Artificial Satellites-Journal of Planetary Geodesy最新文献

{"title":"Positional Accuracy Evaluation of Google Earth in Addis Ababa, Ethiopia","authors":"Yalemzewd Abere Mulu, S. D. Derib","doi":"10.2478/arsa-2019-0005","DOIUrl":"https://doi.org/10.2478/arsa-2019-0005","url":null,"abstract":"Abstract From the time when it was first launched in 2005, satellite data generated from Google Earth are freely available online. Hence, without being conducting concrete studies about the accuracy of satellite data from Google Earth, Google Earth are chiefly used for different field of studies in different sectors for different purposes in Ethiopia. In this regard, it was planned to conduct this study by establishing the main objective to evaluate the positional accuracy of Google Earth. Hence, in order to address the aforementioned objective, a brief methodology for collecting and analyzing data was performed. The positional accuracy of Google Earth for both horizontal and vertical cases was evaluated. The acquired horizontal RMSE of Google Earth was found fit to produce a class-1 map of having 1:20000 scale as recommended by ASPRS-1990. Unlike for horizontal case, the computed RMSE for vertical positional accuracy of Google Earth was not found fit for preparing class-1 map. However, making correlations between field survey and GE can provide 95% fitness, and also, subtracting the acquired RMSE for the vertical case from the original Google Earth elevation data can provide a 90% fitness for preparing class-1 map as well.","PeriodicalId":43216,"journal":{"name":"Artificial Satellites-Journal of Planetary Geodesy","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42955573","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"New High-Precision Values of the Geodetic Rotation of the Mars Satellites System, Major Planets, Pluto, the Moon and the Sun","authors":"V. Pashkevich, A. Vershkov","doi":"10.2478/ARSA-2019-0004","DOIUrl":"https://doi.org/10.2478/ARSA-2019-0004","url":null,"abstract":"Abstract In this study the relativistic effects (the geodetic precession and the geodetic nutation, which consist of the effect of the geodetic rotation) in the rotation of Mars satellites system for the first time were computed and the improved geodetic rotation of the Solar system bodies were investigated. The most essential terms of the geodetic rotation were computed by the algorithm of Pashkevich (2016), which is applicable to the study of any bodies of the Solar system that have long-time ephemeris. As a result, in the perturbing terms of the physical librations and Euler angles for Mars satellites (Phobos and Deimos) as well as in the perturbing terms of the physical librations for the Moon and Euler angles for major planets, Pluto and the Sun the most significant systematic and periodic terms of the geodetic rotation were calculated. In this research the additional periodic terms of the geodetic rotation for major planets, Pluto and the Moon were calculated.","PeriodicalId":43216,"journal":{"name":"Artificial Satellites-Journal of Planetary Geodesy","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44068637","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Improving the Stochastic Model for VRS Network-Based GNSS Surveying","authors":"Thanate Jongrujinan, C. Satirapod","doi":"10.2478/arsa-2019-0003","DOIUrl":"https://doi.org/10.2478/arsa-2019-0003","url":null,"abstract":"Abstract The VRS network-based technique has become the main precise GNSS surveying method especially for medium-range baselines (approximately 20-70 km). The key concept of this approach is to use the observables of multiple reference stations to generate the network correction in the form of a virtual reference station for mitigating distance-dependent errors including atmospheric effects and orbital uncertainty at the user’s location. Numerous GNSS data processing strategies have been adopted in the functional model in order to improve both the positioning accuracy and the success of ambiguity resolution. However, it is impossible to completely model the aforementioned errors. As a result, the unmodelled residuals still remain in the virtual reference station observables when the least squares estimation is employed. An alternative approach to deal with these residuals is to construct a more realistic stochastic model whereby the variance-covariance matrix is assumed to be homoscedastic. This research aims to investigate a suitable stochastic model used for the VRS technique. The rigorous statistical method, MINQUE has been applied to estimate the variance-covariance matrix of the double-difference observables for a virtual reference station to rover baseline determination. The findings of the comparison to the equal-weight model and the satellite elevation-based model indicated that the MINQUE procedure could enhance the positioning accuracy. In addition, the reliability of ambiguity resolution is also improved.","PeriodicalId":43216,"journal":{"name":"Artificial Satellites-Journal of Planetary Geodesy","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2019-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42721653","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Single-Frequency Ionospheric-Delay Correction from BeiDou & GPS Systems for Northern Hemisphere","authors":"A. Farah","doi":"10.2478/arsa-2019-0002","DOIUrl":"https://doi.org/10.2478/arsa-2019-0002","url":null,"abstract":"Abstract The range delay caused by the ionosphere layer is the major current source of error for GNSS users with single-frequency receivers. GNSS advice users to correct this type of error using ionospheric models whose coefficients are sent in their navigation messages. GPS-users use the Klobuchar model to correct this type of error. GPS navigation message contains the model’s eight coefficients which vary on the basis of seasonal ionospheric