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Assesment of Galileo High Accuracy Service
Nosek, Jakub ; Douša, Jan ; Václavovic, Pavel ; Kala, Michael
The paper deals with the testing of the Galileo High Accuracy Service (HAS), which will be officially launched in January 2023 as part of the HAS Initial Service phase. The results of the HAS comparison with the precise GNSS product showed a high accuracy of the HAS corrections and the fulfillment of the declared accuracy. Data processing at 3 selected stations of the EUREF Permanent Network showed that the officially declared HAS accuracy (horizontal accuracy 20 cm, vertical accuracy 40 cm) is achievable, but with a longer required convergence time (kinematic processing 22 min, static processing 8 min) than the required convergence time (5 min).
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Precise Real-Time GNSS Positioning Using Different Correction Representation
Nosek, Jakub ; Václavovic, Pavel
The paper deals with the comparison of the Real Time Kinematic (RTK) method and the Precise Point Positioning (PPP) method with fast ambiguity resolution (PPP-RTK). Both methods use different correction models that affect their results. Data from 6 permanent GNSS stations from 28th August 2022 to 30th August 2022 were processed. The results show that the RTK method provides increasingly accurate results (standard deviations of the NEU coordinate components sN = 0.003 m, sE = 0.002 m, sU = 0.006 m). The PPP-RTK method provides slightly worse results (sN = 0.011 m, sE = 0.009 m, sU = 0.028 m). On the other hand, it is more independent of current problems in the network of reference stations.
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Contribution to Monitoring of Galileo Open Service
Douša, Jan ; Kala, Michael ; Václavovic, Pavel ; Bezděka, Petr
Since 2018, the analysis center of the Geodetic Observatory Pecný (GOP) of the Research Institute of Geodesy, Topography and Cartography has contributed to navigation performance monitoring of the Galileo Open Service (OS) Signal in Space (SIS). The activity is performed within the Member States support of the Galileo Reference Centre (GRC), the GRC-MS project. The contribution consists of the four main tasks: 1) monitoring of the quality of multi-GNSS data from 65 GRC-MS reference stations, 2) generating merged and quality controlled navigation files, 3) generating reference GPS and Galileo satellites orbit and clock products with a maximum latency of 6 and 42 hours, and 4) estimating selected key-parameter indicators for the Galileo OS navigation performance consisting of the service volume availability of dual-frequency OS SIS and PDOP < 6, and the site-measured horizontal and vertical positioning service accuracy. The main advantage of the GOP monitoring processes including all the mandatory inputs consists in used tools (the G-Nut software), reference products (GOP rapid precise satellite orbits and clocks), and consolidated navigation messages, in particular their independence from the service provider or any GRC or GRC-MS solution.
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Acceleration of PPP Integer Ambiguity Resolution When Emploing Ionospheric Delays
Nosek, Jakub ; Václavovic, Pavel ; Zhao, Lewen ; Douša, Jan
Precise Point Positioning (PPP) is a powerful method for GNSS data processing, when observations from only one receiver are utilized. Since any systematic error is not eliminated by between-stations differencing, introduced precise products and models are crucial for precise positioning. While precise satellite orbits and clocks corrections are essential for traditional float PPP, satellite phase biases are required for integer ambiguity resolution (PPP-AR). When considering also local ionospheric and tropospheric parameters, the integer ambiguity resolution is achievable very fast, which helps to reduce the initial convergence significantly. When exploiting such precise atmospheric corrections, the solution can be considered an alternative for the popular Real Time Kinematic (RTK) method. Therefore, the solution is usually abbreviated by PPP-RTK. We processed daily GNSS data from EUREF Permanent Network (EPN) using PPP, PPP-AR, and PPP-RTK. The tropospheric delay was not introduced as a product but estimated together with other parameters. The assessment of the convergence time has shown a significant benefit of the resolved integer ambiguities. The average time to reach 10 cm horizontal accuracy was 22, 11, and 7 min when processing in PPP, PPP-AR, and PPP-RTK mode, respectively. The first fixed epoch was obtained after 10 and 2 minutes in the case of PPP-AR and PPP-RTK, respectively. The accuracy assessment of Slant Total Electron Content (STEC) estimated at collocated stations showed their good consistency expressed by the average standard deviation of 0.08 TEC Units.
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Geodetic Observatory Pecny GNSS Analysis Supporting Solid Earth Tide Modelling
Nosek, Jakub ; Douša, Jan ; Václavovic, Pavel ; Běloch, Lukáš
The TILDE project deals with local solid Earth tide (LSET) modeling based on direct LSET observations using long-term GNSS time series. Geodetic Observatory Pecný of the RIGTC contributes to the TILDE project by processing GNSS data. We collected GNSS data from 98 stations, which were divided into three subnetworks. Quality control of all observational data was performed using advanced tools from the G-Nut library. High-accuracy GNSS processing using the GNSS-PPP method was performed using REPRO_2020 precise products by the CODE. The results were coordinate displacement component data. Based on these data, LSET models from individual critical areas will be created. These LSET models can be used to assess the risks of earthquakes and volcanic activity caused due to LSET.
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