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PPP-RTK: from common-view to all-in-view GNSS networks / Baocheng Zhang in Journal of geodesy, vol 96 n° 12 (December 2022)
[article]
Titre : PPP-RTK: from common-view to all-in-view GNSS networks Type de document : Article/Communication Auteurs : Baocheng Zhang, Auteur ; Pengyu Hou, Auteur ; Robert Odolinski, Auteur Année de publication : 2022 Article en page(s) : n° 102 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] ambiguïté entière
[Termes IGN] erreur de phase
[Termes IGN] positionnement cinématique en temps réel
[Termes IGN] positionnement par GNSS
[Termes IGN] positionnement ponctuel précis
[Termes IGN] précision du positionnement
[Termes IGN] résolution d'ambiguïtéRésumé : (auteur) Integer ambiguity resolution-enabled precise point positioning (PPP), otherwise known as PPP real-time kinematic (PPP-RTK), recovers the integer nature of ambiguities at a user receiver by delivering the satellite phase biases (SPBs) estimated from a global navigation satellite system (GNSS) network. Due to the rank-deficiency existing between the satellite and receiver phase biases and the ambiguities, the formulation of PPP-RTK model needs to choose a set of unknown parameters as the datum (or the S-basis). Despite the fact that there are non-unique datum choices, one prefers a PPP-RTK model where the estimable SPBs contain a minimum number of datum ambiguities. We will show that otherwise there will be discontinuities occurring in datum ambiguities that will lead to unfavorable jumps in the estimated SPBs and frequent ambiguity resolution (re-)initialization on the user side. For this to occur one normally restricts to a common-view (CV) network, where the satellites are commonly visible to all receivers involved, and constructs the PPP-RTK model by choosing the phase biases and the ambiguities, pertaining to one receiver, as the datum. In doing so the CV model is capable of estimating the SPBs with each bias containing only one datum ambiguity. In this contribution we extend the CV model to an all-in-view (AV) network case where the satellites tracked can differ across receivers, but at least one satellite is commonly visible; this is practical as the network size is normally consisting of baseline lengths of several hundreds of kilometers. Contrary to the CV model, in the AV model the phase biases and the ambiguities pertaining to one satellite is selected as the datum, such that, the number of datum ambiguities entering into the estimable SPBs is always at the minimum as the SPBs are formulated in a between-satellite single-differenced form. The benefits with AV model are that it relieves the stringent satellite visibility as required by the CV model and, at the same time, reduces to the best possible extent any jumps in the estimated SPBs as well as the necessary ambiguity resolution (re-)initialization on the user side. Experiments conducted using multi-GNSS data collected in both CV and AV networks verify that the AV model always outperforms the CV one, as measured by both the time-to-first-fix as well as the positioning accuracy when compared to very precise benchmark coordinates. Numéro de notice : A2022-899 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-022-01693-y Date de publication en ligne : 13/12/2022 En ligne : https://doi.org/10.1007/s00190-022-01693-y Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102257
in Journal of geodesy > vol 96 n° 12 (December 2022) . - n° 102[article]Improving accuracy of local geoid model using machine learning approaches and residuals of GPS/levelling geoid height / Mosbeh R. Kaloop in Survey review, vol 54 n° 387 (November 2022)
[article]
Titre : Improving accuracy of local geoid model using machine learning approaches and residuals of GPS/levelling geoid height Type de document : Article/Communication Auteurs : Mosbeh R. Kaloop, Auteur ; Samui Pijush, Auteur ; Mostafa Rabah, Auteur ; et al., Auteur Année de publication : 2022 Article en page(s) : pp 505 - 518 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] apprentissage automatique
[Termes IGN] géoïde gravimétrique
[Termes IGN] géoïde local
[Termes IGN] Koweit
[Termes IGN] MNS SRTM
[Termes IGN] modèle de géopotentiel
[Termes IGN] nivellement avec assistance GPS
[Termes IGN] processus gaussien
[Termes IGN] régression
[Termes IGN] régression multivariée par spline adaptative
[Termes IGN] résiduRésumé : (auteur) This study aims to use GPS/Levelling data and machine learning techniques (MLs) to model a high precision local geoid for Kuwait. To improve the accuracy of a local geoid the global geopotential model and local terrain effect should be incorporated. The geoid model was improved based on the modelling of geoid residuals using three MLs. Minimax Probability Machine Regression (MPMR), Gaussian Process Regression (GPR), and Multivariate Adaptive Regression Splines (MARS) MLs were developed for modelling the calculated geoid residuals. The results show that the accuracy of the three MLs was improved compared to previous studies, and the accuracy of the GPR model was better than the other models. The standard deviations of Kuwait geoid undulation determined by GPS/Levelling, gravimetric, and developed GPR models were 1.377, 1.375, 1.375 m, respectively. Thus, the developed GPR model has successfully predicted an accurate geoid height of Kuwait with maximum variation approaches ±0.02 m. Numéro de notice : A2022-829 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/00396265.2021.1970918 Date de publication en ligne : 27/08/2021 En ligne : https://doi.org/10.1080/00396265.2021.1970918 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102013
