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A geometry-free and ionosphere-free multipath mitigation method for BDS three-frequency ambiguity resolution / Dezhong Chen in Journal of geodesy, vol 90 n° 8 (August 2016)  

Public [article]  inJournal of geodesy > vol 90 n° 8 (August 2016) . - pp 703 – 714 Titre : A geometry-free and ionosphere-free multipath mitigation method for BDS three-frequency ambiguity resolution Type de document : Article/Communication Auteurs : Dezhong Chen, Auteur ; Shirong Ye, Auteur ; Jingchao Xia, Auteur ; et al., Auteur Année de publication : 2016 Article en page(s) : pp 703 – 714 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] correction du trajet multiple [Termes IGN] erreur systématique [Termes IGN] positionnement par BeiDou [Termes IGN] résolution d'ambiguïté [Termes IGN] signal BeiDou [Termes IGN] station de référence [Termes IGN] trajet multiple [Termes IGN] troposphère Résumé : (auteur) Because of the unknown systematic errors and special satellite constellations in the Beidou system (BDS), it is difficult to quickly and reliably determine the ambiguity over long-range baselines in continuously operating reference station (CORS) network. This study seeks to improve the effectiveness and reliability of BDS ambiguity resolution (AR) by combining the geometry-free and ionosphere-free (GFIF) combination and multipath mitigation algorithm. The GFIF combination composed with three-frequency signals is free of distance-dependent errors and can be used to determine the narrow lane ambiguity. The presence of multipath errors means that not all ambiguities can be correctly achieved by rounding the averaged GFIF ambiguity series. A multipath model of the single-differenced (SD) GFIF combination from the previous period is established for each individual satellite. This model is subtracted from the SD GFIF combination for the current day to remove the effects of multipath errors. Using three triangle networks with lengths of approximately 120, 80 and 50 km, we demonstrate that the proposed method improves the AR performance. The ambiguity averaged first fixing time is typically less than 1801 s for inclined geosynchronous orbit (IGSO) and medium earth orbit (MEO) satellites and less than 2007 s for the ∼42∘ elevation geostationary earth orbit (GEO) C02 satellite. However, it is more time consuming for the low-elevation GEO satellites C04 (∼18∘) and C05 (∼28∘). Kalman filtering is used to estimate the troposphere delays and two unfixed ambiguities by employing the ionosphere-free observations of all ambiguity-fixed/unfixed satellites. The experimental results show that only tens of seconds are required for AR in around 90 km baselines. Numéro de notice : A2016-503 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-016-0903-z En ligne : http://dx.doi.org/10.1007/s00190-016-0903-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81527 [article]

A new computerized ionosphere tomography model using the mapping function and an application to the study of seismic-ionosphere disturbance / Jian Kong in Journal of geodesy, vol 90 n° 8 (August 2016)  

Public [article]  inJournal of geodesy > vol 90 n° 8 (August 2016) . - pp 741 – 755 Titre : A new computerized ionosphere tomography model using the mapping function and an application to the study of seismic-ionosphere disturbance Type de document : Article/Communication Auteurs : Jian Kong, Auteur ; Yi Bin Yao, Auteur ; Lei Liu, Auteur ; et al., Auteur Année de publication : 2016 Article en page(s) : pp 741 – 755 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] altération [Termes IGN] correction troposphérique [Termes IGN] International Reference Ionosphere [Termes IGN] Japon [Termes IGN] séisme [Termes IGN] teneur totale en électrons [Termes IGN] tomographie [Termes IGN] troposphère Résumé : (auteur) A new algorithm for ionosphere tomography using the mapping function is proposed in this paper. First, the new solution splits the integration process into four layers along the observation ray, and then, the single-layer model (SLM) is applied to each integration part using a mapping function. Next, the model parameters are estimated layer by layer with the Kalman filtering method by introducing the scale factor (SF) γ to solve the ill-posed problem. Finally, the inversed images of different layers are combined into the final CIT image. We utilized simulated data from 23 IGS GPS stations around Europe to verify the estimation accuracy of the new algorithm; the results show that the new CIT model has better accuracy than the SLM in dense data areas and the CIT residuals are more closely grouped. The stability of the new algorithm is discussed by analyzing model accuracy under different error levels (the max errors are 5TECU, 10TECU, 15TECU, respectively). In addition, the key preset parameter, SFγ, which is given by the International Reference Ionosphere model (IRI2012). The experiment is designed to test the sensitivity of the new algorithm to SF variations. The results show that the IRI2012 is capable of providing initial SF values. Also in this paper, the seismic-ionosphere disturbance (SID) of the 2011 Japan earthquake is studied using the new CIT algorithm. Combined with the TEC time sequence of Sat.15, we find that the SID occurrence time and reaction area are highly related to the main shock time and epicenter. According to CIT images, there is a clear vertical electron density upward movement (from the 150-km layer to the 450-km layer) during this SID event; however, the peak value areas in the different layers were different, which means that the horizontal movement velocity is not consistent among the layers. The potential physical triggering mechanism is also discussed in this paper. Compared with the SLM, the RMS of the new CIT model is improved by 16.78%, while the CIT model could provide the three-dimensional variation in the ionosphere. Numéro de notice : A2016-504 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-016-0906-9 En ligne : http://dx.doi.org/10.1007/s00190-016-0906-9 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81528 [article]

