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Brainy positioning: processing GPS data with neural networks / Rodrigo Figueiredo Leandro in GPS world, vol 18 n° 9 (September 2007)
[article]
Titre : Brainy positioning: processing GPS data with neural networks Type de document : Article/Communication Auteurs : Rodrigo Figueiredo Leandro, Auteur ; C. Da Silva, Auteur ; P. Segantine, Auteur ; M.C. Santos, Auteur Année de publication : 2007 Article en page(s) : pp 60 - 65 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] phase GPS
[Termes IGN] positionnement par GPS
[Termes IGN] réseau neuronal artificiel
[Termes IGN] simulation
[Termes IGN] temps réel
[Termes IGN] traitement de données GNSSRésumé : (Editeur) The brain is a fascinating organ. [...] In an effort to better understand how the brain works, neuroscientists teamed up with computer scientists to develop mathematical models to describe how networks of interconnected neurons process information. By the late 1950s, they had arrived at a basic model which has been improved on over the years. Each neuron in the network performs a simple computation; it receives signals from its input links, which it weights and then uses to compute its activation level (or output). The success of neural network models to mimic the basic operation of brain cells led computer scientists to the idea that artificial neural networks could be used to solve mathematical problems. They were able to show that, through a training or learning process, such networks are capable of solving virtually any problem that involves mapping input data to output data. Artificial neural networks have served as the basis for a variety of a tasks ranging from intelligent simulation, to real-time adaptation, to data analysis. While not a direct replacement for our traditional least-squares and Kalman filtering techniques, artificial neural networks have been used effectively for a number of applications in geodesy and navigation, including the processing of GPS data. But the handling of GPS data for use in a neural network processor is not without problems. In this month's column, we take a look at how artificial neural networks can be used as a tool in GPS applications, including the preprocessing necessary to successfully ingest the data. Copyright Questex Media Group Inc Numéro de notice : A2007-444 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28807
in GPS world > vol 18 n° 9 (September 2007) . - pp 60 - 65[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 067-07091 SL Revue Centre de documentation Revues en salle Disponible GPS sidereal filtering: coordinate- and carrier-phase-level strategies / A.E. Ragheb in Journal of geodesy, vol 81 n° 5 (May 2007)
[article]
Titre : GPS sidereal filtering: coordinate- and carrier-phase-level strategies Type de document : Article/Communication Auteurs : A.E. Ragheb, Auteur ; Peter J. Clarke, Auteur ; S.J. Edwards, Auteur Année de publication : 2007 Article en page(s) : pp 325 - 335 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] autocorrélation
[Termes IGN] données GPS
[Termes IGN] filtrage du signal
[Termes IGN] phase GPS
[Termes IGN] positionnement par GPS
[Termes IGN] traitement de données GNSS
[Termes IGN] trajet multipleRésumé : (Auteur) Multipath error is considered one of the major errors affecting GPS observations. One can benefit from the repetition of satellite geometry approximately every sidereal day, and apply filtering to help minimize this error. For GPS data at 1 s interval processed using a double-difference strategy, using the day-to-day coordinate or carrier-phase residual autocorrelation determined with a 10-h window leads to the steadiest estimates of the error-repeat lag, although a window as short as 2 h can produce an acceptable value with > 97% of the optimal lag’s correlation. We conclude that although the lag may vary with time, such variation is marginal and there is little advantage in using a satellite-specific or other time-varying lag in double-difference processing. We filter the GPS data either by stacking a number of days of processed coordinate residuals using the optimum “sidereal” lag (23 h 55 m 54 s), and removing these stacked residuals from the day in question (coordinate space), or by a similar method using double-difference carrier-phase residuals (observational space). Either method results in more consistent and homogeneous set of coordinates throughout the dataset compared with unfiltered processing. Coordinate stacking reduces geometry-related repeating errors (mainly multipath) better than carrier-phase residual stacking, although the latter takes less processing time to achieve final filtered coordinates. Thus, the optimal stacking method will depend on whether coordinate precision or computational time is the over-riding criterion. Copyright Springer Numéro de notice : A2007-122 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-006-0113-1 En ligne : https://doi.org/10.1007/s00190-006-0113-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28485
in Journal of geodesy > vol 81 n° 5 (May 2007) . - pp 325 - 335[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 266-07051 RAB Revue Centre de documentation En réserve L003 Disponible 266-07052 RAB Revue Centre de documentation En réserve L003 Disponible Higher order ionospheric effects in precise GNSS positioning / M. Mainul Hoque in Journal of geodesy, vol 81 n° 4 (April 2007)
[article]
Titre : Higher order ionospheric effects in precise GNSS positioning Type de document : Article/Communication Auteurs : M. Mainul Hoque, Auteur ; N. Jakowski, Auteur Année de publication : 2007 Article en page(s) : pp 259 - 268 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] correction ionosphérique
[Termes IGN] phase GPS
[Termes IGN] positionnement par GNSS
[Termes IGN] réfraction atmosphérique
[Termes IGN] résidu
