## 5 Laboratory Tests and Real-Time Validation
### FPGA Design and BEE-Cube SDR
Speed of center variation changes from 500 to 3 k (rad/s) and JSR changes from \(-15\) dB (weak power) to 0 dB (powerful). Because the detector is benefiting from the smooth power spectrum, it has outstanding results in weak narrowband detection; however, it is more sensitive to the speed of center variation. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \begin{tabular}{c} **Center** \\ **Frequency** \\ \end{tabular} & \begin{tabular}{c} **Signal** \\ **Bandwidth** \\ \end{tabular} & \begin{tabular}{c} **Transmitted** \\ **Signal** \\ **Power** \\ \end{tabular} & \begin{tabular}{c} **SDR** \\ **Sample** \\ **Rate** \\ \end{tabular} & \begin{tabular}{c} **\(\mathbf{\alpha}\)** \\ **Parameter** \\ \end{tabular} & \begin{tabular}{c} **Desired** \\ **Precision** \\ \(\mathbf{\varepsilon_{T}}\) \\ \end{tabular} & \
\begin{tabular}{c} **Downsampling** \\ **Factor** \\ \end{tabular} &
\begin{tabular}{c} **FFT Size** \\ **of Intererences** \\ \end{tabular} \\ \hline
1.28 GHz & 5 MHz & \(-40\) dBm & 40 MHz & 0.9 & 0.001 & 2 & 2048 & 3 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Parameters used for the practical test. Figure 17: Block diagram of test bench set up for practical and real-time test. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \begin{tabular}{c} **Variation Speed of Center** \\ **Frequency (rad/s)** \\ \end{tabular} & \begin{tabular}{c} **JSR = \(-15\) dB** \\ \end{tabular} & \begin{tabular}{c} **JSR = \(-10\) dB** \\ \end{tabular} & \
\begin{tabular}{c} **JSR = \(-5\)** \\ \end{tabular} &
\begin{tabular}{c} **JSR = 0 dB** \\ \end{tabular} \\ \hline
500 & 97.21 & 98.21 & 99.01 & 99.84\% \\ \hline
1 k & 95.72 & 96.68 & 97.58 & 98.21 \\ \hline
1.5 k & 93.64 & 95.01 & 96.01 & 96.45 \\ \hline
2 k & 92.01 & 92.2 & 94.26 & 93.27 \\ \hline
2.5 k & 90.3 & 91.06 & 92.36 & 92.07 \\ \hline
3 k & 89.47\% & 90.1 & 91.09 & 91.58\% \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Detector performance in the practical test. Figure 18a represents one example of the DVB-S2 power spectrum and multiple CWIs with different power and center frequencies. Figures 18b,c compares mitigation with adaptive notch bandwidth adjustment and notch filter with constant bandwidth. When the notch filter is used with a fixed \(r\) value, part of the interference remains and the desired signal spectrum is damaged more for a larger gap. In the adaptive system (Figure 18c), calculated optimum \(r\) parameters are saved inside the FPGA design as LUT and the detector adjust the notch bandwidth based on the interference power measurement. The filtered signal is completely interference free and a very small amount of valuable data got removed in the process. Now, let us look at the DVB-S2 receiver protected by the proposed algorithm. In a digital receiver, the final product and the output of the last physical layer block are the symbols that are represented in the two-dimensional signal constellation. Quality  
Figure 18: Example of MCWI on the power spectrum of the DVB-S2 signal represented by Technronic; (**a**) three peaks of MCWI before filtering; (**b**) example of notch filtering with constant bandwidth; (**c**) spectrum enhancement by notch filtering with adaptive bandwidth. of reception can be expressed by measuring the distance of received symbols from the original points of constellation. The interference and noise deflect the received symbols from the original transmitted shape and make the distance between the original points and received symbols different. By taking distance, SNR and quality of service decrease [37]. Figure 19a explains that, in the presence of CWI, received symbols spread on a circle by the ratios related to the interference power and it degrades the user QoS dramatically and causes residual error in the data stream. After mitigation (Figure 19b), symbols shape of the original signal constellation and SNR improves hugely. Figure 19c compares the received SNR with the DVB-S2 receiver in different situations.