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GPS code phase variations (CPV) for GNSS receiver antennas and their effect on geodetic parameters and ambiguity resolution / Tobias Kersten in Journal of geodesy, vol 91 n° 6 (June 2017)  

Public [article]  inJournal of geodesy > vol 91 n° 6 (June 2017) . - pp 579 - 596 Titre : GPS code phase variations (CPV) for GNSS receiver antennas and their effect on geodetic parameters and ambiguity resolution Type de document : Article/Communication Auteurs : Tobias Kersten, Auteur ; Steffen Schön, Auteur Année de publication : 2017 Article en page(s) : pp 579 - 596 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] antenne GNSS [Termes IGN] centre de phase [Termes IGN] erreur de mesure [Termes IGN] phase GNSS [Termes IGN] résolution d'ambiguïté [Vedettes matières IGN] Traitement de données GNSS Résumé : (Auteur) Precise navigation and geodetic coordinate determination rely on accurate GNSS signal reception. Thus, the receiver antenna properties play a crucial role in the GNSS error budget. For carrier phase observations, a spherical radiation pattern represents an ideal receiver antenna behaviour. Deviations are known as phase centre corrections. Due to synergy of carrier and code phase, similar effects on the code exist named code phase variations (CPV). They are mainly attributed to electromagnetic interactions of several active and passive elements of the receiver antenna. Consequently, a calibration and estimation strategy is necessary to determine the shape and magnitudes of the CPV. Such a concept was proposed, implemented and tested at the Institut für Erdmessung. The applied methodology and the obtained results are reported and discussed in this paper. We show that the azimuthal and elevation-dependent CPV can reach maximum magnitudes of 0.2–0.3 m for geodetic antennas and up to maximum values of 1.8 m for small navigation antennas. The obtained values are validated by dedicated tests in the observation and coordinate domain. As a result, CPV are identified to be antenna- related properties that are independent from location and time of calibration. Even for geodetic antennas when forming linear combinations the CPV effect can be amplified to values of 0.4–0.6 m. Thus, a significant fractional of the Melbourne–Wübbena linear combination. A case study highlights that incorrect ambiguity resolution can occur due to neglecting CPV corrections. The impact on the coordinates which may reach up to the dm level is illustrated. Numéro de notice : A2017-285 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-016-0984-8 En ligne : http://dx.doi.org/10.1007/s00190-016-0984-8 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=85318 [article]

Determination of a high spatial resolution geopotential model using atomic clock comparisons / Guillaume Lion in Journal of geodesy, vol 91 n° 6 (June 2017)    

Public [article]  inJournal of geodesy > vol 91 n° 6 (June 2017) . - pp 597 - 611 Titre : Determination of a high spatial resolution geopotential model using atomic clock comparisons Type de document : Article/Communication Auteurs : Guillaume Lion , Auteur ; Isabelle Panet , Auteur ; Peter Wolf, Auteur ; C. Guerlin, Auteur ; Sébastien Bize, Auteur ; Pacôme Delva, Auteur Année de publication : 2017 Projets : FIRST-TF / , AdOC / , ITOC / Article en page(s) : pp 597 - 611 Note générale : Bibliographie We gratefully acknowledge financial support from Labex FIRST-TF, ERC AdOC(Grant No. 617553 and EMRP ITOC (EMRP is jointly funded by the EMRP participating countries within EURAMET and the European Union). Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] Alpes (France) [Termes IGN] champ de pesanteur local [Termes IGN] collocation par moindres carrés [Termes IGN] covariance [Termes IGN] erreur systématique [Termes IGN] horloge atomique [Termes IGN] horlogerie [Termes IGN] levé gravimétrique [Termes IGN] Massif central (France) [Termes IGN] modèle de géopotentiel local [Termes IGN] qualité des données Résumé : (Auteur) Recent technological advances in optical atomic clocks are opening new perspectives for the direct determination of geopotential differences between any two points at a centimeter-level accuracy in geoid height. However, so far detailed quantitative estimates of the possible improvement in geoid determination when adding such clock measurements to existing data are lacking. We present a first step in that direction with the aim and hope of triggering further work and efforts in this emerging field of chronometric geodesy and geophysics. We specifically focus on evaluating the contribution of this new kind of direct measurements in determining the geopotential at high spatial resolution (≈10 km). We studied two test areas, both located in France and corresponding to a middle (Massif Central) and high (Alps) mountainous terrain. These regions are interesting because the gravitational field strength varies greatly from place to place at high spatial resolution due to the complex topography. Our method consists in first generating a synthetic high-resolution geopotential map, then drawing synthetic measurement data (gravimetry and clock data) from it, and finally reconstructing the geopotential map from that data using least squares collocation. The quality of the reconstructed map is then assessed by comparing it to the original one used to generate the data. We show that adding only a few clock data points (less than 1% of the gravimetry data) reduces the bias significantly and improves the standard deviation by a factor 3. The effect of the data coverage and data quality on the results is investigated, and the trade-off between the measurement noise level and the number of data points is discussed. Numéro de notice : A2017-286 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-016-0986-6 Date de publication en ligne : 11/01/2017 En ligne : http://dx.doi.org/10.1007/s00190-016-0986-6 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=85319 [article]

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GPS coordinate time series measurements in Ontario and Quebec, Canada / Hadis Samadi Alinia in Journal of geodesy, vol 91 n° 6 (June 2017)  

