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Modeling multifrequency GPS multipath fading in land vehicle environments / Vicente Carvalho Lima Filho in GPS solutions, vol 25 n° 1 (January 2021)
Titre : Modeling multifrequency GPS multipath fading in land vehicle environments Type de document : Article/Communication Auteurs : Vicente Carvalho Lima Filho, Auteur ; Alison Moraes, Auteur Année de publication : 2021 Article en page(s) : 14 p. Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal
[Termes descripteurs IGN] densité de probabilité
[Termes descripteurs IGN] interférence
[Termes descripteurs IGN] propagation du signal
[Termes descripteurs IGN] qualité du signal
[Termes descripteurs IGN] signal GPS
[Termes descripteurs IGN] simulation de signal
[Termes descripteurs IGN] trajet multiple
[Termes descripteurs IGN] véhiculeRésumé : (auteur) The reliability and performance of GPS receivers depend on the quality of the signal received, which can be largely affected by the interference caused by buildings, trees, and other obstacles. Since obstacles are always present in practical applications, several statistical representations have been developed along the years to measure, predict, and compensate errors induced by interferences. Two of the most used models to characterize GPS signal fading are the Nakagami-m and Rice, but in this work, we present evidence that supports the κ–μ distribution as the best fit to deal with multifrequency GPS multipath channels inside urban, rural, and forest areas. A synthetic signal simulator was developed to create propagation cases involving scattering clusters and specular reflections. Additionally, experimental measurements are presented to confirm the κ–μ distribution as the best distribution to characterize different situations on the available three GPS frequencies. We then present typical values of fading coefficients in L1, L2C, and L5 signals, for cases involving urban canyons, regular urban, rural, and dense vegetation areas. These coefficients can also be used to evaluate the receiver performance under similar cases or may be applied in weights measurement methods for positioning computation improvement. Numéro de notice : A2021-002 Affiliation des auteurs : non IGN Thématique : IMAGERIE/POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s10291-020-01040-8 date de publication en ligne : 09/10/2020 En ligne : https://doi.org/10.1007/s10291-020-01040-8 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96080
in GPS solutions > vol 25 n° 1 (January 2021) . - 14 p.[article]
Titre : Novel communication channel model for signal propagation and loss through layered earth Type de document : Article/Communication Auteurs : David O. LeVan, Auteur Année de publication : 2020 Article en page(s) : pp 5393 - 5399 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal
[Termes descripteurs IGN] atténuation du signal
[Termes descripteurs IGN] champ électromagnétique
[Termes descripteurs IGN] cible souterraine
[Termes descripteurs IGN] géophysique
[Termes descripteurs IGN] mine de charbon
[Termes descripteurs IGN] modèle de simulation
[Termes descripteurs IGN] modèle mathématique
[Termes descripteurs IGN] modélisation
[Termes descripteurs IGN] propagation du signal
[Termes descripteurs IGN] Terre (planète)Résumé : (auteur) Signal propagation through-the-Earth (TTE) is of great importance to geophysicists searching for underground resources such as oil and gas, homeland defense searching for tunnels and underground structures, and mining operations. The Earth is a conductive medium, unlike air or space, which tends to “short-out” electromagnetic fields traditionally used for wireless communications. The magnitude of this effect depends on many factors, such as frequency and the type of Earth-material. Mathematical models of energy propagation have been developed to help us understand the signal propagation issues, and some models can be used to predict the performance of the specific electromagnetic energies being used. There are numerous ways of modeling the Earth to study energy propagation. Some early literature presented models of signal propagation through a homogeneous Earth. These were fairly accurate for signals traveling from one point in the Earth to another point. However, signals traveling from below the ground to the surface of the Earth encounter many different layers of the Earth. This realization led to the development of models of a layered Earth. A novel layered-Earth communication model is presented and evaluated as to its accuracy by using measured data gathered during TTE communication tests from 2007 to 2012. Evaluations show that the new layered-EARTH model provides improved accuracy for the prediction of signal propagation performance from within a subterranean space, such as a mine, to and from the surface of the Earth. Numéro de notice : A2020-472 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2020.2965398 date de publication en ligne : 28/01/2020 En ligne : https://doi.org/10.1109/TGRS.2020.2965398 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95575
