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Novel communication channel model for signal propagation and loss through layered earth / David O. LeVan in IEEE Transactions on geoscience and remote sensing, vol 58 n° 8 (August 2020)
[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 IGN] atténuation du signal
[Termes IGN] champ électromagnétique
[Termes IGN] cible cachée
[Termes IGN] géophysique
[Termes IGN] mine de charbon
[Termes IGN] modèle de simulation
[Termes IGN] modèle mathématique
[Termes IGN] modélisation
[Termes IGN] propagation du signal
[Termes 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]Effects of a navigation spoofing signal on a receiver loop and a UAV spoofing approach / Chao Ma in GPS solutions, Vol 24 n° 3 (July 2020)
[article]
Titre : Effects of a navigation spoofing signal on a receiver loop and a UAV spoofing approach Type de document : Article/Communication Auteurs : Chao Ma, Auteur ; Jun Yang, Auteur ; Jianyun Chen, Auteur ; et al., Auteur Année de publication : 2020 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal
[Termes IGN] amplitude
[Termes IGN] atténuation du signal
[Termes IGN] autocorrélation
[Termes IGN] drone
[Termes IGN] erreur de phase
[Termes IGN] interférence
[Termes IGN] leurrage
[Termes IGN] récepteur Doppler
[Termes IGN] utilisateur civilRésumé : (auteur) A civil navigation signal is vulnerable to interference and tampering owing to its open interface and low signal power. We focus on navigation spoofing. First, using a piecewise function, we quantitatively analyze the effects of the navigation spoofing signal on the receiver tracking loop. For a phase-locked loop, the spoofing signal extends the pull-in range of the discriminator. The autocorrelation gain of the spoofing signal has a different effect on the slope of the discriminator, depending on whether the discriminator is related to the signal amplitude. For the delay-locked loop, taking the non-coherent early minus late power method as an example, the unlocking condition and interval are analyzed quantitatively using the spoofing amplitude gain and the initial phase cosine of the spoofing and authentic carriers. A carrier frequency difference between the spoofing signal and authentic signal causes a phase jump and attenuation of the amplitude gain. Second, in luring an unmanned aerial vehicle (UAV) to a designated location, we assume a UAV model and provide a spoofing strategy. Experimental results show that it is feasible to lure a civilian quadrotor UAV to a designated location about 50 m from where the UAV believes it is located. Numéro de notice : A2020-326 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueNat DOI : 10.1007/s10291-020-00986-z Date de publication en ligne : 09/05/2020 En ligne : https://doi.org/10.1007/s10291-020-00986-z Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95207
in GPS solutions > Vol 24 n° 3 (July 2020)[article]Semi-automatic identification of submarine pipelines with synthetic aperture sonar Images / Victor Hugo Fernandes in Marine geodesy, Vol 43 n° 4 (July 2020)
[article]
Titre : Semi-automatic identification of submarine pipelines with synthetic aperture sonar Images Type de document : Article/Communication Auteurs : Victor Hugo Fernandes, Auteur ; Nilcilene Das Graças Medeiros, Auteur ; Dalto Domingues Rodrigues, Auteur ; et al., Auteur Année de publication : 2020 Article en page(s) : pp 376 - 395 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal
[Termes IGN] canalisation
[Termes IGN] détection de contours
[Termes IGN] filtrage du bruit
[Termes IGN] scène sous-marine
[Termes IGN] sonarRésumé : (Auteur) Synthetic Aperture Sonar (SAS) is a sensor that was designed for hydrographic survey of the seabed. It detects small targets, enabling high geometric resolution images. However, the images generated by SAS are susceptible to speckle noise, which makes digital processing difficult, since the noises are confused with the targets of interest. The goal of this study was to develop a semi-automatic routine for SAS image processing to verify the structural integrity of submarine pipelines. The method presented incorporates four stages: pre-processing to reduce noise and highlight the targets of interest; extraction of features aiming to recognize features related to the pipelines; post-processing to reduce the fragmentation generated during feature extraction; validation to quantify the results from the reference images to estimate the performance of the proposed methodology. The results showed that more than 80% of the submarine pipelines were mapped in the semi-automatic mode, which considerably reduced the time needed to manually identify a large number of pipelines operating on offshore oilfields. Numéro de notice : A2020-248 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/01490419.2020.1755916 Date de publication en ligne : 25/04/2020 En ligne : https://doi.org/10.1080/01490419.2020.1755916 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95362
in Marine geodesy > Vol 43 n° 4 (July 2020) . - pp 376 - 395[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]Asymptotically exact data augmentation : models and Monte Carlo sampling with applications to Bayesian inference / Maxime Vono (2020)
Titre : Asymptotically exact data augmentation : models and Monte Carlo sampling with applications to Bayesian inference Type de document : Thèse/HDR Auteurs : Maxime Vono, Auteur ; Nicolas Dobigeon, Directeur de thèse ; Pierre Chainais, Auteur Editeur : Toulouse : Université de Toulouse Année de publication : 2020 Importance : 200 p. Format : 21 x 30 cm Note générale : bibliographie
Thèse en vue de l'obtention du Doctorat de l'Université de Toulouse, Signal, Image, Acoustique et OptimisationLangues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal
[Termes IGN] échantillonnage
[Termes IGN] échantillonnage de Gibbs
[Termes IGN] estimation bayesienne
[Termes IGN] méthode de Monte-Carlo
[Termes IGN] méthode de Monte-Carlo par chaînes de Markov
[Termes IGN] optimisation (mathématiques)
[Termes IGN] processus gaussien
