【作者】 雷亚辉；

【导师】 丁士圻；

【作者基本信息】 哈尔滨工程大学 ， 通信与信息系统， 2010， 博士

【摘要】 本论文的研究工作以时间反转法为基础,针对复杂浅海环境中沉底、掩埋目标在强海底混响背景下的探测问题进行理论分析、仿真和实验验证,研究和讨论目标探测中亟待解决的关键技术问题。本论文包括了作者对时反法水下目标探测的理论和仿真研究工作,及在某基础声探测项目中的部分实验成果和工作内容。强混响干扰背景下的目标探测,尤其是掩埋目标探测一直是探雷声纳工作中检测和识别的重要工作内容之一。一般方法是通过对混响信号进行建模和预测处理,直接对混响干扰下的回波信号进行处理,滤除混响的干扰以达到增强信混比的效果。但由于混响的形成机理比较复杂,表象上具有随机性而统计上又存在一定的规律性,因此长期以来,虽然抗混响研究取得了一定的技术进步,但仍然有较大的不足需要进一步的研究和发展。时间反转法作为一种具有独特优点的自适应聚焦方法,可以在没有信道条件先验知识的情况下,实现自适应聚焦,同时对混响和噪声信号具有一定的抑制作用。这对于传统的主动声纳探测技术来说,具有一定的工程应用前景。尤其对于浅海水下目标探测,特定海域的强混响和强吸收的复杂环境使得时间反转法可以提高聚焦增益的作用更具吸引力。论文首先简单的介绍了时间反转法的起源、发展历程和研究现状,从总体上对时间反转法理论进行了回顾和总结;介绍了时间反转法在水下目标探测中的应用,以及国内外对这一方法的研究现状和取得的成果。通过对时间反转法水下目标探测的理论方法进行了分析和总结;论文基于射线声学的理论模型,对水下波导中的时反目标探测进行了理论分析和仿真验证,证明了时反法的可行性和稳健性,并进一步讨论和仿真验证了迭代时间反转法的原理和特性。其次通过对混响建模的仿真和计算,就时间反转法在沉底和掩埋条件下水下目标探测中抑制混响、增强回波的性能和效果进行了比较详细的分析,为工程应用奠定了理论和方法的基础;针对沉底和掩埋目标探测的特点讨论了噪声和混响对时反法的影响及时反法多目标探测的鲁棒性。然后论文针对掩埋目标声探测的强混响和弱回波信号的情况,利用匹配滤波和混沌信号处理的方法对回波信号进行处理,以检测和定位目标回波信号,从而能够以较短的时间窗截取和获得时反信号。对信号进行处理以降低混响强度和进行回波信号的提取,有利于提高低信混比条件下的时反处理的效果。因此,论文讨论了混响的混沌属性,利用混沌模型对混响序列进行建模,并在此基础上对混响背景下信号的混沌处理方法做了一定的分析研究,实现了对较低信混比条件下回波的检测和提取。最后论文通过信道水池实验,对信道水池条件下的单通道悬浮和掩埋小目标的时反探测进行了研究和分析,给出了单时反阵元时反法水下目标探测的分析结果,获得了一些实际工程应用时间反转镜系统目标探测的经验,其结果和结论对后续理论和应用研究具有一定的参考价值。并就工程中应用时反探测方法的系统方案以及面临的技术问题进行了设计和分析,为以后的实际工程应用打下了一定的基础。更多还原

【Abstract】 The work of this thesis is based on the Time Reversal Theory. According to the problem of small target detection which is sunk on or buried in the seafloor in the strong reverberation background, we analyze and validate with theory and experiment about the essential problem of small target detection which is desired to be resolved in the complex shallow sea environment. Work of the paper includes theory analyzing and simulation about time reversal method on mine detection, and includes some experiment achievement and work in a certain acoustic detection foundation project.The problem of buried target detection in the strong reverberation environment is all along important study content. General methods are modeling or predicting process, which direct treat with reverberation signal. Then we can filter out reverberation signal and enhance signal-reverberation ratio. But, because of the complex forming mechanism of reverberation, it has randomness of the representation and regularity of the statistics. So a long time, although anti-reverberation of some of the technical progress has been made, but there are still large requirement for further research and development. Time reversal method has unique advantages as a self-adaptive focusing method with nothing prior knowledge of channel conditions, and it has inhibiting effect while reverberation and noise signals have a certain extent. So, time reversal method has good prospects of engineering application than traditional active sonar detection methods. Especially for mine detection in the shallow sea, it has strong attraction in the complex environment which has strong reverberation and strong absorption.Firstly, the paper has a brief introduction of the origin of time reversal method, the development and the status quo. The general theory of time reversal methods are reviewed and summarized, and the domestic and foreign researching status and achievements of this method are introduced. Based on ray acoustics theoretical model, the detection problem is analyzed and simulated about the target which in the underwater waveguide with time reversal method. It is proved that time reversal method is feasibility and robustness. And it need analyz and simulates further of the iterative time reversal method.Secondly, through simulation modeling and calculation of reverberation, the performance and effects of inhibiting reverberation and echo enhance of time reversal method about the sunk or buried target detection are more detailed analyzed. This laid a foundation of theory and method for further practical engineering application. The paper discusses the effects of noise and reverberation on the law and the robustness of a single target or multiple target detection by time reversal method.Thirdly, according to the strong reverberation and weak echo signal condition of buried target detection, the paper use match-filter and chaotic signal processing method for the time reversal processing to reduce reverberation intensity and signal extraction. The paper discusses the chaotic properties of reverberation, and uses chaotic model for the reverberation sequence modeling. Next, the paper do some analysis about the signal in the reverberation background based on the chaotic process method, and realize effective detection and extraction of target echo signal in the low signal-reverberation ratio background.Fourthly, this thesis study and analyze the experiment of time reversal detection of hanged and buried small target in the acoustic channel pool by single TRA (time reversal array) element, then get some result of underwater target detection, and achieve some useful experience about the practical engineering application of TRM (time reversal mirror). These result and conclusion have some reference value for further theory and application study.Finally, this thesis design and analyze the system programs and the essential technologies about time reversal detection method in the practical engineering application, and made some foundation for practical engineering application in the future. For the certain acoustic detection foundation project, a sixth channel arbitrary wave generator is designed and implementated.更多还原