in Survey review > vol 54 n° 387 (November 2022) . - pp 505 - 518[article]A new partial ambiguity resolution method based on modified solution separation and GNSS epoch-differencing / Yang Jiang in Journal of geodesy, vol 96 n° 11 (November 2022)
[article]
Titre : A new partial ambiguity resolution method based on modified solution separation and GNSS epoch-differencing Type de document : Article/Communication Auteurs : Yang Jiang, Auteur ; Wei Ding, Auteur ; Yuting Gao, Auteur ; et al., Auteur Année de publication : 2022 Article en page(s) : n° 88 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] compensation Lambda
[Termes IGN] erreur de positionnement
[Termes IGN] phase
[Termes IGN] positionnement cinématique en temps réel
[Termes IGN] récepteur GNSS
[Termes IGN] résolution d'ambiguïtéRésumé : (auteur) Partial ambiguity resolution has been widely used in real-time kinematic (RTK) positioning to provide accurate and continuous centimeter-level positioning solutions. Current PAR methods are concerned with the exclusion of ambiguities that otherwise would result in low rate of full ambiguity resolution (FAR). With an assumption of unbiased ambiguities, the traditional PAR methods use the ambiguity-domain test statistics and probability-domain quantitative evaluation to select and validate the ambiguity subset. Consequentially, they would degrade the performance using low-cost devices in challenging environments where ambiguity biases exist, causing high probabilities of false alarm and missed detection of PAR and subsequently poor availability and accuracy of PAR. To deal with this issue, in this study, we propose a new PAR method for application in challenging environments. The proposed method consists of two major steps. First, a global navigation satellite system epoch-differencing (GED) algorithm is applied to derive a prior ambiguity solution. Second, we use a modified solution separation (SS) method with the prior ambiguity solution as an external input to obtain more accurate ambiguity test statistics. Based on a dynamic road test under environments with significant signal blockages, the performance of the proposed method is analyzed by using a low-cost GNSS receiver. The proposed method provides ambiguity test statistics with higher accuracy and can achieve 73.19% and 50.55% improvement in the accuracy and availability of the fixed solution, compared with the traditional PAR methods. Besides, the RMS of positioning errors with fixed solution are 1.03 cm, 0.70 cm, and 1.50 cm for the proposed PAR method in the east, north, and upward directions, respectively, which are 1.06 cm, 0.72 cm, and 1.35 cm for SS-based PAR, and 5.29 cm, 0.86 cm, and 5.56 cm for ILS-based PAR. The proposed PAR method achieves 90.36% fixed epochs, versus 79.06%, and 88.28%, for ILS-based PAR and SS-based PAR, respectively. Numéro de notice : A2022-810 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-022-01674-1 Date de publication en ligne : 02/11/2022 En ligne : https://doi.org/10.1007/s00190-022-01674-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101967
in Journal of geodesy > vol 96 n° 11 (November 2022) . - n° 88[article]On the relation of GNSS phase center offsets and the terrestrial reference frame scale: a semi-analytical analysis / Oliver Montenbruck in Journal of geodesy, vol 96 n° 11 (November 2022)
[article]
Titre : On the relation of GNSS phase center offsets and the terrestrial reference frame scale: a semi-analytical analysis Type de document : Article/Communication Auteurs : Oliver Montenbruck, Auteur ; Peter Steigenberger, Auteur ; Arturo Villiger, Auteur ; Paul Rebischung , Auteur Année de publication : 2022 Article en page(s) : n° 90 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] antenne GNSS
[Termes IGN] centre de phase
[Termes IGN] décalage d'horloge
[Termes IGN] hauteur (coordonnée)
[Termes IGN] International Terrestrial Reference Frame
[Termes IGN] orbitographie
[Termes IGN] phase
[Termes IGN] positionnement par GNSS
[Termes IGN] retard troposphérique zénithal
[Termes IGN] station GNSSRésumé : (auteur) Phase center offsets (PCOs) of global navigation satellites systems (GNSS) transmit antennas along the boresight axis introduce line-of-sight-dependent range changes in the modeling of GNSS observations that are strongly correlated with the estimated station heights. As a consequence, changes in the adopted PCOs impact the scale of GNSS-based realizations of the terrestrial reference frame (TRF). Vice versa, changes in the adopted TRF scale require corrections to the GNSS transmit antenna PCOs for consistent observation modeling. Early studies have determined an approximate value of α=−0.050 for the ratio of station height changes and satellite PCO changes in GPS orbit determination and phase center adjustment. However, this is mainly an empirical value and limited information is available on the actual PCO-scale relation and how it is influenced by other factors. In view of the recurring need to adjust the IGS antenna models to new ITRF scales, a semi-analytical model is developed to determine values of α for the four current