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EN
A geoid or quasigeoid model allows the integration of satellite measurements with ground levelling measurements in valid height systems. A precise quasigeoid model has been developed for the city of Krakow. One of the goals of the model construction was to provide a more detailed quasigeoid course than the one offered by the national model PL-geoid2011. Only four measurement points in the area of Kraków were used to build a national quasigeoid model. It can be assumed that due to the small number of points and their uneven distribution over the city area, the quasigeoid can be determined less accurately. It became the reason for developing a local quasigeoid model based on a larger number of evenly distributed points. The quasigeoid model was based on 66 evenly distributed points (from 2.5 km to 5.0 km apart) in the study area. The process of modelling the quasigeoid used height anomalies determined at these points on the basis of normal heights derived through levelling and ellipsoidal heights derived through GNSS surveys. Height anomalies coming from the global geopotential model EGM2008 served as a long-wavelength trend in those derived from surveys. Analyses showed that the developed height anomaly model fits the empirical data at the level of single millimetres – mean absolute difference 0.005 m. The developed local model QuasigeoidKR2019, similar to the national model PL-geoid2011, are models closely related to the reference and height systems in Poland. Such models are used to integrate GNSS and levelling observations. A comparison of the local QuasigeoidKR2019 and national PL-geoid2011 model was made for the reference frame PL-ETRF2000 and height datum PL-KRON86-NH. The comparison of the two models with respect to GNSS/levelling height anomalies shows a triple reduction in the values of individual quartiles and a mean absolute difference for the developed local model. These summary statistics clearly indicate that the accuracy of the local model for the city of Krakow is significantly higher than that of the national one.
EN
Satellite technologies of communication, navigation and surveillance play an important role in modern transport, and particularly in aviation. High effectiveness of global air navigation system is provided by applying data broadcasted from great numbers of satellites, located on Earth orbits. The totality of existing satellite navigation system forms global radio navigation field which parameters should be constantly monitored and controlled for providing safety requirements. The aim of this article is to share experience of creating a laboratory of satellite technologies at the National Aviation University that performs simultaneously educational and scientific tasks.
PL
VRSNET jest komercyjną aktywną siecią geodezyjną składającą się ze stacji referencyjnych znajdujących się na terytorium Polski oraz na terytorium państw sąsiednich. W pracy przedstawiono analizę przestrzenną lokalizacji stacji permanentnych VRSNET, których anteny i odbiorniki satelitarne w sposób ciągły odbierają i rejestrują sygnały transmitowane przez GNSS (Global Navigation Satellite Systems). Rozważania skupiły się na delimitacji obszaru Polski pod względem potencjalnego zasięgu średniego poszczególnych stacji. W badaniach wykorzystano analizy przestrzenne m.in. diagram Voronoi/Thiessen (tesselacje Dirichleta) oraz bufory przestrzenne. W pracy oceniono geometrię sieci VRSNET dla potrzeb wykonywania pomiarów techniką Real Time Kinematic (RTK) z wykorzystaniem wektorów bazowych opartych wyłącznie na analizowanych stacjach. Podjęto także dyskusję dotyczącą możliwego rozwoju sieci VRSNET poprzez uruchomienie nowych stacji referencyjnych. W wyniku przeprowadzonych analiz przestrzennych wskazano lokalizację i zasięg obszarów wymagających zagęszczenia sieci VRSNET. W obszarach określonych w toku delimitacji powierzchni Polski wskazano lokalizacje 16 nowych stacji referencyjnych. W celu walidacji zagęszczoną o nowoprojektowane stacje sieć VRSNET poddano ponownej ocenie z użyciem diagramu Voronoi/Thiessena oraz buforów przestrzennych. Otrzymane wyniki porównano z parametrami dotyczącymi państwowej sieci ASG-EUPOS (Active Geodetic Network – European Position Determination System). Wykazano wynikającą z zaproponowanego scenariusza rozbudowy sieci VRSNET poprawę parametrów pomiarów techniką RTK. Zagęszczenie sieci może także wpływać pozytywnie na wyniki pomiarów techniką Network Real Time Kinematic (RTN).
