# Bistatic Sea Clutter Suppression Method Based on Compressed Sensing Optimization
## 4 Simulation
### Simulation Experiment 1  
Based on the analysis and modeling of signals in Section 2.1, we simulate and construct two sets of mixed echoes consisting of target reflection signals, bistatic sea clutter, and thermal noise. Subsequently, we reconstruct and suppress the sea clutter in the mixed echo. The basic simulation parameters are: radar operating frequency \(f_{c}=3\) GHz; Bragg peak frequency \(f_{\text{Bragg}}=5.19\) Hz; the target Doppler frequency is \(f_{\text{tar}}=4\) Hz; the target reflection signal and sea clutter signal-to-clutter ratio of two sets of mixed echoes are \(\text{SCR}1=-25\) dB and \(\text{SCR}2=-30\) dB, respectively; Meanwhile, the degree of peak splitting and spectral broadening under \(\text{SCR}2\) conditions is more severe than that under \(\text{SCR}1\) conditions. Figure 4 shows the comparison of echo power spectra before and after sea clutter suppression using different algorithms under the condition of \(\text{SCR}1=-25\) dB. The degree of sea clutter spectrum peak splitting and spectrum broadening is relatively slight. From Figure 4, it is evident that without sea clutter suppression, the bistatic first-order sea clutter is obviously stronger than target reflection signals, and the sea clutter component occupies the main part of the range unit signal. Both the traditional root method and the SVD method have a certain suppression effect on the bistatic first-order sea clutter. Obviously, the power of the first-order sea clutter Bragg peak and the broadened sea clutter near Bragg peak significantly reduced after the cancellation and suppression. Further, Figure 4a-c strongly illustrates that the proposed method has a better suppression effect. Applying this method to suppress sea clutter, the frequency unit where the target signal is located is 2.1 dB higher than the highest value of the other frequency domain units, which makes it easier to extract target information in subsequent processing. Figure 5 shows the comparison of echo power spectra before and after sea clutter suppression using different algorithms under the condition of \(\text{SCR}2=-30\) dB. The degree of sea clutter spectrum peak splitting and spectrum broadening is relatively serious. Comparing the processing effects of three different algorithms in Figure 5a-c, it can be seen that the root method is basically the same as the SVD method. After the suppression processing by the two traditional methods, the power of the strongest frequency unit in the remaining sea clutter is equivalent to the power of the target reflection signal, but the root method has a large frequency estimation error. By contrast, the proposed method has a significantly better suppression effect because it can accurately reconstruct the broadened first-order sea clutter interference signal. Consequently, the remaining components of sea clutter after reconstruction and cancellation are substantially reduced. Following suppression by this method, the frequency unit where the target reflection signal is located is 4 dB higher than the highest value of the other clutter frequency domain units. Therefore, it is easier to extract target information in subsequent processing. These three methods essentially reconstruct sea clutter through parameter estimation, and then utilize the reconstructed results to cancel and suppress. Here, we compare the performance of three methods with the sea clutter Bragg peak Doppler frequency estimation error, interference reduction amplitude, and the difference value of power between the target and the maximum clutter as the metrics. Taking \(\text{SCR2}=-30\) dB as an example, we repeat the experiment 200 times, presenting the mean values of the three metrics in Table 1.  
Based on Table 1, it is evident that the proposed method can effectively decrease the estimation error in Bragg peak Doppler frequency, while enhancing the performance of interference suppression when compared to the two conventional methods.