【作者】 张敏；

【导师】 张婷；

【作者基本信息】 浙江大学 ， 信息与通信工程， 2022， 硕士

【摘要】 波达方向(Direction of Arrival,DOA)估计是阵列信号处理领域的重要研究课题,也是声呐系统的重要功能。声呐设备昂贵,且空间部署易受到实际水下环境限制。为降低硬件成本,用更少的阵元实现高性能DOA估计,研究基于互质阵列的DOA估计方法具有重要意义。在水声工程领域中,信道的复杂性会给信号的接收、检测和估计造成不利影响。浅海波导环境具有更为复杂的物理特性,声信号在浅海的传播受到海面、海底环境、海水介质等多重因素共同作用。当使用常规互质阵DOA估计方法(乘法处理器或最小处理器)对浅海环境下垂直互质阵接收的声信号进行处理时,会产生“伪峰”,即交叉项,导致估计结果失效。交叉项问题已经在对SACLANT实验中利用互质阵接收数据进行乘法处理和最小处理时被观察到。论文围绕解决交叉项问题,对浅海波导环境下互质阵DOA估计方法展开研究。论文首先进一步研究了交叉项的形成机理,通过构造两种互质阵列分析互质因子对浅海环境下互质阵DOA估计的影响,通过理论推导和实验仿真指出了两类不同的相干交叉项。其次,将基于压缩感知的稀疏DOA估计方法应用于该场景,指出了稀疏重建算法处理一类相干交叉项问题的有效性,分析了基于平面波假设的信号处理方法发生模型失配的问题。最后论文基于压缩感知框架,根据浅海声信道中的简正波模型,引入上行平面波和下行平面波信息,重新构建了符合浅海声传播物理机制的信号处理模型,进而提出了结构化牛顿正交匹配追踪算法,实现了在浅海条件下,准确稳健的垂直互质阵DOA估计。理论推导和仿真实验均证明了所提出算法具有更高的信噪比增益。对SACLANT试验的数据处理结果表明,相较于乘法处理器和最小处理器,所提出的算法具有更高的分辨力和更低的旁瓣水平;相较于牛顿正交匹配追踪算法等基于平面波假设的稀疏重建算法,所提出算法具有更良好的稳健性和可靠性。最后,论文总结了全文的工作和研究成果,并对基于压缩感知的浅海垂直互质阵DOA估计后续研究进行了展望。更多还原

【Abstract】 Direction of Arrival(DOA)estimation is important in array signal processing.Also,it is an important function of sonar systems.Sonar equipment is expensive,and the deployment is limited by the actual underwater environment.In order to reduce the hardware cost and achieve high-performance with fewer sensors,it is of great significance to study the DOA estimation method based on coprime arrays.In the field of hydroacoustic engineering,the complexity of the channel can adversely affect the reception,detection and estimation of the signal.The shallow sea waveguide environment has more complex physical characteristics,and the propagation of acoustic signals in the shallow water is affected by multiple factors such as the sea surface,the seabed environment,and the seawater medium.When the conventional coprime DOA estimation method(multiplier processor or minimum processor)is used to process the acoustic signal received by the vertical coprime array in the shallow sea environment,"pseudo-peak",that is,the cross term,will be generated,which will lead to the invalidation of the estimation result.The cross-term problem has been observed in the SACLANT experiments using a vertical coprime line array to process data with multiplicative processor and minimum processor.Focusing on solving the cross-term problem,this paper studies the DOA estimation method of coprime arrays in the shallow waveguide environment.The paper first further studies the formation mechanism of the cross term,and analyzes the influence of the coprime factor on the DOA estimation of the coprime array in the shallow water environment by constructing two coprime arrays,and points out two different coherent cross terms through theoretical derivation and experimental simulation.Secondly,the sparse DOA estimation method based on compressed sensing is applied to this scene,the effectiveness of the sparse reconstruction algorithm in dealing with a class of coherent cross-term problems is pointed out,and the problem of model mismatch in the signal processing method based on the plane wave assumption is analyzed.Finally,based on the compressed sensing framework,according to the characteristics of the shallow ocean acoustic channel,combined with the normal wave model,the paper introduces the information of the upward plane wave and the downward plane wave,and reconstructs the signal processing model that conforms to the physical mechanism of shallow ocean acoustic propagation,and then proposes a structured Newtonlized orthogonal matching pursuit algorithm,to achieve accurate and robust DOA estimation of vertical coprime arrays in shallow water waveguide.Theoretical derivation and simulation experiments both prove that the proposed algorithm has higher signal-to-noise ratio gain.The data processing results of the SACLANT experiment show that the proposed algorithm has higher resolution and lower sidelobe level than the multiplication processor and the minimum processor.Compared to plane-wave-based sparse reconstruction algorithm,the proposed algorithm has better robustness and reliability.Finally,the thesis summarizes the study work and prospectes the follow-up research on DOA estimation with vertical coprime line array in shallow water waveguide.更多还原