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Ground deformation monitoring at the open pit mine Koźmin has been conducted since 2008. The principles and results of the precise determination of the three dimensional displacements using GPS technology has been presented in this paper. In specific, establishment of the control network, patented technology of the field measurements, the strategy of GPS data postprocessing, as well as the obtained displacements in the control network with their accuracy analysis have been presented. The research conducted with the developed technology indicates a high accuracy and reliability of the determined displacements of the controlled points. ARTICLE INFO

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 into account that at middle latitudes EGNOS satellites are observed at low elevations what results in higher atmospheric errors affecting its signals.

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.

The paper presents the foundations of MAFA method, as well as its application to the processing of new GPS and Galileo signals. The presented numerical tests have been carried out on the basis of data obtained from a hardware GNSS signal simulator as there are currently too few Galileo satellites on orbit. In the proposed methodology, first linear combinations have been formed using new GNSS signals. These linear combinations constitute a data set for a cascade adjustment algorithm employing extended MAFA method. Feasibility of a single-epoch precise positioning has been tested. The singleepoch positioning is particularly important for reliable real-time landslide and deformation monitoring. The obtained test results show a high success rate of the extended MAFA method. The number of the correct single-epoch solutions varied from 85 % to over 99 % depending on the baseline length and accuracy of an a priori position. Thus, the MAFA method may be successfully used with new GPS and Galileo signals, even for the processing of single-epoch data.

GPS (Global Positioning System) technique has become a major tool in contemporary surveying and geodesy. This concerns mostly measurements of horizontal point coordinates, where centimeter-level accuracies are usually required and easily achievable. For the height component, however, these requirements are higher and millimeter-level accuracy is necessary. On the other hand, the intrinsic precision of GPS-derived heights is clearly lower comparing to the horizontal components. This is due to unfavorable satellite geometry, adverse effects of the troposphere or GPS antenna phase center offset and variations. In order to overcome these effects one has to carefully model all the error sources and rigorously process the GPS data. This paper presents studies on the optimal GPS data processing strategy suitable for precise leveling. This was done through the extensive testing and selection of the most appropriate observational session duration, ambiguity resolution strategy, network geometry, troposphere and ionospheric delay reduction methods, signal linear combination, elevation angle cut-off, etc. The analyzed processing strategies were evaluated through the processing of a test network. The test network consisted of 19 monitored points and 5 control points, and covered the area of 20 km x 60 km. The obtained results show that the precise GPS leveling with the selected optimal processing strategy allows for about 3 mm repeatability of height measurements when processing 4-hour long sessions. In our opinion GPS leveling may serve as fast and cost-effective replacement of classic geometric leveling, especially in applications where the heights in orthometric or normal height systems are not necessary. This is the case in, e.g., ground deformation studies.