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Making a difference with GPS: time differences for kinematic positioning with low-cost receivers / J. Traugott in GPS world, vol 19 n° 5 (May 2008)
[article]
Titre : Making a difference with GPS: time differences for kinematic positioning with low-cost receivers Type de document : Article/Communication Auteurs : J. Traugott, Auteur ; Dennis Odijk, Auteur ; Oliver Montenbruck, Auteur ; et al., Auteur Année de publication : 2008 Article en page(s) : pp 48 - 54 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal
[Termes IGN] GPS en mode différentiel
[Termes IGN] phase GPS
[Termes IGN] positionnement cinématique
[Termes IGN] récepteur GPS
[Termes IGN] traitement de données GNSSRésumé : (Editeur) Most radio signals consist of a carrier wave that is modulated in some way. This includes the GPS satellite signals. The pseudorandom-noise ranging codes and the navigation message are modulated onto the L-band carriers using binary biphase modulation. A GPS receiver uses the ranging codes to determine its distance from multiple satellites and then, through the process of multilateration, its position. But what about the carrier phase? Is it just a means to convey the ranging codes and navigation message? Definitely not. A GPS receiver determines its velocity as well as its position and it does this not by differencing sequential code-based positions, which would not be very accurate, but rather by measuring the Doppler shift of the received carrier. But the carrier can be used in other ways too. In fact, it can be used for determining positions, just like the code, but with much higher precision. Over 20 years ago, surveyors and geodesists devised ways to make use of recorded measurements of the phase of the received carriers to determine accurate relative positions between a roving receiver and a base or reference receiver at a known location. The technique was enhanced over the years, evolving into an approach known as RTK or real-time kinematic positioning. As its name suggests, RTK is usually employed in real time using auxiliary radio communications (often cell-phone-based) between the base and rover receivers. However, RTK-style positioning can also be used to postprocess collected data, achieving the same high-accuracy standards. But one of the difficulties with the RTK approach is resolving the so-called carrier-phase ambiguities. One cycle of the carrier looks just like the next, so how can you determine the exact number of cycles in the carrier between the satellite's antenna and the receiver's antenna? Well, it can be done, but even with increasingly sophisticated techniques, there is a limit to how far away a rover can be from the base station. Isn't there a way to get rid of the integer ambiguity problem? There is. If you time-difference sequential carrier-phase measurements, the ambiguity actually disappears! As we'll see in this month's column, you can determine accurate relative positions using time-differenced carrier-phase measurements. But there are some caveats. Read on. Copyright Questex Media Group Inc Numéro de notice : A2008-164 Affiliation des auteurs : non IGN Thématique : IMAGERIE/POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29159
in GPS world > vol 19 n° 5 (May 2008) . - pp 48 - 54[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 067-08051 RAB Revue Centre de documentation En réserve L003 Disponible A new method for three-carrier GNSS ambiguity resolution / U. Fernandez-Plazaola in Journal of geodesy, vol 82 n° 4-5 (April - May 2008)
[article]
Titre : A new method for three-carrier GNSS ambiguity resolution Type de document : Article/Communication Auteurs : U. Fernandez-Plazaola, Auteur ; T. Martin-Guerrero, Auteur ; J. Entrambasaguas, Auteur Année de publication : 2008 Article en page(s) : pp 269 - 278 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal
[Termes IGN] factorisation de Cholesky
[Termes IGN] phase GPS
[Termes IGN] résolution d'ambiguïté
[Termes IGN] signal GNSSRésumé : (Auteur) A new method for resolving the carrier-phase integer ambiguity in Global Navigation Satellite Systems (GNSS) is presented: the MOdified Cholesky factorization for Ambiguity (MOCA) resolution. The characteristics and features of this method are described and results obtained using a software simulator and an emulator are presented to validate its efficiency. The results are then compared to those obtained using another existing method and good performance of the MOCA method in new GNSS systems is shown. Furthermore, the proposed method yields accurate results even when short time spans are used or when there are poor estimations of measurement error, making it immune to non-ideal conditions and ultimately a practical solution for real applications. Copyright Springer Numéro de notice : A2008-170 Affiliation des auteurs : non IGN Thématique : IMAGERIE/POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-007-0177-6 En ligne : https://doi.org/10.1007/s00190-007-0177-6 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29165
