LF频段信号相对于HF频段能够增加探测距离，其探测分辨率是本文分析的重

The LF band signal can increase the detection distance compared to the HF band, and its detection resolution is the focus of this article's analysis. In this section, the SIRT method, the Green's function iterative inversion method and the Green's function iterative inversion method based on the Laplace operator constraint are used to detect the 30kHz frequency Tomography was performed to verify detection resolution of low-frequency signals. We establish the inclined fault anomaly as shown in Figure 3a. The inversion results of the three methods can prove that due to the addition of the Laplace operator, Figure 3d basically shows the direction and size of the inclined fault. The Green's function iterative inversion method inverts The boundary blurring phenomenon in the inversion results is serious, and it is difficult to identify inclined faults in conventional SIRT inversion results.

The LF frequency band signal can increase the detection distance compared to the HF frequency band, and its detection resolution is the focus of this article's analysis. This section uses the SIRT method, Green's function iterative inversion method, and Laplace operator constrained Green's function iterative inversion method to perform tomography imaging at a frequency of 30kHz to verify the detection resolution of low-frequency signals. We established an anomalous body of inclined faults as shown in Figure 3a, and the inversion results of the three methods can prove that due to the addition of the Laplace operator, Figure 3d basically presents the strike and size of inclined faults. The boundary blurring phenomenon in the inversion results of the Green's function iteration inversion method is severe, and conventional SIRT inversion results are difficult to identify inclined faults.

Compared with HF band, LF band signal can increase the detection distance, and its detection resolution is the focus of this paper. In this section, SIRT method, Green's function iterative inversion method and Green's function iterative inversion method based on Laplace operator constraint are used to tomography the frequency of 30kHz to verify the detection resolution of low-frequency signals. We set up an abnormal body of inclined faults as shown in Figure 3a. The inversion results of the three methods can prove that the trend and size of inclined faults are basically presented in Figure 3d due to the addition of Laplace operator, and the boundary ambiguity of the inversion results of Green's function iterative inversion method is serious, while the conventional SIRT inversion results are difficult to identify inclined faults.