## 4 Result of the Experiment and Discussion
### Real Data Processing  
To further validate the effectiveness of the proposed method, an equivalent validation experiment was carried out by imaging a farmland scene using airborne dual-channel SAR \begin{table}
\begin{tabular}{c c} \hline
**Image** & **Entropy** \\ \hline Figure 8a & 15.9 \\ Figure 8b & 15.8 \\ Figure 8c & 15.6 \\ Figure 8d & 15.4 \\ \hline \end{tabular}
\end{table} 
Table 2: The entropy of Figure 8.  
Figure 8: Comparison of scene simulation results. (**a**) Imaging results of the traditional method with a velocity of 2 m/s and an acceleration of 5 m/s\({}^{2}\). (**b**) Imaging results of the traditional method with a velocity of 1 m/s and an acceleration of 1 m/s\({}^{2}\). (**c**) Imaging results of the traditional method with a velocity of 1 m/s and an acceleration of 0.1 m/s\({}^{2}\). (**d**) Imaging results of the proposed method with a velocity of 2 m/s and an acceleration of 5 m/s\({}^{2}\). at a location in Shaanxi. Figure 9 shows the optical map of the experimental scene. In addition to the farmland in the scene, there are some private houses with strong scattering. The system used is a dual-channel radar system with a hybrid baseline, using a single-output multiple-input mode, and the specific operating parameters are shown in Table 3.  
According to the parameters shown in Table 3, the equivalent phase centers between channels are 1.85 m, 0.10 m, and 0.04 m in \(x\), \(y\), and \(z\). First, the azimuth window is added to the echoes to equivalently reduce the azimuth beamwidth and azimuth resolution of the system; therefore, since the initial pulse repetition frequency of the system is larger than the azimuth bandwidth, there is no azimuth ambiguity. As a result, the data of both channels are downsampled by a factor of 10 through azimuth sampling point extraction for the equivalent azimuth downsampling case. Channel 1 extracts the 1 st, 11 th, 21 st, etc., slow time samples and Channel 2 extracts the 5 th, 15 th, 25 th, etc., slow time samples. After extraction, the equivalent single-channel pulse repetition frequency becomes 125 Hz, which is smaller than the signal azimuth Doppler bandwidth. The combination of the two channels' data can constitute a sampling sequence of a distributed SAR hybrid baseline. This data processing can be used to verify the performance of the distributed SAR signal error estimation and compensation method. Figure 10 shows the schematic diagram of two-channel data extraction, where the circle indicates the actual sampling position of Channel 1, the triangle indicates the actual sampling position of Channel 2, and the solid shape indicates the actual extraction, which is used for signal error estimation and compensation. After combining the channel data, the process is carried out according to the procedure described in Section 3.1. The TDCM is used to estimate the channel phase error, and the results of the TDCM channel error estimation are shown in Figure 11.  
Figure 9: Optical map of the imaging scene. Figure 11 shows that the channel error has a certain slope which is consistent with the analysis of Equation (15); the slope is due to the radial acceleration of the platform. After compensating for the channel error by linear fitting, the slope and Equation (18) are used to obtain the radial acceleration estimate of 0.2736 m/s\({}^{2}\) to compensate for the effect caused by the acceleration. The spectrum is then reconstructed by using the transfer function method, and SAR imaging is performed by applying the chirp scaling (CS) method. As a comparison, the results of single-channel undersampling imaging are shown in Figure 12, where the yellow boxes are for Target A and B and the red boxes are the positions of the ambiguous components. The ambiguity suppression effect of HRWS imaging is subsequently evaluated with Target A and B.