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GPS sidereal filtering: coordinate- and carrier-phase-level strategies / A.E. Ragheb in Journal of geodesy, vol 81 n° 5 (May 2007)  

Public [article]  inJournal of geodesy > vol 81 n° 5 (May 2007) . - pp 325 - 335 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 multiple Résumé : (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 [article]

Exemplaires(2)

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

The topographic bias by analytical continuation in physical geodesy / Lard Erik Sjöberg in Journal of geodesy, vol 81 n° 5 (May 2007)  

Public [article]  inJournal of geodesy > vol 81 n° 5 (May 2007) . - pp 345 - 350 Titre : The topographic bias by analytical continuation in physical geodesy Type de document : Article/Communication Auteurs : Lard Erik Sjöberg, Auteur Année de publication : 2007 Article en page(s) : pp 345 - 350 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] erreur systématique [Termes IGN] formule de Stokes [Termes IGN] géoïde terrestre [Termes IGN] potentiel de pesanteur terrestre Résumé : (Auteur) This study emphasizes that the harmonic downward continuation of an external representation of the Earth’s gravity potential to sea level through the topographic masses implies a topographic bias. It is shown that the bias is only dependent on the topographic density along the geocentric radius at the computation point. The bias corresponds to the combined topographic geoid effect, i.e., the sum of the direct and indirect topographic effects. For a laterally variable topographic density function, the combined geoid effect is proportional to terms of powers two and three of the topographic height, while all higher order terms vanish. The result is useful in geoid determination by analytical continuation, e.g., from an Earth gravity model, Stokes’s formula or a combination thereof. Copyright Springer Numéro de notice : A2007-123 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-006-0112-2 En ligne : https://doi.org/10.1007/s00190-006-0112-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28486 [article]

Exemplaires(2)

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

Influence of ambiguity precision on the success rate of GNSS integer ambiguity bootstrapping / Peter J.G. Teunissen in Journal of geodesy, vol 81 n° 5 (May 2007)  

Public [article]  inJournal of geodesy > vol 81 n° 5 (May 2007) . - pp 351 - 358 Titre : Influence of ambiguity precision on the success rate of GNSS integer ambiguity bootstrapping Type de document : Article/Communication Auteurs : Peter J.G. Teunissen, Auteur Année de publication : 2007 Article en page(s) : pp 351 - 358 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] ambiguïté entière [Termes IGN] estimateur [Termes IGN] matrice de covariance [Termes IGN] positionnement par GNSS [Termes IGN] résolution d'ambiguïté Résumé : (Auteur) In this contribution, we study the dependence of the bootstrapped success rate on the precision of the GNSS carrier phase ambiguities. Integer bootstrapping is, because of its ease of computation, a popular method for resolving the integer ambiguities. The method is however known to be suboptimal, because it only takes part of the information from the ambiguity variance matrix into account. This raises the question in what way the bootstrapped success rate is sensitive to changes in precision of the ambiguities. We consider two different cases. (1) The effect of improving the ambiguity precision, and (2) the effect of using an approximate ambiguity variance matrix. As a by-product, we also prove that integer bootstrapping is optimal within the restricted class of sequential integer estimators. Copyright Springer Numéro de notice : A2007-124 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-006-0111-3 En ligne : https://doi.org/10.1007/s00190-006-0111-3 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28487 [article]

Exemplaires(2)

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

A comparison of GPS, VLBI and model estimates of ocean tide loading displacements / I.D. Thomas in Journal of geodesy, vol 81 n° 5 (May 2007)  

Public [article]  inJournal of geodesy > vol 81 n° 5 (May 2007) . - pp 359 - 368 Titre : A comparison of GPS, VLBI and model estimates of ocean tide loading displacements Type de document : Article/Communication Auteurs : I.D. Thomas, Auteur ; Matt A. King, Auteur ; Peter J. Clarke, Auteur Année de publication : 2007 Article en page(s) : pp 359 - 368 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] analyse comparative [Termes IGN] interférométrie à très grande base [Termes IGN] positionnement par GPS [Termes IGN] positionnement par ITGB [Termes IGN] surcharge océanique Résumé : (Auteur) In recent years, ocean tide loading displacements (OTLD) have been measured using the Global Positioning System (GPS) and Very Long Baseline Interferometry (VLBI). This study assesses the accuracy of GPS measurements of OTLD by comparison with VLBI measurements and estimates derived from numerical ocean tide models. A daily precise point positioning (PPP) analysis was carried out on ?11 years of GPS data for each of 25 sites that have previous OTLD estimates based on data from co-located VLBI sites. Ambiguities were fixed to integer values where possible. The resulting daily estimates of OTLD, at eight principal diurnal and semi-diurnal tidal frequencies, were combined to give GPS measurements of OTLD at each site. The 3D GPS and VLBI measurements of OTLD were compared with estimates computed (by convolution with Green’s functions) from five modern ocean tide models (CSR4.0, FES2004, GOT00.2, NAO99b and TPXO6.2). The GPS/model agreement is shown to be similar to the VLBI/model agreement. In the important radial direction, the GPS/model misfit is shown to be smaller than the VLBI/model misfit for seven of the eight tidal constituents; the exception being the K2 constituent. Fixing of GPS carrier-phase ambiguities to integer values resulted in a marginal improvement to the GPS/model agreement. Statistically, it is shown there is no significance to the difference between the fit of the GPS and VLBI measurements of OTLD to modelled values. Equally, differences in fit of either the complete set of GPS or VLBI estimates to the five sets of model-derived values cannot be identified with statistical significance. It is thus concluded that, overall, we cannot distinguish between GPS and VLBI measurements of OTLD, and that at the global scale, present ocean tide models are accurate to within the current measurement noise of these techniques. Copyright Springer Numéro de notice : A2007-125 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-006-0118-9 En ligne : https://doi.org/10.1007/s00190-006-0118-9 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28488 [article]

Exemplaires(2)

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