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An accurate train positioning method using tightly-coupled GPS + BDS PPP/IMU strategy / Wei Jiang in GPS solutions, vol 26 n° 3 (July 2022)  

Public [article]  inGPS solutions > vol 26 n° 3 (July 2022) . - n° 67 Titre : An accurate train positioning method using tightly-coupled GPS + BDS PPP/IMU strategy Type de document : Article/Communication Auteurs : Wei Jiang, Auteur ; Mengyang Liu, Auteur ; Baigen Cai, Auteur Année de publication : 2022 Article en page(s) : n° 67 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] ambiguïté entière [Termes IGN] Chine [Termes IGN] filtre de Kalman [Termes IGN] phase [Termes IGN] positionnement inertiel [Termes IGN] positionnement par BeiDou [Termes IGN] positionnement par GPS [Termes IGN] positionnement ponctuel précis [Termes IGN] signal GPS [Termes IGN] simple différence [Termes IGN] train Résumé : (auteur) A new GNSS/IMU tightly coupled positioning system is introduced to train positioning. To fulfil a train control system’s aim of reducing the need to install trackside equipment, the GNSS precise point positioning (PPP) method is applied in place of the conventional differential GNSS method. As the railway environment has the character of long operational mileage and complex GNSS measurement conditions, the GPS and BDS constellations are combined with measurement processing to improve the system’s continuity and stability. Ultra-rapid GNSS orbit and clock product is used for real-time PPP. The GNSS-PPP and IMU are tightly coupled using an Extended Kalman filter with single-differenced ionospheric-free GPS + BDS carrier phase and pseudorange observations. The carrier phase ambiguities are estimated as “float” values every epoch to reduce the impact of GNSS signal loss-of-lock and cycle slips. A train experiment was conducted on the Qinghai-Tibet Railway to evaluate system performance. The results show that the proposed system has a better performance than the conventional methods, including GPS + BDS PPP, LC GPS + BDS PPP/IMU and TC GPS PPP/IMU, with 52.1%, 49.4% and 52.1%, respectively. The tightly-coupled GPS + BDS PPP/IMU system under conditions of partly blocked GNSS coverage was evaluated to evaluate the system's continuity. It was confirmed that the proposed system had more stable positioning results and higher positioning accuracy. Numéro de notice : A2022-361 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10291-022-01250-2 Date de publication en ligne : 08/04/2022 En ligne : https://doi.org/10.1007/s10291-022-01250-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=100580 [article]

Generating GPS decoupled clock products for precise point positioning with ambiguity resolution / Shuai Liu in Journal of geodesy, vol 96 n° 1 (January 2022)  

Public [article]  inJournal of geodesy > vol 96 n° 1 (January 2022) . - n° 6 Titre : Generating GPS decoupled clock products for precise point positioning with ambiguity resolution Type de document : Article/Communication Auteurs : Shuai Liu, Auteur ; Yunbin Yan, Auteur Année de publication : 2022 Article en page(s) : n° 6 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] erreur de phase [Termes IGN] horloge du récepteur [Termes IGN] modèle stochastique [Termes IGN] onde porteuse [Termes IGN] positionnement cinématique [Termes IGN] positionnement ponctuel précis [Termes IGN] résolution d'ambiguïté Résumé : (auteur) Carrier-phase integer ambiguity resolution (AR) is the key to improving the positioning accuracy of precise point positioning (PPP). However, in theory, the integer property of ambiguities in PPP are destroyed due to the absorption of phase biases. In this study, we analyzed a set of clock products consisting of a code clock, phase clock and wide-lane (WL) bias based on the decoupled clock (DCK) model, to facilitate PPP AR. The determination of the datum of the receiver clock as well as ambiguity were analyzed in detail to arrive at ways to eliminate rank deficiency. To fix ambiguity at the server end, we propose an approach by rounding directly with “fixing solution” (FS) and “partial ambiguity hold” (PAH) strategies, to increase the fixing rate and avoid the biased solution resulting from ambiguity datum loss. With respect to the International GNSS Service (IGS) legacy clocks, the mean standard deviations (STDs) of the phase clock and code clock were about 0.02 and 1.05 ns respectively, while the WL bias was about 0.12 cycles. Additionally, the convergence speed and stability of the decoupled phase clock are significantly improved compared with the conventional PPP model. Experiments on PPP positioning performance were conducted using 1 week of GPS data from more than 100 stations, considering the IGS weekly solutions as a benchmark. The ambiguity-fixed PPP with decoupled clocks had almost the same accuracy as the integer-recovered clock model, but the average accuracy improvements compared with the conventional PPP model in the east, north, and up components were 59.2, 32.4, and 20.3%, respectively, in the static mode, and approximately 38.0, 26.2, and 19.2% in the kinematic mode. These results demonstrate that users can achieve ambiguity-fixed solutions and obtain high-precision positioning coordinates with our decoupled clock products. Numéro de notice : A2022-093 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-021-01593-7 En ligne : https://doi.org/10.1007/s00190-021-01593-7 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=99517 [article]