in IEEE Transactions on geoscience and remote sensing > vol 58 n° 8 (August 2020) . - pp 5393 - 5399[article]
Titre : Modeling the VLBI delay for Earth satellites Type de document : Article/Communication Auteurs : Frédéric Jaron, Auteur ; Axel Nothnagel, Auteur Année de publication : 2019 Article en page(s) : pp 953 - 961 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes descripteurs IGN] E-GRASP
[Termes descripteurs IGN] Geodetic Reference Antenna in Space
[Termes descripteurs IGN] interférométrie à très grande base
[Termes descripteurs IGN] point de liaison (géodésie)
[Termes descripteurs IGN] poursuite de satellite
[Termes descripteurs IGN] propagation du signal
[Termes descripteurs IGN] retard troposphérique
[Termes descripteurs IGN] système international de référence célesteRésumé : (auteur) Very-long-baseline interferometry (VLBI) observations of satellites orbiting the Earth and emitting an artificial radio signal have the potential of becoming an important technique for improving the frame ties between celestial and terrestrial reference frames. Modeling the delay of the signal reception at one station with respect to the other station of a baseline is a fundamental step for correlation and parameter estimation. The near-field VLBI delay models developed so far include numerical computation, which may become expensive in terms of computation time. This applies especially when partial derivatives are to be computed, which is the normal case for least squares adjustments. Furthermore, all the models are formulated in the barycentric celestial reference system requiring large numbers. Here we present an analytical expression for the VLBI delay for the special case of satellites orbiting the Earth, observed by ground-based radio telescopes. We analytically solve the light time equation for each signal propagation path from the source to receiver one and to receiver two under the simplification of linearizing the trajectory of the satellite. By approximating the motion of the Earth as uniform during the short signal travel times we are able to work in the geocentric celestial reference system. We investigate differences between numerical and analytical solutions by simulating VLBI observations of Earth satellites. These tests reveal that delays computed with the analytical formula are consistent with those computed with the numerical solution below the detection level of VLBI but at less computational cost. Numéro de notice : A2019-354 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-018-1217-0 date de publication en ligne : 20/11/2018 En ligne : https://doi.org/10.1007/s00190-018-1217-0 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93408
in Journal of geodesy > vol 93 n°7 (July 2019) . - pp 953 - 961[article]
Titre : The impact of solid Earth-tide model error on tropospheric zenith delay estimates and GPS coordinate time series Type de document : Article/Communication Auteurs : Fei Li, Auteur ; Jintao Lei, Auteur ; Chao Ma, Auteur ; Weifeng Hao, Auteur ; et al., Auteur Année de publication : 2018 Article en page(s) : pp 355 - 363 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes descripteurs IGN] coordonnées GPS
[Termes descripteurs IGN] erreur de modèle
[Termes descripteurs IGN] marée terrestre
[Termes descripteurs IGN] propagation du signal
[Termes descripteurs IGN] retard troposphérique zénithal
[Termes descripteurs IGN] série temporelleRésumé : (Auteur) Any unmodelled or mismodelled subdaily signals left in the model may not only affect the instantaneous site positions and the associated estimates, but also propagate into spurious seasonal signals, contaminating the daily coordinate time series. To demonstrate how subdaily ‘error’ in the modelling of the solid Earth-tide affects the estimates of tropospheric zenith total delay (ZTD) and how it propagates into long-period signal in the daily GPS time series, we analyse GPS observations collected between 2009 and 2013 for 13 sites in the coastal regions of Antarctica using the GAMIT/GLOBK 10.6 software. We find that ZTD differenced time series, with amplitude at 2 mm level, have inverse correlation with the input K1 correction, and the corresponding admittances range from 6% to 14%; Propagated spurious annual signals are evident in the vertical component of coordinate differenced time series, with amplitudes at the mm level and admittances of around 2–11%. Numéro de notice : A2018-444 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/00396265.2016.1277657 date de publication en ligne : 12/01/2017 En ligne : https://doi.org/10.1080/00396265.2016.1277657 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91018
