# A Comparative Study of Signal Processing Methods for Contactless Geodetic Monitoring
## 5 Conclusions  
Methods of the dynamic response of building structures for function practice represent an extremely important area. With such measurements, we obtain the information needed to analyze the behavior of structures. There are many ways to perform such measurements, but today in this area, preference is given to methods that can be performed using contactless monitoring with which we can observe the structure very accurately at a relatively large distance regardless of the size and accessibility of measuring points. Geodetic non-contact monitoring is based on the analysis of measured signals. In our case, we performed monitoring with three different geodetic instruments on the bridging structure, which was loaded with four mutually different load tests. We used two robotic total stations (RTS Leica TS30 and RTS Leica TS50) and a global navigation receiver (GNSS Topcon Hiper Pro). Simultaneously with the geodetic monitoring, we also performed measurements with the help of physical measuring equipment Instantel Minimate Plus, which helped us to compare and evaluate the accuracy of the measured values with which we can control the dynamic response of such structures. For each type of equipment used, we performed an analysis of the results of the measured values. The general finding of the useful value of measurements with GNSS measuring equipment is that this equipment enables the monitoring of the dynamic response, but the results of the dynamic monitoring are not sufficiently accurate for struction practice. We found that for a frequency spectrum above 10 Hz accompanied by small displacements, the measurements are not accurate enough. This equipment is only useful for measuring larger displacements at low frequencies over a long period of time. The error of the GNSS method in our case can be attributed to the incorrectly selected RTK method. To determine the dynamic response, it would make more sense to use the static GNSS method, which provides us with more accurate and reliable results. In the analysis of monitoring with RTS geodetic equipment, we found that the results obtained in the frequency range between 6 and 26 Hz are comparable. We observed minor deviations on the basis of which we can conclude that the frequency of signal capture has a decisive influence on the accuracy of measured values. In analyzing the results, we found that the use of algorithms for spectral analysis such as FFT and LS represents a very good mathematical tool that allows the interpretation of the frequency components of the oscillation. Both used total robotic stations--RTS in the frequency range between 6 and 26 Hz enabled engineeringly accurate monitoring. The mutual comparison of the results of dynamic response measurements with geodetic measuring equipment determined by the dominant frequency is, in all cases, a comparable value, even in the case of measurements with physical measuring equipment. Monitoring the dynamic response of a bridging structure with geodetic and physical equipment presented in this article provides representative and useful results for struction practice. The use of geodetic monitoring, which must be monitored by physical monitoring, represents a very reliable and technically perfect possibility for monitoring the behavior of the facility during its use. **Author Contributions:** Conceptualization, B.K. and S.L. ; methodology, S.L. ; software, B.K. ; validation, B.K. and S.L. ; formal analysis, B.K. ; investigation, S.L. and B.K. ; resources, B.K. ; data curation B.K. and S.L. ; writing--original draft preparation, B.K. and S.L. ; writing--review and editing, B.K. and S.L. ; visualization, B.K. ; supervision, S.L. ; project administration, B.K. All authors have read and agreed to the published version of the manuscript. This research received no external funding. **Institutional Review Board Statement:** Not applicable. **Informed Consent Statement:** Not applicable. **Data Availability Statement:** The data presented in this study are available on request from the corresponding author.