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Analysis of ocean tide loading displacements by GPS kinematic precise point positioning: a case study at the China coastal site SHAO / H. Zhao in Survey review, vol 51 n° 365 (March 2019)
[article]
Titre : Analysis of ocean tide loading displacements by GPS kinematic precise point positioning: a case study at the China coastal site SHAO Type de document : Article/Communication Auteurs : H. Zhao, Auteur ; Q. Zhang, Auteur ; R. Tu, Auteur ; Z. Liu, Auteur Année de publication : 2019 Article en page(s) : pp 172 - 182 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] analyse spectrale
[Termes IGN] Chine
[Termes IGN] données GPS
[Termes IGN] données marégraphiques
[Termes IGN] GPS en mode cinématique
[Termes IGN] littoral
[Termes IGN] marée océanique
[Termes IGN] positionnement ponctuel précis
[Termes IGN] série temporelle
[Termes IGN] surcharge océaniqueRésumé : (Auteur) Ocean tide loading (OTL) displacement amplitudes and phase lags of SHAO site are estimated by global positioning system (GPS), kinematic precise point positioning (PPP) and spectral analysis using 19 years of continuous GPS observations. In kinematic PPP, the 66 additional harmonic displacement parameters are replaced by the three time-varying displacement parameters without a priori modelled OTL displacements. By comparing the results with predictions from hybrid regional/global models, we are able to demonstrate that GPS/model agreements are at the level of 0.2 mm (horizontal) and 0.6 mm (vertical) for the four lunar constituents, 0.4 mm (horizontal) and 1.35 mm (vertical) for the four solar/sidereal constituents, and 0.2 mm (horizontal) and 0.3 mm (vertical) for the three long-period constituents. Finally, we conclude that GPS-derived lunar constituents can substitute for the model corrections in GPS data processing and the accuracy of GPS-derived solar/sidereal constituents needs to be improved by further studies. Numéro de notice : A2019-190 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/00396265.2017.1407392 Date de publication en ligne : 30/11/2017 En ligne : https://doi.org/10.1080/00396265.2017.1407392 Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92634
in Survey review > vol 51 n° 365 (March 2019) . - pp 172 - 182[article]Integrating dendrochronology and geomatics to monitor natural hazards and landscape changes / Marco Ciolli in Applied geomatics, vol 11 n° 1 (March 2019)
[article]
Titre : Integrating dendrochronology and geomatics to monitor natural hazards and landscape changes Type de document : Article/Communication Auteurs : Marco Ciolli, Auteur ; Marco Bezzi, Auteur ; Giovanni Comunello, Auteur ; et al., Auteur Année de publication : 2019 Article en page(s) : pp 39 - 52 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Analyse spatiale
[Termes IGN] Albanie
[Termes IGN] analyse diachronique
[Termes IGN] avalanche
[Termes IGN] couvert forestier
[Termes IGN] dendrochronologie
[Termes IGN] forêt
[Termes IGN] GRASS
[Termes IGN] IDRISI
[Termes IGN] lit majeur
[Termes IGN] Pinus sylvestris
[Termes IGN] positionnement par GPS
[Termes IGN] QGIS
[Termes IGN] reboisement
[Termes IGN] risque naturel
[Termes IGN] TrenteRésumé : (Auteur) The monitoring of natural hazards is of extreme importance in the areas of Italy where there are high hydrogeological and avalanche risks. Despite the fact that records of past events are sometimes available, some of their data are often incomplete and show that the monitoring and mapping of these phenomena are never enough to avoid damage. We present the results of different studies where an integrated approach has been used by combining geomatics and dendrochronology techniques. In particular, we refer to case studies concerning avalanches, debris flows, natural reforestation in Italy and riverbed path changes in Albania. The position of all the plants sampled for dendrochronology was taken by GPS (Global Positioning System). The cartographic information used in these studies was provided by official sources from public organisations or processed by extracting them from aerial photographs or satellite imagery. With the Geographic Information System, it was possible to spatialise and analyse the information from dendrochronological sampling through the creation of multi-temporal morphological and potential risk maps showing the effects of the phenomena on forest cover. The GIS software used in these studies are GRASS, QGIS and IDRISI. The results showed that avalanches, debris flow, riverbed and landscape change can be studied effectively by integrating geomatics and dendrochronological techniques. This integration enabled spatial and temporal modelling, including the reconstruction of paths and volumes of past phenomena. The analysis of growth disturbances over time also enabled the reconstruction of the frequency of avalanches and debris flow activity over the last 50 years and, in some areas, over the last century. A detailed analysis of one of the avalanche tracks provided interesting results regarding the reconstruction of avalanche dynamics. Analysis of scars on buried stems of Pinus sylvestris also provided interesting results in terms of debris volume estimation. The dendrochronological reconstruction of the patterns of natural reforestation led to the determination of forest expansion rates that were used for modelling future scenarios and refining the changes of river morphology. Dendrochronology strongly improved the results of GIS satellite imagery analysis. These reconstructions are particularly important for the areas that are more exposed to the direct risk of avalanches, debris flows and floods in order to prevent the consequences of such phenomena in a changing climate. Numéro de notice : A2019-160 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s12518-018-0236-0 Date de publication en ligne : 21/08/2018 En ligne : https://doi.org/10.1007/s12518-018-0236-0 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92521