in Journal of geodesy > vol 82 n° 4-5 (April - May 2008) . - pp 269 - 278[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 266-08042 RAB Revue Centre de documentation En réserve L003 Disponible 266-08041 RAB Revue Centre de documentation En réserve L003 Disponible Improving long-range RTK: getting a better handle on the biases / D. Kim in GPS world, vol 19 n° 3 (March 2008)
[article]
Titre : Improving long-range RTK: getting a better handle on the biases Type de document : Article/Communication Auteurs : D. Kim, Auteur ; R.B. Langley, Auteur Année de publication : 2008 Article en page(s) : pp 50 - 56 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal
[Termes IGN] correction atmosphérique
[Termes IGN] GPS en mode cinématique
[Termes IGN] phase GPS
[Termes IGN] positionnement cinématique en temps réel
[Termes IGN] propagation ionosphérique
[Termes IGN] propagation troposphérique
[Termes IGN] résolution d'ambiguïtéRésumé : (Editeur) Scientists and engineers continue to improve high-accuracy GPS positioning techniques - techniques pioneered a quarter of a century ago. The first GPS satellite, SVN01/PRN04, was launched from Cape Canaveral on February 22, 1978. And between 1978 and 1985, the U.S. Air Force orbited nine more prototype or Block I satellites to test key technologies before deploying the operational constellation. Surveyors and geodesists were among the earliest users of the Block I satellites. Using the satellite signals, they developed accurate positioning techniques based on the use of carrier-phase observations - about two orders of magnitude more precise than code measurements. To reduce the effect of biases and errors in the measurements, they developed the concepts of between-satellite and between-receiver single differencing of the carrier-phase data as well as double and triple differencing. Raw measurements were recorded by receivers and then post-processed to obtain receiver coordinates. Clever approaches were developed to handle the integer ambiguity of the carrier phases. With the launch of the Block II satellites beginning in 1989, further improvements in positioning accuracy and efficiency became possible, including real-time carrier-phase based positioning with a radio link between a reference receiver and a remote receiver. This technique became known as real-time kinematic or RTK, as it permitted the remote receiver to rove and occupy different points in a single positioning exercise. But carrier-phase ambiguity resolution issues coupled with inaccurately modeled satellite orbit and atmospheric effects has limited consistent single-baseline RTK operation between reference and rover receivers to tens of kilometers. On longer baselines, inaccurate modeling can result in significant positioning errors. Network RTK, using simultaneously operating reference stations to better determine error corrections, can extend the area of coverage of RTK but it, too, has limitations. In this month's column, I am joined by my colleague Don Kim who has developed an innovative approach to long-range RTK. We describe how accurate modeling of atmospheric effects coupled with an ionosphere-free ambiguity resolution process results in successful long-range RTK that can be implemented in either single-baseline or network mode. Has the ultimate RTK approach been developed? Probably not. But we're getting closer. Copyright Questex Media Group Inc Numéro de notice : A2008-162 Affiliation des auteurs : non IGN Thématique : IMAGERIE/POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29157
in GPS world > vol 19 n° 3 (March 2008) . - pp 50 - 56[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 067-08031 RAB Revue Centre de documentation En réserve L003 Disponible Analyse et traitement des signaux / E. Tisserand (2008)
Titre : Analyse et traitement des signaux : méthodes et applications au son et à l'image : cours et exercices corrigés Type de document : Guide/Manuel Auteurs : E. Tisserand, Auteur ; J.F. Pautex, Auteur ; P. Schweitzer, Auteur Mention d'édition : 2 Editeur : Paris : Dunod Année de publication : 2008 Collection : Sciences Sup Sous-collection : Sciences de l'ingénieur Importance : 316 p. Format : 17 x 24 cm ISBN/ISSN/EAN : 978-2-10-052437-2 Note générale : Bibliographie Langues : Français (fre) Descripteur : [Vedettes matières IGN] Traitement du signal
[Termes IGN] acquisition d'images
[Termes IGN] analyse spectrale
[Termes IGN] compression d'image
[Termes IGN] convolution (signal)
[Termes IGN] échantillonnage de signal
[Termes IGN] filtrage du signal
[Termes IGN] onde acoustique
[Termes IGN] signal analogique
[Termes IGN] signal numérique
[Termes IGN] traitement d'image
[Termes IGN] transformation de FourierIndex. décimale : 24.20 Traitement du signal Résumé : (Editeur) Cet ouvrage s'adresse aux étudiants en fin de 1er cycle (Licence, DUT, BTS) et en début de Master. Son contenu est adapté aux formations en automatique, électronique, informatique, physique et mathématiques appliquées.
