摘要
本文给出海上实验数据表明舰船噪声在几十赫以下频段有着很强的低频线谱,这些线谱与螺旋桨转速等工作特征紧密联系在一起.所以螺旋桨识别特征的提取除了从解调制谱线谱来得到外,还可直接从低频线谱来得到,本文讨论了在噪声中低频线谱和解调制谱线谱的检测性能,在噪声掩盖下,低频线谱的信号高度与信噪比成正比,而解调制谱线谱的信号高度随信噪比下降是非线性的,当信噪比大时下降得很慢,当信噪比小时下降得很快.
The analysis of the radiated-noise of vessels given in this paper shows some strong superposed line components in low frequency spectrum below 100OHz occurring at discrete frequencies which correspond with the rotation speed of propeller shaft, propeller blade frequency and their harmonic frequency. The line components reflect propeller's working characteristics, so the propeller's features can be extracted directly from these line components. The other way to extract the features is from demodulated line component.So there are two ways to extract the features, the direct way and the demodulation way. Detection performance of the line component in background-noise is discussed in this paper. The signal level is defined as the difference between the PDF's (Probability Density Function) mean of the peak of the line component and PDF's mean of the background-noise. In the direct way the signal level of the line component is proportional to the signal to noise ratio (S/N). In the demodulation way the signal level of demodulated line component reduces with S/N descent, but the signal level reduces slowly if S/N is high and very fast if S/N is low.
出处
《声学学报》
EI
CSCD
北大核心
1993年第3期210-216,共7页
Acta Acustica
基金
国家自然科学基金资助项目