EN
The VRSNET is a commercial active geodetic network of reference stations deployed on Polish territory and in neighbouring countries. The paper presents a spatial analysis of locations of VRSNET permanent stations whose antennas and satellite receivers continuously record signals transmitted by Global Navigation Satellite Systems (GNSS). The study focused on delimiting the potential average range of individual stations in Poland. Spatial analyses, including Voronoi/Thiessen diagram (Dirichlet tessellations) and spatial buffers were used in the research. The study evaluated the geometry of the VRSNET network for the Real Time Kinematic (RTK) measurements that use base vectors solely from the analysed stations. Possible development of the VRSNET network through launching new reference stations was elaborated, too. The spatial analyses indicated the localisation and range of areas with an insufficient density of the VRSNET network. The locations of 16 new reference stations have been delimited on Polish territory. The VRSNET network with newly designed stations was reassessed for validation using the Voronoi/Thiessen diagram and spatial buffers. The results were compared with the parameters for the Active Geodetic Network – European Position Determination System (ASG-EUPOS). Improved RTK measurement geometric parameters resulting from the proposed scenario of the VRSNET network development have been demonstrated. Network density can also have a positive impact on the measurement results of the Network Real Time Kinematic (NRTK).
EN
Unmanned Aerial Vehicles (UAVs) equipped with photogrammetric or remote sensing instrumentations offer numerous opportunities in mapping and data collection for topographic modelling. An example is an emerging technique known as Structure-from-Motion (SfM) photogrammetry used for the collection of low-cost, high spatial resolution, three-dimensional data. This study utilised the real time kinematic-based point-to-point validation technique and two sets of randomly selected ground control points to assess the capability and geometric accuracy of SfM-technology for three-dimensional (3D) terrain mapping over a small study area to contribute to the knowledge of applicability. The data used was collected in Garscube Sports Complex, Glasgow City Council, Scotland. The study utilised fifteen (15) Ground Control Points (GCPs) coordinated by the Real Time Kinematic Global Navigation Satellite System (RTK GNSS) positioning technique, while a DJI Phantom 3 Professional unmanned aerial vehicle was used to obtain the aerial photos in a single flight to minimise cost. The processing of the photos was done using Pix4Dmapper Pro software version 4.2.27. A point-to-point validation method was used to evaluate the 3D positional accuracy of the orthophoto and DSM. The results of the validation with ten checkpoints suggest a high level of accuracy and acceptability given a Root Mean Square Error of 20.93 mm, 18.48 mm and 46.05 mm in the X, Y and Z coordinates respectively. In conclusion, the study has shown that SfM technique can be used to produce high-resolution and accurate topographic data for geospatial applications with significant advantages over the traditional methods. However, it is to be noted that the quality of the data captured is dependent on the methodology adopted and should be taken into consideration.
EN
Continuously Operating Reference Stations (CORS) are reference stations of the Global Navigation Satellite System (GNSS), providing fundamental positioning infrastructure that is accurate and reliable. As such, CORS are designed to meet the needs of a wide range of users requiring high three-dimensional (3D) positional accuracy. The Continuously Operating Reference Station at the Engineering Faculty (CREF), University of Lagos was set up in order to support research applications in Surveying, Mapping and Geodesy. This study evaluates the seasonal variations in the 3D coordinates of CREF using metrics such as coordinate differences, Standard Deviation (SD) and Standard Error (SE). The Canadian Spatial Reference System (CSRS), known as CSRS – Precise Point Positioning (CSRS-PPP) was used to compute the station’s daily coordinates over a three-year period from 2016 to 2018. In the analysis, the daily coordinates were divided into two seasons - the wet and the dry. The results obtained show that the dry and the wet seasons had SDs (5.4 mm, 3.9 mm, and 2.0 mm) and (5.2 mm, 18.6 mm and 14.4 mm) in the x, y and z-directions respectively. Generally, the dry season presents a better result than the wet season as revealed by the accuracy metrics. These results have led to an increased understanding of the seasonal variability inherent in the data acquired by GNSS CORS, and must be taken into consideration: in particular, for GNSS applications such as the weather prediction and water vapour estimation. This study concludes that more needs to be done regarding the maintenance of CREF to ensure data continuity and reliability for geodetic studies.
