Aerial photogrammetry was chosen as an additional observation method of the subsidence depression that was created above exploited coal mining panels near Karviná. While individual points of a permanent observation network were repeatedly surveyed by GNSS, the whole subsidence depression was surveyed by the aerial photogrammetry. As this method was applied three times (during three years) we can compare its results in individual years and observe the major surface changes on the undermined area. Also, a comparison was realized between the points’ coordinates gained from both aerial photogrammetry and GNSS. The results show that the method of aerial photogrammetry enriches and complements the GNSS observation in monitoring the spatial development and shape of the subsidence depression, especially in the areas of active recultivation., Vlastimil Kajzar, Hana Doležalová, Kamil Souček and Lubomír Staš., and Obsahuje bibliografii
Using GNSS method, fixed points of an observation network were repeatedly surveyed on the surface of the undermined area. Below the surface, at the depth of c. 1 km, there were four mining panels exploited subsequently. The main reaction of the surface points to the changes in the rock massif and the movement of the points were different, according to their surface position, local geo-mechanical conditions etc. This paper analyses the time-dependence of the surface points mining subsidence and horizontal movements on the progress of the exploitation., Hana Doležalová, Vlastimil Kajzar, Kamil Souček and Lubomír Staš., and Obsahuje bibliografické odkazy
This research evaluates the potential benefits of the tightly combined processing of a global navigation satellite system together with the additional ranging observations from a satellite based augmentation system. In specific, the experiment presents performance of precise instantaneous single-frequency positioning based on European Galileo and EGNOS navigation systems. Due to currently low number of Galileo satellites, the test observational data were obtained with hardware GNSS signal simulator. All calculations were performed with in-house developed software - GINPOS. The results show that it is possible to obtain improvement in the accuracy and reliability of single-frequency precise positioning when including observations from SBAS systems. However, one must take in to account that at middle latitudes EGNOS satellites are observed at low elevations what results in higher atmospheric errors affecting its signals., Jacek Paziewski, Paweł Wielgosz and Marta Krukowksa., and Obsahuje bibliografické odkazy
A Global Navigation Satellite System (GNSS) software library called G-Nut has been devel oped at the Geodetic Observatory Pecný (GOP) since 2011. Several applications built of the library will be provided as an open source in 2013 and consequently users are able to modify source code and use it for processing their own data free of charge. The main purpose of the project is to create a programming package suitable for implementing various end-user a pplications such as kinematic position estimation, long-term permanent station coordinates monitoring, zenith tropospheric delay estimation, satellite clock estimation and others. The library is written in C++ programming language following the object-oriented concept. Basic class structure implementing inputs/outputs and product/d ata containers support both real-time and post-processing modes. Integration of all available global navigation satellite systems (GPS, GLONASS, Galileo, BeiDou, QZSS) as well as new tracking signals is properly handled. The configuration is governed through the XML format. The estimation model currently supports the least square adjustment, the Kalman and square root covariance filtering methods based on processing undifferenced data and fixed precise orbit and clock products. The estimated state vector includes receiver coordinates and clocks, troposphere zenith path delays and initial carrier phase ambiguities. The first applications based on G-Nut library are shown with examples for off-line/online kinematic/static precise point positioning and ultra-fast troposphere estimation., Pavel Václavovic, Jan Douša and Gabriel Györi., and Obsahuje bibliografické odkazy
A new observation network has been built to observe the surface manifestations of undermining at Gabriela locality. This locality lies in the Czech part of the Upper Silesian Coal Basin and the history of the hard coal underground exploitation is more than 150 years long here. Recently, the last coal mining panel was started to be exploited here. Its location and mining parameters are very suitable for the analysis of the actual and future surface changes caused by undermining. The fixed points of the observation network are surveyed by geodetic GNSS me thod. This method enables the evaluation of both vertical subsidence and horizontal displacements. Such complex evalua tion of processes on the surface of the undermined territory makes it possible to understand the progress of the subsidence depression and to capture the final phase of the surface undermining changes, i.e. the phase of the subsidence decline., Vlastimil Kajzar, Hana Doležalová, Kamil Souček and Lubomír Staš., and Obsahuje bibliografické odkazy
Latest studies of recent geodynamic movements going on major geological structures of the Sněžník metamorphic unit are closely related to geodetic satellite measurements, especially to permanent and ep och GNSS satellite methods. For this reason the Institute of Geodesy, Faculty of Civil Engineering, Brno University of Technology (IG FCE-BUT) continues measurements in Local Geodynamic Sněžník Network (LGSN) which was established in 1992 in Czech-Polish cooperation for the purpose of lithosphere movement monitoring. A special attention was devoted to detection of possible displacements of the local blocks of Králický Sněžník Massif. The results confirm the significant horizontal and vertical movements within relatively small territory. All these and other detected contemporary geodynamic phenomena are presented and discussed., Otakar Švábenský, Josef Weigel and Lubomil Pospíšil., and Obsahuje bibliografické odkazy
