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Efficiency of carrier-phase integer ambiguity resolution for precise GPS positioning in noisy environments / L. Zhu in Journal of geodesy, vol 81 n° 2 (February 2007)
[article]
Titre : Efficiency of carrier-phase integer ambiguity resolution for precise GPS positioning in noisy environments Type de document : Article/Communication Auteurs : L. Zhu, Auteur ; Y.C. Lai, Auteur ; M. Shah, Auteur ; et al., Auteur Année de publication : 2007 Article en page(s) : pp 149 - 156 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] ambiguïté entière
[Termes IGN] brouillage
[Termes IGN] bruit (théorie du signal)
[Termes IGN] méthode des moindres carrés
[Termes IGN] phase GPS
[Termes IGN] positionnement par GPS
[Termes IGN] résolution d'ambiguïtéRésumé : (Auteur) Precise GPS positioning relies on tracking the carrier-phase. The fractional part of carrier-phase can be measured directly using a standard phase-locked loop, but the integer part is ambiguous and the ambiguity must be resolved based on sequential carrier-phase measurements to ensure the required positioning precision. In the presence of large phase-measurement noise, as can be expected in a jamming environment for example, the amount of data required to resolve the integer ambiguity can be large, which requires a long time for any generic integer parameter estimation algorithm to converge. A key question of interest in significant applications of GPS where fast and accurate positioning is desired is then how the convergence time depends on the noise amplitude. Here we address this question by investigating integer least-squares estimation algorithms. Our theoretical derivation and numerical experiments indicate that the convergence time increases linearly with the noise variance, suggesting a less stringent requirement for the convergence time than intuitively expected, even in a jamming environment where the phase noise amplitude is large. This finding can be useful for practical design of GPS-based systems in a jamming environment, for which the ambiguity resolution time for precise positioning may be critical. Copyright Springer Numéro de notice : A2007-048 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-006-0096-y En ligne : https://doi.org/10.1007/s00190-006-0096-y Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28413
in Journal of geodesy > vol 81 n° 2 (February 2007) . - pp 149 - 156[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 266-07021 RAB Revue Centre de documentation En réserve L003 Disponible 266-07022 RAB Revue Centre de documentation En réserve L003 Disponible Least-square variance component estimation / AliReza Amiri-Simkooei (2007)
Titre : Least-square variance component estimation : Theory and GPS applications Type de document : Monographie Auteurs : AliReza 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 : Monographie Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=62689 Réservation
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Code-barres Cote Support Localisation Section Disponibilité 15303-01 30.61 Livre Centre de documentation Géodésie Disponible Workshop on satellite navigation user equipment technologies / Huibert-Jan Lekkerkerk in Geoinformatics, vol 10 n° 1 (01/01/2007)
[article]
Titre : Workshop on satellite navigation user equipment technologies Type de document : Article/Communication Auteurs : Huibert-Jan Lekkerkerk, Auteur Année de publication : 2007 Article en page(s) : pp 52 - 53 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] Galileo
[Termes IGN] milieu urbain
[Termes IGN] navigation automobile
[Termes IGN] phase GPS
[Termes IGN] positionnement en intérieur
[Termes IGN] positionnement par géodésie spatiale
[Termes IGN] récepteur GPSRésumé : (Auteur) For the third time, the European Space Agency (ESA) held a workshop on satellite navigation user equipment technologies, Navitec 2006. The conference centre of Estec in Noordwijk, the Netherlands, was filled with scientists from all over Europe from Finland to Portugal. The eleventh to thirteenth of december, the conference filled the two Newton conference rooms with parallel sessions. The topic varied from receiver technologies and developments to carrier phase algorithms and indoor and urban navigation. The fourteenth of december there was a course on the Galileo system. Copyright GEOinformatics Numéro de notice : A2007-075 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28440
