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.

One of the most critical factors which determine the accuracy of deformation maps provided by Differential Synthetic Aperture Radar Interferometry (DInSAR) are atmospheric artefacts. Nowadays, one of the most popular approaches to minimize atmospheric artefacts is Generic Atmospheric Correction Online Service for InSAR (GACOS). Nevertheless, in the literature, the authors reported various effects of GACOS correction on the deformation estimates in different study areas Therefore, this paper aims to assess the effect of GACOS correction on the accuracy of DInSAR-based deformation monitoring in USCB by using Sentinel-1 data. For the accuracy evaluation, eight Global Navigation Satellite Systems (GNSS) permanent stations, as well as five low-cost GNSS receivers were utilized. GACOS-based DInSAR products were evaluated for: (1) single interferograms in different geometries; (2) cumulative deformation maps in various geometries and (3) decomposed results delivered from GACOS-based DInSAR measurements. Generally, based on the achieved results, GACOS correction had a positive effect on the accuracy of the deformation estimates in USCB by using DInSAR approach and Sentinel-1 data in each before mentioned aspect. When considering (1), it was possible to achieve Root Mean Square Error (RMSE) below 1 cm for a single interferogram for only 20% and 26% of the ascending and descending investigated interferograms, respectively when compared with GNSS measurements. The RMSE below 2 cm was achieved by 47% and 66% of the descending and ascending interferograms, respectively.

EPOS-PL+ is the Polish national realization of the European Plate Observing System (EPOS) project that aims to build a multidisciplinary infrastructure. It allows integration of a variety of geoscience expertise and techniques to better understand the geohazard related to the underground mining of coal in the Upper Silesian Coal Basin (USCB) in Poland. The study case in this project is the Marcel Mine, located within USCB, where the detected subsidence for the analyzed period of four months reaches 91 cm. Various interferometric processing techniques demonstrated some advantages and also some limitations in the context of mining deformation measurement, including accuracy, spatial resolution, detectable deformation rate, atmospheric delay, and  ability to detect the maximal deformation gradients. This is especially important from a mining perspective. Therefore, we investigated three different interferometric processing techniques to monitor fast mining deformation in the Marcel hard coal mine area. More specifically, we used conventional DInSAR, Small Baseline Subsets (SBAS), and Persistent Scattered Interferometry (PSInSAR). The result confirmed that none of these methods can be considered as the best. The DInSAR approach allows capturing the maximal deformation gradient, which was not possible with the PSInSAR and SBAS approaches. On the contrary, PSInSAR and SBAS allow us to provide less noisy and reliable results in the area of safety pillars.

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