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Multipath detection with the combination of SNR measurements – Example from urban environment / Peter Spanik in Geodesy and cartography, vol 66 n° 2 (December 2017)
[article]
Titre : Multipath detection with the combination of SNR measurements – Example from urban environment Type de document : Article/Communication Auteurs : Peter Spanik, Auteur ; Jan Hefty, Auteur Année de publication : 2017 Article en page(s) : pp 305 - 316 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement
[Termes IGN] données Galileo
[Termes IGN] données GLONASS
[Termes IGN] données GPS
[Termes IGN] mesurage de phase
[Termes IGN] milieu urbain
[Termes IGN] rapport signal sur bruit
[Termes IGN] trajet multipleRésumé : (auteur) Multipath is one of the most severe station-dependent error sources in both static and kinematic positioning. Relatively new and simple detection technique using the Signal-to-Noise (SNR) measurements on three frequencies will be presented based on idea of Strode and Groves. Exploitation of SNR measurements is beneficial especially for their unambiguous character. Method is based on the fact that SNR values are closely linked with estimation of pseudo-ranges and phase measurements during signal correlation processing. Due to this connection, combination of SNR values can be used to detect anomalous behavior in received signal, however some kind of calibration in low multipath environment has to be done previously. In case of multipath, phase measurements on different frequencies will not be affected in the same manner. Specular multipath, e.g. from building wall introduces additional path delay which is interpreted differently on each of the used carrier, due to different wavelengths. Experimental results of multipath detection in urban environment will be presented. Originally proposed method is designed to work with three different frequencies in each epoch, thus only utilization of GPS Block II-F and Galileo satellites is possible. Simplification of detection statistics to use only two frequencies is made and results using GPS and GLONASS systems are presented along with results obtained using original formula. Numéro de notice : A2017-789 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1515/geocart-2017-0020 En ligne : https://doi.org/10.1515/geocart-2017-0020 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89101
in Geodesy and cartography > vol 66 n° 2 (December 2017) . - pp 305 - 316[article]Small reflectors for ground motion monitoring with InSAR / Prabu Dheenathayalan in IEEE Transactions on geoscience and remote sensing, vol 55 n° 12 (December 2017)
[article]
Titre : Small reflectors for ground motion monitoring with InSAR Type de document : Article/Communication Auteurs : Prabu Dheenathayalan, Auteur ; Miguel Caro Cuenca, Auteur ; Peter Hoogeboom, Auteur ; Ramon F. Hanssen, Auteur Année de publication : 2017 Article en page(s) : pp 6703 - 6712 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications
[Termes IGN] coin réflecteur
[Termes IGN] déformation de la croute terrestre
[Termes IGN] fouillis d'échos
[Termes IGN] interféromètrie par radar à antenne synthétique
[Termes IGN] rapport signal sur bruit
[Termes IGN] surveillance géologiqueRésumé : (Auteur) In recent years, synthetic aperture radar interferometry has become a recognized geodetic tool for observing ground motion. For monitoring areas with low density of coherent targets, artificial corner reflectors (CRs) are usually introduced. The required size of a reflector depends on radar wavelength and resolution and on the required deformation accuracy. CRs have been traditionally used to provide a high signal-to-clutter ratio (SCR). However, large dimensions can make the reflector bulky, difficult to install and maintain. Furthermore, if a large number of reflectors are needed for long infrastructure, such as vegetation-covered dikes, the total price of the reflectors can become unaffordable. On the other hand, small reflectors have the advantage of easy installation and low cost. In this paper, we design and study the use of small reflectors with low SCR for ground motion monitoring. In addition, we propose a new closed-form expression to estimate the interferometric phase precision of resolution cells containing a (strong or weak) point target and a clutter. Through experiments, we demonstrate that the small reflectors can also deliver displacement estimates with an accuracy of a few millimeters. To achieve this, we apply a filtering method for reducing clutter noise. Numéro de notice : A2017-765 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2017.2731424 En ligne : https://doi.org/10.1109/TGRS.2017.2731424 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=88802
in IEEE Transactions on geoscience and remote sensing > vol 55 n° 12 (December 2017) . - pp 6703 - 6712[article]Enhanced resolution stripmap mode using dynamic metasurface antennas / Andreas Pedross-Engel in IEEE Transactions on geoscience and remote sensing, vol 55 n° 7 (July 2017)