variations and average solar flux. The correction accuracy of Klobuchar model is about 50% (rms) of the ionospheric range delay. Beidou system calculates and broadcast 8 parameters of Klobuchar model based on continuous monitoring stations. BeiDou system updates the ionospheric coefficients every two hours. GPS-Klobuchar model uses completely different coefficients than BeiDou-Klobuchar model. This research demonstrates a comparison study between the Klobuchar model using the GPS broadcast coefficients and the same model using BeiDou-coefficients. The correction accuracy offered by the two models has been judged using the most accurate International GNSS Service-Global Ionospheric Maps (IGS-GIMs) for three different-latitude stations along northern hemisphere, one station in low-latitude region, the second station is in mid-latitude region and the third station is in high-latiude region to reflect models’ behaviour in different geographic regions. The study was applied over three different months of the year 2017 that each of them reflects a different activity state for the ionosphere layer. The study proves that BeiDou model is able to show the ionosphere’s day-to-day fluctuations while GPS model can’t. It can be concluded that GPS model offers better behaviour than BeiDou model in correcting range delay in low-latitude and high-latitude geographic regions under any activity state for the ionosphere. BeiDou model offers better correction accuracy than GPS model in mid-latitude under any activity state for the ionosphere.","PeriodicalId":43216,"journal":{"name":"Artificial Satellites-Journal of Planetary Geodesy","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2019-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49637631","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Erratum to the paper on “Nequick2 Model Behaviour for Global Ionospheric Delay Mitigation During Solar Cycle-24”","authors":"","doi":"10.2478/arsa-2019-0001","DOIUrl":"https://doi.org/10.2478/arsa-2019-0001","url":null,"abstract":"","PeriodicalId":43216,"journal":{"name":"Artificial Satellites-Journal of Planetary Geodesy","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2019-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45076383","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nequick2 Model Behaviour for Global Ionospheric Delay Mitigation During Solar Cycle-24","authors":"A. Farah","doi":"10.2478/arsa-2018-0010","DOIUrl":"https://doi.org/10.2478/arsa-2018-0010","url":null,"abstract":"Abstract The ionospheric delay is the major current source of potential range delay for single-frequency GNSS users. Different ionospheric delay mitigation methods have been developed to mitigate the ionospheric delay effects for single-frequency users. The NeQuick is a quick-run ionospheric electron density model particularly designed for trans-ionospheric propagation applications developed at the Aeronomy and Radio propagation Laboratory of the Abdus Salam International Centre for Theoretical Physics (ICTP), Italy. NeQuick2 is the latest version of the NeQuick ionosphere electron density model. NeQuick model been used by the European Space Agency (ESA) European Geostationary Navigation Overlay Service (EGNOS) project for assessment analysis and has been adopted for single-frequency positioning applications in the frame work of the European satellite navigation system (Galileo). NeQuick2 model adopted modifications related to the modeling of the F1 layer peak electron density, height and thickness parameter. Also, a new formulation of the shape parameter k has been adopted. This paper presents a global study for the behavior of the modified NeQuick2 model. The zenith ionospheric range delay correction by the model has been assessed using the highly accurate IGS-Global Ionospheric Maps (IGS-GIMs) for two different-latitude stations (Aswan, Egypt) (low-latitude) (24.1o N) and (Helsinki, Finland) (high-latitude) (60.2o N). The study was carried out during current solar cycle-24 over three different months that each of them reflects a different state of solar activity. It can be concluded that NeQuick2 model globally presents overestimation for ionospheric delay for quiet and medium ionospheric activity states respectively, while the model presents underestimation for high activity state of the ionosphere layer.","PeriodicalId":43216,"journal":{"name":"Artificial Satellites-Journal of Planetary Geodesy","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2018-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48632318","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhanced Local Ionosphere Model for Multi-Constellations Single Frequency Precise Point Positioning Applications: Egyptian Case Study","authors":"Emad El Manaily, M. Abd Rabbou, A. El-Shazly, M. Baraka","doi":"10.2478/arsa-2018-0011","DOIUrl":"https://doi.org/10.2478/arsa-2018-0011","url":null,"abstract":"Abstract The positioning accuracy of single frequency precise point positioning (SFPPP) attributes mainly to the ionosphere error, which strongly affects GNSS signals. When GNSS signals pass through the various ionosphere layers, they will be bent and their speed will be changed due to dispersive nature of ionosphere. To correct the ionosphere error, it is common to use Klobuchar ionosphere model or Global Ionosphere Maps (GIM). However, Klobuchar can deal with only about 50% of the Ionosphere effect and global Ionosphere maps are often inadequate to describe detailed features of local ionosphere because of limited precision and resolution. In this paper, an enhanced local ionosphere model was developed relying on modeling of measurements from a dense Egyptian permanent tracking GNSS network in order to achieve high precision ionosphere delay correction. The performance of the developed enhanced Egyptian ionosphere model (EIM) was verified