Du multimédia aux télécommunications, du capteur à la mesure, du contrôle industriel à l'imagerie médicale, la plupart des secteurs scientifiques et techniques exploitent les méthodes d'analyse et de traitement des signaux. La connaissance et la maîtrise de cette discipline sont devenues indispensables aux techniciens, ingénieurs et chercheurs.
Les objectifs de cet ouvrage sont les suivants : proposer une approche scientifique des signaux sonores et des images ; comprendre les opérations d'échantillonnage, de quantification et de synthèse d'un signal ; analyser ses composantes spectrales et mesurer ses relations de dépendance ; maîtriser et appliquer les méthodes de filtrage analogiques et numériques.
Dans cette nouvelle édition actualisée, des nouveautés sont introduites : la modélisation de la transformation 3D/2D, la calibration géométrique d'une prise de vue, la représentation d'un signal dans une base quelconque et la transformation de Hilbert. Une place plus importante est consacrée aux exercices d'application qui complètent chaque chapitre.Note de contenu : - Propriétés et acquisition des signaux sonores
- Acquisitions et représentation des images
- Echantillonnage, quantification et restitution des signaux
- Analyse corrélative des signaux
- Décomposition et analyse spectrale des signaux
- Filtrage des signaux analogiques
- Filtres numériques à réponse impulsionnelle finie
- Prédiction linéaire et filtrage adaptatif des signaux
- Traitements des images numériquesNuméro de notice : 20505 Affiliation des auteurs : non IGN Thématique : IMAGERIE/POSITIONNEMENT Nature : Manuel de cours Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=46798 Réservation
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Code-barres Cote Support Localisation Section Disponibilité 20505-01 24.20 Livre Centre de documentation Physique Disponible
Titre : Free discontinuity problems in image and signal segmentation Type de document : Thèse/HDR Auteurs : A. Vitti, Auteur Editeur : Trente : Universita degli studi di Trento Année de publication : 2008 Importance : 134 p. Format : 21 x 30 cm Note générale : Bibliographie
Doctoral thesis in environmental engineeringLangues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal
[Termes IGN] calcul variationnel
[Termes IGN] discontinuité
[Termes IGN] discrétisation
[Termes IGN] méthode des éléments finis
[Termes IGN] segmentation d'image
[Termes IGN] signal monodimensionnel
[Termes IGN] traitement du signalIndex. décimale : THESE Thèses et HDR Résumé : (Auteur) [introduction] This thesis aims to inspect and to understand, from an engineering point of view, the mathematical framework of variational problems and in particular of ”Free Discontinuity Problems” where the concept of image and signal segmentation can be rigorously formulated. The second objective is to develop end-user software libraries and programs implementing two variational segmentation models to perform practically images and one dimensional signals segmentation. In the thesis there are no original mathematical contributions, that would be outside the competences of the author. The mathematical problems have been approached and studied with the aim of making a bridge between the theory and the applications. Part 1 of the thesis is the outcome of this study. The main thesis results are the development of original software libraries and programs to perform segmentation of images and of one dimensional signals and the application