双发多收合成孔径声纳技术研究

发布时间：2018-04-22 09:22

本文选题：合成孔径声纳 + MIMO技术　；参考：《电子科技大学》2014年硕士论文

【摘要】：合成孔径声纳(Synthetic Aperture Sonar,SAS)是进行水下成像探测的主要技术手段之一,与SAR系统类似可以在大范围成像并且拥有恒定的分辨率,拥有其他声纳系统无法比拟的大范围成像效果。但是,由于水声环境的限制,SAS一直受到测绘效率低等问题的困扰。本文结合MIMO新体制研究合成孔径声纳系统,旨在提高SAS系统的测绘效率,使得其效能可以在实际运用中更大的发挥出来。本论文主要集中研究一种新型的双发多收合成孔径声纳技术。从系统设计开始,优化原先单发多收线阵的声纳系统结构,研究双发多收合成孔径声纳布阵结构,并根据等效相位中心假设给出其基本的声程关系以及信号处理流程。由于双发射机的布局,以及信号之间的正交性,新体制相比原先系统多出一倍的等效相位中心。这使得系统可以在其他条件不变的情况下,每次脉冲周期多获得一倍的方位向采样,从而提高了系统的测绘效率。MIMO合成孔径技术的关键是正交发射波形设计,保证各组信号之间没有干扰。本文主要研究四种典型信号:频分线性调频信号,正负线性调频信号,正交跳频信号以及正交编码信号。对它们的正交性进行了推导以及仿真,并对每种信号的功率谱,匹配滤波结果进行分析。其中通过遗传算法,对跳频信号对进行了互相关自相关联合优化。并比较了各种正交信号对的优缺点。推导了双发多收合成孔径声纳回波信号模型。成像算法是SAS系统信号处理的核心内容,这里对上述的典型信号根据经典成像算法进行了仿真验证,从成像质量上对新系统的正交发射信号进行性能评价。运动补偿技术是提高成像质量的重要手段,论文从重叠相位中心算法入手研究新系统下的像差校正。并给出仿真结果。最后将正负线性调频信号多普勒频移性质运用于水下强点目标相对速度测定以及定位技术。该技术可以仅通过一次回波信息对声纳孔径范围内的水底静止目标进行相对定位,通过利用正线性调频信号与负线性调频信号在脉冲压缩时对于相同多普勒频移时的不同方向的主瓣偏移测量回波信号的多普勒频移,从而测定相对速度,结合脉冲压缩得到的声程信息即可进行目标定位,使得合成孔径声纳的探测目标的定位更加精确。
[Abstract]:Synthetic Aperture Sonar Sas (synthetic Aperture Sonar) is one of the main techniques for underwater imaging detection. Similar to SAR system, it can be imaged in a large range and has constant resolution, and has a large range imaging effect that other sonar systems can't compare with other sonar systems. However, because of the limitation of underwater acoustic environment, SAS has been troubled by low mapping efficiency. The purpose of this paper is to improve the mapping efficiency of SAS system and make it more effective in practical application by combining the new MIMO system with synthetic aperture sonar system. This paper focuses on a novel dual-transmitter multi-receiver synthetic aperture sonar technology. Starting from the design of the system, the structure of the sonar system with single transmitter and multi-receiver linear array is optimized, and the structure of the dual-transmit multiple-receiver synthetic aperture sonar array is studied. The basic acoustic path relationship and signal processing flow are given according to the assumption of the equivalent phase center. Due to the layout of the dual transmitters and the orthogonality between the signals, the new system has twice as many equivalent phase centers as the original system. This makes it possible for the system to obtain more than one time azimuth sampling for each pulse period without any other conditions, thus improving the mapping efficiency of the system. The key to MIMO synthetic aperture technology is the design of orthogonal transmitting waveforms. Make sure there is no interference between the signals. This paper mainly studies four kinds of typical signals: frequency division linear frequency modulation signal, positive and negative linear frequency modulation signal, quadrature frequency hopping signal and orthogonal coded signal. The orthogonality of each signal is deduced and simulated, and the power spectrum and matched filtering results of each signal are analyzed. The genetic algorithm is used to optimize the frequency hopping signal pair by cross correlation autocorrelation. The advantages and disadvantages of various orthogonal signal pairs are compared. The model of double-transmit multi-receiving synthetic aperture sonar echo signal is derived. The imaging algorithm is the core of signal processing in SAS system. In this paper, the typical signal is simulated according to the classical imaging algorithm, and the performance of the quadrature transmitted signal of the new system is evaluated in terms of imaging quality. Motion compensation is an important method to improve the imaging quality. This paper studies the aberration correction in the new system based on the overlapping phase center algorithm. The simulation results are given. Finally, the Doppler frequency shift property of positive and negative LFM signals is applied to the determination of relative velocity of underwater strong spot target and positioning technology. This technique can locate the underwater static target in the range of sonar aperture by only one echo information. The Doppler frequency shift of echo signal is measured by using positive linear frequency modulation signal and negative linear frequency modulation signal during pulse compression for different directions of the same Doppler frequency shift, so as to determine the relative velocity. Combined with the acoustic path information obtained by pulse compression, target location can be carried out, which makes the target location of synthetic aperture sonar more accurate.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TB566

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