Study on line-spectrum stability of ship underwater radiated noise

摘要

Ship radiated noise is usually comprised of continuously distributed broad-band noises and several narrow-band line spectrum components on discrete frequencies. Generated by periodical machinery rotation and propeller blade rotation, the line spectrum with high strength has its central frequency located in the low frequency range, so that its long-distance transmission loss is small. It is an important information source for passive target detection, tracing and recognition. Due to the comprehensive influence of sound source characteristics, transmission channels and Doppler phenomena, the magnitude and frequency of the line spectrum always fluctuates, which will definitely influence the performance of a sonar system. Addressing the problem, this paper proposes an analytical approach to evaluate the line spectrum stability of ship radiated noise. The validity of the method is checked by analyzing actually-measured radiated noise data of a ship at sea from the perspectives of magnitude and frequency. This research provides a new approach to improve the performance of line spectrum detection.