is a major challenge for GLONASS phase-based applications. The integer-estimable frequency-division multiple-access (IE-FDMA) model succeeds in formulating a set of estimable GLONASS phase ambiguities and preserving the integer property, to which the classical integer ambiguity resolution, typically the least-squares ambiguity decorrelation adjustment (LAMBDA), becomes readily applicable. The initial assessment of the IE-FDMA model demonstrated instantaneous ambiguity resolution capability in case of short-baseline real-time kinematic (RTK) positioning based on ionosphere-fixed formulation, in which the data processing strategy is window (batch)-based least-squares estimation with window length ranging from one to a few epochs. Here, we extend the applicability of the IE-FDMA model to Kalman-filter-based, ionosphere-fixed, ionosphere-weighted, and ionosphere-free cases, which are, respectively, adoptable for short-, medium-, and long-baseline RTK positioning. To adapt the IE-FDMA model to the Kalman filter, we estimate, at each epoch, first the estimable ambiguities, then transform them into integer-estimable ones, and finally resolve them into correct integers. This enables the rigorous integer ambiguity resolution and, at the same time, eases the recursive construction of integer-estimable ambiguities. We analyze global positioning system (GPS) and GLONASS data of nine baselines with lengths varying from several meters to more than one hundred kilometers. The results demonstrate the feasibility of fast ambiguity resolution not only for the GLONASS phase-only short-baseline RTK positioning, but for the GPS + GLONASS medium- and long-baseline RTK positioning as well. In all cases, the fixed solution with faster (several-minutes) convergence and higher (centimeter-level) precision indicates the benefits from GLONASS ambiguity resolution as compared to the float solution. Moreover, the dual-system solution with decreased ambiguity dilution of precision (ADOP) and improved positioning precision confirms the advantages of integrating GLONASS with GPS in contrast to the GPS-only situation. Numéro de notice : A2020-524 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s10291-020-01008-8 Date de publication en ligne : 11/07/2020 En ligne : https://doi.org/10.1007/s10291-020-01008-8 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95699
in GPS solutions > Vol 24 n° 4 (October 2020) . - 14 p.[article]Antenna phase center correction differences from robot and chamber calibrations: the case study LEIAR25 / Grzegorz Krzan in GPS solutions, vol 24 n° 2 (April 2020)
[article]
Titre : Antenna phase center correction differences from robot and chamber calibrations: the case study LEIAR25 Type de document : Article/Communication Auteurs : Grzegorz Krzan, Auteur ; Karol Dawidowicz, Auteur ; Pawel Wielgosz, Auteur Année de publication : 2020 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] antenne GLONASS
[Termes IGN] antenne GNSS
[Termes IGN] antenne GPS
[Termes IGN] centre de phase
[Termes IGN] chambre anéchoïque
[Termes IGN] correction du signal
[Termes IGN] étalonnage d'instrument
[Termes IGN] instrumentation Leica
[Termes IGN] positionnement par GNSS
[Termes IGN] positionnement ponctuel précis
[Termes IGN] robot
[Termes IGN] série temporelle
[Termes IGN] signal GNSSRésumé : (auteur) In recent years, the Global Navigation Satellite Systems (GNSS) have been intensively modernized, resulting in the introduction of new carrier frequencies for GPS and GLONASS and the development of new satellite systems such as Galileo and BeiDou (BDS). For this reason, the absolute field antenna calibrations performed so far for the two legacy carrier frequencies, the GPS and GLONASS, seem to be insufficient. Hence, all antennas will require a re-calibration of their phase center variations for the new signals to ensure the highest measurement accuracy. Currently, two absolute calibration methods are used to calibrate GNSS antennas: field calibration using a robot and calibration in an anechoic chamber. Unfortunately, differences in these methodologies also result in a disparity in the obtained antenna phase center corrections (PCC). Therefore, we analyze the differences between individual PCC obtained with these two methods, specifically for the Leica AR-25 antenna model (LEIAR25). In addition, the influence of PCC differences on the GNSS-derived position time series for 19 EUREF Permanent GNSS Network (EPN) stations was also assessed. The results show that the calibration method has a noticeable impact on PCC models. PCC differences determined for the ionosphere-free combination may reach up over 20 mm and can be transferred to the position domain. Further tests concerning the positioning accuracy showed that for horizontal coordinates differences between solutions were mostly below 1 mm, exceeding 2 mm only at two stations for the GLONASS solution. However, the height component differences exceeded 5 mm for four, six and six stations out of 19 for the GPS, GLONASS and Galileo solutions, respectively. These differences are strongly dependent on large L2 calibration differences. Numéro de notice : A2020-081 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s10291-020-0957-5 Date de publication en ligne : 11/02/2020 En ligne : https://doi.org/10.1007/s10291-020-0957-5 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94650
