准周期随机声脉冲序列信号海洋信道中远程传输特性

To realize the passive detection of weak signals of ship noise in the ocean, the changes of ship noise characteristics caused by the long-distance transmission in ocean channel must be studied.As a time domain model of ship noise, quasi-periodic random sound pulse sequence signal has revealed from the physical meaning that, in most cases, the ship noise itself does not directly contain any sine wave, while the sine wave information carried by the pulse sequence signal must be obtained by nonlinear transformation.The quasi-periodic random sound pulse sequence signal will be built by computer simulation in this project,and its characteristics changes after random ocean channel transmission will be studied by theorecical analysis, computer simulation and experimental tests. The influence of frequency selective fading and time selective fading caused by multi-path, randomness and the Doppler effect of moving scatters in ocean channel on quasi-periodic random sound pulse sequence signal will be discussed, and the focus will be to study the effect of ocean channel randomness on the quasi-periodicity and sequence pulse shape, and revealing the essentil reason of the "extra" attenuation of ship noise low frequency line spectrums after long-distance transmission.This project will also use the periodic cycle statistics characteristics to analyze the quasi-periodic random sound pulse sequence signal, and discuss the change of its cyclic higher-order statistics characteristics after the transmission in ocean channel. The results of this project will provide a physical basis and technology foundation for the long-distance weak signal detection of underwater target.

实现海洋中船舶噪声远程微弱信号被动检测，必须研究掌握经过海洋信道远程传输后船舶噪声特征的变化。准周期随机声脉冲序列信号作为船舶噪声一种时域模型,从物理层面揭示,在大多数情况下船舶噪声本身并不直接含有任何正弦波分量，它所携带的正弦波信息需经非线性变换获得。本项目研究计算机仿真构建准周期随机声脉冲序列信号，理论分析、计算机模拟和海上试验研究它经过随机海洋信道传输后特性的变化，研究海洋信道多途和随机性、运动散射体多普勒等因素引起的频率选择性衰落和时间选择性衰落，对准周期随机声脉冲序列信号的作用；侧重探讨海洋信道的随机性对其准周期性和序列脉冲形状的作用，揭示远程传输后船舶噪声低频线谱产生"额外"衰减的本质原因。本项目还将采用周期性循环特征量来分析准周期随机声脉冲序列信号,探讨其循环高阶特征量在海洋信道传输后的变化。项目的研究结果将可为远程水下目标噪声微弱信号检测提供物理依据和技术基础。

海洋是大国之间声、光、电、磁等信息对抗的主要战场之一。声能量是目前发现的能够在水中远距离传输的唯一能量形式，声信息对抗是水下信息对抗的最重要的方式之一。对海洋中舰船水下辐射噪声远程较低频微弱信号的被动检测、舰船辐射噪声信息安全隐藏以及水下兵器对抗处于优势地位，都要求研究掌握经过海洋信道远程传输后舰船水下辐射噪声信号的特征变化。.项目分析了大量实测典型舰船水下辐射噪声数据；完善了准周期随机声脉冲序列模型，计算机仿真构建舰船水下辐射噪声信号并与真实舰船水下辐射噪声功率谱进行对比；理论分析、数值模拟和海上试验研究准周期随机声脉冲序列信号经过随机海洋信道传输后特性的变化，研究海洋信道多途和随机性等对准周期随机声脉冲序列信号周期性的作用。.项目组做了大量的海上实验，获取了较多的典型航船噪声数据以及舰船噪声波导传播实验数据，通过理论分析和数据处理，项目研究主要结果如下：.舰船水下辐射噪声功率谱强度基本遵循先随频率增加而增加、后随频率增加而减小，即存在谱峰的总体规律；舰船水下辐射噪声功率谱在谱峰位置前，普遍存在大量线谱；模型引入的爆炸型余弦脉冲信号作为仿真采用的单元脉冲，该单元脉冲可以产生具有谱峰的功率谱，很好的吻合了实际舰船水下辐射噪声功率谱变化特征，具有实际应用价值；多途效应以及信号在远程传输过程中的声速剖面的扰动作用加剧舰船水下辐射噪声线谱的额外衰减。.项目建立和完善了一种舰船噪声时域模型，为舰船噪声的科学研究开辟了新的视角，也可作为一种编码信号对海洋波导进行反演。同时探讨海洋信道环境对舰船水下辐射噪声信号特性的影响，研究线谱额外衰减的机理。可为水下低噪声目标被动检测和舰船噪声减震降噪提供物理依据。.