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Wavelet modeling of the gravity field over Japan / Isabelle Panet in Bulletin of the Geographical survey institute, vol 57 (December 2009)
[article]
Titre : Wavelet modeling of the gravity field over Japan Type de document : Article/Communication Auteurs : Isabelle Panet , Auteur ; Yuki Kuroishi, Auteur ; Matthias Holschneider, Auteur Année de publication : 2009 Article en page(s) : pp 19 - 33 Note générale : Bibliographie
2e partie article : https://www.gsi.go.jp/common/000054750.pdfLangues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] bruit blanc
[Termes IGN] champ de pesanteur local
[Termes IGN] géoïde local
[Termes IGN] harmonique sphérique
[Termes IGN] Japon
[Termes IGN] levé gravimétrique
[Termes IGN] modèle de géopotentiel local
[Termes IGN] ondelette sphérique
[Termes IGN] transformation en ondelettesRésumé : (Auteur) Knowing the geoïd over Japan is essential for many geodetical and geophysical applications. Because of the tectonic settings of the area, significant geoid undulations occur in a wide range of spatial scales and make the determination of the geoïd a complex task. In some applications, high absolute accuracy at long and medium wavelengths is required for geoïd models with high resolution, which can be achieved by a proper combination of satellite gravity information with densely-distributed surface gravity data after careful consideration of their respective error characteristics. Here we show how to realize such a combination in a flexible way using spherical wavelets. The gravity potential is expressed as a linear combination of wavelets, whose coefficients are obtained by a least squares adjustment of the datasets. The combination needs to handle a large system of equations and we apply a domain decomposition method. First, we define sub-domains as subsets of wavelets. Based on the localization properties of the wavelets in space and frequency, we define hierarchical sub-domains of wavelets at different scales. On each scale, blocks of sub-domains are defined by using a tailored spatial splitting of the area. Second, we approximate the normal matrix for each block by introducing local approximation of the wavelets depending on the scale, in which local averages of the data are actually used for computation. Finally, we solve the system iteratively. In the beginning we validate the method with synthetic data, considering two kinds of noise: white noise and colored noise. We then apply the method to data over Japan: a satellite-based geopotential model, EIGEN-GL04S, and a local gravity model from a combination of land and marine gravity data and an altimetry-derived marine gravity model. A hybrid spherical harmonics/wavelet model of the geoïd is obtained at about 15 km resolution and the residuals indicate the existence of possible biases in the surface model. This information is used to correct the local model and the method is repeated with the corrected data, resulting in an improved hybrid model of the gravity field over Japan. Copyright Geographical Survey Institute Numéro de notice : A2009-558 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans En ligne : https://www.gsi.go.jp/common/000054749.pdf Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30187
in Bulletin of the Geographical survey institute > vol 57 (December 2009) . - pp 19 - 33[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 250-09011 RAB Revue Centre de documentation En réserve L003 Disponible Consideration of time-correlated errors in a Kalman filter applicable to GNSS / M.G. Potovello in Journal of geodesy, vol 83 n° 1 (January 2009)
[article]
Titre : Consideration of time-correlated errors in a Kalman filter applicable to GNSS Type de document : Article/Communication Auteurs : M.G. Potovello, Auteur ; Kyle O'Keefe, Auteur ; Gérard Lachapelle, Auteur ; M.E. Cannon, Auteur Année de publication : 2009 Article en page(s) : pp 51 - 56 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] bruit blanc
[Termes IGN] covariance
[Termes IGN] erreur corrélée au temps
[Termes IGN] filtre de Kalman
[Termes IGN] GPS en mode cinématique
[Termes IGN] GPS en mode différentiel
[Termes IGN] positionnement par GNSS
[Termes IGN] traitement différé
[Termes IGN] traitement du signalRésumé : (Auteur) An algorithm for considering time-correlated errors in a Kalman filter is presented. The algorithm differs from previous implementations in that it does not suffer from numerical problems; does not contain inherent time latency or require reinterpretation of Kalman filter parameters, and gives full consideration to additive white noise that is often still present but ignored in previous implementations. Simulation results indicate that the application of the new algorithm yields more realistic and therefore useful state and covariance information than the standard implementation. Results from a field test of the algorithm applied to the problem of kinematic differential GPS demonstrate that the algorithm provides slightly pessimistic covariance estimates whereas the standard Kalman filter provides optimistic covariance estimates. Copyright Springer Numéro de notice : A2009-181 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-008-0231-z En ligne : https://doi.org/10.1007/s00190-008-0231-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29811