Python software to transform GPS SNR wave phases to volumetric water content / Angel Martín in GPS solutions, vol 26 n° 1 (January 2022)  

Public [article]  inGPS solutions > vol 26 n° 1 (January 2022) . - n° 7 Titre : Python software to transform GPS SNR wave phases to volumetric water content Type de document : Article/Communication Auteurs : Angel Martín, Auteur ; Ana Belén Anquela, Auteur ; Sara Ibáñez, Auteur ; et al., Auteur Année de publication : 2022 Article en page(s) : n° 7 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] humidité du sol [Termes IGN] phase [Termes IGN] Python (langage de programmation) [Termes IGN] rapport signal sur bruit [Termes IGN] réflectométrie par GNSS [Termes IGN] signal GPS [Termes IGN] teneur en vapeur d'eau Résumé : (auteur) The global navigation satellite system interferometric reflectometry is often used to extract information about the environment surrounding the antenna. One of the most important applications is soil moisture monitoring. This manuscript presents the main ideas and implementation decisions needed to write the Python code to transform the derived phase of the interferometric GPS waves, obtained from signal-to-noise ratio data continuously observed during a period of several weeks (or months), to volumetric water content. The main goal of the manuscript is to share the software with the scientific community to help users in the GPS-IR computation. Numéro de notice : A2022-004 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s10291-021-01190-3 Date de publication en ligne : 27/10/2021 En ligne : https://doi.org/10.1007/s10291-021-01190-3 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=98919 [article]

Robust GNSS phase tracking using variational bayesian inference / Fabio Fabozzi (2022)  

Public Titre : Robust GNSS phase tracking using variational bayesian inference Titre original : Méthodes de poursuite robuste de phase pour signaux GNSS basées sur l’inférence bayésienne variationnelle Type de document : Thèse/HDR Auteurs : Fabio Fabozzi, Auteur ; Stéphanie Bidon, Auteur Editeur : Toulouse : Université de Toulouse Année de publication : 2022 Importance : 173 p. Format : 21 x 30 cm Note générale : bibliographie Thèse en vue de l'obtention du Doctorat de l'Université de Toulouse, délivré par l'Institut Supérieur de l’Aéronautique et de l’Espace, Spécialité Signal, Image, acoustique et optimisation Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal [Termes IGN] données GNSS [Termes IGN] filtrage bayésien [Termes IGN] filtre de Kalman [Termes IGN] glissement de cycle [Termes IGN] inférence statistique [Termes IGN] méthode robuste [Termes IGN] phase [Termes IGN] rapport signal sur bruit [Termes IGN] récepteur GNSS [Termes IGN] signal GNSS Index. décimale : THESE Thèses et HDR Résumé : (auteur) In this Ph.D. thesis, we are interested in robust carrier-phase estimation by using Variational Bayesian filtering. Carrier-phase measurement has become a fundamental task in many various engineering applications such as precise point positioning in GNSS (Global Navigation Satellite System). Unfortunately, phase measurements obtained by traditional phase tracking techniques may be strongly affected by the presence of ambiguous phase jumps, known as cycle slips. The latter may strongly impact the performance of the considered phase tracking algorithm leading to, in the worst case, a permanent loss of lock (drop-lock) of the signal. A re-acquistion process is then necessary which afflicts the tracking performance. Therefore, to address this problem, we propose a robust nonlinear filter for carrier-phase tracking based on Restricted Variational Bayes inference. This methodology gives us a closed-form and easy-to-implement expression of the estimator. First, the algorithm is developed only for slow phase dynamics (i.e., first-order loop), then, its order is augmented by estimating a state vector formed by the carrier-phase and its derivatives. The performance of the proposed algorithm is compared with that of conventional techniques such as DPLL (Digital Phase Lock Loop) and KF (Kalman Filter)-based DPLL in terms of precision of estimation (root-mean-square error) and cycle slipping occurrence (mean-time-to-first-slip and cycle slip rate). The comparison is firstly conducted using synthetic data, and then, real GNSS data into a GNSS software-defined-radio receiver. Results show that the proposed method outperforms the conventional linear filters, when the signal-to-noise ratio is low. Note de contenu : Introduction 1- Introduction to GNSS 2- DPLL and robust phase tracking techniques 3- RVB algorithm in case of slow dynamics 4- RVB algorithm in case of high-order dynamics 5- RVB algorithm using real GNSS data Conclusion Numéro de notice : 15268 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse française Note de thèse : thèse de Doctorat : Signal, Image, acoustique et optimisation : Toulouse : 2022 Organisme de stage : ISAE-ONERA SCANR DOI : sans En ligne : https://depozit.isae.fr/theses/2022/2022_Fabozzi_Fabio.pdf Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=100684

