水声波导中包络线谱强度数值预报

为了预报声呐远距离检测包络线谱的性能,本文分析在辐射噪声传播过程中包络线谱强度衰减的原因及提出在水声波导中包络线谱强度的数值预报方法。依据周期性局部平稳过程对舰船辐射噪声建模,推导出无噪声干扰及有噪声干扰下的包络线谱强度的数学表达式,获得了包络线谱强度传播衰减的规律,在水声波导中包络线谱声级传播规律与平稳谱一致,但包络线谱高出连续谱的强度的衰减取决于随信噪比变化的调幅深度修正因子。包络线谱强度数值预报方法如下:先利用传播衰减的数值方法例如用简正波方法波数积分方法PE方法等求出平稳辐射噪声的传播衰减,再求信噪比,最后依据调幅深度修正因子获得包络线谱强度降低的分贝数,预报出在水声波导中任意一点包络线谱信号高度。该理论和数值预报方法具有创新性,实用,简单,适合工程应用。 

Numerical prediction of envelope line spectrum intensity in underwater acoustic waveguide

In order to predict detectible range and region of passive sonar in underwater channel,an attenuation theory of envelope line-spectrum height for radiated noise of vessel in propagation and an approach of numerical prediction are proposed.In the paper a model for radiated noise of vessel is established by a periodically locally stationary random process,two formulae of the envelope line-spectrum height with background-noise and without backgroundnoise are deduced,therefore the attenuation rule of the envelope line-spectrum height is obtained,the result shows:the transmission loss of the sound level of the envelope line-spectrum is same as the sound level of the stationary spectrum, but the decrease of envelope line-spectrum height depends on a modified scale of amplitude modulation depth which is variable with the ratio of signal to noise.The numerical prediction approach as follows:first,the transmission loss of the stationary radiated noise is found out using the numerical approaches of normal modes or wavenumber integration or PE etc.,then the ratio of signal to noise on sound field is calculated,finally the decrease of envelope line-spectrum height is obtained according to the modified scale and the envelope line-spectrum heights in sound field can be predicted.The theory and the numerical prediction approach possess innovation,practicality,simplicity,suitability for engineering.