through multi-constellations SFPPP accuracy for static and kinematic modes. For static mode, 24 hours multi-constellations datasets collected at three selected stations, Alexandria, Cairo, and Aswan, in Egypt on February 27, 2017, to investigate the performance of the developed local ionospheric model in comparison with the Klobuchar, GIM and ionosphere free models. After session time of half an hour, the results show that the performance of static SFPPP based on the developed Egyptian ionospheric map (EIM) achieved a comparable accuracy WRT using ionosphere free model. While using EIM, achieved an improvements of (38%, 28%, and 42%) and (32%, 10%, and 37%) for accuracy of latitude, longitude, and altitude in comparison with using Klobuchar and GIM models, respectively For kinematic mode, datasets of 2 hours of observations with 1 second sampling rate were logged during vehicular test; the test was carried out on the ring road of the city of Cairo, Egypt, on September 16, 2017. After half an hour of kinematic SFPPP data-processing, the performance of using Egyptian ionospheric map (EIM) for ionosphere delay correction, achieved an improvements of three dimension coordinates of (83%, 47%, and 62%) and (57%, 65%, and 21%) with respect to using Klobuchar model and GIM model, respectively.","PeriodicalId":43216,"journal":{"name":"Artificial Satellites-Journal of Planetary Geodesy","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2018-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45427092","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigation of Deformations of the Earth Crust on the Territory of Ukraine Using a Gnss Observations","authors":"M. Ishchenko","doi":"10.2478/arsa-2018-0009","DOIUrl":"https://doi.org/10.2478/arsa-2018-0009","url":null,"abstract":"Abstract A regional GNSS network consisting of 202 permanent GNSS stations established to study the recent crustal strain deformation in the Ukrainian territory. The GNSS observations (from December 7, 1997 to January 28, 2017) collected and processed using Bernese GNSS Software ver. 5.2 in accordance with the recommendations of the Central Bureau of the EUREF Permanent GNSS Network. Based on the above results the velocity vectors were estimated using Bernese GNSS Software ver. 5.2 for the future calculation of deformation. In particular, ellipses of distortion, rotation, maximum shear strain, and deformation area are obtained. Due to the differences in rate of the horizontal extension and rotation the area is divided in two main blocks. The first block shows compression that prevails in the North-East direction. Stretch in both directions is prevailing on second block. The obtained results can indicate the presence of some force which could effect on the study area.","PeriodicalId":43216,"journal":{"name":"Artificial Satellites-Journal of Planetary Geodesy","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46994764","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Relativistic Rotation of the Rigid Body in the Rodrigues – Hamilton Parameters: Lagrange Function and Equations of Motion","authors":"V. Pashkevich, G. Eroshkin","doi":"10.2478/arsa-2018-0008","DOIUrl":"https://doi.org/10.2478/arsa-2018-0008","url":null,"abstract":"Abstract The main purposes of this research are to obtain Lagrange function for the relativistic rotation of the rigid body, which is generated by metric properties of Riemann space of general relativity and to derive the differential equations, determining the rigid body rotation in the terms of the Rodrigues - Hamilton parameters. The Lagrange function for the relativistic rotation of the rigid body is derived from the Lagrange function of the nonrotation point of masses system in the relativistic approximation.","PeriodicalId":43216,"journal":{"name":"Artificial Satellites-Journal of Planetary Geodesy","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48980303","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Performance of Absolute Real-Time Multi-GNSS Kinematic Positioning","authors":"K. Kaźmierski","doi":"10.2478/arsa-2018-0007","DOIUrl":"https://doi.org/10.2478/arsa-2018-0007","url":null,"abstract":"Abstract Recently, we observe the rapid development of the Global Navigational Satellite Systems (GNSS), including autonomous positioning techniques, such as Precise Point Positioning (PPP). The GNSS have different conceptions, different spacecraft and use different types of orbits which is why the quality of real-time orbit and clock products is inconsistent, thus, the appropriate approach of the multi-GNSS observation processing is needed to optimize the solution quality. In this paper, the kinematic field experiment is conducted in order to examine multi-GNSS real-time Standard Point Positioning (SPP) and PPP performance. The test was performed on the 26 km-long car route through villages, forests, the city of Wrocław, crossing under viaducts and a high tension line. For the first time, the solution is based on GPS + GLONASS + Galileo + BeiDou observations using streamed corrections for orbits and clocks with two different weighting scenarios. Thanks to the usage of the multi-GNSS constellation the number of positioning epochs possible to determine increases by 10%. The results show also that the appropriate weighting approach can improve the root mean square error in the SPP solution by about 13% and 42% for the horizontal and vertical coordinate components, respectively. In the case of PPP, the maximum quality improvement equals 70% for the horizontal component and the results for the vertical component are comparable with those obtained for the GPS-only solution.","PeriodicalId":43216,"journal":{"name":"Artificial Satellites-Journal of Planetary Geodesy","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43790185","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}