in Journal of geodesy > vol 83 n° 1 (January 2009) . - pp 51 - 56[article]Exemplaires(2)
Code-barres Cote Support Localisation Section Disponibilité 266-09011 RAB Revue Centre de documentation En réserve L003 Disponible 266-09012 RAB Revue Centre de documentation En réserve L003 Disponible Fast error analysis of continuous GPS observations / M. Bos in Journal of geodesy, vol 82 n° 3 (March 2008)
[article]
Titre : Fast error analysis of continuous GPS observations Type de document : Article/Communication Auteurs : M. Bos, Auteur ; R. Fernandes, Auteur ; S. Williams, Auteur ; et al., Auteur Année de publication : 2008 Article en page(s) : pp 157 - 166 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] bruit blanc
[Termes IGN] classification par maximum de vraisemblance
[Termes IGN] données GPS
[Termes IGN] incertitude des données
[Termes IGN] série temporelleRésumé : (Auteur) It has been generally accepted that the noise in continuous GPS observations can be well described by a power-law plus white noise model. Using maximum likelihood estimation (MLE) the numerical values of the noise model can be estimated. Current methods require calculating the data covariance matrix and inverting it, which is a significant computational burden. Analysing 10 years of daily GPS solutions of a single station can take around 2 h on a regular computer such as a PC with an AMD AthlonTM 64 X2 dual core processor. When one analyses large networks with hundreds of stations or when one analyses hourly instead of daily solutions, the long computation times becomes a problem. In case the signal only contains power-law noise, the MLE computations can be simplified to a O(N log N) process where N is the number of observations. For the general case of power-law plus white noise, we present a modification of the MLE equations that allows us to reduce the number of computations within the algorithm from a cubic to a quadratic function of the number of observations when there are no data gaps. For time-series of three and eight years, this means in practise a reduction factor of around 35 and 84 in computation time without loss of accuracy. In addition, this modification removes the implicit assumption that there is no environment noise before the first observation. Finally, we present an analytical expression for the uncertainty of the estimated trend if the data only contains power-law noise. Copyright Springer Numéro de notice : A2008-167 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-007-0165-x En ligne : https://doi.org/10.1007/s00190-007-0165-x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29162
in Journal of geodesy > vol 82 n° 3 (March 2008) . - pp 157 - 166[article]Exemplaires(2)
Code-barres Cote Support Localisation Section Disponibilité 266-08031 RAB Revue Centre de documentation En réserve L003 Disponible 266-08032 RAB Revue Centre de documentation En réserve L003 Disponible
Titre : Least-square variance component estimation : Theory and GPS applications Type de document : Thèse/HDR Auteurs : Ali Reza Amiri-Simkooei, Auteur Editeur : Delft : Netherlands Geodetic Commission NGC Année de publication : 2007 Collection : Netherlands Geodetic Commission Publications on Geodesy, ISSN 0165-1706 num. 64 Importance : 208 p. Format : 17 x 24 cm ISBN/ISSN/EAN : 978-90-6132-301-3 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] analyse de variance
[Termes IGN] analyse multivariée
[Termes IGN] bruit blanc
[Termes IGN] bruit rose
[Termes IGN] coordonnées GPS
[Termes IGN] estimation statistique
[Termes IGN] matrice de covariance
[Termes IGN] méthode des moindres carrés
[Termes IGN] modèle stochastique
[Termes IGN] série temporelle
[Termes IGN] signal GPS
[Termes IGN] varianceIndex. décimale : 30.61 Systèmes de Positionnement par Satellites du GNSS Résumé : (Auteur) Data processing in geodetic applications often relies on the least-squares method, for which one needs a proper stochastic model of the observables. Such a realistic covariance matrix allows one first to obtain the best (minimum variance) linear unbiased estimator of the unknown parameters; second, to determine a realistic precision description of the unknowns; and, third, along with the distribution of the data, to correctly perform hypothesis testing and assess quality control measures such as reliability. In many practical applications the covariance matrix is only partly known. The covariance matrix is then usually written as an unknown linear combination of known cofactor matrices. The estimation of the unknown (co)variance components is generally referred to as variance component estimation (VCE). In this