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Improving the precision and accuracy of geodetic GPS / A. Bilich (2006)

Public Titre : Improving the precision and accuracy of geodetic GPS : applications to multipath and seismology Type de document : Thèse/HDR Auteurs : A. Bilich, Auteur ; K. Larson, Directeur de thèse Editeur : Boulder [Etats-Unis] : University of Colorado Année de publication : 2006 Importance : 374 p. Format : 21 x 28 cm ISBN/ISSN/EAN : 978-0-542-94205-1 Note générale : Bibliographie A thesis submitted to the Faculty of the graduate school of the University of Colorado in partial fulfillment of the requirements for the degree of Doctor of philosophy, department of aerospace engineering sciences Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] égalisation [Termes IGN] erreur de positionnement [Termes IGN] filtrage du bruit [Termes IGN] mesurage de phase [Termes IGN] mesurage de pseudo-distance [Termes IGN] positionnement par GPS [Termes IGN] rapport signal sur bruit [Termes IGN] réduction [Termes IGN] séisme [Termes IGN] sismologie [Termes IGN] trajet multiple Index. décimale : THESE Thèses et HDR Résumé : (Auteur) The Global Positioning System (GPS) enables precise and accurate determination of position anywhere on anywhere on the Earth, a boon to the field of geodesy. Although great advances in geodetic GPS positioning precision and accuracy have been made over the last decade, improvements can still be made. This dissertation addresses GPS positioning error from two different directions---understanding and taking advantage of the repeating nature of some errors, or understanding and taking advantage of the relationship between errors in different contemporaneous GPS observables. In the area of high-rate GPS positioning, repeating errors have a substantial impact on the solution. In this dissertation, I study high-rate GPS error reduction using data from the 2002 Denali Fault earthquake. I apply the techniques of modified sidereal filtering and spatial filtering to positions from 25 GPS stations throughout northwestern North America, and I develop improvements to these methods such as data equalization and careful selection of sidereal filtering sites. Substantial reduction in noise magnitude is achieved through proper application of sidereal and spatial filters, and the resulting 'GPS seismograms' show excellent agreement to records from seismometers. Multipath, where GPS signals arrive by more than one path and thereby create a range error, can be understood through the GPS observables. Multipath effects on GPS carrier phase, pseudorange, and signal-to-noise ratio (SNR) measurements are different but linked by the same underlying principles. In this dissertation, I explain multipath effects on the GPS observables and define multipath in terms of conditions specific to geodetic GPS installations and receivers. I develop two approaches to multipath errors, both using SNR measurements---a graphical method for multipath assessment, and a computational method for multipath modeling and carrier phase error reduction. The graphical method shows great promise for understanding spatial and temporal variability in multipath errors, but provides no avenue for removing these errors. The theory behind SNR modeling is robust, but complicated to implement with geodetic GPS measurements of SNR. I discuss the difficulties inherent in SNR modeling and demonstrate how this technique is of limited utility for geodetic GPS even in the most simple of multipath environments. Note de contenu : 1 Introduction 1.1 Global Positioning System Background 1.2 GPS Observables 1.3 Position Estimation with GIPSY 1.3.1 Satellite Orbits 1.3.2 Earth and Observation Models 1.3.3 Removing Ionospheric Effects 1.3.4 Unmodeled Terms 1.3.5 Position Solution 2 Overview of High-Rate Positioning Research 2.1 Comparision of GPS and Seismologic Measurements 2.2 Previous Work in GPS Seismology 2.3 Case Study: 2002 November 3 Denali Fault Event 2.3.1 Denali Fault earthquake 2.3.2 GPS network and analysis 2.3.3 Error-reduction methodology 3 High-rate GPS Techniques 3.1 Sidereal Filtering 3.1.1 Orbital repeat period 3.1.2 Modified sidereal filtering (MSF) method 3.1.3 Variables in sidereal filtering process 3.2 Additional Data Analysis 3.2.1 Ambiguity resolution 3.2.2 Data editing 3.3 Spatial Filtering 3.3.1 Common-mode errors 3.3.2 Spatial filtering method 3.3.3 Spatial filtering sites 3.3.4 Role of the reference site and filter order 4 High-rate GPS Results and Discussion 4.1 Surface Waves Recorded by GPS 4.2 Positioning Noise 4.2.1 Noise floor of GPS receivers 4.2.2 Generalized noise in GPS positions 4.3 Comparison to Seismic Recordings 4.4 Summary and Conclusions 4.5 Future Work 5 Overview of Multipath Research 5.1 Previous Work 5.2 Research Motivation and Overview 6 Principles of Multipath and SNR 6.1 GPS Receiver Signal Tracking 6.2 Multipath Terminology 6.3 Multipath Effects on GPS Observables 6.3.1 Pseudorange multipath 6.3.2 Carrier phase multipath 6.3.3 Effect of multipath on SNR 6.4 Summary of Multipath Theory 7 Multipath Under Geodetic GPS Conditions 7.1 Multipath Geometry for the Geodetic Case 7.1.1 Multipath geometry and errors 7.1.2 Time-varying behavior of ø and SNR 7.1.3 Multipath geometry and periodicity 7.1.4 Resolvable multipath frequencies 7.1.5 Multipath phasor spin 7.1.6 Direct and multipath amplitudes 7.1.7 Summary 7.2 Geodetic GPS Receivers 7.2.1 Computation and reporting of SNR 7.2.2 Characteristics of geodetic GPS SNR 7.2.3 Correlation of SNR and pseudorange multipath 7.2.4 Conclusions 8 Multipath Assessment for Permanent GPS Stations 8.1 SNR Power Spectral Maps 8.1.1 Spectral power estimates 8.1.2 Representation of gridded spectral power 8.2 Examples of Power Spectral Maps 8.2.1 TASH: tall pillar 8.2.2 MKEA: reflections from angled surfaces 8.2.3 CHUR: variable topography 8.3 Discussion and Future Work 9 Estimation of SNR-based Multipath Corrections 9.1 Direct Signal Amplitude and SNR Due to Multipath 9.2 Signal Conditioning 9.3 Multipath Frequency Estimation Via Sliding-Window Fast Fourier Transform (SWFFT) 9.4 Amplitude and Multipath Phase Estimation Via Adaptive Least Squares (ALS) 9.5 Construction of SNR and Multipath Corrections 9.6 Simulations 10 Phase Multipath Mitigation for GPS Stations 10.1 Salar de Uyuni Experiment 10.1.1 Phase errors 10.1.2 Phase multipath corrections 10.1.3 Effect of corrections on residuals and positions 10.2 TASH/KIT3 Network 10.2.1 SNR data 10.2.2 Phase multipath corrections 10.2.3 Phase errors and corrections 10.3 Discussion and Future Work 11 Conclusions Numéro de notice : 14325 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse française Note de thèse : Thèse de doctorat : philosophy. department of aerospace engineering sciences : Boulder,University of Colorado : 2006 nature-HAL : Thèse DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=45244

