Models for amplitude fluctuation of underwater acoustic narrow band signal based on modified modal scintillation index  

基于修正模式闪烁指数的水声窄带信号幅度波动模型(英文)

作　　者：安良[1] 方世良[1] 陈励军[1] 

机构地区：[1]东南大学水声信号处理教育部重点实验室,南京210096

出　　处：《Journal of Southeast University(English Edition)》2013年第3期235-241,共7页东南大学学报（英文版）

基　　金：The National Natural Science Foundation of China(No.11104029)

摘　　要：A self-normalized statistic the modified modal scintillation index MMSI is proposed and defined as the variance of the modulus of modal excitation normalized by the square of its expected value over some observation intervals.It is proved in an analytical form that the MMSI is a depth dependent signature and independent of the source level and the source range under the condition of the ideal waveguide while the classical modal scintillation index MSI depends on both the source level and the source range.The MSI and the MMSI in the Pekeris waveguide at 70 Hz are simulated with different source levels and source ranges by the Kraken normal mode model.The simulation results are consistent with the theoretical deduction.The MMSI probability density functions PDFs of different normal modes for surface and submerged sources are calculated using the mode filtering methods with the same variations of vertical motions.It is indicated that the PDFs can be used to separate the submerged and the surface sources except for the fourth mode.提出了一种自归一化的修正模式闪烁指数,定义为一段观测时间内模式激励函数模的方差与模式激励函数模的数学期望平方的比值.在理想水声波导的条件下,解析地证明了修正模式闪烁指数是一种与目标深度相关、与目标距离和强度无关的统计量,而传统的模式闪烁指数与目标距离和强度都相关.利用Kraken简正波模型进行了Pekeris波导中的不同目标强度和距离情况下的模式闪烁指数和修正模式闪烁指数计算仿真,信号频率为70 Hz.仿真结果与理论推导的结果一致.在相同的目标垂直运动方差情况下,利用简正波过滤的方法进行了水下目标和水面目标的修正模式闪烁指数概率密度函数的估计.计算结果表明,除了4号简正波模式外,其余简正波模式的修正模式闪烁指数概率密度函数可以用来区分水下和水面目标.

关 键 词：modified modal scintillation index amplitudefluctuation mode filtering Pekeris waveguide 

分 类 号：O427.3[理学—声学]