thesis we study the method of least-squares variance component estimation (LSVCE) and elaborate on theoretical and practical aspects of the method. We show that LS-VCE is a simple, flexible, and attractive VCE-method. The LS-VCE method is simple because it is based on the well-known principle of least-squares. With this method the estimation of the (co)variance components is based on a linear model of observation equations. The method is flexible since it works with a user-defined weight matrix. Different weight matrix classes can be defined which all automatically lead to unbiased estimators of (co)variance components. LS-VCE is attractive since it allows one to apply the existing body of knowledge of least-squares theory to the problem of (co)variance component estimation. With this method, one can 1) obtain measures of discrepancies in the stochastic model, 2) determine the covariance matrix of the (co)variance components, 3) obtain the minimum variance estimator of (co)variance components by choosing the weight matrix as the inverse of the covariance matrix, 4) take the a-priori information on the (co)variance component into account, 5) solve for a nonlinear (co)variance component model, 6) apply the idea of robust estimation to (co)variance components, 7) evaluate the estimability of the (co)variance components, and 8) avoid the problem of obtaining negative variance components. LS-VCE is capable of unifying many of the existing VCE-methods such as MINQUE, BIQUE, and REML, which can be recovered by making appropriate choices for the weight matrix. An important feature of the LS-VCE method is the capability of applying hypothesis testing to the stochastic model, for which we rely on the w-test, v-test, and overall model test. We aim to find an appropriate structure for the stochastic model which includes the relevant noise components into the covariance matrix. The w-test statistic is introduced to see whether or not a certain noise component is likely to be present in the observations, which consequently can be included in the stochastic model. Based on the normal distribution of the original observables we determine the mean and the variance of the w-test statistic, which are zero and one, respectively. The distribution is a linear combination of mutually independent central chi-square distributions each with one degree of freedom. This distribution can be approximated by the standard normal distribution for some special cases. An equivalent expression for the w-test is given by introducing the v-test statistic. The goal is to decrease the number of (co)variance components of the stochastic model by testing the significance of the components. The overall model test is introduced to generally test the appropriateness of a proposed stochastic model. We also apply LS-VCE to real data of two GPS applications. LS-VCE is applied to the GPS geometry-free model. We present the functional and stochastic model of the GPS observables. The variance components of different observation types, satellite elevation dependence of GPS observables’ precision, and correlation between different observation types are estimated by LS-VCE. We show that the precision of the GPS observables clearly depends on the elevation angle of satellites. Also, significant correlation between observation types is found. For the second application we assess the noise characteristics of time series of daily coordinates for permanent GPS stations. We apply LS-VCE to estimate white noise and power-law noise (flicker noise and random walk noise) amplitudes in these time series. The results confirm that the time series are highly time correlated. We also use the w-test statistic to find an appropriate stochastic model of GPS time series. A combination of white noise, autoregressive noise, and flicker noise in general best characterizes the noise in all three position components. Unmodelled periodic effects in the data are then captured by a set of harmonic functions, for which we rely on least-squares harmonic estimation (LS-HE) developed in the same framework as LS-VCE. The results confirm the presence of annual and semiannual signals, as well as other significant periodic patterns in the series. To avoid the biased estimation of the variance components, such sinusoidal signals should be included in the functional part of the model before applying LS-VCE. Note de contenu : 1. Introduction
2. Least-Squares Estimation and Validation
3. Variance Component Estimation: A Review
4. Least-Squares Variance Component Estimation
5. Detection and Validation in Stochastic Model
6. Multivariate Variance-Covariance Analysis
7. GPS Geometry-Free Model
8. GPS Coordinate Time Series
9. Conclusions and Recommendations
A. Mathematical Background
B. Derivation of Equations
C. Moments of Normally Distributed Data
D. Mixed model with hard constraints
