浅海波导中水下目标辐射噪声干涉条纹的理论分析和试验结果

Theoretical analysis and experimental results of interference striation pattern of underwater target radiated noise in shallow water waveguide

浅海波导不变量的研究是近30年来水声学中引人注意的课题之一。水下目标辐射噪声的直达波和海面、海底反射波之间的干涉现象可以认为是浅海波导的典型例子,直达波和反射波之间的干涉条纹对了解浅海波导的机理是非常有效的。本文给出由水下目标辐射噪声直达波和海面、海底反射波产生的干涉现象的理论分析,指出由海面反射波引起的干涉条纹集中在高频段,而由海底反射引起的干涉条纹既可能在低频段也可能在高频段,它与海底的声学特性密切相关。文中给出了干涉条纹图和目标位置、海洋环境以及接收传感器等参数的关系,指出干涉条纹具有双曲线的形状,而一族双曲线的渐近线为直线。海试给出了若干有趣的结果,部分数据处理的例子证实了理论分析的正确性。本文所述的理论与试验结果表明在一定条件下,干涉条纹图可以用于目标检测与识别。

Waveguide invariant in shallow water is an attractive topic in recent three decades.The interference phenomena of direct wave of radiated noise of underwater target and reflection wave from sea surface and sea bottom can be considered as a typical case of shallow water waveguide.The interference striation pattern of direct wave and its reflection is the effective and comprehensive figure for better understanding the essence of shallow water waveguide invariant. The theoretical analysis of interference phenomena generated by direct wave of radiated noise of underwater target and its reflection wave from sea surface and sea bottom is presented in this paper.It is shown that the interference wave resulted by sea surface reflection produces striation pattern centered at high frequency band.But the interference of nulling frequency resulted by sea bottom reflection may be at low frequency or high frequency,it strongly depends on the acoustic behavior of sea bottom.The relationship between main parameters of interference striation pattern and target, receiver,and environment is derived.It is shown that the interference striation has the shape of hyperbolic curve.The equation set of the hyperbolic curve and its asymptotic line are presented.The at-sea experiment carried out in South China sea shows some interesting results.A part of data processing results are illustrated in this paper.The results expressed in this paper show that the interference striation pattern can be used,in some conditions,as a potential means for target recognition.