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Time-frequency analysis of differences between coordinates of three permanent GNSS stations in Krakow

Kosek Wiesław, Siejka Zbigniew

Reports on Geodesy and Geoinformatics

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2023

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Vol. 116

61--68

EN

This paper applies time-frequency analysis to a 3-day time series with a sampling interval of 1 second of the changes in E, N and H coordinates of three permanent GNSS stations: WRON, KR10, and KRUR in Krakow, as well as differences between them. Time-frequency analysis was conducted using a Fourier transform band-pass filter, which separates time series into frequency components. By analyzing the differences between these coordinates, it was observed that the WRON station shows a systematic error in the form of a regular wideband oscillation with a period of 75 minutes, whose amplitude varies from approximately 1 to 3 mm with a period of about 1 day. In the horizontal plane, this oscillation takes the shape of a flattened ellipse with a semi-major axis oriented in the northwest direction. The most probable cause of this regular oscillation is the day-to-day variability of the multipath signal environment.

2

Planning measurement campaigns for precise GNSS positioning in various observation conditions

Siejka Zbigniew, Hlotov Volodymyr, Fys Mykhailo

Geomatics, Landmanagement and Landscape

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2022

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no. 3

75--92

EN

Currently, GNSS (Global Navigation Satellite System) positioning systems are becoming widely used not only in geodesy, but in broad positioning in very many areas of the economy and society. The growing popularity of GNSS, especially recent, is related to their significantly increasing availability and a reduction of measurement time to a minimum, while maintaining high positioning accuracy. High positioning accuracy is ensured, among other things, by applications that allow planning observation sessions so that measurement is taken at the best time windows. It is the moment when the impact of measurement errors due to the constellation of observed satellites is the smallest. The following paper presents an example of the use of such an application and its benefits for planning GNSS observations. This type of research is particularly important for urban areas, where conditions for receiving GNSS signals are particularly difficult. Increasing the number of observable satellites and simultaneously minimizing the value of the Position Dilution of Precision (PDOP) parameter allows obtaining position coordinates (3D) with high accuracy from the point of view of relevance to GNSS measurements. The paper demonstrates the fundamental significance of satellite constellation geometry for GNSS applications requiring high accuracy position determinations, for which correct planning of a measurement campaign is crucial. It avoids this way large errors or conditions that render the observations of a particular GNSS measurement method impossible.

PL

Aktualnie, satelitarne systemy pozycjonowania GNSS (Global Navigation Satellite System) znajdują coraz szersze zastosowania nie tylko w geodezji, ale w szeroko pojętym pozycjonowaniu w bardzo wielu dziedzinach gospodarki i życia społecznego. Coraz większa popularność GNSS wynika z faktu, że szczególnie w ostatnich latach istotnie zwiększyła się ich dostępność oraz skrócił do minimum czas pomiaru, zapewniając jednocześnie wysoką dokładność pozycjonowania. Wysoką dokładność pozycjonowania zapewniają między innymi aplikacje, umożliwiające odpowiednie zaplanowanie sesji obserwacyjnej pod względem znalezienia najlepszego okna czasowego do wykonania pomiaru. Wówczas wpływ błędów pomiarowych wynikający z konstelacji obserwowanych satelitów jest najmniejszy. W niniejszej pracy przedstawiono przykład zastosowania takiej aplikacji oraz korzyści wynikające z jej wykorzystania do planowania obserwacji GNSS. Tego typu badania są szczególnie ważne w terenach zurbanizowanych, które charakteryzują trudnymi warunkami odbioru sygnałów GNSS. Zwiększając liczbę możliwych do zaobserwowania satelitów i jednocześnie minimalizując wartość parametru PDOP (Position Dilusion of Precision) rozwiązujemy problemem umożliwiający uzyskanie współrzędnych pozycji (3D) z wysoką dokładnością z punktu widzenia znaczenia dla pomiarów GNSS. W pracy wykazano fundamentalne znaczenie wpływu geometrii konstelacji satelitów dla aplikacji GNSS wymagających wysokich dokładności wyznaczeń pozycji, dla których poprawne zaplanowanie kampanii pomiarowej jest bardzo istotne. Unika się w ten sposób sytuacji pojawienia się dużych błędów lub w ogóle braku warunków obserwacyjnych dla zastosowani danej metody pomiarów GNSS.