GNSSs from first principles without a need for actual network data processing. Given the close coupling of satellite boresight angle and station zenith angle, satellite PCO changes are essentially compensated by a combination of station height, zenith troposphere delay, and receiver clock offset. As such, the value of α depends not only on the orbital altitude of the considered GNSS but also on the elevation-dependent distribution of GNSS observations and their weighting, as well as the elevation mask angle and the tropospheric mapping function. Based on the model, representative values of αGPS=−0.051, αGLO=−0.055, αGAL=−0.041, and αBDS-3=−0.046 are derived for GPS, GLONASS, Galileo, and BeiDou-3 at a 10∘ elevation cutoff angle. These values may vary by Δα≈0.003 depending on the specific model assumptions and data processing parameters in a precise orbit determination or precise point positioning. Likewise changes of about ±0.003 can be observed when varying the cutoff angle between 5∘ and 15∘. Numéro de notice : A2022-836 Affiliation des auteurs : UMR IPGP-Géod+Ext (2020- ) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-022-01678-x Date de publication en ligne : 09/11/2022 En ligne : https://doi.org/10.1007/s00190-022-01678-x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102033
in Journal of geodesy > vol 96 n° 11 (November 2022) . - n° 90[article]Testing of new ionospheric models along the meridian 110° E over the Northern Hemisphere / Olga Maltseva in Geodesy and Geodynamics, vol 13 n° 6 (November 2022)
[article]
Titre : Testing of new ionospheric models along the meridian 110° E over the Northern Hemisphere Type de document : Article/Communication Auteurs : Olga Maltseva, Auteur ; Artem Kharakhashyan, Auteur ; Tatyana Nikitenko, Auteur Année de publication : 2022 Article en page(s) : pp 544 - 553 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] hémisphère Nord
[Termes IGN] méridien
[Termes IGN] modèle ionosphérique
[Termes IGN] teneur totale en électronsRésumé : (auteur) Despite the continuous improvement of the widely used empirical model international reference ionosphere (IRI), the recently appeared new models must be tested worldwide. Testing along the meridians has the advantage of dealing with the latitudinal dependent parameters. This paper uses new models of parameters foF2 (critical frequency), TEC (total electron content), and τ (equivalent slab thickness of the ionosphere), which are of great importance for evaluating the effects of space weather. IRI-Plas, NNT2F2, and NTSM models were tested using data from 6 ionosondes located along the meridian 110° E in March 2012. It is shown that the IRI-Plas model provides the closest values to experiment with respect to τ, while the NTSM model provides a rather limited reflection of the latitude dependence. Analyses of foF2(NNT2F2) have shown that, the NNT2F2 model provides good conformity with experimental values in this area, but it is very dependent on the TEC processing method. The latitudinal dependences of foF2 obtained with TEC and polynomial dependence τ(Appr) showed the presence of positive deviations from medians not only during disturbances but also quiet periods, longitudinally at the meridian. Numéro de notice : A2022-763 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1016/j.geog.2022.06.002 Date de publication en ligne : 02/07/2022 En ligne : https://doi.org/10.1016/j.geog.2022.06.002 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101783
in Geodesy and Geodynamics > vol 13 n° 6 (November 2022) . - pp 544 - 553[article]The employment of quasi-hexagonal grids in spherical harmonic analysis and synthesis for the earth's gravity field / Xingxing Li in Journal of geodesy, vol 96 n° 11 (November 2022)PermalinkUnification of GNSS CORS coordinates in Thailand / Somchai Kriengkraiwasin in Survey review, vol 54 n° 387 (November 2022)PermalinkUsing converted WW1 Army Grid Referencing Systems to identify locations where Australian soldiers fell Europe / Rodney Deakin in International journal of cartography, vol 8 n° 3 (November 2022)PermalinkChallenges and limitations of earthquake-induced building damage mapping techniques using remote sensing images : A systematic review / Sahar S. Matin in Geocarto international, Vol 37 n° 21 ([01/10/2022])PermalinkDetermination of local geometric geoid model for Kuwait / Ahmed Zaki in Journal of applied geodesy, vol 16 n° 4 (October 2022)PermalinkA determination of the motion based on GNSS observations between 2000 and 2021 using the IGS points in the polar regions / Atinç Pirti in Geodesy and cartography, vol 48 n° 3 (October 2022)PermalinkGNSS best integer equivariant estimation combining with integer least squares estimation: an integrated ambiguity resolution method with optimal integer aperture test / Liye Ma in GPS solutions, vol 26 n° 4 (October 2022)PermalinkInvestigating the efficiency of deep learning methods in estimating GPS geodetic velocity / Omid Memarian Sorkhabi in Earth and space science, vol 9 n° 10 (October 2022)PermalinkModelling and prediction of GNSS time series using GBDT, LSTM and SVM machine learning approaches / Wenzong Gao in Journal of geodesy, vol 96 n° 10 (October 2022)PermalinkMulti‑constellation GNSS interferometric reflectometry for the correction of long-term snow height retrieval on sloping topography / Wei Zhou in GPS solutions, vol 26 n° 4 (October 2022)Permalink