## 2 Materials and Methods  
First, it is appropriate to mention the technology principle fundamentals of RTK receivers. RTK receivers calculate the absolute position of the phase centre of a GNSS antenna, like GNSS receivers, determining the position point anywhere on Earth's surface by estimating the pseudoranges from individual satellites moving in orbit [33]. As described in other papers [6; 34; 35], RTK uses observations to improve its positioning accuracy, which is doubly differentiated by a common pseudorange estimate and a correction signal. The correction signal is usually received from a stationary RTK receiver, called a \"base station\". It is possible to use a dedicated base station [1; 29] or to rent corrections from a base station of the built RTK correction network without the need to build a new one [26]. The base station must be located several kilometres from the RTK receiver. In some of the cases described in the literature [7; 13], the desirable distance is up to 10 km or even 5 km, in some cases. The work of the authors of reference [17] described the Virtual reference Station (VRS) method based on the principle of a base station arbitrarily located in the vicinity of the surveyed area. The author of reference [7] compared VRS corrections with a common source of corrections. A more comprehensive pairwise comparison of the GNSS survey methods PPP and NRTK and static mode solutions was presented by the authors of reference [34]. There, the highest agreement was confirmed for the NRTK and static mode methods at the expense of the PPP method. This study reported only a relative accuracy relationship; a comprehensive statistical evaluation was lacking. The study focused only on the marginal deviations (minimum and maximum) in three directions. The work of the authors of reference [35] focused on a detailed investigation of the dependence of the carrier-to-noise ratio (C/N\({}_{0}\)) on the satellite elevation angle, base station baseline and frequency. One low-cost multifrequency RTK receiver u-blox ZED-F9P was used for verification, and it was confirmed that, even in static measurements, this receiver showed \(SSR\) ranging from 43.3% to 97.9%. This study also showed a twofold degradation in the vertical accuracy when replacing the fixed base station with an identical low-cost RTK receiver. The use of so-called \"moving base\" technology was suggested as a suitable alternative for precision agriculture [36]. Scientific resources from the agricultural sector have not been devoted to this technology. Yet, a base station placed on a moving device could be used for corrections, allowing for the reduction of the baseline between the base and the rover. In general, RTK positioning errors arise from the same causes as the GNSS. As described by [PERSON] and [PERSON], the so-called multipath signal propagation can have a negative effect on a system's accuracy, especially in environments with high obstacles obscuring the view of the orbit [37]. These and other typical reasons were described by the author of reference [23] and summarised by the collective authors of reference [38] as follows: the influence of signal transmission changes through the atmosphere (troposphere and ionosphere), deviations of ephemeris calculations (satellite trajectory), deviations of the satellite clock, construction properties and the location of the antenna. Especially, RTK receivers generally fail to solve the phase integer ambiguity of a signal for the measurement of the pseudorange. If they are able to solve this ambiguity, their measurements are precise [17]. In contrast to older technologies, today's low-cost RTK receivers use only single-frequency and single-GNSS RTK methods [19]. As a result, the use of RTK receivers operating as multi-frequency and multi-GNSS allows for a successful estimation of the ambiguity. The authors of reference [39] compared a single-frequency RTK receiver using GPS with a combination of GPS + GLONASS and concluded with a positive result of the latter.