## 4 Experimental Results
### Simulation Results  
Simulations are conducted using a DVB-T signal in 2K mode with quadrature phase shift keying (QPSK) as the symbol mapping scheme. The simulation parameters are presented in Table 1.  
Based on the parameters in Table 1, the delay for Target 1 and Target 2 are both 17.1 \(\upmu\)s, while the delay for Target 3 is 20.6 \(\upmu\)s. The Doppler frequencies of Target 1, Target 2, and Target 3 are \(-\)76.3 Hz, \(-\)62.7 Hz, and 26.8 Hz, respectively. Therefore, the delay for Targets 1 and 2 are the same, and their Doppler frequencies are close. The CAF result of the simulated signals is shown in Figure 5. It can be observed that all three targets appear in the delay-Doppler domain. Among them, Target 1 and Target 2 are closely located in the delay-Doppler domain, indicating the need for the separation of the two targets.  
As the 13 dB detection threshold can guarantee a detection probability of 90% and a false alarm probability of \(10^{-6}\), the iterative initial value \(\sigma^{0}_{r,c}\in\mathbb{R}^{2L^{\prime}M^{\prime}\times 1}\) is set as  
\[\sigma^{0}_{r,c}=\begin{bmatrix}\sigma^{0}_{S,r,c}\\ \boldsymbol{0}^{L^{\prime}M^{\prime}\times 1}\end{bmatrix} \tag{37}\]  
where the elements of \(\sigma^{0}_{S,r,c}\in\mathbb{R}^{L^{\prime}M^{\prime}\times 1}\) corresponding to values greater than 13 dB in \(\boldsymbol{a}_{S,r,c}\) are set to 1, and all other elements are set to 0. When \(\sigma^{0}_{S,r,c}=\boldsymbol{0}^{L^{\prime}M^{\prime}\times 1}\), the sparse recovery  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Parameters** & **Values** & **Parameters** & **Values** \\ \hline Carrier frequency & 600 MHz & Target 1 RCS & 1 m\({}^{2}\) \\ Sample rate & 10 MHz & Target 2 RCS & 10 m\({}^{2}\) \\ Integration time & 0.25 s & Target 3 RCS & 5 m\({}^{2}\) \\ IO coordinate & (200 km, 0, 0.15 km) & Transmitter power & 1 kW \\ PBR coordinate & (0, 0, 5 m) & Transmitter gain & 12.5 dB \\ Target 1 coordinate & (80 km, 20.1 km, 9.9 km) & Receiver gain & 16 dB \\ Target 2 coordinate & (80 km, 20 km, 10 km) & Receiver bandwidth & 10 MHz \\ Target 3 coordinate & (100 km, \(-\)23 km, 10 km) & Receiver temperature & 298.15 K \\ Target 1 velocity & (45 m/s, 96 m/s, 0) & & \\ Target 2 velocity & (50 m/s, 80 m/s, 0) & & \\ Target 3 velocity & (70 m/s, 30 m/s, 0) & & \\ \hline \hline \end{tabular}
\end{table}
Table 1: Simulation Parameters.  
Figure 5: The CAF result of the simulated signals.  
operation is not performed on the \((r,c)\)-th CAF block. In other words, the iterative result is \(\mathbf{\sigma}_{r,c}^{*}=\mathbf{0}^{2L^{\prime}M^{\prime}\times 1}\).  
Under different values of \(R\) and \(C\), the sparse recovery results of the simulated signals are shown in Figure 6.  
From Figure 6, it can be observed that under different sub-block partitioning schemes, both Target 1 and Target 2 are separated in the delay-Doppler domain. Therefore, the sparse recovery results are shown in Figure 6.  
Figure 6: The sparse recovery results of the simulated signals. (**a**) Sparse recovery result with \(R=1,C=2\). (**b**) Doppler frequency direction of the sparse recovery result with \(R=1,C=2\). (**c**) Sparse recovery result with \(R=2,C=2\). (**d**) Doppler frequency direction of the sparse recovery result with \(R=2,C=2\). (**e**) Sparse recovery result with \(R=4,C=4\). (**f**) Doppler frequency direction of the sparse recovery result with \(R=4,C=4\).  
recovery approach allows for the detection of weak targets, overcoming the influence of non-ideal factors from CAF.