The paper concerns analysis of solutions obtained during common processing of data from GNSS permanent stations situated on mountainous terrain: the Western Carpathians, the Sudetes Mountains and adjacent areas. As the outcome daily and weekly solutions (ellipsoidal coordinates) of forty Polish, Czech, Slovak, Ukrainian and German sites were obtained. Weekly solutions were used to determine velocity field and vertical movements, daily solutions enabled quality and precision of sites’ coordinates estimation to check if permanent GNSS sites can be used as a stable reference frame for geodetic, geological and geodynamical measurements in the mountainous area. First investigations concerning data from permanent GNSS stations in the Sudetes Mountains were made in 2007 using daily solutions from EPN sites obtained in test reprocessing of the whole regional network performed in Centre of Applied Geomatics. Since that time, national systems became operational increasing density of GNSS network, so the data can be used for wider range of investigations. As the majority of examined stations started to gather data in 2008, analysis were based on relatively short observation period, so they rather play a role of tests for further investigations and they give the preliminary estimation of individual sites’ activity., Mariusz Figurski, Karolina Szafranek, Janusz Bogusz and Paweł Kamiński., and Obsahuje bibliografii
The Global Navigation Satellite System (GNSS) can provide the daily position time series for the geodesy and geophysical studies. However, due to various unpredictable factors, such as receiver failure or bad observation conditions, missing data inevitably exist in GNSS position time series. Most traditional time series analysis methods require the time series should be completed. Therefore, filling the missing data is a valuable step before analyzing the GNSS time series. In this study, a new method named Iteration Empirical Mode Decomposition (Iteration EMD) is proposed to fill the missing data in GNSS position time series. The simulation experiments are performed by randomly removing different missing percentages of the synthetic time series, with the added different types noise. The results show that Iteration EMD approach performs well regardless of high or low missing percentage. When the missing percentage increases from 5 % to 30 % with a step of 5 %, all the Root Mean Square Errors (RMSE) and Mean Absolute Errors (MAE) of Iteration EMD are smaller than Interpolation EMD. The relative improvements at different percentages of Iteration EMD relative to Interpolation EMD are significant, especially for the high missing percentage. The real GNSS position time series of eight stations were selected to further evaluate the performance of Iteration EMD with an average missing percentage 8.15 %. Principal Component Analysis (PCA) was performed on the filled time series, which is used to assess the interpolation performance of Iteration EMD and Interpolation EMD. The results show that Iteration EMD can preserve variance 75.9 % with the first three Principal Components (PC), more than 66.5% of interpolation EMD. Therefore, we can conclude that Iteration EMD is an efficient interpolation method for GNSS position time series, which can make full use of available information in existing time series to fill the missing data.
Global Navigation Satellite System (GNSS) positioning has characteristics of simple operation, high efficiency and high precision technique for landslide surface monitoring. In recent years, finalization of modern GNSS systems Galileo and BeiDou has brought a possibility of multi-GNSS positioning. The paper focuses on evaluation of possible benefits of multi-GNSS constellations in landslide monitoring. While simulating observational conditions of selected Recica landslide in the Czech Republic, one-month data from well-established permanent GNSS reference stations were processed. Besides various constellation combinations, differential and Precise Point Positioning techniques, observation data lengths and observation sampling intervals were evaluated. Based on the results, using a combination of GPS and GLONASS, or GPS, GLONASS and Galileo systems can be recommended, together with a static differential technique and observation periods for data collection exceeding eight hours. In the last step, data from GNSS repetitive campaigns realized at the Recica landslide during two years were processed with optimal setup and obtained displacement results were compared to standard geotechnical measurements.
The aim of this study was to assess the performance of several approximation techniques for ionospheric total electron content (TEC) mapping. Approximation techniques based on data-fitting with local or general two-dimensional polynomials, local planes or distance-dependent interpolation were applied and tested. For the ionosphere modeling, dual-frequency GPS data from Polish GBAS system (ASG-EUPOS) were used, and TEC was estimated together with hardware delays from phasesmoothed pseudoranges. Next, grids of vertical TEC values with spatial resolution of 0.25 degrees in both latitude and longitude were generated using the evaluated approximation techniques. Subsequently the grids were used to create regional TEC maps with 5-minute temporal resolution, and also to create ionospheric delay corrections for GPS positioning. The quality of the resulting ionospheric maps was tested twofold, firstly by comparison to high-quality CODE global ionosphere maps (GIM), which were generated using data from about 150 GPS sites of the International GNSS Service (IGS). Secondly, by creating double-differenced ionospheric delay corrections and comparing them to reference values derived from the reference network data processing. For the correction tests, two perpendicular baselines directed North-South (N-S) and West-East (W-E) and reaching up to 100 km were selected. The approximation methods were analyzed with a special emphasis on the diverse ionospheric conditions. For the testing, a quiet ionosphere day of 20 March 2012 and an active ionosphere day of 9 March 2012 were selected. The results show that the regional models properly represent the changing ionosphere, with the best results provided by data-fitting into local functions., Anna Krypiak-Gregorczyk, Pawel Wielgosz, Dariusz Gosciewski and Jacek Paziewski., and Obsahuje bibliografii