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Improved GPS-based single-frequency orbit determination for the CYGNSS spacecraft using GipsyX / Alex V. Conrad in Navigation : journal of the Institute of navigation, vol 70 n° 1 (Spring 2023)  

Public [article]  inNavigation : journal of the Institute of navigation > vol 70 n° 1 (Spring 2023) . - n° 565 Titre : Improved GPS-based single-frequency orbit determination for the CYGNSS spacecraft using GipsyX Type de document : Article/Communication Auteurs : Alex V. Conrad, Auteur ; Penina Axelrad, Auteur ; Bruce J. Haines, Auteur ; et al., Auteur Année de publication : 2023 Article en page(s) : n° 565 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Techniques orbitales [Termes IGN] données GRACE [Termes IGN] étalonnage d'instrument [Termes IGN] mesurage de phase [Termes IGN] orbite précise [Termes IGN] orbitographie [Termes IGN] récepteur monofréquence [Termes IGN] trajet multiple Résumé : (auteur) This paper presents methods for the precise orbit determination (POD) of a satellite in the CYGNSS constellation based on available single-frequency GPS code and carrier measurements. The contributions include the development and evaluation of procedures for single-frequency POD with GipsyX, improvement of CYGNSS orbit knowledge, and an assessment of its final accuracy. Ionospheric effects are mitigated using the GRAPHIC processing method, and spacecraft multipath effects are calibrated with an azimuth/elevation-dependent antenna calibration map. The method is demonstrated using comparable data from the GRACE mission, from which we infer the expected accuracy of the CYGNSS results. Processing more than 170 days of data from each mission, a 1σ CYGNSS orbit accuracy of 2.8 cm radial, 2.4 cm cross-track, and 6 cm in-track is demonstrated. We expect that achieving this level of performance will expand the set of future scientific investigations that can be undertaken using satellites equipped with single-frequency GNSS. Numéro de notice : A2023-141 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.33012/navi.565 Date de publication en ligne : 20/10/2022 En ligne : https://doi.org/10.33012/navi.565 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102708 [article]

The importance of co-located VLBI Intensive stations and GNSS receivers / Christopher Dieck in Journal of geodesy, vol 97 n° 3 (March 2023)  

Public [article]  inJournal of geodesy > vol 97 n° 3 (March 2023) . - n° 21 Titre : The importance of co-located VLBI Intensive stations and GNSS receivers Type de document : Article/Communication Auteurs : Christopher Dieck, Auteur ; Megan C. Johnson, Auteur ; Daniel S. MacMillan, Auteur ; et al., Auteur Année de publication : 2023 Article en page(s) : n° 21 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] Hawaii (Etats-Unis) [Termes IGN] interférométrie à très grande base [Termes IGN] positionnement par ITGB [Termes IGN] rapport signal sur bruit [Termes IGN] récepteur GNSS [Termes IGN] station GNSS [Termes IGN] station VLBI [Termes IGN] temps universel coordonné Résumé : (auteur) Frequent, low-latency measurements of the Earth’s rotation phase, expressed as UT1−UTC critically support the current estimate and short-term prediction of this highly variable Earth orientation parameter (EOP). Very long baseline interferometry (VLBI) Intensive sessions provide the required data. However, the Intensive UT1− UTC measurement accuracy depends on the accuracy of numerous models, including the VLBI station position. Intensives observed with the Maunakea (Mk) and Pie Town (Pt) stations of the Very Long Baseline Array (VLBA) illustrate how a geologic event (i.e., the Mw 6.9 Hawai‘i Earthquake of May 4th, 2018) can cause a station displacement and an associated offset in the values of UT1−UTC measured by that baseline, rendering the data from the series useless until it is corrected. Using the nonparametric Nadaraya–Watson estimator to smooth the measured UT1−UTC values before and after the earthquake, we calculate the offset in the measurement to be 75.7 ± 4.6 μs. Analysis of the sensitivity of the Mk-Pt baseline’s UT1−UTC measurement to station position changes shows that the measured offset is consistent with the 67.2 ± 5.9 μs expected offset based on the 12.4 ± 0.6 mm total coseismic displacement of the Maunakea VLBA station determined from the displacement of the co-located global navigation satellite system (GNSS) station. GNSS station position information is known with a latency on the order of tens of hours and thus can be used to correct the a priori position model of a co-located VLBI station such that it can continue to provide accurate measurements of the critical EOP UT1−UTC as part of Intensive sessions. In the absence of a co-located GNSS receiver, the VLBI station position model would likely not be updated for several months, and a near real-time correction would not be possible. This contrast highlights the benefit of co-located GNSS and VLBI stations in support of the monitoring of UT1−UTC with single-baseline Intensives. Numéro de notice : A2023-133 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-022-01690-1 Date de publication en ligne : 03/03/2023 En ligne : https://doi.org/10.1007/s00190-022-01690-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102678 [article]

