## 2 The Measuring System for Monitoring Vibrations of Building Structures
Examples of selected En values for one sample in one location from the interlaboratory comparison are presented in Table 3.  
The measurement system was developed in the LabVIEW (National Instruments) development environment. LabVIEW is a graphical development environment (Figure 8). Its biggest advantage is the easy integration of input/output devices, such as measurement cards, devices compatible with the GPIB, PXI, and IMAQ standard, and PLC controllers. LabVIEW environments provide tools for controlling and retrieving data from hardware. Input data can be entered directly by the user, come from data stored on the disk, come from control and measurement equipment, from network sources based on standard communication protocols (TCP/IP, FTP, etc. ), and from internal environment protocols (e.g., data socket). Data processing in the basic version is limited to implementing algebraic, logical, and trigonometric functions. More advanced environment distributions have predefined groups of subroutines, allowing to use more complex functions to do more or less complex calculations: filtering, spectral analysis, FFT transform, and Hilbert transform. Communication with the equipment can be carried out using devices connected locally by cable or wireless, and devices with a network interface or using the http protocol and websites. The measurement system developed in the LabVIEW version 2019 is dedicated to work in MS Windows 10 and newer operating systems. The following stages can be distinguished in the system (Figure 9):  
* Initial declaration of the program's working time (e.g., 1 week),
* Parallel readout of measurement values from 3 accelerometer channels,
* Filtering the signal with a low-pass filter,
* Filter data with 1/3 octave filter, \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Middle Frequency (Hz)**} & \multicolumn{3}{c}{**Accredited Laboratory**} & \multicolumn{3}{c}{**Developed System**} \\ \cline{2-6}  & \multicolumn{3}{c}{**Peak Acceleration in 1/3 oct (\(\mathrm{m}\cdot\mathrm{s}^{-2}\))**} & **En** **(-)** \\ \cline{2-6}  & **Direction X** & **Direction Y** & **Direction X** & **Direction Y** & **(-)** \\ \hline
1 & 0.00005 & 0.00005 & 0.00007 & 0.00050 & 0.32 \\ \hline
2 & 0.00005 & 0.00007 & 0.00009 & 0.00029 & 0.26 \\ \hline
5 & 0.00007 & 0.00011 & 0.00010 & 0.00017 & 0.11 \\ \hline
10 & 0.00009 & 0.00021 & 0.00017 & 0.00030 & 0.11 \\ \hline
20 & 0.00068 & 0.00147 & 0.00079 & 0.00179 & 0.06 \\ \hline
50 & 0.00886 & 0.04412 & 0.00751 & 0.04184 & 0.02 \\ \hline
100 & 0.03168 & 0.06526 & 0.01366 & 0.04622 & 0.12 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Exemplary, selected En values for one sample in one location from an interlaboratory comparison. * Numerical integration,
* Generating the dependence \(A_{max}=f(f)\) (maximal amplitude of acceleration versus frequency),
* Comparison of the characteristics of \(A_{max}=f(f)\) with the values permitted by the standard [37],
* Data export as a CSV file (comma-separated values) to a webserver,
* Data formatting according to the template applied on the webserver,
* Presentation of data to the user. For the end user, a panel created on a public webserver is tested. The panel will be accessible via web browsers, as shown in Figure 10. Access to the panel is protected by a password. After logging in, the user has access to dedicated measurement systems. Figure 8: A sample part of the code of the data acquisition and processing system developed in the LabVIEW environment. Figure 9: Simplified algorithm of the basic part of the LabVIEW data acquisition system. After selecting a specific location of the measurement system, six groups of data are made available:  
* \"Current data--Description\"--daily summary of data on the maximum values of accelerations in three axes, maximum values of speeds in three axes, maximum values of the normative WODB index, and a summary in the form of qualifying vibrations to one of the normative vibration impact zones on the object (Figure 11).