An Interference Suppression Method Incorporating Sound Field Characteristics for Depth Estimation

Accurate target depth estimation in deep-water reliable acoustic path (RAP) environments is challenging due to the impact of strong interference on the energy of beam outputs from vertical line arrays (VLAs) in the target direction. This article presents a sound field characteristicsbased generalized sidelobe canceller (SFC-GSC) method. The method applies sidelobe cancellation by assigning weights to interference directions, creating nulls in multiple interference paths. These weights are designed based on the multipath arrival structure of interference, effectively distinguishing weak targets from interference components. The resulting nulls enhance target trajectory visibility, enabling automatic extraction. The refined target energy is further processed using the spatial domain Fourier transform (SpFT) to achieve precise depth estimation. Simulation results indicate that the method achieves a depth estimation RMSE of less than 5 meters under a -40 dB signal-to-interference ratio (SIR). Experimental data from the South China Sea strongly interfered with the environment, further confirming its feasibility, with the estimated depth deviating by two meters from interference-free results.