Coastal GNSS-R phase altimetry based on the combination of L1 and L5 signals under high sea states / Yunqiao He in Journal of geodesy, vol 97 n° 2 (February 2023)  

Public [article]  inJournal of geodesy > vol 97 n° 2 (February 2023) . - n° 19 Titre : Coastal GNSS-R phase altimetry based on the combination of L1 and L5 signals under high sea states Type de document : Article/Communication Auteurs : Yunqiao He, Auteur ; Fan Gao, Auteur ; Tianhe Xu, Auteur ; et al., Auteur Année de publication : 2023 Article en page(s) : n° 19 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] diffusion de Rayleigh [Termes IGN] hauteurs de mer [Termes IGN] niveau de la mer [Termes IGN] phase GNSS [Termes IGN] précision altimétrique [Termes IGN] Quasi-Zenith Satellite System [Termes IGN] rapport signal sur bruit [Termes IGN] récepteur bifréquence [Termes IGN] réflectométrie par GNSS [Termes IGN] signal GNSS [Vedettes matières IGN] Altimétrie Résumé : (auteur) High-precision sea surface heights retrieved from the Global Navigation Satellite System Reflectometry (GNSS-R) measurements will be valuable in the fields of geodesy and oceanography studies. Due to the short wavelengths and low power of GNSS signals, the continuously tracked carrier phase measurements of reflected signals are usually unavailable for sea surfaces with big roughness, varying over space and time. In coastal conditions, persisting spatial coherence assumption can be made within the antenna coverage when the waves are not greatly breaking. To deal with temporal incoherence, we propose an improved algorithm to extract the combined interferometric phase difference measurements between direct and reflected signals under high sea states. After initial tracking the direct signals, dual-frequency observations are combined in the complex domain and the resulting interferometric signal is refined through open-loop tracking with 60-s coherent integration before the phase difference measurements are extracted, without tracking their respective carrier phase measurements in advance. In order to verify our method, a coastal experiment under different sea conditions was conducted and raw intermediate frequency data were collected. The raw data were then processed by a GNSS-R software-defined receiver to compute the path delay measurements of Quasi-Zenith Satellite System signals, which had good visibility during our experiment. For high sea states, that is, when the Rayleigh criterion is not fulfilled for the individual wavelengths, the phase delay measurements of L1 and L5 were random over time, while phase delay can still be well recovered for their combination. Also, the phase delay combination can be well extracted with a higher elevation angle than the previous studies. Finally, the altimetry solutions derived from the carrier phase delay measurements combination were compared with the in situ observations from a 26-GHz radar altimeter. The results show that centimeter-level altimetry accuracy using the combined measurements of L1 and L5 can be achieved under high sea states. Numéro de notice : A2023-132 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-023-01712-6 Date de publication en ligne : 27/03/2023 En ligne : https://doi.org/10.1007/s00190-023-01712-6 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102675 [article]

Parameterisation of the GNSS troposphere tomography domain with optimisation of the nodes’ distribution / Estera Trzcina in Journal of geodesy, vol 97 n° 1 (January 2023)  

Public [article]  inJournal of geodesy > vol 97 n° 1 (January 2023) . - n° 2 Titre : Parameterisation of the GNSS troposphere tomography domain with optimisation of the nodes’ distribution Type de document : Article/Communication Auteurs : Estera Trzcina, Auteur ; Witold Rohm, Auteur ; Kamil Smolak, Auteur Année de publication : 2023 Article en page(s) : n° 2 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] données GNSS [Termes IGN] interpolation bilinéaire [Termes IGN] modèle météorologique [Termes IGN] optimisation (mathématiques) [Termes IGN] radiosondage [Termes IGN] récepteur GNSS [Termes IGN] retard troposphérique [Termes IGN] retard troposphérique zénithal [Termes IGN] système de grille globale discrète [Termes IGN] teneur en vapeur d'eau [Termes IGN] tomographie [Termes IGN] troposphère Résumé : (auteur) Water vapour is a highly variable constituent of the troposphere; thus, its high-resolution measurements are of great importance to weather prediction systems. The Global Navigation Satellite Systems (GNSS) are operationally used in the estimation of the tropospheric state and assimilation of the results into the weather models. One of the GNSS techniques of troposphere sensing is tomography which provides 3-D fields of wet refractivity. The tomographic results have been successfully assimilated into the numerical weather models, showing the great potential of this technique. The GNSS tomography can be based on two different approaches to the parameterisation of the model’s domain, i.e. block (voxel-based) or grid (node-based) approach. Regardless of the parameterisation approach, the tomographic domain should be discretised, which is usually performed in a regular manner, with a grid resolution depending on the mean distance between the GNSS receivers. In this work, we propose a new parameterisation approach based on the optimisation of the tomographic nodes’ location, taking into account the non-uniform distribution of the GNSS information in the troposphere. The experiment was performed using a dense network of 16 low-cost multi-GNSS receivers located in Wrocław and its suburbs, with a mean distance of 3 km. Cross-validation of four different parameterisation approaches is presented. The validation is performed based on the Weather Research and Forecasting model as well as radiosonde observations. The new approach improves the results of wet refractivity estimation by 0.5–2 ppm in terms of RMSE, especially for altitudes of 0.5–2.0 km. Numéro de notice : A2023-044 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : https://doi.org/10.1007/s00190-022-01691-0 Date de publication en ligne : 30/12/2022 En ligne : https://doi.org/10.1007/s00190-022-01691-0 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102343 [article]

