A Comprehensive Detection Method for Weak Shaft-Rate Electric Field Signals of Underwater Targets

Abstract

Shaft-rate electric field is an important detectable signal in underwater target detection. To address the challenge of weak shaft-rate electric field signals that are susceptible to noise interference, this article proposes a detection method based on a detection-first and selective-enhancement strategy. The method first employs improved complete ensemble empirical mode decomposition with adaptive noise (ICEEMDAN) combined with the narrowband power spectrum energy peak entropy ratio (EPER) to extract spectral features. Subsequently, through a process involving a sliding window, dynamic thresholding, multigating, and continuous valid detection decision-making, a stable target signal detection result is obtained under low signal-to-noise ratio (SNR) conditions. Upon successful detection, a second-order matched stochastic resonance (SMSR) technique coupled with a variable step-size least mean P-norm (VSS-LMP) algorithm is introduced to enhance the line-spectrum features and accurately extract the characteristic frequency of the target signal. Simulation results demonstrate that the proposed method achieves a detection rate exceeding 90% with a false alarm rate of approximately 25% at an SNR of −12 dB. Sea trials with a 500-A $\cdot $ m artificial electric-dipole source demonstrate effective detection under low-SNR conditions, with detection distances exceeding 2 km. This work provides a technical approach with practical reference value for the detection of weak shaft-rate electric field signals from vessels.