## 6 Modeling the Sensitivity of UAV-TEM Technology Based on the Obtained Data  
Electromagnetic survey data obtained in a real case allows one to assess the sensitivity of the created UAS and simulate the effectiveness of its application in other geological situations.  
Using the methods and 3D modeling programs developed by the authors [28; 34; 35], a preliminary analysis of obtained data was carried out, the approximate front of the current decay in the transmitter line and the possible range of signal measurement were determined. Figure 13 shows a graph of changes in the signal along survey line 3, which shows that in the range of 50-140 us, this technology allowed us to confidently map the contact of environments.  
After that, 3D modeling was carried out in order to study the resolution of the measuring system, taking into account the characteristics obtained in practice. A three-dimensional model of the geological environment was created, which is a contact of rocks with different resistance (1000 \(\Omega\cdot\)m and 5000 \(\Omega\cdot\)m), and containing a local conducting object with a resistance of 5 \(\Omega\cdot\)m and dimensions of about 200 \(\times\) 400 \(\times\) 20 m, which corresponds, for example, to a concentration of sulfide minerals (Figure 14a,b). Modeling was carried out for two depths of the object: h = 30 m and h = 100 m. The results of modeling the data obtained using the UAV-TEM technology for this geological environment are shown in Figure 14c-f in the form of graphs of changes in the measured signal at time delays of 80 us and 150 us along two survey lines. The survey lines were located on different sides of the transmitter line and therefore the signals along them had different signs. Survey line 3 intersected the projection of the local object, but survey line 7 did not. In Figure 14c-f bold red line on the abscissa axis shows the interval of intersection of survey line 3 with the projection of the object.  
Figure 12: (a) Geological map corrected according to the results of the UAV-TEM: 1—metasedimentary deposits, 2—granites, 3,4—zones of faults; (b) original geological map: 2—metasedimentary deposits, 3—granites, 5—faults.  
The signal clearly shows an anomaly from both the separation of environment with different electrical resistance, and from a local conducting object located both at a depth of 30 m and at a depth of 100 m. At the same time, a sufficiently high anomaly is observed both above the survey line that intersects the object (its projection) and above the survey line that does not cross the object. For a deep object, even the magnitude of the anomaly is approximately the same on these survey lines. In addition, at a time delay of 80 \(\upmu\)s, the anomaly manifests itself on the side of the deep object. This is particularly problematic when using 1D inversion, but not particularly difficult when using geometric 3D inversion [28, 35]. Thus, it is shown that the developed UAS allows solving the problems of geological mapping and searching for local inhomogeneities not only in the case considered in Section 5, but also in the general case.  
Figure 13: Decay of current in the transmitter **(a);** an example of the convergence of the calculated transient curve with the practical one **(b);** plot of signal measurement along survey line 3 at a time delay of 80 \(\upmu\)s **(c).**