in Applied geomatics > vol 11 n° 1 (March 2019) . - pp 39 - 52[article]Influence of subdaily model for polar motion on the estimated GPS satellite orbits / Natalia Panafidina in Journal of geodesy, vol 93 n° 2 (February 2019)
[article]
Titre : Influence of subdaily model for polar motion on the estimated GPS satellite orbits Type de document : Article/Communication Auteurs : Natalia Panafidina, Auteur ; Urs Hugentobler, Auteur ; Manuela Seitz, Auteur Année de publication : 2019 Article en page(s) : pp 229 - 240 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] analyse diachronique
[Termes IGN] élément orbital
[Termes IGN] erreur systématique
[Termes IGN] International Terrestrial Reference Frame
[Termes IGN] marée océanique
[Termes IGN] mouvement du géocentre
[Termes IGN] mouvement du pôle
[Termes IGN] orbite
[Termes IGN] positionnement par GPS
[Termes IGN] rotation de la Terre
[Termes IGN] satellite GPS
[Termes IGN] traitement du signalRésumé : (auteur) In this contribution, it is shown that GPS orbits are able to absorb some diurnal signals in polar motion. The arising implications for the influence of the subdaily pole model on GPS solutions are discussed. Two signals in polar motion can be absorbed by GPS orbits: a retrograde signal with a period of a sidereal day (23 h 56 min 4 s) and a prograde signal with a period matching the revolution period of the GPS satellites in the terrestrial reference frame (23 h 55 min 56 s). We show that the retrograde signal contributes to the absolute orientation of the orbital planes in space and the prograde signal, due to coincidence of its period with the period of revolution of the GPS satellites, contributes to the position of the geocenter for each individual satellite. It is known from previous studies that there are systematic differences between orbital parameters from GPS solutions computed with different subdaily pole models. We show in this paper that this behavior can be explained by the absorption effects in 1-day GPS orbits. Diurnal signals cannot be spectrally separated over a time interval of 1 day. Adjustment of any diurnal prograde or retrograde signal to a subdaily pole time series given by a subdaily model over 24 h will lead to an estimated signal with a nonzero amplitude. Thus, any subdaily pole model used in the processing of space geodetic observations contains a part which corresponds numerically to the discussed prograde signal and a part which corresponds to the retrograde diurnal signal. Different pole models show different amplitudes of the diurnal signals which will be absorbed by the orbits. As a result, GPS orbits computed with different subdaily pole models have systematically different orientation and position in space. Using 1-day GPS solutions over a time span of 13 years (1994–2007), we show that the systematic variations in orbit position and orientation caused by individual tidal terms in polar motion can be well predicted and explained by the suggested mechanism. Numéro de notice : A2019-080 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-018-1153-z Date de publication en ligne : 24/05/2018 En ligne : https://doi.org/10.1007/s00190-018-1153-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92198
in Journal of geodesy > vol 93 n° 2 (February 2019) . - pp 229 - 240[article]Accounting for the differential inter-system bias (DISB) of code observation in GPS+BDS positioning / Xiang Cao in Journal of applied geodesy, vol 13 n° 1 (January 2019)
[article]
Titre : Accounting for the differential inter-system bias (DISB) of code observation in GPS+BDS positioning Type de document : Article/Communication Auteurs : Xiang Cao, Auteur ; Qing Wang, Auteur ; Chengfa Gao, Auteur ; Jie Zhang, Auteur Année de publication : 2019 Article en page(s) : pp 63 - 68 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] erreur systématique inter-systèmes
[Termes IGN] mesurage de pseudo-distance
[Termes IGN] positionnement différentiel
[Termes IGN] positionnement par BeiDou
[Termes IGN] positionnement par GPS
