摘要
对物体空投入水产生的水下瞬态信号的研究分析有着极其重要的意义,如果能够较早的检测到该信号,那么就可以及时的防御空投目标的袭击。本文主要工作是结合矢量水听器技术对物体空投入水信号进行研究,对物体空投入水信号进行检测和特征提取,为防御空投目标的袭击进行有益的探索。
本文首先阐述了矢量信号处理技术的基本原理,包括单矢量水听器和矢量阵对目标方位的估计原理,并对一种重要的空间谱估计理论——MUSIC算法做了仿真分析。通过仿真分析可知,矢量水听器比声压水听器在处理水声信号上具有优势,MUSIC在目标方位估计上具有较高的分辨力。希尔伯特黄变换是一种处理非平稳信号的理论,通过仿真分析可知该理论比其它时频方法具有很大的优点。EMD能够将多分量信号分解为单分量信号,利用EMD的这个特性,将EMD分解方法应用到矢量信号处理当中,在方位估计和矢量阵波束形成上进行了信号仿真分析,通过仿真分析可知,该方法能够降低噪声的影响,有效地检测到弱目标,提高了方位估计的分辨力。
针对鱼雷空投入水产生的水下瞬态信号,对信号组成部分及物体入水过程做了简要的分析,并根据实测瞬态信号,对其进行了数学建模,给出了瞬态信号模型在声压、振速和加速度上的数学模型,基于该模型利用矢量阵波束形成技术进行了方位估计仿真分析,取得了较好的效果。本文最后对试验数据进行了处理,对空投物体入水信号进行了方位估计,利用时域、频域和时频域结合的方法对瞬态信号特征进行了分析,完成了对物体空投入水信号的检测和特征提取。
As aircraft torpedo is a menace of submarine, researching the underwater instantaneous signal produced by launching a torpedo is very important. So if we find the torpedo by detecting the underwater instantaneous signal in time, defending against the torpedo attack is easy. Given that the condition of ocean is complicated, it is a hard spot to research in this domain. Presented in this thesis are a study of the underwater instantaneous signal with vector signal processing technology and testing out theories by experiment.
In the first part, basic principle of vector signal processing technology and common methods of signal analysis based on the time-frequency field are introduced. Hilbert-huang transform is particularly introduced because it has advantages in processing the non-stationary signals. In this thesis,Hilbert-huang transformis used to analysis the frequency contents of instantaneous signal. Meanwhile, EMD decomposing in Hilbert-huang transform is applied to vector signal processing, then simulation and analysis are made on DOA estimation and vector array beam forming. Through simulation and analysis, it is proved that this method can reduce the impact of the niose , effectively detect weak targets and enhance resolution of the DOA estimation, vector hydrophone is superior in acoustic signal processing to acoustic pressure hydrophone.
A mathematical model is made based on the analysis of the underwater instantaneous signal, which is produced when aircraft torpedo is dropping into water.this mathematical model includes the acoustic pressure ,velocity, and acceleration of the underwater instantaneous signal. We provide a theory of underwater instantaneous signal processing by deducing the mathematical model with vector signal processing technology. Finally, a series of experiments which were designed for testing the theory, the experimental data was processed based on energy detection and short-time fourier transform. What is more, signal detection and feature extraction of acoustic signal of target were completed.
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