## 3 Proposed Jamming Suppression Method
### Analysis of Performance Degradation Under a Unified Suppression Strategy
For chirp jamming, TDPB shows the poorest performance (mean \(C/N_{0}\) of 23.8 dB/Hz); FDPB outperforms AFF when \(C/N_{0}\) is below 41 dB/Hz, whereas AFF surpasses FDPB beyond this threshold. The simulation results indicate that the optimal algorithm choice is highly scenario-dependent, and even within the same interference type, different parameter configurations may lead to varying optimal suppression strategies. The interference suppression performance is evaluated using the output carrier-to-noise ratio, defined as \(C/N_{0_{\text{out}}}=S/(N+J_{res})\), where \(J_{res}\) denotes the residual interference power. The ideal upper bound is achieved when \(J_{res}=0\), resulting in \(C/\text{N}_{0_{max}}=S/N\). However, most methods incur unavoidable residual loss. The lower bound is given by \(\left(C/N_{0}\right)_{min}=S/(N+\eta J)\), where \(\eta\) is the leakage factor. The theoretical upper and lower bounds of \(C/N_{0_{\text{out}}}\) for each algorithm under typical interference conditions are derived, as shown in Table 1. In the table, \(\delta f\) represents the frequency offset between the notch and the interference center, \(\Delta f_{bin}=f_{s}/N_{FFT}\) is the frequency resolution, \(B_{int}\) and \(B_{chirp}\) denote the interference and chirp bandwidths, respectively, \(n\) is the number of missed  
Figure 2: Comparison of suppression performance for three typical types of jamming. bins under the threshold, \(n_{min}\) is the theoretical minimum number of missed bins, \(D\) is the pulse duty cycle, and \(\Delta f_{notch}\) is the effective bandwidth of the notch filter. The normalized anti-jamming efficiency coefficient is defined as follows. \[\Gamma=\frac{\left(C/N_{0}\right)_{alg}-\left(C/N_{0}\right)_{min}}{\left(C/N_{ 0}\right)_{max}-\left(C/N_{0}\right)_{min}},\Gamma\in[0,1] \tag{12}\]  
Here, \(\left(C/N_{0}\right)_{alg}\) represents the actual output carrier-to-noise ratio. Figure 3 quantifies the anti-jamming efficiency \(\Gamma\) under varying leakage factors \(\eta\) and interference power levels \(J\). \(\Gamma\) is defined as a normalized performance metric representing the effectiveness of interference suppression, relative to the theoretical optimum (\(\Gamma=1\)) and the unsuppressed case (\(\Gamma=0\)). The value of \(\Gamma\) reflects the degree of structural alignment between the algorithm and the interference characteristics, as well as the suppression capability. When \(\Gamma\) approaches 1, the algorithm performance nears the ideal limit; when \(\Gamma\) approaches 0, it indicates suppression failure. For example, TDPB achieves the highest \(\Gamma\) value under pulse jamming, whereas its mean \(\Gamma\) under the chirp and narrowband interference scenarios is close to 0, confirming the varying sensitivity of its time-domain processing mechanism to different interference dynamics. \begin{table}
\begin{tabular}{c c c c} \hline
**Jamming** & **Algorithm** & \(\left(\mathbf{C/N_{0}}\right)_{max}\) & \(\left(\mathbf{C/N_{0}}\right)_{min}\) \\ \hline \multirow{4}{*}{NB} & AFF & \(S/N\) & \(S/\left(N+\left(\frac{\pi L}{2}\frac{\delta f}{f}\right)^{2}\right)_{Ires}\) \\  & FDPB & \(S/\left(N+\frac{n_{min}\Delta f_{bin}}{B_{int}}J_{Ires}\right)\) & \(S/\left(N+\frac{n\Delta f_{bin}}{B_{int}}J_{Ires}\right)\) \\  & TDPB & \(S/\left(N+J_{res}\right)\) \\ \hline \multirow{4}{*}{Pulse} & AFF & \(S/(N+J)\) & \(S/(N+\eta J)\) \\  & FDPB & \(S/(N(1-D))\) & \(S/\left(N+\left(1-D_{eff}\right)\right)_{Ires}\) \\ \hline \multirow{4}{*}{Chirp} & AFF & \(S/(N+J)\) & \(S/(N+\left(1-\frac{\Delta f_{notch}}{B_{disp}}\right)_{Ires})\) \\  & FDPB & \(S/(N+\frac{n_{min}\Delta f_{bin}}{B_{disp}}J_{Ires})\) & \(S/(N+\frac{n\Delta f_{bin}}{B_{disp}}J_{Ires})\) \\ \cline{1-1}  & TDPB & \(S/(N+J)\) \\ \hline \end{tabular}
\end{table} 
Table 1: Theoretical upper and lower bounds of \(C/N_{0_{max}}\) for FDPB, TDPB, and AFF under typical disturbances. Figure 3: Comparison of anti-jamming efficiency \(\Gamma\) distributions based on leakage factor and interference power.