Global Navigation Satellite Systems (GNSS) have revolutionized land surveying, by determining position coordinates with centimeter-level accuracy in real-time or up to sub-millimeter accuracy in post-processing solutions. Although low-cost single-frequency receivers do not meet the accuracy requirements of many surveying applications, multi-frequency hardware is expected to overcome the major issues. Therefore, this paper is aimed at investigating the performance of a u-blox ZED-F9P receiver, connected to a u-blox ANN-MB-00-00 antenna, during multiple field experiments. Satisfactory signal acquisition was noticed but it resulted as >7 dB Hz weaker than with a geodetic-grade receiver, especially for low-elevation mask signals. In the static mode, the ambiguity fixing rate reaches 80%, and a horizontal accuracy of few centimeters was achieved during an hour-long session. Similar accuracy was achieved with the Precise Point Positioning (PPP) if a session is extended to at least 2.5 h. Real-Time Kinematic (RTK) and Network RTK measurements achieved a horizontal accuracy better than 5 cm and a sub-decimeter vertical accuracy. If a base station constituted by a low-cost receiver is used, the horizontal accuracy degrades by a factor of two and such a setup may lead to an inaccurate height determination under dynamic surveying conditions, e.g., rotating antenna of the mobile receiver.

The GNSS (Global Navigation Satellite System) coordinates time series are still used as a source for determining the velocities of GNSS permanent stations. These coordinates, apart from the geodynamical signals, also contain an interference signal. This paper shows the results of the comparative analysis of the GNSS coordinates time series with a deformation of the Earth's crust obtained from loading models. In the analysis, coordinates time series are used (CODE Repro2013) without loading models (Atmospheric Pressure Loading, Hydrology, Non-Tidal Ocean Loading) at the stage of the reprocessing of GNSS archival data. The analyses showed that in the case of the Up component there is a high correlation between the GNSS coordinates changes and deformations of the Earth's crust from the loading models (coefficient 0.5-0.8). Additionally, we noticed that for horizontal components (North, East) changes occur in the phase shift between coordinates, and the Earth's crust deformations signals are accelerated or delayed each other (-150 to 200 days). This article shows new methods of iLSE (iteration Least Square Estimation) to determine periodic signals in the time series. Additionally, we compared the values of estimated amplitudes for GNSS and deformation time series. ARTICLE INFO

Analysis of the time series of coordinates is extremely important in geodynamic research. Indeed, the correct interpretation of coordinate changes may facilitate an understanding of the diverse geophysical processes taking place in the earth’s crust. At present, when rigorously processing global navigation satellite system (GNSS) observations, the influence of deformations in the surface of the earth’s crust is not considered. This article presents signal modelling for the influence on the analysis of noise occurring in the time series of GNSS station coordinates. The modelling of coordinate time series was undertaken using the classic least-squares estimation (LSE) method and the inverse continuous wavelet transform (CWT). In order to determine the type of noise character, the coefficient spectral index was used. Analyses have demonstrated that the nature of noise in measurement data does not depend on the signal estimation method. The differences between classic modelling (LSE) of the time series with annual and semiannual oscillation and signal reconstruction are very small ( Δ κ = 0.0 ÷−0.2).

Recent geodynamic activity of the Sudeten in the area of Poland and the Czech Republic has been confirmed by the results of geodynamic, seismic, geodetic and other tests. This is especially the case for the periodical (the last 25 years) satellite GPS/GNSS and gravimetric measurements in the regional research network GEOSUD, SILESIA, SUDETY and the local geodynamic polygons ("Snieznik", "Stolowe Mts."), as well as observation of crack-gauges on several tectonic faults. Vertical movements are indicated in the maps of recent movements of the Earth's crust. Two adjacent countries in the area of the Sudeten achieved results from +0.5 mm/year to-2 mm/year with reference to the tide gauge on the coast of the Baltic Sea. They present absolute value received on the basis of a comparison of the results of repeated (in intervals of 20-30 years) measurements of 1 st order levelling lines. The characteristics of this data do not allow for an assessment of recent tectonic activity in the Sudety Mts. because the isolines of absolute velocities of vertical movements of the Earth's crust surface on the maps (Wyrzykowski, 1985; Kowalczyk, 2006; Vyskočil, 2002) present "smoothed" large-area changes without a proof of dynamic changes in the Sudeten tectonic zones. This paper presents results of analysis archival data on repeated measurement precise levelling networks. The results of analysis were used to produce maps of vertical movements of the Earth's crust surface. Analysis is focused on the part of levelling lines which intersect Sudeten main tectonic faults. This paper included methodology of data processing. In research period relative vertical movements of tectonic zones are referencing to the relative stable benchmark. The values of these velocities between-0.8 ÷ +0.8 mm/year confirm recent geodynamic mobility in this Central European area.

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This article presents an analysis of the extent of the impact of deformations of the earth’s crust resulting from geophysical models on changes in the coordinates of Global Navigation Satellite System (GNSS) stations. The author presents the results of analyses of the spatial correlation coefficient of deformation components for the non-tidal atmospheric loading (NTAL), non-tidal ocean loading (NTOL) and hydrological loading (HYDRO) models of geophysical deformation. In addition, the author calculated the correlation coefficients between station’s coordinate series to determine whether the deformations of the earth’s crust have a more global, large-area (regional scale) or local-range (local scale) impact, limited to the nearest of stations. In addition to correlation coefficients, the author analysed the similarity in periodic components between station coordinates by calculating the coherence between them. The results of the analysis showed that for the height components (Up), we observe the global range of deformation models, and the NTAL deformation has the greatest influence on the change in them. The lack of correlation between coordinate signals for horizontal components may result from specific local conditions in the place of the station, low-resolution of geophysical models and small amplitudes of these signals in relation to noise. An analysis of the coherence coefficients showed that each station coordinates shows completely different periodic components in the North, East and Up directions.

This research is focused on sensor fusion to determine the two-dimensional position and heading orientation using only low-cost sensors like GNSS receivers, IMU (without accelerometer and magnetometer), and odometry. In this task, we used classical extended Kalman Filter with additional observations as a control input (angular rate and odometry distance). The combination of high stability GNSS observation over time with short-term high accuracy IMU and odometry gives us a very accurate position and heading after fusion. As a result, we obtained a 0.62-degree accuracy for heading, 3.9 cm, and 2.2 cm for the position (North and East respectively). Additionally, we noticed and resolved a problem with time synchronization between sensors which is very important to get high-standard results (accuracy better than one decimetre).