of such programs to real data sets. The developed numerical programs allowed also to study and to reproduce in practice the well known features of the theoretical formulations of segmentation approached as a ”Free Discontinuity Problem”. This work deals with the Mumford and Shah functional and with the Blake and Zisserman functional. The Mumford and Shah functional in dimension two is introduced, studied, implemented numerically and applied to the segmentation of images. An extension of the Mumford and Shah is treated analogously. The Blake and Zisserman functional is introduced and studied in dimension two and then in dimension one, while the numerical implementation and the applications are performed in dimension one, i.e to the segmentation of one dimensional signals. Specifically, the thesis faces the problem of segmenting environmental images, such as aerophotogrammetry images and one dimensional signal time series arising from Geodesy, such as GNSS (Global Navigation Satellite System) permanent stations coordinates. [...] Note de contenu : Introduction
Part 1 A Review of the Mathematical Theory of Variational Segmentation
1 Mathematical Framework
1.1 Variational Problems
1.1.1 Classical and Direct Methods in the Calculus of Variations
1.2 Free Discontinuity Problems
1.2.1 A General Introduction
1.2.2 The Space of Special Functions of Bounded Variation
1.2.3 Some Essential Features About ¡-convergence
1.3 Variational Segmentation: The Mumford and Shah Model
2 The Mumford and Shah Model
2.1 The Mumford and Shah Model for Image Segmentation
2.1.1 The Mumford and Shah Functional
2.1.2 Weak Formulation in SBV
2.1.3 Approximations of the Weak Formulation
2.1.4 Drawbacks of the Mumford and Shah Model
2.2 Controlling the Curvature in the Mumford and Shah Model
2.3 Euler Equation and Gradient Flow
2.3.1 The Euler Equation Associated to the Elliptic Approximation of the Mumford and Shah Model without and with the Curvature Term
2.4 Finite Differences Discretisation
2.5 The Gradient Effect in Dimension One
3 The Blake and Zisserman Model
3.1 The Blake and Zisserman Model for One Dimensional Signal Segmentation
3.2 The Ambrosio and Tortorelli Approximation
3.3 Finite Elements Discretisation
Part 2 Numerical Applications
4 Software Implementations
4.1 The seglib Library for Images Segmentation
4.1.1 The GRASS GIS module r.seg
4.2 The seglib1d Library for One Dimensional Signals Segmentation
4.2.1 The sigseg Program
5 Segmentation of Images
5.1 Segmentation of Synthetic Images
5.1.1 Test Image A
5.1.2 Test Image B
5.1.3 Test Image C
5.1.4 Test Image D
5.2 Segmentation of Real Images
5.2.1 Lenna
5.2.2 Aeroplane
5.3 Segmentation of Real ”Environmental” Images
5.3.1 Pebbles
5.3.2 Braided River-bed
5.3.3 High Resolution Ortho-Photo
6 Segmentation of One Dimensional Signals
6.1 Segmentation of Synthetic One Dimensional Signals
6.1.1 Occurrence and overcoming of the Gradient Effect
6.1.2 A Complex Signal and a Complex Noisy Signal
6.2 Segmentation of GNSS Coordinates Time Series
6.2.1 Detection of a Singular Jump
6.2.2 Different Segmentations of the Same Time SeriesNuméro de notice : 13785 Affiliation des auteurs : non IGN Thématique : IMAGERIE/POSITIONNEMENT Nature : Thèse française Note de thèse : Thèse de doctorat : ingénierie de l'environnement : Italie, université de Trente : 2008 nature-HAL : Thèse DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=45233 Documents numériques
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