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Remote sensing of atmospheric water vapor with the Global Positioning System / John Joseph Braun (2004)  

Public Titre : Remote sensing of atmospheric water vapor with the Global Positioning System Type de document : Thèse/HDR Auteurs : John Joseph Braun, Auteur ; Judith Curry, Directeur de thèse Editeur : Boulder [Etats-Unis] : University of Colorado Année de publication : 2004 Importance : 158 p. Format : 21 x 30 cm Note générale : bibliographie A thesis submitted to the Faculty of the Graduate School of the University of Colorado in partial fulfillment of the requirements for the degree of Doctor of Philosophy Department of Aerospace Engineering Sciences Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] atmosphère terrestre [Termes IGN] Etats-Unis [Termes IGN] teneur en vapeur d'eau Résumé : (auteur) Signals from the Global Positioning System (GPS) are used to retrieve the integrated amount of water vapor along the path between a transmitting satellite and a receiving station. This integrated quantity is called slant water vapor (SW). Measurements of SW allow for an improved assessment of the spatial distribution of water vapor within the atmosphere. This technique is developed and validated through simulations and comparisons to similar measurements from a pointing microwave water vapor radiometer. Absolute accuracy of zenith scaled SW is found to be 1.5 mm with a relative precision that is better than 0.5 mm. Dual and single frequency GPS stations are used to measure SW. Previously, only dual frequency GPS stations have been used for atmospheric remote sensing. The use of single frequency stations, which are significantly less expensive than dual frequency ones, allows for a denser placement of stations. The effects of the ionosphere on single frequency GPS observations are eliminated using global ionosphere models and double difference processing with short station separation. Networks of GPS stations are deployed in the Southern Great Plains of the United States. Combining SW measurements from all stations within a dense network allows for an estimation of the three dimensional distribution of water vapor above the network. This tomographic technique is improved by including vertical profiles from radiosondes. The retrieval of SW is utilized during the International H20 Project 2002 (IHOP_2002). Significant water vapor structure is observed within the atmospheric boundary layer, including dryline convergence and horizontal convective rolls. Tomography results computed during squall line passage indicate elevated levels of water vapor in the free troposphere prior to the onset of rainfall. A statistical analysis of the results obtained during IHOP_2002 show coherent water vapor structure across horizontal lengths ranging from less than 1 to almost 100 kilometers. A significant diurnal cycle of atmospheric water vapor variability is also found. Numéro de notice : 14872 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse étrangère Note de thèse : PhD : Aerospace Engineering Sciences : University of Colorado : 2004 DOI : sans En ligne : https://scholar.colorado.edu/concern/graduate_thesis_or_dissertations/3n203z351 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=75928