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Enabling RTK positioning under jamming: Mitigation of carrier-phase distortions induced by blind spatial filtering / Tobias Bamberg in Navigation : journal of the Institute of navigation, vol 70 n° 1 (Spring 2023)  

Public [article]  inNavigation : journal of the Institute of navigation > vol 70 n° 1 (Spring 2023) . - n° 556 Titre : Enabling RTK positioning under jamming: Mitigation of carrier-phase distortions induced by blind spatial filtering Type de document : Article/Communication Auteurs : Tobias Bamberg, Auteur ; A. Konovaltsev, Auteur ; Michael Meurer, Auteur Année de publication : 2023 Article en page(s) : n° 556 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal [Termes IGN] brouillage [Termes IGN] compensation [Termes IGN] erreur de phase [Termes IGN] filtrage du bruit [Termes IGN] filtrage du signal [Termes IGN] interférence [Termes IGN] positionnement cinématique en temps réel [Termes IGN] signal GNSS Résumé : (auteur) New GNSS applications demand resilience against radio interference and high position accuracy. Separately, these demands can be fulfilled by multi-antenna systems using spatial filtering and carrier-phase positioning algorithms like real-time kinematic (RTK), respectively. However, combining these approaches encounters a severe issue: The spatial filtering induces a phase offset into the measured carrier phase leading to a loss of position accuracy. This paper presents a new approach to compensate for the phase offset in a blind manner, (i.e., without knowing the antenna array radiation pattern or the direction of arrival of the signals). The proposed approach is experimentally validated in two jamming scenarios. One includes a jammer with increasing power and the other includes a moving jammer. The results demonstrate that the approach successfully compensates for the phase offset and, hence, allows for the combined use of RTK positioning and spatial filtering even under jamming. Numéro de notice : A2023-140 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.33012/navi.556 Date de publication en ligne : 09/08/2022 En ligne : https://doi.org/10.33012/navi.556 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102703 [article]

Signal Processing for GNSS Reflectometry / Corentin Lubeigt (2023)    

Public Titre : Signal Processing for GNSS Reflectometry Type de document : Thèse/HDR Auteurs : Corentin Lubeigt, Auteur ; Eric Chaumette, Directeur de thèse ; Jordi Vilà-Valls, Directeur de thèse Editeur : Toulouse : Institut Supérieur de l’Aéronautique et de l’Espace Année de publication : 2023 Importance : 217 p. Format : 21 x 30 cm Note générale : Bibliographie Thèse pour obtenir le grade de Docteur de l'Université de Toulouse, Spécialité Informatique et Télécommunications Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal [Termes IGN] convolution (signal) [Termes IGN] distorsion du signal [Termes IGN] réflectométrie par GNSS [Termes IGN] réflexion (rayonnement) [Termes IGN] théorie de l'estimation Index. décimale : THESE Thèses et HDR Résumé : (Auteur) Global Navigation Satellite Systems (GNSS) Reflectometry, or GNSS-R, is the study of GNSS signals reflected from the Earth’s surface. These so-called signals of opportunity, usually seen as a nuisance in standard navigation applications, contain meaningful information on the nature and relative position of the reflecting surface. Depending on the receiver platform (e.g., ground-based, airplane, satellite) and the reflecting surface itself (e.g., rough sea, lake), the reflected signal, more or less distorted, is difficult to model, and the corresponding methods to estimate the signal parameters of interest may vary. This thesis starts from the navigation multipath problem in harsh environments, which can be seen as a dual source estimation problem where the main source is the signal of interest, and the secondary one is a single reflection of the main source. Depending on the scenario and the resources at hand, it is possible i) to estimate the parameters of interest (i.e., time-delay, Doppler frequency, amplitude and phase) of both sources, or ii) to estimate only one source’s parameters, although these estimates may be biased because of the interfering source. Either way, it is necessary to know the achievable performance for these estimation problems. For this purpose, tools from the estimation theory, such as the Cramér-Rao bound (CRB), can be used. In this thesis a CRB expression was derived for the properly specified case (dual source), and the misspecified one (single source). These bounds were compared to the performance obtained with different estimators, in order to theoretically characterize the problem at hand. This study allowed to establish a clear mathematical framework that also fits the ground-based GNSS-R problem, for which the reflected signal is little distorted by the reflecting surface. In this case, the direct and reflected signals are close in time, which inevitably leads to interference, or crosstalk, and then to a clear performance degradation. Standard GNSS-R techniques, which do not perform well in this ground-based scenario, were compared to the CRB and two proposed approaches: i) a Taylor approximation of the dual source likelihood criterion when both sources are very close in time, and ii) a dual source estimation strategy to reduce or cancel the crosstalk. This part on ground-based GNSS-R was supported by a real data set, obtained from a data collection campaign organized by CNES (Toulouse, France). The problem changes slowly when the satellite elevation increases: the reflection, assumed coherent so far, turns non-coherent because of the reflecting surface roughness. The automatic detection of this transition (i.e., from coherent to non-coherent) is of great interest for future satellite missions. Reflection coherence is mainly observed by looking at the relative phase between the reflected and direct signals. Consequently, a statistical study of phase difference time series allowed to build tests that depend on the time series Gaussianity or regularity. The proposed tests were applied to a data set provided by the IEEC (Barcelona, Spain). Finally, for scenarios where the reflecting surface distorts the signal significantly, it is necessary to adapt the signal model. The approach proposed in this thesis is to consider the received signal as a convolution between the transmitted signal and the reflecting surface impulse response. This signal model goes with the derivation of the corresponding CRB and the implementation of the maximum likelihood estimator. The question of the impulse response size determination, that is, the determination of the number of pulses required to describe the impulse response, was also tackled based on hypothesis tests. Simulation results show the potential of this approach. Note de contenu : Introduction 1. Concepts and Tools: From Estimation Theory to GNSS-R 1.1 Introduction 1.2 Background on Deterministic Estimation Theory 1.3 Global Navigation Satellite Systems 1.4 The Multipath Problem 1.5 GNSS Reflectometry 1.6 Conclusion 2. Multipath Effect and Its Impact on Positioning Performance 2.1 Introduction 2.2 MPEE for Different Multipath Mitigation Techniques 2.3 Joint Delay-Doppler Estimation Performance in a Dual Source Context 2.4 A Metric for Multipath-Robust Signal Design and Analysis 2.5 Misspecified Cramér-Rao Bounds in Multipath Scenarios 2.6 Conclusion 3. Ground-Based GNSS-R 3.1 Introduction 3.2 Gruissan Data Campaign 3.3 Crosstalk Characterization 3.4 Approximate Maximum Likelihood for Narrowband GNSS Signals 3.5 Performance on Simulated Data 3.6 Altimetry Using Wideband GNSS Signals 3.7 Conclusion 4. Towards Diffuse Scattering 4.1 Introduction 4.2 Coherence Analysis 4.3 Impulse Response Estimation 4.4 Impulse Response Size Determination: A Detection Problem 4.5 Conclusion Conclusion and Perspectives Numéro de notice : 26963 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse française Note de thèse : Thèse de Doctorat : Informatique et Télécommunications : Toulouse : 2023 nature-HAL : Thèse DOI : sans Date de publication en ligne : 27/02/2023 En ligne : https://hal.science/tel-04006612v1/document Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102915