Public [article]  inJournal of geodesy > vol 91 n° 6 (June 2017) . - pp 653 - 683 Titre : GPS coordinate time series measurements in Ontario and Quebec, Canada Type de document : Article/Communication Auteurs : Hadis Samadi Alinia, Auteur ; Christy F. Tiampo, Auteur ; Thomas S. James, Auteur Année de publication : 2017 Article en page(s) : pp 653 - 683 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes IGN] Bernese [Termes IGN] bruit (théorie du signal) [Termes IGN] bruit blanc [Termes IGN] champ de vitesse [Termes IGN] coordonnées GPS [Termes IGN] épaisseur de la glace [Termes IGN] Hudson, baie d' [Termes IGN] méthode du maximum de vraisemblance (estimation) [Termes IGN] Ontario (Canada) [Termes IGN] Québec (Canada) [Termes IGN] série temporelle [Termes IGN] station permanente Résumé : (Auteur) New precise network solutions for continuous GPS (cGPS) stations distributed in eastern Ontario and western Québec provide constraints on the regional three-dimensional crustal velocity field. Five years of continuous observations at fourteen cGPS sites were analyzed using Bernese GPS processing software. Several different sub-networks were chosen from these stations, and the data were processed and compared to in order to select the optimal configuration to accurately estimate the vertical and horizontal station velocities and minimize the associated errors. The coordinate time series were then compared to the crustal motions from global solutions and the optimized solution is presented here. A noise analysis model with power-law and white noise, which best describes the noise characteristics of all three components, was employed for the GPS time series analysis. The linear trend, associated uncertainties, and the spectral index of the power-law noise were calculated using a maximum likelihood estimation approach. The residual horizontal velocities, after removal of rigid plate motion, have a magnitude consistent with expected glacial isostatic adjustment (GIA). The vertical velocities increase from subsidence of almost 1.9 mm/year south of the Great Lakes to uplift near Hudson Bay, where the highest rate is approximately 10.9 mm/year. The residual horizontal velocities range from approximately 0.5 mm/year, oriented south–southeastward, at the Great Lakes to nearly 1.5 mm/year directed toward the interior of Hudson Bay at stations adjacent to its shoreline. Here, the velocity uncertainties are estimated at less than 0.6 mm/year for the horizontal component and 1.1 mm/year for the vertical component. A comparison between the observed velocities and GIA model predictions, for a limited range of Earth models, shows a better fit to the observations for the Earth model with the smallest upper mantle viscosity and the largest lower mantle viscosity. However, the pattern of horizontal deformation is not well explained in the north, along Hudson Bay, suggesting that revisions to the ice thickness history are needed to improve the fit to observations. Numéro de notice : A2017-287 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-016-0987-5 En ligne : http://doi.org/10.1007/s00190-016-0987-5 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=85320 [article]

Multivariate analysis of GPS position time series of JPL second reprocessing campaign / Ali Reza Amiri-Simkooei in Journal of geodesy, vol 91 n° 6 (June 2017)  

Public [article]  inJournal of geodesy > vol 91 n° 6 (June 2017) . - pp 685 - 704 Titre : Multivariate analysis of GPS position time series of JPL second reprocessing campaign Type de document : Article/Communication Auteurs : Ali Reza Amiri-Simkooei, Auteur ; T.H. Mohammadloo, Auteur ; Donald F. Argus, Auteur Année de publication : 2017 Article en page(s) : pp 685 - 704 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] analyse multivariée [Termes IGN] bruit blanc [Termes IGN] bruit rose [Termes IGN] campagne GPS [Termes IGN] centre de phase [Termes IGN] coordonnées GPS [Termes IGN] série temporelle [Termes IGN] terme de Chandler [Vedettes matières IGN] Traitement de données GNSS Résumé : (Auteur) The second reprocessing of all GPS data gathered by the Analysis Centers of IGS was conducted in late 2013 using the latest models and methodologies. Improved models of antenna phase center variations and solar radiation pressure in JPL’s reanalysis are expected to significantly reduce errors. In an earlier work, JPL estimates of position time series, termed first reprocessing campaign, were examined in terms of their spatial and temporal correlation, power spectra, and draconitic signal. Similar analyses are applied to GPS time series at 89 and 66 sites of the second reanalysis with the time span of 7 and 21 years, respectively, to study possible improvements. Our results indicate that the spatial correlations are reduced on average by a factor of 1.25. While the white and flicker noise amplitudes for all components are reduced by 29–56 %, the random walk amplitude is enlarged. The white, flicker, and random walk noise amount to rate errors of, respectively, 0.01, 0.12, and 0.09 mm/yr in the horizontal and 0.04, 0.41 and 0.3 mm/yr in the vertical. Signals reported previously, such as those with periods of 13.63, 14.76, 5.5, and 351.4 / n for n=1,2,…,8 days, are identified in multivariate spectra of both data sets. The oscillation of the draconitic signal is reduced by factors of 1.87, 1.87, and 1.68 in the east, north and up components, respectively. Two other signals with Chandlerian period and a period of 380 days can also be detected. Numéro de notice : A2017-297 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-016-0991-9 En ligne : http://dx.doi.org/10.1007/s00190-016-0991-9 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=85328 [article]