Abstract:To address the challenge of feature extraction from ship-radiated noise in complex environments with low signal-to-noise ratio (SNR), this paper proposes a method based on Symplectic Geometry Mode Decomposition (SGMD) and Multiscale Improved Permutation Entropy (MIPE). The proposed method utilizes SGMD to denoise the radiated noise signals from three types of ships, effectively suppressing noise interference while retaining the intrinsic signal characteristics. Subsequently, the MIPE features are extracted as classification parameters and fed into a Probabilistic Neural Network (PNN) for classification and recognition. Experimental results demonstrate that under low SNR conditions of 0 dB and 5 dB, the average recognition rates of the proposed method reach 96.89% and 99.56%, respectively. These represent significant improvements of 9.11% and 7.79% compared to the results obtained without the denoising process, thereby validating the excellent feature robustness and classification performance of the proposed method under low SNR conditions.