EN
The aim of the present study was to investigate the possibility of using smart phone grade GNSS receivers for surveying purposes and to examine their ac curacy in terms of positioning. The paper presents an analysis of the results of test measurements made using two smartphones: a Huawei P8 lite, powered by Android 6.0 and an iPhone 6s, operating on IOS 10.1.1. Both devices were equipped with GPS and GLONASS modules and had the supporting sys tem, A-GPS. Measurements were made on two test parcels of different shapes and sizes. The test procedure encompassed three measurement series (I–III), each of which consisted of five determinations. The determinations were done at 5-min time intervals and each new measuring session began after 90 min from the previous one. Measurements with the Huawei P8 lite were taken using the Locus Map app, and measurements with the iPhone 6s were performed with the use of Map o meter. The study consisted of determining the positioning accuracy of the test smartphones by comparing the results with reference coordinates obtained from RTN measurements using the Topcon HiPer V receiver with Magnet Tools software. Determinations of the reference coordinates were done with the help of the TPI NetPro network real time service corrections.
PL
Celem pracy jest odpowiedź na pytanie o możliwość wykorzystania odbiorników GNSS zainstalowanych w telefonach komórkowych typu smartfon do celów geodezyjnych oraz zbadanie dokładności wyznaczania pozycji. W pracy przeanalizowano wyniki pomiarów testowych wykonanych za pomocą dwóch smartfonów: Huawei P8 lite z systemem Android 6.0 oraz Iphone 6s z systemem IOS 10.1.1. Oba urządzenia wyposażone są w odbiornik GPS i GLONASS oraz system wspomagający A-GPS. Pomiary wykonano na dwóch działkach testowych o różnym kształcie i powierzchni. Procedura testowa obejmowała trzy serie pomiarowe, przy czym każda z nich składała się z pięciu wyznaczeń. Między kolejnymi wyznaczeniami zachowano odstęp czasowy 5 minut, a każda sesja pomiarowa rozpoczynała się po upływie 90 minut. W czasie pomiaru smartfonem Huawei P8 lite skorzystano z aplikacji Locus Map, zaś podczas pomiaru smartfonem Iphone 6s z aplikacji Map o meter. Działki testowe znajdowały się na terenie Lublin przy ulicy Józefa Sowińskiego. Badania polegały na określeniu dokładności wyznaczenia pozycji przez wybrane smartfony na podstawie porównania otrzymanych wyników ze współrzędnymi referencyjnymi uzyskanymi z pomiaru metodą powierzchniową RTN odbiornikiem Topcon Hiper V z oprogramowaniem Magnet Tools. W czasie wyznaczania współrzędnych referencyjnych skorzystano z poprawek serwisu czasu rzeczywistego sieci TPI NETpro.
EN
GNSS station movements as an indicator of the movement of the Earth’s crust are determined by many researchers with the use of various position and trend determination methods. One of such methods is PPP method which allows the determination of a trend for the station without a correlation (direct determination of the position of each station separately). To achieve accuracy comparable with relative positioning, there is the need to use external, high precision data or models (e.g. precise satellite orbits and clocks, ionosphere and tropo sphere models, etc.) while the PPP method is applied. The main purpose of the presented research is preliminary analyses of the results of processing daily GPS observations from permanent stations with the use of the PPP method. Daily GPS observational data in RINEX format have been acquired from a total of nine selected GNSS permanent stations from the Polish ASG EUPOS and the Ukrainian UA-EUPOS/ZAKPOS systems. As external data for PPP solutions JPL products have been used. A seven year time series was created for each station.
9
Content available remote Efficiency of using GNSS-PPP for digital elevation model (DEM) production
EN
In the developing countries, cost-effective observation techniques are very important for earthwork estimation, map production, geographic information systems, and hydrographic surveying. One of the most cost-effective techniques is Precise Point Positioning (PPP); it is a Global Navigation Satellite Systems (GNSS) positioning technique to compute precise positions using only a single GNSS receiver. This study aims to evaluate the efficiency of using Global Positioning System (GPS) and GPS/ Globalnaya Navigatsionnaya Sputnikovaya Sistema (GLONASS) post-processed kinematic PPP solution for digital elevation model (DEM) production, which is used in earthwork estimation. For this purpose, a kinematic trajectory has been observed in New Aswan City in an open sky area using dual-frequency GNSS receivers. The results showed that, in case of using GPS/GLONASS PPP solution to estimate volumes, the error in earthwork volume estimation varies between 0.07% and 0.16% according to gridding level. On the other hand, the error in volume estimation from GPS PPP solution varies between 0.40% and 0.99%.