A method to determine secondary codes and carrier phases of short snapshot signals / Xiao Liu in Navigation : journal of the Institute of navigation, vol 69 n° 4 (Fall 2022)  

Public [article]  inNavigation : journal of the Institute of navigation > vol 69 n° 4 (Fall 2022) . - n° 541 Titre : A method to determine secondary codes and carrier phases of short snapshot signals Type de document : Article/Communication Auteurs : Xiao Liu, Auteur ; Pau Closas, Auteur ; Adria Gusi-Amigó, Auteur ; et al., Auteur Année de publication : 2022 Article en page(s) : n° 541 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal [Termes IGN] ambiguïté entière [Termes IGN] phase [Termes IGN] positionnement cinématique en temps réel [Termes IGN] signal GNSS [Termes IGN] temps instantané Résumé : (auteur) Recently, the Snapshot Real-Time Kinematic (SRTK) technique was demonstrated, which aims at achieving high accuracy navigation solutions with a very short signal collection. The main challenge in implementing SRTK is the generation of valid carrier-phase measurements, which relies on a data bit ambiguity (DBA) resolution process. For pilot signals, this step is equivalent to the correct selection of secondary code indexes (SCIs) from the ambiguous sets obtained from a multi-hypotheses (MH) acquisition process. Currently, SCI ambiguities are solved independently for each satellite. However, this method is ineffective when the snapshot signal is relatively short. In order to tackle this problem, this article proposes a new method that makes use of assistance data and processes information from all satellites to jointly solve the DBA issue. This new method is shown to be more effective in determining the correct SCI and enabling valid snapshot carrier-phase measurements, largely expanding the scope of high-accuracy snapshot positioning. Numéro de notice : A2022-868 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.33012/navi.541 Date de publication en ligne : 21/04/2022 En ligne : https://doi.org/10.33012/navi.541 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102161 [article]

Navigation and Ionosphere Characterization Using High-Frequency Signals: A Performance Analysis / Yoav Baumgarten in Navigation : journal of the Institute of navigation, vol 69 n° 4 (Fall 2022)  