Estimation of satellite antenna phase center offsets for Galileo / Peter Steigenberger in Journal of geodesy, vol 90 n° 8 (August 2016)  

Public [article]  inJournal of geodesy > vol 90 n° 8 (August 2016) . - Pages 773 - 785 Titre : Estimation of satellite antenna phase center offsets for Galileo Type de document : Article/Communication Auteurs : Peter Steigenberger, Auteur ; M. Fritsche, Auteur ; Rolf Dach, Auteur ; et al., Auteur Année de publication : 2016 Article en page(s) : Pages 773 - 785 Note générale : bibliograohie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] antenne Galileo [Termes IGN] centre de phase [Termes IGN] compensation [Termes IGN] orbitographie [Termes IGN] positionnement par GNSS [Termes IGN] signal Galileo [Termes IGN] soleil (étoile) Résumé : (auteur) Satellite antenna phase center offsets for the Galileo In-Orbit Validation (IOV) and Full Operational Capability (FOC) satellites are estimated by two different analysis centers based on tracking data of a global GNSS network. The mean x- and y-offsets could be determined with a precision of a few centimeters. However, daily estimates of the x-offsets of the IOV satellites show pronounced systematic effects with a peak-to-peak amplitude of up to 70 cm that depend on the orbit model and the elevation of the Sun above the orbital plane. For the IOV y-offsets, no dependence on the orbit model exists but the scatter strongly depends on the elevation of the Sun above the orbital plane. In general, these systematic effects are significantly smaller for the FOC satellites. The z-offsets of the two analysis centers agree within the 10–15 cm level, and the time series do not show systematic effects. The application of an averaged Galileo satellite antenna model obtained from the two solutions results in a reduction of orbit day boundary discontinuities by up to one third—even if an independent software package is used. Numéro de notice : A2016-505 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-016-0909-6 En ligne : http://dx.doi.org/10.1007/s00190-016-0909-6 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81529 [article]

Ground-based phase wind-up and its application in yaw angle determination / M. Cai in Journal of geodesy, vol 90 n° 8 (August 2016)  

Public [article]  inJournal of geodesy > vol 90 n° 8 (August 2016) . - pp 757 – 772 Titre : Ground-based phase wind-up and its application in yaw angle determination Type de document : Article/Communication Auteurs : M. Cai, Auteur ; W. Chen, Auteur ; D. Dong, Auteur ; et al., Auteur Année de publication : 2016 Article en page(s) : pp 757 – 772 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] antenne GNSS [Termes IGN] positionnement cinématique en temps réel [Termes IGN] positionnement ponctuel précis [Termes IGN] précision du positionnement [Termes IGN] récepteur Résumé : (auteur) Ground-based phase wind-up effect (GPWU) is caused by the rotation of receiving antenna. It had been studied and applied in rapidly rotation platforms, such as sounding rocket, guided missile and deep space exploration. In Global Navigation Satellite System high accuracy positioning applications, however, most studies treated it as an error source and focused on eliminating this effect in Precision Point Positioning and Real Time Kinematic (RTK) positioning. The GPWU effect is also sensitive to the rotational status of the antenna, in particular the yaw angle variations. In this paper we explore the feasibility of yaw angle determination of relatively slow rotation platforms based on the GPWU effect. We use the geometry-free carrier phase observations from a RTK base and a moving station receivers to estimate the cumulative yaw angle of the moving platform. Several experiments, including rotating platform tests, vehicle and shipborne tests were carried out. The cumulative errors of rotating platform tests are under 0.38∘, indicating good long-term accuracy of the GPWU determined yaw angle. But the RMS are in a range of 11.98∘and 17.39∘, indicating the errors, such as multipath effect, are not negligible and should be further investigated. The RMS of vehicle and shipborne tests using a base station of 9–11 km are 24.77∘ and 23.66∘. In order to evaluate the influence of the differential ionospheric delay, another vehicle test was carried out using a base station located less than 1 km to the vehicle. The RMS reduces to 15.11∘, which gains 39.00 % improvement than before, and demonstrates that the differential ionospheric delay even from a few kilometers long baseline still cannot be neglected. These tests validate the feasibility of GPWU for real-time yaw angle determination. Since this method is able to determine the yaw angle with a minimum one satellite, such a unique feature provides potential applications for attitude determination in the environment with poor sky visibility. Numéro de notice : A2016-506 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-016-0908-7 Date de publication en ligne : 10/05/2016 En ligne : https://doi.org/10.1007/s00190-016-0908-7 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81530 [article]