3

Validation of the accuracy of geodetic automated measurement system based on GNSS platform for continuous monitoring of surface movements in post-mining areas

Sokoła-Szewioła Violetta, Siejka Zbigniew

Reports on Geodesy and Geoinformatics

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2021

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Vol. 112

47--57

EN

The problem involving the monitoring of surface ground movements in post-mining areas is particularly important during the period of mine closures. During or after flooding of a mine, mechanical properties of the rock mass may be impaired, and this may trigger subsidence, surface landslides, uplift, sinkholes or seismic activity. It is, therefore, important to examine and select updating methods and plans for long-term monitoring of post-mining areas to mitigate seismic hazards or surface deformation during and after mine closure. The research assumed the implementation of continuous monitoring of surface movements using the Global Navigation Satellite System (GNSS) in the area of a closed hard coal mine ‘Kazimierz-Juliusz’, located in Poland. In order to ensure displacement measurement results with the accuracy of several millimetres, the accuracy of multi-GNSS observations carried out in real time as a combination of four global navigation systems, Global Positioning System (GPS), Globalnaja Navigacionnaja Sputnikova Sistema (GLONASS), Galileo and BeiDou, was determined. The article presents the results of empirical research conducted at four reference points. The test observations were made in variants comprising measurements based on: GPS, GPS and GLONASS systems, GPS, GLONASS and Galileo systems, GPS, GLONASS, Galileo and BeiDou systems. For each adopted solution, daily measurement sessions were performed using the RTK technique. The test results were subjected to accuracy analyses. Based on the obtained results, it was found that GNSS measurements should be carried out with the use of three navigation systems (GPS, GLONASS, Galileo), as an optimal solution for the needs of continuous geodetic monitoring in the area of the study.

4

Determining of correlation relationship between roll, pitch, and yaw for UAVs

Hlotov Volodymyr, Hunina Alla, Yurkiv Mariana, Siejka Zbigniew

Reports on Geodesy and Geoinformatics

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2019

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Vol. 107

13--18

EN

Currently, UAVs are intensively being introduced into topographic-photogrammetric production for topographic digital aerial photography and laser scanning. These technologies have a number of advantages: they don’t require specially prepared platforms and launchers, they are relatively inexpensive unlike large aircrafts, and they are safe. However, there are still many unsolved problems for ultralight UAVs, especially when the aerial photography is made. As you know, the requirements for the implementation of the aerial survey process are quite stringent, first of all, for horizontal flight: the angles of inclination must be within 3–5 degrees, since exceeding these tolerances significantly affects the accuracy for determining the spatial coordinates of objects. Therefore, there was an idea to conduct researches of dependences between the pitch α, roll ω and yaw κ. For this purpose, 100 images obtained from aircraft-type UAV ‘Arrow’ developed and created by specialists from Lviv Polytechnic National University and ‘Abris’ were used. As a result of the study, the multiple correlation coefficient and the parameters of the linear regression equation for the angular elements of the exterior orientation of digital images were calculated. In addition, statistical quality evaluations for the obtained regression model were carried out. Analysis of the received data allows to assert that angular elements of exterior orientation are correlated with each other. Therefore, in the further imaging materials, processing it becomes possible to make compensation of this fact and to improve calculation accuracy of spatial coordinates of points.

5

Evaluation of integration degree of the ASG-EUPOS Polish reference networks with Ukrainian GeoTerrace network stations in the border area

Siejka Zbigniew

Artificial Satellites : Journal of Planetary Geodesy

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2017

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Vol. 52, No. 3

71--84

EN

GNSS systems are currently the basic tools for determination of the highest precision station coordinates (e.g. basic control network stations or stations used in the networks for geodynamic studies) as well as for land, maritime and air navigation. All of these tasks are carried out using active, large scale, satellite geodetic networks which are complex, intelligent teleinformatic systems offering post processing services along with corrections delivered in real-time for kinematic measurements. Many countries in the world, also in Europe, have built their own multifunctional networks and enhance them with their own GNSS augmentation systems. Nowadays however, in the era of international integration, there is a necessity to consider collective actions in order to build a unified system, covering e.g. the whole Europe or at least some of its regions. Such actions have already been undertaken in many regions of the world. In Europe such an example is the development for EUPOS which consists of active national networks built in central eastern European countries. So far experience and research show, that the critical areas for connecting these networks are border areas, in which the positioning accuracy decreases (Krzeszowski and Bosy, 2011). This study attempts to evaluate the border area compatibility of Polish ASG-EUPOS (European Position Determination System) reference stations and Ukrainian GeoTerrace system reference stations in the context of their future incorporation into the EUPOS. The two networks analyzed in work feature similar hardware parameters. In the ASG-EUPOS reference stations network, during the analyzed period, 2 stations (WLDW and CHEL) used only one system (GPS), while, in the GeoTerrace network, all the stations were equipped with both GPS and GLONASS receivers. The ASG EUPOS reference station network (95.6%) has its average completeness greater by about 6% when compared to the GeoTerrace network (89.8%).