in Survey review > vol 50 n° 361 (July 2018) . - pp 355 - 363[article]
Titre : Interferometry and Synthesis in Radio Astronomy Type de document : Monographie Auteurs : A.R. Thompson, Auteur ; James M. Moran, Auteur ; George W. Swenson Jr, Auteur Editeur : Berlin, Heidelberg, Vienne, New York, ... : Springer Année de publication : 2017 Importance : 910 p. ISBN/ISSN/EAN : 978-3-319-44429-1 Note générale : bibliography Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes descripteurs IGN] étalonnage radiométrique
[Termes descripteurs IGN] interférence
[Termes descripteurs IGN] interférométrie à très grande base
[Termes descripteurs IGN] polarimétrie
[Termes descripteurs IGN] prétraitement du signal
[Termes descripteurs IGN] propagation du signal
[Termes descripteurs IGN] propagation ionosphérique
[Termes descripteurs IGN] radioastronomie
[Termes descripteurs IGN] télédétection en hyperfréquence
[Termes descripteurs IGN] TerraSAR-X
[Termes descripteurs IGN] traitement du signalRésumé : (éditeur) The third edition of this indispensable book in radio interferometry provides extensive updates to the second edition, including results and technical advances from the past decade; discussion of arrays that now span the full range of the radio part of the electromagnetic spectrum observable from the ground, 10 MHz to 1 THz; an analysis of factors that affect array speed; and an expanded discussion of digital signal-processing techniques and of scintillation phenomena and the effects of atmospheric water vapor on image distortion, among many other topics.With its comprehensiveness and detailed exposition of all aspects of the theory and practice of radio interferometry and synthesis imaging, this book has established itself as a standard reference in the field. It begins with an overview of the basic principles of radio astronomy, a short history of the development of radio interferometry, and an elementary discussion of the operation of an interferometer. From this foundation, it delves into the underlying relationships of interferometry, sets forth the coordinate systems and parameters to describe synthesis imaging, and examines configurations of antennas for multielement synthesis arrays. Various aspects of the design and response of receiving systems are discussed, as well as the special requirements of very-long-baseline interferometry (VLBI), image reconstruction, and recent developments in image enhancement techniques and astrometric observations. Also discussed are propagation effects in the media between the source and the observer, and radio interference, factors that limit performance. Related techniques are introduced, including intensity interferometry, optical interferometry, lunar occultations, tracking of satellites in Earth orbit, interferometry for remote Earth sensing, and holographic measurements of antenna surfaces. This book will benefit anyone who is interested in radio interferometry techniques for astronomy, astrometry, geodesy, or electrical engineering. Note de contenu : 1- Introduction and historical review
2- Introductory Theory of Interferometry and Synthesis Imaging
3- Analysis of the Interferometer Response
4- Geometrical Relationships, Polarimetry, and the Interferometer Measurement Equation
5- Antennas and Arrays
6- Response of the Receiving System
7- System Design
8- Digital Signal Processing
9- Very-Long-Baseline Interferometry
10- Calibration and Imaging
11- Further Imaging Techniques
12- Interferometer Techniques for Astrometry and Geodesy
13- Propagation Effects: Neutral Medium
14- Propagation Effects: Ionized Media
15- Van Cittert–Zernike Theorem, Spatial Coherence, and Scattering
16- Radio Frequency Interference
17- Related TechniquesNuméro de notice : 25743 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Monographie En ligne : https://doi.org/10.1007/978-3-319-44431-4 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94930