Ionospheric tomographic common clock model of undifferenced uncombined GNSS measurements / German Olivares-Pulido in Journal of geodesy, vol 95 n° 11 (November 2021)  

Public [article]  inJournal of geodesy > vol 95 n° 11 (November 2021) . - n° 122 Titre : Ionospheric tomographic common clock model of undifferenced uncombined GNSS measurements Type de document : Article/Communication Auteurs : German Olivares-Pulido, Auteur ; Manuel Hernández-Pajares, Auteur ; Haixia Lyu, Auteur ; et al., Auteur Année de publication : 2021 Article en page(s) : n° 122 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] correction ionosphérique [Termes IGN] horloge du satellite [Termes IGN] mesurage par GNSS [Termes IGN] modèle ionosphérique [Termes IGN] phase [Termes IGN] positionnement ponctuel précis [Termes IGN] teneur totale en électrons [Termes IGN] tomographie par GPS [Termes IGN] voxel [Termes IGN] Wide Area Augmentation System [Vedettes matières IGN] Traitement de données GNSS Résumé : (auteur) In this manuscript, we introduce the Ionospheric Tomographic Common Clock (ITCC) model of undifferenced uncombined GNSS measurements. It is intended for improving the Wide Area precise positioning in a consistent and simple way in the multi-GNSS context, and without the need of external precise real-time products. This is the case, in particular, of the satellite clocks, which are estimated at the Wide Area GNSS network Central Processing Facility (CPF) referred to the reference receiver one; and the precise realtime ionospheric corrections, simultaneously computed under a voxel-based tomographic model with satellite clocks and other geodetic unknowns, from the uncombined and undifferenced pseudoranges and carrier phase measurements at the CPF from the Wide Area GNSS network area. The model, without fixing the carrier phase ambiguities for the time being (just constraining them by the simultaneous solution of both ionospheric and geometric components of the uncombined GNSS model), has been successfully applied and assessed against previous precise positioning techniques. This has been done by emulating real-time conditions for Wide Area GPS users during 2018 in Poland. Numéro de notice : A2021-776 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-021-01568-8 Date de publication en ligne : 13/10/2021 En ligne : https://doi.org/10.1007/s00190-021-01568-8 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=98839 [article]

Real-time GNSS precise point positioning using improved robust adaptive Kalman filter / Abdelsatar Elmezayen in Survey review, Vol 53 n° 381 (November 2021)  

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Visualization of GNSS multipath effects and its potential application in IGS data processing / Weiming Tang in Journal of geodesy, vol 95 n° 9 (September 2021)  

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Comparison of polar ionospheric behavior at Arctic and Antarctic regions for improved satellite-based positioning / Arun Kumar Singh in Journal of applied geodesy, vol 15 n° 3 (July 2021)  

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GNSS-based statistical analysis of ionospheric anomalies during typhoon landings in Taiwan/Japan / Hai Peng in IEEE Transactions on geoscience and remote sensing, vol 59 n° 6 (June 2021)  

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Integer phase clock method with single-satellite ambiguity fixing and its application in LEO satellite orbit determination / Kai Shao in Acta Geodaetica et Cartographica Sinica, vol 50 n° 4 ([20/04/2021])  

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Impact of the third frequency GNSS pseudorange and carrier phase observations on rapid PPP convergences / Jiang Guo in GPS solutions, vol 25 n° 2 (April 2021)  

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Multi-GNSS real-time precise clock estimation considering the correction of inter-satellite code biases / Liang Chen in GPS solutions, vol 25 n° 2 (April 2021)  

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A highly adaptable method for GNSS cycle slip detection and repair based on Kalman filter / Xianwen Yu in Survey review, Vol 53 n° 377 (February 2021)  

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High accuracy terrestrial positioning based on time delay and carrier phase using wideband radio signals / Han Dun (2021)  

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Integrated Kalman filter of accurate ranging and tracking with wideband radar / Shaopeng Wei in IEEE Transactions on geoscience and remote sensing, Vol 58 n° 12 (December 2020)  

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