两个宽带噪声矢量场模型的空间相关特性

Spatial correlation of two broadband vector noise models

针对宽带噪声矢量场的空间相关特性问题,文章讨论了各向同性噪声模型和表面噪声模型。在高频近似条件下,根据射线声学理论和简谐平面行波满足的欧拉公式,采用时域建模方法分别建立了宽带各向同性噪声和表面噪声矢量场模型。给出了噪声场相关函数的积分表达式和竖直方向空间相关系数的解析表达式。数值分析结果表明,相较于窄带噪声矢量场,宽带噪声矢量场各分量空间相关系数振荡幅度更小,随空间两点间距的增大更快地趋近于零;噪声源指向性对表面噪声场竖直方向上的空间相关特性的影响显著。相较于已有的宽带噪声空间相关系数计算方法,文中模型无需使用傅里叶合成方法,可通过时域建模直接获得宽带噪声空间相关函数。

Two simple noise models,namely isotropic noise and surface noise,are discussed regarding the spatial correlation of a noise vector field in this paper.Given that the interference noises of different sonar systems have different bandwidths and according to acoustic geometric theory and the Euler formula satisfied by harmonic plane waves,time-domain modeling is used to establish spatial correlation models of the vector fields of isotropic noise and surface noise,and their frequency bands are adjustable.An integral expression for the correlation function of the noise field and an analytical expression for the vertical correlation coefficient of the noise field are given.With the analytical solutions of the normalized spatial correlation functions,the single-frequency or narrowband results are obtained by calculation while taking the appropriate limit,and they are the same as those already presented in the literature.The results show that the change of the radiation noise spectrum structure of noise source affects the spatial correlation radius of broadband noise vector field.And the directivity of the noise source has a significant effect on the spatial correlation of the surface noise field in the vertical direction.Compared with the existing method for calculating the spatial correlation coefficient of broadband noise,the model can directly obtain the spatial correlation function of broadband noise through time domain modeling without requiring a numerical Fourier synthesis of the frequency domain formulations to do so.