in GPS solutions > vol 24 n° 2 (April 2020)[article]Performance of Galileo precise time and frequency transfer models using quad-frequency carrier phase observations / Pengfei Zhang in GPS solutions, vol 24 n° 2 (April 2020)
[article]
Titre : Performance of Galileo precise time and frequency transfer models using quad-frequency carrier phase observations Type de document : Article/Communication Auteurs : Pengfei Zhang, Auteur ; Rui Tu, Auteur ; Yuping Gao, Auteur Année de publication : 2020 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal
[Termes IGN] bruit atmosphérique
[Termes IGN] décalage d'horloge
[Termes IGN] erreur systématique interfréquence d'horloge
[Termes IGN] fréquence multiple
[Termes IGN] modèle mathématique
[Termes IGN] phase
[Termes IGN] positionnement ponctuel précis
[Termes IGN] signal BeiDou
[Termes IGN] signal Galileo
[Termes IGN] signal GLONASS
[Termes IGN] signal GNSS
[Termes IGN] signal GPS
[Termes IGN] temps-fréquence
[Termes IGN] transmission de donnéesRésumé : (auteur) GNSSs, such as Galileo and modernized GPS, BeiDou and GLONASS systems, offer new potential and challenges in precise time and frequency transfer using multi-frequency observations. We focus on the performance of Galileo time and frequency transfer using the E1, E5a, E5b and E5 observations. Dual-frequency, triple-frequency and quad-frequency models for precise time and frequency transfer with different Galileo observations are proposed. Four time and transfer links between international time laboratories are used to assess the performances of different models in terms of time link noise level and frequency stability indicators. The average RMS values of the smoothed residuals of the clock difference series are 0.033 ns, 0.033 ns and 0.034 ns for the dual-frequency, triple-frequency and quad-frequency models with four time links, respectively. With respect to frequency stability, the average stability values at 15,360 s are 9.51 × 10−15, 9.46 × 10−15 and 9.37 × 10−15 for the dual-frequency, triple-frequency and quad-frequency models with four time links, respectively. Moreover, although biases among different models and receiver the inter-frequency exist, their characteristics are relatively stable. Generally, the dual-/triple-/quad-frequency models show similar performance for those time links, and the quad-frequency models can provide significant potential for switching among and unifying the three multi-frequency solutions, as well as further enhancing the redundancy and reliability compared to the current dual-frequency time transfer method. Numéro de notice : A2020-083 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s10291-020-0955-7 Date de publication en ligne : 04/02/2020 En ligne : https://doi.org/10.1007/s10291-020-0955-7 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94652
in GPS solutions > vol 24 n° 2 (April 2020)[article]Absolute field calibration for multi-GNSS receiver antennas at ETH Zurich / Daniel Willi in GPS solutions, vol 24 n° 1 (January 2020)PermalinkImpact of GPS processing on the estimation of snow water equivalent using refracted GPS signals / Ladina Steiner in IEEE Transactions on geoscience and remote sensing, vol 58 n° 1 (January 2020)PermalinkPermalinkRobust acquisition at GPS receivers in unsafe locations using complex wavelet transform / M. Moazedi in Survey review, vol 51 n° 369 (November 2019)PermalinkPostprocessing synchronization of a laser scanning system aboard a UAV / Marcela do Valle Machado in Photogrammetric Engineering & Remote Sensing, PERS, vol 85 n° 10 (October 2019)PermalinkDiscovery of new code interference phenomenon in GPS observables / Connor D. Flynn in GPS solutions, vol 23 n° 3 (July 2019)PermalinkSensitivity of GPS tropospheric estimates to mesoscale convective systems in West Africa / Samuel Nahmani in Atmospheric chemistry and physics, vol 19 n° 14 (July 2019)PermalinkPerformance analysis of dual-frequency receiver using combinations of GPS L1, L5, and L2 civil signals / Padma Bolla in Journal of geodesy, vol 93 n° 3 (March 2019)PermalinkRecalage conjoint de données de cartographie mobile et de modèles 3D de bâtiments / Miloud Mezian (2019)PermalinkEnhanced local ionosphere model for multi-constellations single frequency precise point positioning applications: Egyptian case study / Emad El Manaily in Artificial satellites, vol 53 n° 4 (December 2018)PermalinkDetermining inter-system bias of GNSS signals with narrowly spaced frequencies for GNSS positioning / Yumiao Tian in Journal of geodesy, vol 92 n° 8 (August 2018)PermalinkGPS receiver phase biases estimable in PPP-RTK networks : dynamic characterization and impact analysis / Baocheng Zhang in Journal of geodesy, vol 92 n° 6 (June 2018)PermalinkCarrier phase bias estimation of geometry-free