in Geoinformatics > vol 10 n° 1 (01/01/2007) . - pp 52 - 53[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 262-07011 SL Revue Centre de documentation Revues en salle Disponible GPS time transfer: using precise point positioning for clock comparisons / François Lahaye in GPS world, vol 17 n° 11 (November 2006)
[article]
Titre : GPS time transfer: using precise point positioning for clock comparisons Type de document : Article/Communication Auteurs : François Lahaye, Auteur ; D. Orgiazzi, Auteur ; P. Tavella, Auteur ; G. Cerretto, Auteur Année de publication : 2006 Article en page(s) : pp 44 - 49 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] analyse comparative
[Termes IGN] Global Positioning System
[Termes IGN] mesurage de pseudo-distance
[Termes IGN] phase GPS
[Termes IGN] positionnement ponctuel précis
[Termes IGN] récepteur bifréquence
[Termes IGN] récepteur GPS
[Termes IGN] temps atomique internationalRésumé : (Documentaliste) Les auteurs relatent les résultats d'une expérience menée avec la méthode de transfert de temps "Precise Point Positioning PPP" de post-traitement des données GPS par comparaison avec les mesures de transfert de temps et fréquence du satellite par 2 voies (Two-Way Satellite Time and Frequency Transfer TWSTFT). La méthode PPP permet une précision au niveau de la nano-seconde, sans avoir recours au réseau des stations. Numéro de notice : A2006-474 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28198
in GPS world > vol 17 n° 11 (November 2006) . - pp 44 - 49[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 067-06111 RAB Revue Centre de documentation En réserve L003 Disponible Tracking first responders: integrated Nav with software-defined radio (SDR) / A. Brown in GPS world, vol 17 n° 11 (November 2006)
[article]
Titre : Tracking first responders: integrated Nav with software-defined radio (SDR) Type de document : Article/Communication Auteurs : A. Brown, Auteur ; et al., Auteur Année de publication : 2006 Article en page(s) : pp 26 - 33 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] navigation pédestre
[Termes IGN] positionnement en intérieur
[Termes IGN] positionnement par GPS
[Termes IGN] secours d'urgence
[Termes IGN] signal GPSRésumé : (Auteur) A networked radionavigation approach that augments GPS signals with time-of-arrival observations using a software-defined radio can overcome attenuation, and often complet blockage, of GPS inside buildings [indoor] or in urban canyons. The SDR can operate both as a GPS receiver and also as a 900MHz transceiver operating within the ISM band. Applications for this technology include firefighters and other first responders, and military operations in urban terrain. Copyright Questex Media Group Inc Numéro de notice : A2006-564 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28287
in GPS world > vol 17 n° 11 (November 2006) . - pp 26 - 33[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 067-06111 RAB Revue Centre de documentation En réserve L003 Disponible Phase wind-up analysis: assessing real-time kinematic performance / D. Kim in GPS world, vol 17 n° 9 (September 2006)PermalinkSystematic effects in absolute chamber calibration of GPS antennas / Philipp Zeimetz in Geomatica, vol 60 n° 3 (September 2006)PermalinkPlatoon, roll! Robots test sensor combos / S. Crawford in GPS world, vol 17 n° 6 (June 2006)PermalinkPractical satellite navigation: part 4 differential GPS systems and RTK techniques / Huibert-Jan Lekkerkerk in Geoinformatics, vol 9 n° 4 (01/06/2006)PermalinkGNSS update, launch of new GNSS receivers and chipsets / Huibert-Jan Lekkerkerk in Geoinformatics, vol 9 n° 3 (01/05/2006)PermalinkGPS + modernized GPS + Galileo signal timing biases / C. Hegarty in GPS world, vol 17 n° 3 (March 2006)PermalinkPractical satellite navigation: part 2 GPS position and time determination / Huibert-Jan Lekkerkerk in Geoinformatics, vol 9 n° 2 (01/03/2006)PermalinkUtilizing calibrated GPS reflected signals to estimate soil reflectivity and dielectric constant: results from SMEX02 / S.J. Katzberg in Remote sensing of environment, vol 100 n° 1 (15/01/2006)PermalinkGPS et Galileo : systèmes de navigation par satellites / Jean-Marc Piéplu (2006)PermalinkGuide pratique du GPS / Paul Correia (2006)Permalink