EN
Fault detection and exclusion (FDE) is the main task for pre-processing of global navigation satellite system (GNSS) positions and is a fundamental process in integrity monitoring that is needed to achieve reliable positioning for applications such as in intelligent transport systems. A widely used method is the solution separation (SS) algorithm. The FDE in SS traditionally builds the models assuming positioning errors are normally distributed. However, in urban environments, this traditional assumption may no longer be valid. The objective of this study is to investigate this and further examine the performance of alternative distributions, which can be useful for FDE modelling and thus improved navigation. In particular, it investigates characterization of positioning errors using GNSS when the Australian satellite-based augmentation system (SBAS) test bed is used, which comprised different positioning modes, including single-point positioning (SPP) using the L1 global positioning system (GPS) legacy SBAS, the second-generation dual-frequency multi-constellation (DFMC) SBAS service for GPS and Galileo, and, finally, precise point positioning (PPP) using GPS and Galileo observations. Statistical analyses are carried out to study the position error distributions over different possible operational environments, including open sky, low-density urban environment, and high-density urban environment. Significant autocorrelation values are also found over all areas. This, however, is more evident for PPP solution. Furthermore, the applied distribution analyses applied suggest that in addition to the normal distribution, logistic, Weibull, and gamma distribution functions can fit the error data in various cases. This information can be used in building more representative FDE models according to the work environment.
EN
The need for accuracy, precision, and data registration in underwater positioning and navigation should be viewed as no less stringent than that which exists on the sea surface. In the same way in which GNSS (Global Navigation Satellite System) receivers rely on the signals from multiple satellites to calculate a precise position, undersea vehicles discern their location by ranging to the acoustic signals originating from several fixed underwater acoustic sources using the Time-of-Arrival algorithm (ToA) through the Ordinary Least Squares method (OLS). In this article, the scope has been limited to only considering underwater positioning systems in which the navigation receiver is acoustically passive. The receiver “listens” to the buoys, receives their messages and solves the problem of finding its own position based on the geographical coordinates of the buoys. Often, such systems are called GNSS-like Underwater Positioning Systems (GNSS-like UPS). It is important to note the distinction between general purpose GNSS-like UPS (mainly civil systems) and special purpose GNSS-like UPS (mainly military systems). In this article, only general purpose GNSS-like UPS systems have been considered. Depending on the scale of system’s service areas, GNSS-like UPS are divided into global, regional, zonal and local systems. Only local GNSS-like UPS systems have been considered in this article. The spoofing of acoustic GNSS-like UPS works as follows: the acoustic GNSS signal generator transmits a simulated signal of several satellites. If the level of the simulated signal exceeds the signal strength of the real satellites, the acoustic receiver of an underwater object will “capture” the fake signal and calculate a false position based on it. All receivers that fall into the spoofing zone will calculate the same coordinates, while the receivers located in different places will have a mismatch in the XYZ coordinates.
EN
Determining the course of a railway track axis using satellite methods relies on ensuring the precise assembly of GNSS receivers in dedicated measuring devices. Depending on the number of receivers, solutions that are based on placing the apparatus directly above the railway track axis (as well as in eccentric positions) are used to indirectly obtain data to form the basis of the desired results. This publication describes the installation of five GNSS receivers on a mobile measuring platform as part of the InnoSatTrack project. The methodology and the procedure of the geodetic measurements required to obtain the geometrical configuration of the measuring apparatus, specified in the technical project, are presented. The publication presents the principles of total station measurement methods as well as the steps taken to achieve precise results from staking out. The process of acquiring the same configuration of the GNSS receivers, based on the geometry of the squares on the two measuring platforms that were used in the research, has been shown. The final determination of the position of the receivers did not exceed an error of 0.010 m with an average error of 0.003 m, despite the occurrence of mounting difficulties. The results have demonstrated the high credibility and effectiveness of the presented solution.