linear combination of GNSS signals for ionospheric TEC modeling / Anna Krypiak-Gregorczyk in GPS solutions, vol 22 n° 2 (April 2018)PermalinkPermalinkParameter estimation with GNSS-reflectometry and GNSS synthetic aperture techniques / Miguel Angel Ribot Sanfelix (2018)PermalinkInitial assessment of the COMPASS/BeiDou-3 : new-generation navigation signals / Xiaohong Zhang in Journal of geodesy, vol 91 n° 10 (October 2017)PermalinkA fresh look at GNSS anti-jamming / Daniele Borio in Inside GNSS, vol 12 n° 5 (September - October 2017)PermalinkGroup delay variations of GPS transmitting and receiving antennas / Lambert Wanninger in Journal of geodesy, vol 91 n° 9 (September 2017)PermalinkFuture Space Service of NavIC (IRNSS) Constellation / Parimal Majithiya in Inside GNSS, vol 12 n° 4 (July - August 2017)PermalinkRobust GPS/BDS/INS tightly coupled integration with atmospheric constraints for long-range kinematic positioning / Houzeng Han in GPS solutions, vol 21 n° 3 (July 2017)PermalinkIonospheric error contribution to GNSS single-frequency navigation at the 2014 solar maximum / Raul Orus Perez in Journal of geodesy, vol 91 n° 4 (April 2017)PermalinkPerformance evaluation of GNSS-TEC estimation techniques at the grid point in middle and low latitudes during different geomagnetic conditions / O. E. Abe in Journal of geodesy, vol 91 n° 4 (April 2017)PermalinkRapid PPP ambiguity resolution using GPS+GLONASS observations / Yanyan Liu in Journal of geodesy, vol 91 n° 4 (April 2017)PermalinkCodeless code tracking of the Galileo E1 PRS / Cillian O'Driscoll in Inside GNSS, vol 12 n° 2 (March - April 2017)PermalinkEstimation and analysis of Galileo differential code biases / Min Li in Journal of geodesy, vol 91 n° 3 (March 2017)PermalinkReflected blessings : position estimation using non-line-of-sight GPS signals / Yuting Ng in GPS world, vol 28 n° 3 (March 2017)PermalinkSpringer handbook of Global Navigation Satellite Systems / Peter J.G. Teunissen (2017)PermalinkA drift line bias estimator: ARMA-based filter or calibration method, and its application in BDS/GPS-based attitude determination / Zhang Liang in Journal of geodesy, vol 90 n° 12 (December 2016)PermalinkMonitoring and prediction of precipitable water vapor using GPS data in Turkey / Kutubuddin Ansari in Journal of applied geodesy, vol 10 n° 4 (December 2016)PermalinkVariations of total electron content over Serbia during the increased solar activity period in 2013 and 2014 / Dragan Blagojevic in Geodetski vestnik, vol 60 n° 4 (December 2016)PermalinkModeling and assessment of triple-frequency BDS precise point positioning / Fei Guo in Journal of geodesy, vol 90 n° 11 (November 2016)PermalinkA phase-altimetric simulator : studying the sensitivity of Earth-reflected GNSS signals to ocean topography / Aaron Maximilian Semmling in IEEE Transactions on geoscience and remote sensing, vol 54 n° 11 (November 2016)PermalinkA statistical characterization of the Galileo-to-GPS inter-system bias / Ciro Gioia in Journal of geodesy, vol 90 n° 11 (November 2016)PermalinkDesign drivers and new trends for navigation message authentication schemes for GNSS systems / Gianluca Caparra in Inside GNSS, vol 11 n° 5 (September - October 2016)PermalinkLong-term soil moisture dynamics derived from GNSS interferometric reflectometry: a case study for Sutherland, South Africa / Sibylle Vey in GPS solutions, vol 20 n° 4 (October 2016)PermalinkOn the significance of periodic signals in noise analysis of GPS station coordinates time series / Janusz Bogusz in GPS solutions, vol 20 n° 4 (October 2016)PermalinkGNSS interferometric radio occultation / Manuel Martín-Neira in IEEE Transactions on geoscience and remote sensing, vol 54 n° 9 (September 2016)PermalinkReal-time cycle-slip detection and repair for BeiDou triple-frequency undifferenced observations / Y.-F. Yao in Survey review, vol 48 n° 350 (September 2016)PermalinkUse of a GPS-derived troposphere model to improve InSAR deformation estimates in the San Gabriel Valley, California / Nicolas Houlié in IEEE Transactions on geoscience and remote sensing, vol 54 n° 9 (September 2016)PermalinkEstimation of satellite antenna phase center offsets for Galileo / Peter Steigenberger in Journal of geodesy, vol 90 n° 8 (August 2016)PermalinkA geometry-free and ionosphere-free multipath mitigation method for BDS three-frequency ambiguity resolution / Dezhong Chen in Journal of geodesy, vol 90 n° 8 (August 2016)PermalinkInterference mitigation in the E5A Galileo band using an open-source simulator / Diego Alonso in Inside GNSS, vol 11 n° 4 (July - August 2016)PermalinkListening for RF noise : An analysis of pre-despreading GNSS interference detection techniques / Ali Jafarnia-Jahromi in Inside GNSS, vol 11 n° 3 (May - June 2016)PermalinkGNSS threat quantification in the United Kingdom in 2015 / Chaz Dixon in Navigation aérienne, maritime, spatiale, terrestre, vol 63 n° 250 (mai - août 2016)PermalinkA study on the dependency of GNSS pseudorange biases on correlator spacing / André Hauschild in GPS solutions, vol 20 n° 2 (April 2016)Permalink