[Termes IGN] régression linéaireIndex. décimale : THESE Thèses et HDR Résumé : (auteur) Numerous machine learning and signal/image processing tasks can be formulated as statistical inference problems. As an archetypal example, recommendation systems rely on the completion of partially observed user/item matrix, which can be conducted via the joint estimation of latent factors and activation coefficients. More formally, the object to be inferred is usually defined as the solution of a variational or stochastic optimization problem. In particular, within a Bayesian framework, this solution is defined as the minimizer of a cost function, referred to as the posterior loss. In the simple case when this function is chosen as quadratic, the Bayesian estimator is known to be the posterior mean which minimizes the mean square error and defined as an integral according to the posterior distribution. In most real-world applicative contexts, computing such integrals is not straightforward. One alternative lies in making use of Monte Carlo integration, which consists in approximating any expectation according to the posterior distribution by an empirical average involving samples from the posterior. This so-called Monte Carlo integration requires the availability of efficient algorithmic schemes able to generate samples from a desired posterior distribution. A huge literature dedicated to random variable generation has proposed various Monte Carlo algorithms. For instance, Markov chain Monte Carlo (MCMC) methods, whose particular instances are the famous Gibbs sampler and Metropolis-Hastings algorithm, define a wide class of algorithms which allow a Markov chain to be generated with the desired stationary distribution. Despite their seemingly simplicity and genericity, conventional MCMC algorithms may be computationally inefficient for large-scale, distributed and/or highly structured problems. The main objective of this thesis consists in introducing new models and related MCMC approaches to alleviate these issues. The intractability of the posterior distribution is tackled by proposing a class of approximate but asymptotically exact augmented (AXDA) models. Then, two Gibbs samplers targetting approximate posterior distributions based on the AXDA framework, are proposed and their benefits are illustrated on challenging signal processing, image processing and machine learning problems. A detailed theoretical study of the convergence rates associated to one of these two Gibbs samplers is also conducted and reveals explicit dependences with respect to the dimension, condition number of the negative log-posterior and prescribed precision. In this work, we also pay attention to the feasibility of the sampling steps involved in the proposed Gibbs samplers. Since one of this step requires to sample from a possibly high-dimensional Gaussian distribution, we review and unify existing approaches by introducing a framework which stands for the stochastic counterpart of the celebrated proximal point algorithm. This strong connection between simulation and optimization is not isolated in this thesis. Indeed, we also show that the derived Gibbs samplers share tight links with quadratic penalty methods and that the AXDA framework yields a class of envelope functions related to the Moreau one. Note de contenu : Introduction
1- Asymptotically exact data augmentation
2- Monte Carlo sampling from AXDA
3- 3A non-asymptotic convergence analysis of the Split Gibbs sampler
4- High-dimensional Gaussian sampling: A unifying approach based on a stochastic proximal point algorithm
5- Back to optimization: The tempered AXDA envelope
ConclusionNuméro de notice : 28575 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Thèse française Note de thèse : thèse de Doctorat : Signal, Image, Acoustique et Optimisation : Toulouse : 2020 Organisme de stage : Institut de Recherche en Informatique de Toulouse En ligne : https://tel.archives-ouvertes.fr/tel-03143936/document Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=97833 PermalinkImaging and diagnostic of sub-wavelength micro-structures, from closed-form algorithms to deep learning / Peipei Ran (2020)PermalinkLow-frequency desert noise intelligent suppression in seismic data based on multiscale geometric analysis convolutional neural network / Yuxing Zhao in IEEE Transactions on geoscience and remote sensing, vol 58 n° 1 (January 2020)PermalinkData-adaptive spatio-temporal filtering of GRACE data / Paoline Prevost in Geophysical journal international, vol 219 n° 3 (December 2019)PermalinkEvaluating the impact of higher-order ionospheric corrections on multi-GNSS ultra-rapid orbit determination / Xinghan Chen in Journal of geodesy, vol 93 n° 9 (September 2019)PermalinkInvestigation of the noise properties at low frequencies in long GNSS time series / Xiaoxing He in Journal of geodesy, vol 93 n° 9 (September 2019)PermalinkOn the application of Monte Carlo singular spectrum analysis to GPS position time series / Seyed Mohsen Khazraei in Journal of geodesy, vol 93 n° 9 (September 2019)PermalinkOn constrained integrated total Kalman filter for integrated direct geo-referencing / Vahid Mahboub in Survey review, vol 51 n° 364 (January 2019)PermalinkSignaux et systèmes / André Quinquis (2019)PermalinkPermalinkPermalinkParameter estimation with GNSS-reflectometry and GNSS synthetic aperture techniques / Miguel Angel Ribot Sanfelix (2018)PermalinkSparse signal modeling: Application to image compression, Image error concealment and compressed sensing / Ali Akbari (2018)PermalinkPermalinkEvaluation of NTCM-BC and a proposed modification for single-frequency positioning / Xiaohong Zhang in GPS solutions, vol 21 n° 4 (October 2017)PermalinkDetermination of the ionospheric foF2 using a stand-alone GPS receiver / Dudy D Wijaya in Journal of geodesy, vol 91 n° 9 (September 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)PermalinkOptimum stochastic modeling for GNSS tropospheric delay estimation in real-time / Tomasz Hadas in GPS solutions, vol 21 n° 3 (July 2017)PermalinkReview of code and phase biases in multi-GNSS positioning / Martin Håkansson in GPS solutions, vol 21 n° 3 (July 2017)Permalink