Performance tests of geodetic receivers with tilt sensors in obstructed environments using the NRTK GNSS technique / Puttipol Dumrongchai in Journal of applied geodesy, vol 17 n° 1 (January 2023)  

Public [article]  inJournal of applied geodesy > vol 17 n° 1 (January 2023) . - pp 39 - 51 Titre : Performance tests of geodetic receivers with tilt sensors in obstructed environments using the NRTK GNSS technique Type de document : Article/Communication Auteurs : Puttipol Dumrongchai, Auteur ; Jittranud Patsadutarn, Auteur ; Chalermchon Satirapod, Auteur Année de publication : 2023 Article en page(s) : pp 39 - 51 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] centrale inertielle [Termes IGN] Continuously Operating Reference Station network [Termes IGN] délimitation [Termes IGN] lever cadastral [Termes IGN] microsystème électromécanique [Termes IGN] positionnement cinématique en temps réel [Termes IGN] récepteur GNSS [Termes IGN] signal GNSS [Termes IGN] station virtuelle de référence [Termes IGN] Thaïlande Résumé : (auteur) The Department of Lands (DOL), Thailand, has adopted the Network-based Real-Time Kinematic (NRTK) Global Navigation Satellite System (GNSS) surveying technique using a Virtual Reference Station (VRS) to support cadastral surveys since 2011. Determining accurate coordinates of parcel boundary markers at building corners or near fences and walls is difficult because a GNSS range pole cannot be leveled with a circular bubble. This study aims to evaluate the performance of the receivers equipped with tilt sensors for horizontal and vertical positioning. Two types of tilt sensors used for evaluation were a magnetometer and micro-electro-mechanical system (MEMS) and an inertial measurement unit (IMU). Conducting the NRTK GNSS surveying tests was based on the pole tilt angles of 0°, 15°, 25°, 35°, and 45° from a plumb line in controlled and obstructed environments. The IMU-based tilt sensor had more advantage of accurately positioning over the MEMS sensor. The results showed that using the IMU, better than 4 cm horizontal positioning accuracy was achievable when the pole was tilted by 15° or less under non-multipath and open-sky conditions. The vertical accuracy was of a few centimeter levels and least sensitive to tilt angles using either type of sensor. However, none of the sensors precisely compensated for pole tilt in strong-multipath and complex environments, causing increased horizontal errors in decimeter levels. Numéro de notice : A2023-111 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1515/jag-2022-0047 Date de publication en ligne : 07/11/2022 En ligne : https://doi.org/10.1515/jag-2022-0047 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102470 [article]

Galileo High Accuracy Service (HAS) ou le service de haute précision de Galileo / Bernard Flacelière in XYZ, n° 173 (décembre 2022)

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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)  

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Precise onboard time synchronization for LEO satellites / Florian Kunzi in Navigation : journal of the Institute of navigation, vol 69 n° 3 (Fall 2022)  

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A new ambiguity resolution method for LEO precise orbit determination / Xingyu Zhou in Journal of geodesy, vol 96 n° 7 (July 2022)  

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Assessing the positioning performance of GNSS receivers under different geomagnetic storm conditions / Chao Yan in Survey review, vol 54 n° 384 (May 2022)  

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Coastal observation of sea surface tide and wave height using opportunity signal from Beidou GEO satellites: analysis and evaluation / Feng Wang in Journal of geodesy, vol 96 n° 4 (April 2022)  

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Detection and mitigation of GNSS spoofing via the pseudorange difference between epochs in a multicorrelator receiver / Xiangyong Shang in GPS solutions, vol 26 n° 2 (April 2022)  

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Results on GNSS spoofing mitigation using multiple receivers / Niklas Stenberg in Navigation : journal of the Institute of navigation, vol 69 n° 1 (Spring 2022)  

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Validating the impact of various ionosphere correction on mid to long baselines and point positioning using GPS dual-frequency receivers / Alaa A. Elghazouly in Journal of applied geodesy, vol 16 n° 2 (April 2022)  

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A new method for evaluation of the positional error of low-cost devices based on GNSS integrity for transportation applications / Luciano Aparecido Barbosa in Boletim de Ciências Geodésicas, vol 28 n° 1 ([01/03/2022])  

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