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Urban area GPS positioning accuracy using ASG-EUPOS POZGEO service as a function of session duration

Dawidowicz K., Krzan G., Świątek K.

Artificial Satellites : Journal of Planetary Geodesy

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2014

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Vol. 49, No. 1

33--42

EN

GNSS observations carried out in a network of Continuously Operating Reference Station (CORS) are a complex systems which offer post-processing as well as corrections sent in realtime. In Poland, such a system has been in operation since June 2008, known as the Polish Active Geodetic Network (ASG-EUPOS). Usually the measurements performed in real time characterized lower accuracy than static measurements. For users who demand the highest precision results the post-processing services are provided. The paper presents an analysis of the position determination accuracy using ASG-EUPOS POZGEO service. It is well known that the final accuracy is e.g. the measuring conditions, time of observations or number of measured frequencies dependent. We processed 4 consecutive days of GPS data to determine how the accuracy of derived positional coordinates depends on the length of the observing session, the characteristics of horizon visibility on points and the used in post-processing observations (L1 or L1+L2). The POZGEO results show that horizontal accuracies of about 1-2 cm and vertical accuracies of 4 cm are achievable provided 0.5 hours dual frequency GPS data. The accuracy clearly decreases for point measured under conditions of strongly limited satellite availability.

2

Evaluation of the possibility of using the predicted tropospheric delays in real time GNSS positioning

Kalita J. Z., Rzepecka Z., Krzan G.

Artificial Satellites : Journal of Planetary Geodesy

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2014

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Vol. 49, No. 4

179--189

EN

Among many sources of errors that influence Global Navigation Satellite System (GNSS) observations, tropospheric delay is one of the most significant. It causes nonrefractive systematic bias in the observations on the level of several meters, depending on the atmospheric conditions. Tropospheric delay modelling plays an important role in precise positioning. The current models use numerical weather data for precise estimation of the parameters that are provided as a part of the Global Geodetic Observation System (GGOS). The purpose of this paper is to analyze the tropospheric data provided by the GGOS Atmosphere Service conducted by the Vienna University of Technology. There are predicted and final delay data available at the Service. In real time tasks, only the predicted values can be used. Thus it is very useful to study accuracy of the forecast delays. Comparison of data sets based on predicted and real weather models allows for conclusions concerning possibility of using the former for real time positioning applications. The predicted values of the dry tropospheric delay component, both zenith and mapped, can be safely used in real time PPP applications, but on the other hand, while using the wet predicted values, one should be very careful.

3

Technologia zintegrowanych pomiarów klasycznych i satelitarnych GPS

Krzan G.

Biuletyn Wojskowej Akademii Technicznej

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2013

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Vol. 62, nr 4

47-61

PL

Integracja klasycznych i satelitarnych technik pomiaru znajduje coraz szersze zastosowanie w precyzyjnych pomiarach geodezyjnych. Połączenie zalet obu metod stanowi kolejny krok w wydajności i automatyzacji prac polowych geodety. Niniejsza praca przedstawia ideę i główne założenia pomiarów zintegrowanych, jako metody łączącej pomiary klasyczne i satelitarne GPS. Ponadto dokonano analizy dokładności wyznaczenia współrzędnych stanowiska tachimetrycznego metodą przestrzennego wcięcia wstecz, będącego istotnym elementem pomiaru zintegrowanego. Otrzymane wysokie dokładności pozwalają na pominięcie w pomiarach czasochłonnego procesu zakładania osnów pomiarowych i zastąpienie ich pomiarem zintegrowanym.

EN

Integration of classical and satellite measurement techniques is becoming widely used for high-precision geodetic measurements. Combination of advantages of both methods of measurement represents another step in performance and automation of field surveys. This article presents the idea and main characteristics of integrated measurement. It also compares integrated measurements with separated methods of classical and satellite measurements. In addition, the process and results of determining operating position by 3D resection were demonstrated. The obtained results allow us to undermine validity of setting up measurement control networks in areas with insufficient density of survey points.

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Analysis of current position determination accuracy in natural resources Canada precise point positioning service

Krzan G., Dawidowicz K., Świątek K.

Artificial Satellites : Journal of Planetary Geodesy

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2013

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Vol. 48, No. 3

111--124

EN

Precise Point Positioning (PPP) is a technique used to determine highprecision position with a single GNSS receiver. Unlike DGPS or RTK, satellite observations conducted by the PPP technique are not differentiated, therefore they require that parameter models should be used in data processing, such as satellite clock and orbit corrections. Apart from explaining the theory of the PPP technique, this paper describes the available web-based online services used in the post-processing of observation results. The results obtained in the post-processing of satellite observations at three points, with different characteristics of environment conditions, using the CSRS-PPP service, will be presented as the results of the experiment. This study examines the effect of the duration of the measurement session on the results and compares the results obtained by working out observations made by the GPS system and the combined observations from GPS and GLONASS. It also presents the analysis of the position determination accuracy using one and two measurement frequencies.