Over the past decade, the development of low-cost GNSS (Global Navigation Satellite System) sensors has enabled them to partially replace professional devices in certain kinematic positioning and spatial georeferencing tasks. A challenge remains, however, as studies systematically assessing their quality and operational limitations are inconsistent and lag behind the rapid technological advancement of these sensors. The primary aim of this doctoral dissertation was to conduct a systematic comparison of the performance of the low-cost sensors u-blox ZED-F9P, ZED-F9R and Septentrio Mosaic-X5 against the professional Leica GS18 T and Septentrio AsteRx-U, evaluating their performance in different environments, including on land, in the air, and over water. The main focus of the doctoral dissertation was the practical evaluation of low-cost GNSS sensors and the assessment of positioning and georeferencing quality in comparison with higher-accuracy spatial data obtained from terrestrial measurements. In parallel, we developed a methodology to evaluate achievable accuracy and define the key limitations of their operation in kinematic mode. Special attention was given to analyzing processing results from one or multiple GNSS constellations across different frequency bands, the potential for mitigating multipath effects in various environments, and the integration of GNSS sensors with an inertial measurement unit using an extended Kalman filter for combined measurement integration. Experiments were conducted in areas with unobstructed signal reception, near tall structures, and over water surfaces, where signal reflections and interruptions most significantly hinder GNSS positioning based on carrier-phase observations. The test results indicate that the use of multiple GNSS constellations significantly increases the number of observations and often enables centimeter-level positioning accuracy, even under challenging measurement conditions with limited signal reception due to the presence of obstacles. A key factor in achieving improved positioning accuracy is the inclusion of observations from the L5 frequency band, particularly when positioning with a single GNSS constellation. Analysis of multipath effects in different environments showed that a calibrated low-cost antenna substantially reduces these effects on land and in the air, while over water the differences between using a simple and a calibrated antenna are less pronounced. Consequently, and due to other external factors, positioning over water surfaces remains more challenging and less accurate than in the air or on land.
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