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Aplikace Galileo High Accuray Service
Kazmierski, Kamil ; Hadas, Tomasz ; Kudłacik, Iwona ; Marut, Grzegorz ; Madraszek, Szymon
Since January 2023 the Galileo High Accuracy Service (HAS) is available to registered users. Within the HAS users can retrieve clock and orbit corrections, as well as code biases for Galileo and GPS constellations. Galileo HAS covers almost the entire globe and is the next system, after the Japanese CLAS (Japanese Centimeter Level Augmentation Service) and the Chinese PPP-B2b, that provides corrections via a satellite signal. These Galileo corrections are transmitted in the Galileo E6 signal but also via the Internet stream. The official HAS Service Definition Document indicates that the positioning accuracy is better than 25 cm and better than 30 cm for horizontal and vertical components, respectively. HAS corrections can be used in difference real-time applications without Internet connection. The presented work shows the use of Galileo HAS corrections in various geoscience applications such as positioning, timing, troposphere monitoring or coseismic vibrations detection. Additionally, the quality of the transmitted HAS correction is also verified using the SISRE parameter. The computations are carried out in the in-house developed GNSS-WARP software with the Internet HAS corrections saved in the ASCII files by the BKG Ntrip Client software. The Galileo HAS corrections quality using SISRE parameter equal to 8.6 cm and 13.0 cm for GPS and Galileo respectively. The experiment with Precise Point Positioning reveal sub-decimeter and centimeters accuracy in kinematic and static approach, respectively. In terms of timing precision Galileo HAS ensure precision of single nanosecond. Zenith Tropospheric Delay estimation with the use of evaluated corrections meet the requirement of troposphere monitoring and coseismic vibrations detection was also possible.
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Kvalita multi-GNSS přesného určení polohy bodů pomocí stochastického modelování parametru hodin
Mikoś, Marcin ; Kazmierski, Kamil ; Sośnica, Krzysztof
The quality of the International GNSS Service (IGS) station coordinates depends, among other things, on the type of oscillator located at the station in undifferenced GNSS solutions. A distinction of the clock standards can be made between internal, rubidium, cesium, and hydrogen maser clocks. The stability of time standards can vary by several orders of magnitude depending on the type of clock. Highaccuracy clocks allow for the introduction of stochastic modeling in the absolute positioning algorithms which contributes to faster solution convergence and superior position accuracy. In the Precise Point Positioning (PPP) measurement technique based on multi-GNSS, the clock parameter may be determined in two ways. Either it is estimated separately for each system, or a single clock parameter is determined for all systems, taking into account the inter-system biases. In this paper, we analyze the impact of stochastic modeling imposed on clock parameters on positioning in a multi-GNSS PPP solution. We use selected IGS stations observing GPS, GLONASS, Galileo, and BeiDou satellites. All analyses for the clock parameter are conducted for different types of oscillators along with the performance characteristics for each system. An important advantage of modeling the clock parameter is to stabilize the station vertical coordinate component in multi-GNSS PPP solutions.
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