13
Content available Cloud-based GNSS navigation spoofing detection
EN
Satellite navigation systems are commonly used to precisely determine the trajectory of transportation equipment. The widespread deployment of GNSS is pushing the current receiver technology to its limits due to the stringent demands for seamless, ubiquitous and secure/reliable positioning information. This fact is further aggravated by the advent of new applications where the miniaturized size, low power consumption and limited computational capabilities of user terminals pose serious risks to the implementation of even the most basic GNSS signal processing tasks. This paper has presented the advantage of Cloud-based GNSS Navigation, which facilitates the possibility of developing innovative applications where their particularities (e.g. massive processing of data, cooperation among users, security-related applications, etc.) make them suitable for implementation using Cloud-based infrastructure.
EN
The article discusses a method applied for combining the results of Global Navigation Satellite Systems (GNSS) and 75-year old triangulation measurements to estimate the crustal movements in central western Bulgaria region. It was examined for joint analysis based on the results of GNSS with angular measurements of the first order triangulation network in Bulgaria during the period 1923–1930 year. As a result of the processing of GNSS and angular measurements, horizontal velocities of 15 points, strain rates, and rotation rates have been obtained. The results show dominating N–S extension at a rate of 1–2 mm/y and the deformation is not uniformly distributed over the studied area. The obtained results indicate the possibility of using old angular measurement of first-order triangulation points, together with GNSS data, to obtain estimates of the horizontal crustal movements.
PL
W artykule dokonano empirycznej weryfikacji założeń dokładnościowych metody pomiaru położenia punktów z wykorzystaniem metody GNSS - RTN przy zastosowaniu poprawek sieciowych typu VRS i MAC, udostępnianych w ramach sieci stacji referencyjnych SmartNet firmy Leica Geosystem. Obserwacje zrealizowano w trzech niezależnych cyklach pomiarowych. Terminy zostały dobrane w taki sposób, aby zapewnić w każdym przypadku podobne warunki pomiarowe oraz atmosferyczne.
EN
The article performed an empirical verification of the assumptions of the precision method of measuring the location of points using the GNSS - RTN method, the VRS and MAC corrections and the Leica Geosystem’s SmartNet network. Observations were made in three measuring cycles. The dates were selected in such a way as to ensure similar measurement and atmospheric conditions on each day. The results of the measurements are presented in the following article.
PL
Omówiono wyniki permanentnych pomiarów pozycji stacji sieci GNSS (ang. Global Navigation Satellite Systems) celem określenia ewentualnych związków pomiędzy charakterystyką szeregów czasowych opisujących zmiany pozycji tej stacji a wystąpieniem wysokoenergetycznych zdarzeń sejsmicznych na obszarze Górnośląskiego Zagłębia Węglowego. Wykazano relacje czasowe pomiędzy obserwowaną sezonową zmiennością składowych horyzontalnych pozycji stacji wyznaczonych dzień po dniu z dobowych rozwiązań dla okresu 2008-2014 i tymi zdarzeniami. Zdarzenia o energii E>107 J miały miejsce zwykle w okresach, w których stacja wykazywała sezonowe przemieszczenia dla składowej N. Związki czasowe są szczególnie widoczne w przypadku wstrząsów zlokalizowanych w niedalekich odległościach od miejsca realizowanych pomiarów (stacja KATO).
EN
Results of permanent measurements of positions of GNSS stations are examined to determine eventual relations between characteristics of time series depicting changes of the positions and high energy seismic events in the area of The Upper Silesian Coal Basin. So temporal relations between seasonal changeability of the horizontal positions of the stations determined day by day from diurnal solutions for the period of 2008-2014 and those events are reported. Events with energy E>107 occurred usually in time intervals, when KATO GNSS station demonstrated seasonal displacements of N coordinate. Temporal relations are particularly clear in case of tremors located in near distances from the measurements (KATO station).