[article]
Titre : Enhanced resolution stripmap mode using dynamic metasurface antennas Type de document : Article/Communication Auteurs : Andreas Pedross-Engel, Auteur ; Claire M. Watts, Auteur ; David R. Smith, Auteur ; Matthew S. Reynolds, Auteur Année de publication : 2017 Article en page(s) : pp 3764 - 3772 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s)
[Termes IGN] faisceau
[Termes IGN] radar à antenne synthétique
[Termes IGN] rapport signal sur bruit
[Termes IGN] traitement du signalRésumé : (Auteur) To maintain sufficient signal-to-noise ratio (SNR) for image reconstruction and image interpretation, conventional synthetic aperture radar (SAR) systems must trade off resolution and scene size. This paper proposes a new SAR mode of operation, which improves resolution while maintaining good SNR and a large scene size. It leverages the unique properties of dynamic metasurface antennas (MSAs) to subsample a large virtual beamwidth utilizing multiple small distinct antenna beams. Due to this parallelization in scene sampling, the constraints on the azimuth sampling rate can be relaxed while maintaining an aliasing-free cross range. Due to the versatile properties of MSAs and their cost effective manufacturing process, this paper proposes SAR systems, which can obtain high resolution images over a wide scene size with lower cost and complexity than competing approaches. Point-spread functions and proof-of-concept SAR simulations are shown to verify this approach. In addition, laboratory experiments using a commercial prototype MSA are presented, which show an improvement of 62% in cross-range resolution of the proposed approach, compared with the cross-range resolution of stripmap mode SAR with the same aperture. Numéro de notice : A2017-486 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2017.2679438 En ligne : http://dx.doi.org/10.1109/TGRS.2017.2679438 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=86413
in IEEE Transactions on geoscience and remote sensing > vol 55 n° 7 (July 2017) . - pp 3764 - 3772[article]Superresolution for UAV images via adaptive multiple sparse representation and its application to 3-D reconstruction / Muhammad Haris in IEEE Transactions on geoscience and remote sensing, vol 55 n° 7 (July 2017)
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Titre : Superresolution for UAV images via adaptive multiple sparse representation and its application to 3-D reconstruction Type de document : Article/Communication Auteurs : Muhammad Haris, Auteur ; Takuya Watanabe, Auteur ; Liu Fan, Auteur ; et al., Auteur Année de publication : 2017 Article en page(s) : pp 4047 - 4058 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique
[Termes IGN] agriculture
[Termes IGN] carte thématique
[Termes IGN] drone
[Termes IGN] image à haute résolution
[Termes IGN] image multi sources
[Termes IGN] rapport signal sur bruit
[Termes IGN] reconstruction 3D
[Termes IGN] série temporelleRésumé : (Auteur) We propose a superresolution (SR) algorithm based on adaptive sparse representation via multiple dictionaries for images taken by unmanned aerial vehicles (UAVs). The SR attainable through the proposed algorithm can increase the precision of 3-D reconstruction from UAV images, enabling the production of high-resolution images for constructing high-frequency time series and for high-precision digital mapping in agriculture. The basic idea of the proposed method is to use a field server or ground-based camera to take training images and then construct multiple pairs of dictionaries based on selective sparse representations to reduce instability during the sparse coding process. The dictionaries are classified on the basis of the edge orientation into five clusters: 0, 45, 90, 135, and nondirection. The proposed method is expected to reduce blurring, blocking, and ringing artifacts especially in edge areas. We evaluated the proposed and previous methods using peak signal-to-noise ratio, structural similarity, feature similarity, and computation time. Our experimental results indicate that the proposed method clearly outperforms other state-of-the-art algorithms based on qualitative and quantitative analysis. In the end, we demonstrate the effectiveness of our proposed method to increase the precision of 3-D reconstruction from UAV images. Numéro de notice : A2017-491 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2017.2687419 En ligne : http://dx.doi.org/10.1109/TGRS.2017.2687419 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=86420
in IEEE Transactions on geoscience and remote sensing > vol 55 n° 7 (July 2017) . - pp 4047 - 4058[article]
Titre : Analysing normal modes of the Earth from high-rate GNSS time series Type de document : Mémoire Auteurs : Zhongyi Chen, Auteur Editeur : Stuttgart : University of Stuttgart Année de publication : 2017 Importance : 78 p. Format : 21 x 30 cm Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] déformation de la croute terrestre