Public [article]  inNavigation : journal of the Institute of navigation > vol 69 n° 4 (Fall 2022) . - n° 546 Titre : Navigation and Ionosphere Characterization Using High-Frequency Signals: A Performance Analysis Type de document : Article/Communication Auteurs : Yoav Baumgarten, Auteur ; M.L. Psiaki, Auteur ; David L. Hysell, Auteur Année de publication : 2022 Article en page(s) : n° 546 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal [Termes IGN] algorithme de Gauss-Newton [Termes IGN] correction du signal [Termes IGN] correction ionosphérique [Termes IGN] matrice de covariance [Termes IGN] mesurage de phase [Termes IGN] modèle ionosphérique [Termes IGN] propagation du signal [Termes IGN] récepteur [Termes IGN] teneur verticale totale en électrons Résumé : (auteur) The performance of a proposed high-frequency (HF) navigation concept is analyzed using simulated data. The method relies on pseudorange and beat carrier-phase measurements of signals that propagate in the ionosphere along curved trajectories, where signals are refracted back downwards from the ionosphere. It has been demonstrated that the location of a receiver can be determined if several signals, broadcast from beacons at different locations, are received and processed at a user receiver. A challenge of determining exact signal paths is the uncertainty in the ionosphere’s electron density distribution. This is addressed by a batch filter that simultaneously estimates the receiver position along with corrections to a parametric model of the ionosphere. A previous paper developed the theory and batch filter for this concept. The present study examines its potential performance. Total horizontal position errors on the order of tens to hundreds of meters are achieved, depending on the case’s characteristics. Numéro de notice : A2022-919 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.33012/navi.546 Date de publication en ligne : 19/06/2022 En ligne : https://doi.org/10.33012/navi.546 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102448 [article]

Detection of GNSS no-line of sight signals using LiDAR sensors for intelligent transportation systems / Tarek Hassan in Survey review, vol 54 n° 385 (July 2022)  

Public [article]  inSurvey review > vol 54 n° 385 (July 2022) . - pp 301 - 309 Titre : Detection of GNSS no-line of sight signals using LiDAR sensors for intelligent transportation systems Type de document : Article/Communication Auteurs : Tarek Hassan, Auteur ; Tamer Fath-Allah, Auteur ; Mohamed Elhabiby, Auteur ; et al., Auteur Année de publication : 2022 Article en page(s) : pp 301 - 309 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal [Termes IGN] détection du signal [Termes IGN] données lidar [Termes IGN] positionnement ponctuel précis [Termes IGN] semis de points [Termes IGN] signal GNSS [Termes IGN] système de transport intelligent [Termes IGN] traitement de données GNSS Résumé : (auteur) The reliability and robustness of positioning systems in urban and suburban environments are intrinsic. This is obvious following the continuous increase of Intelligent Transportation Systems (ITS) applications in such challenging environments. Global Navigation Satellite Systems (GNSS) represent the primary positioning technique used for navigation purposes in these applications, which can be satisfying in open-sky areas. However, GNSS cannot provide the same level of navigation performance in urban environments. One of the main reasons for this is the No-Line of Sight (NLOS) signals. In this study, the integration of GNSS and Light Detection and Ranging (LiDAR) sensors is exploited, and a new algorithm is proposed for the detection of NLOS signals. Real field data are used to test and validate the proposed strategy and algorithm. Phase-smoothed code observations are employed to evaluate the accuracy improvement after excluding the NLOS observations. The results show that the horizontal direction's positional accuracy can be improved significantly after applying the proposed algorithm. This improvement reaches 10.403 m with a mean value of 2.162 m (62.2% improvement) over all epochs with detected NLOS signals. After analysing this improvement in the Cross-Track (CT) and Along-Track (AT) directions, it is found that the accuracy improvement reaches 8.641 m with a mean value of 1.699 m in the CT direction and 6.879 m with a mean value of 1.303 m in the AT direction. Numéro de notice : A2022-535 Affiliation des auteurs : non IGN Thématique : IMAGERIE/POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/00396265.2021.1937458 Date de publication en ligne : 10/06/2021 En ligne : https://doi.org/10.1080/00396265.2021.1937458 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101091 [article]

Detection and mitigation of GNSS spoofing via the pseudorange difference between epochs in a multicorrelator receiver / Xiangyong Shang in GPS solutions, vol 26 n° 2 (April 2022)  

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Results on GNSS spoofing mitigation using multiple receivers / Niklas Stenberg in Navigation : journal of the Institute of navigation, vol 69 n° 1 (Spring 2022)  

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A model you can hear: Audio identification with playable prototypes / Romain Loiseau (2022)  

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A multipath and thermal noise joint error characterization and exploitation for low-cost GNSS PVT estimators in urban environment / Eustachio Roberto Matera (2022)  

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Robust GNSS phase tracking using variational bayesian inference / Fabio Fabozzi (2022)  

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Salt tectonic imaging at crustal and experimental scales by seismic migration and adjoint method / Javier Abreu-Torres (2022)  

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Recurrent neural network for rain estimation using commercial microwave links / Hai Victor Habi in IEEE Transactions on geoscience and remote sensing, vol 59 n° 5 (May 2021)  

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On the polarimetric variable improvement via alignment of subarray channels in PPAR using weather returns / Igor R. Ivić in IEEE Transactions on geoscience and remote sensing, Vol 59 n° 3 (March 2021)  

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Adaptive filtering / Wenping Cao (2021)  

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Applied signal processing / Sadasivan Puthusserypady (2021)  

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