17
Content available Study of the GNSS Jamming in Real Environment
EN
GNSS systems are susceptible to radio interference despite then operating in a spread spectrum. The commerce jammers power up to 2 watts that can block the receiver function at a distance of up to 15 kilometers in free space. Two original methods for GNSS receiver testing were developed. The first method is based on the usage of a GNSS simulator for generation of the satellite signals and a vector signal RF generator for generating different types of interference signals. The second software radio method is based on a software GNSS simulator and a signal processing in Matlab. The receivers were tested for narrowband CW interference, FM modulated signal and chirp jamming signals, and scenarios. The signal to noise ratio usually drops down to 27 dBc-Hz while the jamming to signal ratio is different for different types of interference. The chirp signal is very effective. The jammer signal is well propagated in free space while in the real mobile urban and suburban environment it is usually strongly attenuated.
EN
This review paper presents research results on geodetic positioning and applications carried out in Poland, and related to the activities of the International Association of Geodesy (IAG) Commission 4 “Positioning and Applications” and its working groups. It also constitutes the chapter 4 of the national report of Poland for the International Union of Geodesy and Geodynamics (IUGG) covering the period of 2015-2018. The paper presents selected research, reviewed and summarized here, that were carried out at leading Polish research institutions, and is concerned with the precise multi-GNSS (Global Navigation Satellite Systems) satellite positioning and also GNSS-based ionosphere and troposphere modelling and studies. The research, primarily carried out within working groups of the IAG Commission 4, resulted in important advancements that were published in leading scientific journals. During the review period, Polish research groups carried out studies on multi-GNSS functional positioning models for both relative and absolute solutions, stochastic positioning models, new carrier phase integer ambiguity resolution methods, inter system bias calibration, high-rate GNSS applications, monitoring terrestrial reference frames with GNSS, assessment of the real-time precise satellite orbits and clocks, advances in troposphere and ionosphere GNSS remote sensing methods and models, and also their applications to weather, space weather and climate studies.
EN
This paper summarizes the activity of the chosen Polish geodetic research teams in 2015–2018 in the fields of Earth: rotation, dynamics as well as magnetic field. It has been prepared for the needs of the presentation on the 27th International Union of Geodesy and Geodynamics General Assembly, Montreal, Canada. The part concerning Earth rotation is mostly focused on the use of modelling of diurnal and subdiurnal components of Earth rotation by including low frequency components of polar motion and UT1 in the analysis, study of free oscillations in Earth rotation derived from both space-geodetic observations of polar motion and the time variation of the second degree gravitational field coefficients derived from Satellite Laser Ranging (SLR) and Gravity Recovery and Climate Experiment (GRACE) observations, new methods of monitoring of Earth rotation, as well as studies on applications of the Ring Laser Gyroscope (RLG) for direct and continuous measurements of changes in Earth rotation and investigations of the hydrological excitation of polar motion. Much attention was devoted to the GRACE-derived gravity for explaining the influence of surface mass redistributions on polar motion. Monitoring of the geodynamical phenomena is divided into study on local and regional dynamics using permanent observations, investigation on tidal phenomena, as well as research on hydrological processes and sea level variation parts. Finally, the recent research conducted by Polish scientists on the Earth’s magnetic field is described.
EN
Position time series from permanent Global Navigation Satellite System (GNSS) stations are commonly used for estimating secular velocities of discrete points on the Earth’s surface. An understanding of background noise in the GNSS position time series is essential to obtain realistic estimates of velocity uncertainties. The current study focuses on the investigation of background noise in position time series obtained from thirteen permanent GNSS stations located in Nepal Himalaya using the spectral analysis method. The power spectrum of the GNSS position time series has been estimated using the Lomb–Scargle method. The iterative nonlinear Levenberg–Marquardt (LM) algorithm has been applied to estimate the spectral index of the power spectrum. The power spectrum can be described by white noise in the high frequency zone and power law noise in the lower frequency zone. The mean and the standard deviation of the estimated spectral indices are […] for north, east and vertical components, respectively. On average, the power law noise extends up to a period of ca. 21 days. For a shorter period, i.e. less than ca. 21 days, the spectra are white. The spectral index corresponding to random walk noise (ca. –2) is obtained for a site located above the base of a seismogenic zone which can be due to the combined effect of tectonic and nontectonic factors rather than a spurious monumental motion. Overall, the usefulness of investigating the background noise in the GNSS position time series is discussed.
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