[Termes IGN] temps réelRésumé : (Auteur) If the associated differential inter-system biases (DISBs) are priori known, only one common reference satellite is sufficient, which is called the inter-system model. The inter-system model can help to maximize the redundancy of the positioning model, and thus can improve the positioning performance, especially in harsh environment. However, in practice use not all receivers can be calibrated with DISBs in advance. In this paper, taking combined GPS and BDS pseudorange positioning as the example, we compare three positioning models and their positioning performance. One is traditional intra-system model, and the other two belongs to the inter-system models, i. e. the model with calibration of DISB and the model with real-time estimation of DISB parameter. Positioning performance using the three models is evaluated with simulated obstructed environments. It will be shown that besides the model with calibration of DISB, the model with real-time estimation of DISB parameter can also effectively improve positioning accuracy and reliability compared with the traditional intra-system model, especially for the severely obstructed environment with only a few satellites observed. When no more than 7 satellites visible, the positioning accuracies in each directions can be improved by no less than 15 %. The proposed model can be used alternatively when no priori DISB calibration is available. Numéro de notice : A2019-135 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1515/jag-2018-0025 Date de publication en ligne : 30/08/2018 En ligne : https://doi.org/10.1515/jag-2018-0025 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92465
in Journal of applied geodesy > vol 13 n° 1 (January 2019) . - pp 63 - 68[article]Enhancing real-time precise point positioning time and frequency transfer with receiver clock modeling / Yulong Ge in GPS solutions, vol 23 n° 1 (January 2019)
[article]
Titre : Enhancing real-time precise point positioning time and frequency transfer with receiver clock modeling Type de document : Article/Communication Auteurs : Yulong Ge, Auteur ; Feng Zhou, Auteur ; Tianjun Liu, Auteur ; et al., Auteur Année de publication : 2019 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] horloge du récepteur
[Termes IGN] positionnement par GPS
[Termes IGN] positionnement ponctuel précis
[Termes IGN] temps réel
[Termes IGN] variance d'AllanRésumé : (Auteur) Thanks to the international GNSS service (IGS), which has provided an open-access real-time service (RTS) since 2013, real-time precise point positioning (RT-PPP) has become a major topic in the time community. Currently, a few scholars have studied RT-PPP time transfer, and the correlation of the receiver clock offsets between adjacent epochs have not been considered. We present a receiver clock offset model that considers the correlation of the receiver clock offsets between adjacent epochs using an a priori value. The clock offset is estimated using a between-epoch constraint model rather than a white noise model. This approach is based on two steps. First, the a priori noise variance is based on the Allan variance of the receiver clock offset derived from GPS PPP solutions with IGS final products. Second, by applying the between-epoch constraint model, the RT-PPP time transfer is achieved. Our numerical analyses clarify how the approach performs for RT-PPP time and frequency transfer. Based on five commonly used RTS products and six IGS stations, two conclusions are obtained straightforwardly. First, all RT-PPP solutions with different real-time products are capable of time transfer. The standard deviation (STD) values of the clock difference between the PPP solutions with respect to the IGS final clock products are less than 0.3 ns. Second, the STD values are reduced significantly by applying our approach. The reduction percent of STD values ranges from 4.0 to 35.5%. Moreover, the largest improvement ratio of frequency stability is 12 as compared to the solution of the white noise model. Note that the receiver clock offset from IGS final clock products is regarded as a reference. Numéro de notice : A2019-052 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s10291-018-0814-y Date de publication en ligne : 19/12/2018 En ligne : https://doi.org/10.1007/s10291-018-0814-y Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92081
in GPS solutions > vol 23 n° 1 (January 2019)[article]On constrained integrated total Kalman filter for integrated direct geo-referencing / Vahid Mahboub in Survey review, vol 51 n° 364 (January 2019)PermalinkReal-time capturing of seismic waveforms using high-rate BDS, GPS and GLONASS observations: the 2017 Mw 6.5 Jiuzhaigou earthquake in China / Xingxing Li in GPS solutions, vol 23 n° 1 (January 2019)PermalinkComparative analysis of multi-constellation GNSS single-frequency precise point positioning / Mahmoud Abd Rabbou in Survey review, vol 50 n° 361 (July 2018)PermalinkAdvancement of close range photogrammetry with a portable panoramic image mapping system (PPIMS) / Yung-Chuan Chen in Photogrammetric record, vol 33 n° 162 (June 2018)PermalinkGPS receiver phase biases estimable in PPP-RTK networks : dynamic characterization and impact analysis / Baocheng Zhang in Journal of geodesy, vol 92 n° 6 (June 2018)PermalinkMulti-GNSS phase delay estimation and PPP ambiguity resolution : GPS, BDS, GLONASS, Galileo / Xingxing Li in Journal of geodesy, vol 92 n° 6 (June 2018)PermalinkPerformance of absolute real-time multi-GNSS kinematic positioning / Kamil Kazmierski in Artificial satellites, vol 53 n° 2 (June 2018)PermalinkModeling tropospheric wet delays with national GNSS reference network in China for BeiDou precise point positioning / Fu Zheng in Journal of geodesy, vol 92 n° 5 (May 2018)PermalinkKinematic-PPP using single/dual frequency observations from (GPS, GLONASS and GPS/GLONASS) constellations for hydrography / Ashraf Farah in Artificial satellites, vol 53 n° 1 (March 2018)PermalinkLe réseau et les services Orphéon intègrent Galileo et BeiDou : quels sont les avantages pour le NRTK de haute précision ? / Xiaoguang Luo in XYZ, n° 154 (mars - mai 2018)Permalink