摘要
本文把子波变换多分辨的特点应用于舰船噪声的分析中。这种新的分析方法克服了短时间谱在时频平面上均匀分割带来低频域频率分辨率低，而高频域时间分辨低的缺点。船辐射噪声的尺度谱保留了传统倍频程方法在频率域分割的优点，且还有高频域时间分辨高的特点。从大庆３１号油船辐射噪声的尺度谱上可清楚看到在低频域上有二根横线，其尺度值换算为频率后为２７．８Ｈｚ和４４．１Ｈｚ，反映在此频率附近，信号能量较高；同时还可清楚看到在高频域上有９．５Ｈｚ叶片频的调幅现象。在它的短时谱图中是无法同时看到这二个特征的。本文在描述和显示船辐射噪声的谱特征时充分利用它们符合局部平稳过程的特点，把平稳谱和非平稳谱拆开描述和显示。
Wavelet Transform's multi-resolution characteristics is applied to the analysis of ship radiated noise. In contrast to the fixed resolution in time frequency plane of Short-Time Fourier Transform,Wavelet Transform has arbitrary good time resolution at high frequencies and good frequency resolution at low frequencies. It is showed that Wavelet Transform plays a good role in the time-frequency analysis of the ship-radiated noise. The energy distribution at low frequency band and propeller's modulation to the noise at the whole band can be displayed in one Scalogram, but STFT cannot. When describing and displaying the ship noise's spectrum characteristics, we separate it into two parts of stationary and nonstationary respectively. This separation is based on its local stationary property and it has a good effect in our experiment.
出处
《声学学报》
EI
CSCD
北大核心
1996年第4期700-708,共9页
Acta Acustica
基金
国家自然科学基金