[Termes IGN] teneur totale en électronsRésumé : (Auteur) With the increasing number of precise navigation and positioning applications using Global Navigation Satellite Systems (GNSS) such as the Global Positioning System (GPS), higher order ionospheric effects and their correction become more and more important. Whereas the first-order error can be completely eliminated by a linear combination of dual- frequency measurements, the second- and third-order residual effects remain uncorrected in this approach. To quantify the second-order residual effect, a simple formula has been derived for GNSS users in Germany. Our proposed correction algorithm reduces the second-order effects to a residual error of fractions of 1 mm up to 2 mm at a vertical total electron content level of 1018 electrons/m (100 TECU), depending on satellite azimuth and elevation angles. The correction formula can be implemented in real-time applications as it does not require the knowledge of the geomagnetic field or the electron density distribution in the ionosphere along the signal path. It is expected that the correction will enable more accurate positioning using the line-of-sight carrier-phase measurements. Copyright Springer Numéro de notice : A2007-186 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-006-0106-0 En ligne : https://doi.org/10.1007/s00190-006-0106-0 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28549
in Journal of geodesy > vol 81 n° 4 (April 2007) . - pp 259 - 268[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 266-07041 RAB Revue Centre de documentation En réserve L003 Disponible 266-07042 RAB Revue Centre de documentation En réserve L003 Disponible Calibration errors on experimental slant total electron content (TEC) determined with GPS / L. Ciraolo in Journal of geodesy, vol 81 n° 2 (February 2007)
[article]
Titre : Calibration errors on experimental slant total electron content (TEC) determined with GPS Type de document : Article/Communication Auteurs : L. Ciraolo, Auteur ; F. Azpilicueta, Auteur ; C. Brunini, Auteur ; et al., Auteur Année de publication : 2007 Article en page(s) : pp 111 - 120 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] correction ionosphérique
[Termes IGN] erreur systématique
[Termes IGN] phase GPS
[Termes IGN] positionnement par GPS
[Termes IGN] propagation ionosphérique
[Termes IGN] teneur totale en électrons
[Termes IGN] trajet multipleRésumé : (Auteur) The Global Positioning System (GPS) has become a powerful tool for ionospheric studies. In addition, ionospheric corrections are necessary for the augmentation systems required for Global Navigation Satellite Systems (GNSS) use. Dual-frequency carrier-phase and code-delay GPS observations are combined to obtain ionospheric observables related to the slant total electron content (sTEC) along the satellite-receiver line-of-sight (LoS). This observable is affected by inter-frequency biases [IFB; often called differential code biases (DCB)] due to the transmitting and the receiving hardware. These biases must be estimated and eliminated from the data in order to calibrate the experimental sTEC obtained from GPS observations. Based on the analysis of single differences of the ionospheric observations obtained from pairs of co-located dual-frequency GPS receivers, this research addresses two major issues: (1) assessing the errors translated from the code-delay to the carrier-phase ionospheric observable by the so-called levelling process, applied to reduce carrier-phase ambiguities from the data; and (2) assessing the short-term stability of receiver IFB. The conclusions achieved are: (1) the levelled carrier-phase ionospheric observable is affected by a systematic error, produced by code-delay multi-path through the levelling procedure; and (2) receiver IFB may experience significant changes during 1 day. The magnitude of both effects depends on the receiver/antenna configuration. Levelling errors found in this research vary from 1.4 total electron content units (TECU) to 5.3 TECU. In addition, intra-day vaiations of code-delay receiver IFB ranging from 1.4 to 8.8 TECU were detected. Copyright Springer Numéro de notice : A2007-047 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-006-0093-1 En ligne : https://doi.org/10.1007/s00190-006-0093-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28412
in Journal of geodesy > vol 81 n° 2 (February 2007) . - pp 111 - 120[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 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 Workshop on satellite navigation user equipment technologies / Huibert-Jan Lekkerkerk in Geoinformatics, vol 10 n° 1 (01/01/2007)PermalinkGPS time transfer: using precise point positioning for clock comparisons / François Lahaye in GPS world, vol 17 n° 11 (November 2006)PermalinkPhase wind-up analysis: assessing real-time kinematic performance / D. Kim in GPS world, vol 17 n° 9 (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)PermalinkAnalyse des stochastischen Modells von GPS-Trägerphasenbeobachtungen / J. Howind (2005)PermalinkGPS-Anwendungen in der Sportwissenschaft / T. Blumenbach (2005)PermalinkSpacecraft formation flying: relative positioning using dual-frequency carrier phase / Remco Kroes in GPS world, vol 15 n° 7 (July 2004)PermalinkGPS satellite surveying / Alfred Leick (2004)PermalinkPhase ambiguity determination for the positioning of interferometric SAR data / A. Sowter in Photogrammetric record, vol 18 n° 104 (December 2003 - February 2004)PermalinkZur Bestimmung der GPS-Phasenmehrdeutigkeiten in großräumigen Netzen / K. Wienholz (2003)PermalinkImprovement of GPS phase ambiguity resolution using prior height information as a quasi-observation / Jianjun Zhu in Geomatica, vol 56 n° 3 (September 2002)PermalinkApplication des méthodes de résolution d'ambigüités sur la mesure de phase GPS à l'approche de précision / J.P. Chauveau (2002)PermalinkOn the accuracy of kinematic carrier phase GPS for airborne mapping / A.M. Bruton in Geomatica, vol 55 n° 4 (December 2001)PermalinkDeutsche Beiträge zu GPS-Kampagnen des Scientific Committee on Antarctic Research (SCAR) 1995-1998 / R. Dietrich (2000)PermalinkPräzise Positionierung in regionalen GPS-Referenzstationsnetzen / Lambert Wanninger (2000)PermalinkUntersuchung von GPS-Beobachtungen für kleinräumige geodätische Netze / R. Hollmann (2000)PermalinkZur Entwicklung eines GPS-Programmsystems für Lehre und Tests unter besonderer Berücksichtigung der Ambiguity Function Methode / B. Zebhauser (2000)PermalinkRecursive data processing for kinematic GPS surveying / Christian Tiberius (1998)PermalinkL'aérotriangulation appuyée sur des mesures GPS faites en vol à bord de l'avion : le traitement des mesures / Claude Million in XYZ, n° 72 (juin - août 1997)Permalink