Adaptive Multi-Band Noise Reduction and Intelligent Recognition of Fundamental Frequency for Ship's Shaft-Rate Magnetic Field Signal

The shaft-rate characteristic of the ship target is an important attribute for classifying its type, and accurately extracting this feature is crucial for enhancing underwater target detection. This study analyzes the fundamental frequency of ship magnetic field signals obtained from sea trials. An improved fuzzy judgement method is used to calculate the fundamental frequency confidence level for each frequency within the fundamental frequency distribution band. By setting threshold values for the line spectrum components of the ship's magnetic field fundamental frequency and their corresponding frequency point confidence levels, effective extraction of the fundamental frequency feature is achieved, enabling ship target detection and recognition. Validation using sea trial data demonstrates that applying the proposed fundamental frequency extraction method based on multi-band spectral subtraction combined with information fusion to shaft-rate magnetic field analysis effectively estimates the target's shaft-rate fundamental frequency.