BibliographyNuméro de notice : 15303 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse étrangère DOI : sans En ligne : https://www.ncgeo.nl/downloads/71Memarzadeh.pdf Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=62689 Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 15303-01 30.61 Livre Centre de documentation Géodésie Disponible Error analysis of weekly station coordinates in the DORIS network / Simon D.P. Williams in Journal of geodesy, vol 80 n° 8-11 (November 2006)
[article]
Titre : Error analysis of weekly station coordinates in the DORIS network Type de document : Article/Communication Auteurs : Simon D.P. Williams, Auteur ; Pascal Willis , Auteur Année de publication : 2006 Article en page(s) : pp 525 - 539 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] bruit blanc
[Termes IGN] bruit rose
[Termes IGN] calcul d'erreur
[Termes IGN] données DORIS
[Termes IGN] International Terrestrial Reference Frame
[Termes IGN] méthode du maximum de vraisemblance (estimation)
[Termes IGN] série temporelle
[Termes IGN] station DORIS
[Termes IGN] traitement du signalRésumé : (Auteur) Twelve years of DORIS data from 31 selected sites of the IGN/JPL (Institut Géographique National/Jet Propulsion Laboratory) solution IGNWD05 have been analysed using maximum likelihood estimation (MLE) in an attempt to understand the nature of the noise in the weekly station coordinate time-series. Six alternative noise models in a total of 12 different combinations were used as possible descriptions of the noise. The six noise models can be divided into two natural groups, temporally uncorrelated (white) noise and temporally correlated (coloured) noise. The noise can be described as a combination of variable white noise and one of flicker, first-order Gauss–Markov or power-law noise. The data set as a whole is best described as a combination of variable white noise plus flicker noise. The variable white noise, which is white noise with variable amplitude that is a function of the weekly formal errors multiplied by an estimated scale factor, shows a dependence on site latitude and the number of DORIS-equipped satellites used in the solution. The latitude dependence is largest in the east component due to the near polar orbit of the SPOT satellites. The amplitude of the flicker noise is similar in all three components and equal to about 20 mm/year1/4. There appears to be no latitude dependence of the flicker noise amplitude. The uncertainty in rates (site velocities) after 12 years is just under 1 mm/year. These uncertainties are around 3–4 times larger than if only variable white noise had been assumed, i.e., no temporally correlated noise. A rate uncertainty of 1 mm/year after 12 years in the vertical is similar to that achieved using Global Positioning System (GPS) data but it takes DORIS twice as long to reach 1 mm/year than GPS in the horizontal. The analysis has also helped to identify sites with either anomalous noise characteristics or large noise amplitudes, and tested the validity of previously proposed discontinuities. In addition, several new offsets were found in the time-series that should be used or at least flagged in future work. Copyright Springer Numéro de notice : A2006-534 Affiliation des auteurs : IGN (1940-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-006-0056-6 En ligne : http://doi.org/10.1007/s00190-006-0056-6 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28257
in Journal of geodesy > vol 80 n° 8-11 (November 2006) . - pp 525 - 539[article]Exemplaires(2)
Code-barres Cote Support Localisation Section Disponibilité 266-06102 RAB Revue Centre de documentation En réserve L003 Disponible 266-06101 RAB Revue Centre de documentation En réserve L003 Disponible Estimating the noise in space-geodetic positioning: the case of DORIS / Karine Le Bail in Journal of geodesy, vol 80 n° 8-11 (November 2006)PermalinkPlate kinematic of Nubia-Somalia using combined DORIS and GPS solution / Jean-Mathieu Nocquet in Journal of geodesy, vol 80 n° 8-11 (November 2006)PermalinkPermalinkLong term consistency of multi-technique terrestrial reference frames, a spectral approach / Karine Le Bail (2006)PermalinkEffects of thermosphere total density pertubations on LEO Orbits during severe geomagnetic conditions (Oct-Nov 2003) using Doris and SLR data / Florent Deleflie in Advances in space research, vol 36 n° 3 (March 2005)PermalinkDécomposition de signaux aléatoires stationnaires et non-stationnaires / Philippe Courmontagne (2005)PermalinkThéorie et traitement du signal, 2. Méthodes de base pour l'analyse et le traitement du signal / Messaoud Benidir (2004)PermalinkIntegrating interferometric SAR data with levelling measurements of land subsidence using geostatistic / Y. Zhou in International Journal of Remote Sensing IJRS, vol 24 n° 18 (September 2003)PermalinkMultipath mitigation: how good can it get with new signals ? / L.R. Weill in GPS world, vol 14 n° 6 (June 2003)PermalinkMatched filtering-based estimation of ground elevation using laser altimetry / J.M. Anderson in IEEE Transactions on geoscience and remote sensing, vol 39 n° 10 (October 2001)Permalink