[Termes IGN] oscillation
[Termes IGN] positionnement différentiel
[Termes IGN] positionnement ponctuel précis
[Termes IGN] rapport signal sur bruit
[Termes IGN] séisme
[Termes IGN] série temporelleRésumé : (auteur) Normal modes of the Earth, or Earth’s free oscillations, correspond to a global deformation of the Earth that vibrates at different frequencies, like a bell, after a strong excitation, usually an earthquake of magnitude greater than 6.5. Normal modes of the Earth were first described by Lord Kelvin (Kelvin, 1863) with a computation of the lowest fundamental spheroidal mode 0S2 frequency for a homogeneous Earth model (Lognonné and Clévédé, 2002). With the theory and the deployment of the first long-period sensors in the late 1950s, day-scale Earth’s free oscillation after large earthquakes has been detected by underground instruments such as strainmeters, gravimeters and seismometers (Benioff et al., 1961) (Dziewonski and Gilbert, 1972) (Mendiguren, 1973). In the 1960s, since the U.S. military developed the first satellite navigation system, Transit, the era of Global Navigation Satellite System (GNSS) has arrived. Among all navigation satellite systems, Global Positioning System (GPS), operated by the U.S. Department of Defense (DOD), is currently the world’s most utilized satellite navigation system. With the developments of receiver technology and sampling capability, GPS becomes a powerful tool to study long-period Earth deformations such as plate tectonics and post-glacial rebound, or to monitoring short-period and short-duration motion such as waves generated by earthquakes (Bilich et al., 2008). In recent years, several studies have demonstrated the effective use of GPS in estimating coseismic displacement waveforms induced by an earthquake with accuracies ranging from a few millimeters to a few centimeters. In these studies, two well-known processing strategies, single Precise Point Positioning (PPP) and Different Positioning (DP), have been used to reduce the latency between earthquake occurrence and coseimic displacement waveforms estimation. In this thesis, a new approach named Variometric Approach for Displacements Analysis Standalone Engine (VADASE) is used to detect the normal modes of the Earth. Then the Welch’s PSD estimate is applied to transform the time series into frequency domain. Several simulations have been performed on synthetic time series to investigate the influence of noise level, sampling rate, time series length, window size and overlapping rate of Welch’s method, as well as the influence of stacking. The experiments on real data show the capability of VADASE time series for detecting normal modes of the Earth with the help of the stacking method. Some fundamental modes with small amplitude are not visible because the SNR is not sufficient to lift the signal out of the noise. Note de contenu : 1- Normal modes of the Earth
2- GPS system
3- GPS positioning
4- GPS data processing
5- Spectral analysis
6- Simulations
7- Experiments on real Vadase time seriesNuméro de notice : 17576 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Mémoire masters divers DOI : 10.18419/opus-9317 En ligne : http://dx.doi.org/10.18419/opus-9317 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92281 Télédétection pour l'observation des surfaces continentales, Volume 1. Observation des surfaces continentales par télédétection optique / Nicolas Baghdadi (2017)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)PermalinkGNSS interferometric radio occultation / Manuel Martín-Neira in IEEE Transactions on geoscience and remote sensing, vol 54 n° 9 (September 2016)PermalinkA comparative analysis of measurement noise and multipath for four constellations: GPS, BeiDou, GLONASS and Galileo / Changsheng Cai in Survey review, vol 48 n° 349 (July 2016)PermalinkGNSS multipath detection using three-frequency signal-to-noise measurements / Philip R.R. Strode in GPS solutions, vol 20 n° 3 (July 2016)PermalinkNoise simulation and correction in synthetic airborne TIR Data for mineral quantification / Christoph Hecker in IEEE Transactions on geoscience and remote sensing, vol 54 n° 3 (March 2016)PermalinkNetwork-based estimation of time-dependent noise in GPS position time series / Ksenia Dimitrieva in Journal of geodesy, vol 89 n° 6 (June 2015)PermalinkVegetation sensing using GPS-interferometric reflectometry: theoretical effects of canopy parameters on signal-to-noise ratio data / C.C. Chew in IEEE Transactions on geoscience and remote sensing, vol 53 n° 5 (mai 2015)PermalinkGalileo E1 and E5a Performance for multi-frequency, multi-constellation GBAS / Mihaela-Simona Circiu in GPS world, vol 26 n° 4 (April 2015)PermalinkThe guided bilateral filter: When the joint/cross bilateral filter becomes robust / Laurent Caraffa in IEEE Transactions on image processing, vol 24 n° 4 (April 2015)Permalink