摘要
摘要
声呐系统目前正向系统性、综合性方向发展，意味着声呐系统将越来越复杂，有效的采样及数据传输是重要基础。传统奈奎斯特采样产生的数据量对于声呐系统中的水下数据传输及无线数据传输来说过大。因此，研究面向声呐回波信号的高效的采样方案很有必要。近年来提出的有限新息率（Finite Rate of Innovation, FRI）采样理论能够根据远低于奈奎斯特的采样率获得的采样值，利用恢复算法估计出FRI信号的自由参量。本文将声呐回波信号建模为参数化信号后，可以利用有限新息率采样理论来对声呐回波信号进行欠采样。首先对声呐回波信号进行模拟预处理，然后利用低速采样获得的采样值获得声呐回波信号的傅里叶级数系数集，再根据回波信号特点利用不同的恢复算法估计未知参数。主要研究内容包括：
avoiding1、研究声呐回波信号的建模及FRI采样理论。对声呐回波信号的建模进行了详细的阐述，包括采用亮点模型法对目标回波信号进行建模，采用点散射方法与单元散射方法相结合的方式对混响信号进行建模。研究了FRI采样理论的采样过程及恢复过程，针对不同的采样结构及恢复算法分别进行比较，为利用有限新息率采样理论处理声呐回波信号提供理论基础。
2、针对无混响时静止点目标的检测，提出将声呐回波信号建模为由时延和幅度参数决定的参数化信号，
能够应用FRI采样理论。分别探究了利用单通道调制低通滤波结构及多通道调制积分结构来获取声呐回波信号的傅里叶级数系数，两种结构有各自的优缺点，可根据具体情况选择适合的采样结构，并分析了对两种采样结构恢复效果的影响因素。
3、针对混响背景下的动目标检测，提出将目标回波信号建模为由时延、幅度和多普勒频率参数决定的参数化信号，可以利用FRI采样理论实现欠采样。根据目标回波信号与混响信号多普勒频率不同的特点，应用多普勒聚焦技术对声呐回波信号进行处理，可以排除混响的干扰，先恢复目标的多普勒频率，再恢复时延参数和幅度参数，说明了多普勒聚焦处理的优势并进行了仿真验证。
4、声呐回波信号FRI采样的硬件实验验证。完成了硬件部分的模块设计，搭建了由乘法器模块、放大器模块和模拟低通滤波模块等组成的模拟预处理结构。利用LabVIEW上位机编程控制NI PXIe设备完成了信号模拟输出、数据采集、数据存储及上位机重构等功能。本文通过大量实验证明了所设计的FRI欠采样系统能够实现对声呐回波信号的欠采样，压缩比能够达到4.72%。
关键词：有限新息率；声呐回波信号；多普勒聚焦；目标检测；信号恢复
Abstract
Abstract
The trend of sonar system is systematic and comprehensive, which means it will be more and more complicated, effective sampling and data transmission is an important foundation. The amount of sampled data by traditional Nyquist sampling is too large for data transmission underwater and wireless. Therefore, the rearch of high efficient sampling scheme for sonar echo is necessary. In recent years, Finite Rate of Innovation(FRI) sampling theory is proffered to sample and recover the unknown parameters of FRI signals far below the Nyquist sampling rate. In this paper, the sonar echo is modeled as a parameterized signal, the FRI sampling theory can be ud to subsample sonar echo. Analog preprocessing is first done for the sonar echo, and then implement a low-rate sampling, a t of Fourier ries coefficients of sonar echo can be obtained from the sampled data, various recovery algorithms can be ud to estimate the unknown parameters according to the characteristics of sonar echo. The main work in this paper is:
1. Rearch on the modeling of sonar echo and FRI Sampling Theory. The modeling of the sonar echo is described in detail, including the modeling of the sonar target echo by the bright spot model method, and the reverberation signal is modeled by the combination of the point scattering method and the unit scattering method. The sampling and recovery of FRI sampling theory is analyzed. The performance of different sampling structures and recovery algorithms is compared, which provides the theoretical basis for processing the sonar echo using the FRI principle.
2. Focusing on the detection of stationary point targets in the non-reverberation background. The sonar echo is modeled as a parameterized signal determined by the delays and amplitudes, and the FRI sampling theory can be applied. The Fourier ries coefficients of the sonar echo can be obtained using the single channel modulation low-pass filter structure and the multi-channel modulation integral structure. The two structures have their own advantages and disadvantages, the sampling structure is chon according to the specific situation. The influencing factors of the two sampling structures are analyzed.
3. Focusing on the detection of moving targets in the background of reverberation, the sonar target echo is modeled as a parameterized signal determined by the delays, amplitudes and Doppler frequencies, sub-Nyquist sampling can be realized using the FRI sampling theory. Since the Doppler frequency of the sonar target echo different from the reverberation signal, the Doppler focusing technique is proffered to deal with the sonar echo, which can eliminate the interference of reverberation. Recovering the Doppler
Abstract角先法
frequencies of the target at first, and then the delays and amplitudes can be recovered, the advantages of Doppler focusing processing are illustrated and simulated.
4. Hardware experimental verification of FRI sampling of sonar echo. The design of the hardware module is completed, and the analog preprocessing structure is compod of the multiplier module, the amplifier module and the analog low-pass filter module. The NI PXIe device is controlled by LabVIEW to implement the signal output, data sampling, data storage and PC recovery. This experimental prototype proves that the sub-Nyquist methodology for sonar echo described in this paper is actually feasible in practice, the compression ration can achieve to 4.72%.
Keywords:finite rate of innovation (FRI); sonar echo; Doppler focusing; target detection; signal recovery
目录
目录
荷花花语摘要 ................................................................................................................................. I Abstract ............................................................................................................................... I I 第1章绪论 . (1)
1.1 课题背景及研究目的和意义 (1)
青年减肥1.2 研究历史及现状 (2)
1.2.1 声呐回波信号处理的研究与进展 (2)
1.2.2 有限新息率理论的研究与进展 (4)
排名前10的奶粉1.3 本文的研究内容与结构 (5)
第2章声呐回波模型及FRI采样理论 (7)
2.1 声呐回波信号建模 (7)
2.1.1 目标回波信号建模 (7)
2.1.2 混响信号建模 (9)
2.1.3 仿真实验 (10)
2.2 有限新息率采样理论 (12)
2.2.1 有限新息率信号 (13)
2.2.2 有限新息率采样结构 (14)
2.2.3 有限新息率恢复算法 (19)
2.2.4 仿真实验 (24)
2.3 本章小结 (27)
第3章无混响时的静目标检测 (28)
3.1 声呐回波信号模型 (28)
3.2 声呐回波信号采样结构研究 (28)
3.2.1 单通道调制低通滤波结构 (29)
3.2.2 多通道调制积分结构 (30)
3.3 仿真实验 (31)
3.3.1 单通道调制低通滤波结构 (32)
3.3.2 多通道调制积分结构 (36)
醚链
3.3.3 采样结构比较 (37)
3.4 本章小结 (38)
第4章混响背景下的动目标检测 (39)
4.1 声呐回波信号模型 (39)
目录
4.2 多普勒聚焦 (39)
4.2.1 频域多普勒聚焦 (40)
4.2.2 亮点模型动目标检测 (44)
4.3 信噪比分析 (45)
4.4 仿真实验 (47)
4.4.1 点目标 (47)
4.4.2 亮点模型目标 (49)生活中的传统文化
4.5 本章小结 (51)
第5章声呐回波信号FRI采样的硬件实验验证 (52)
5.1 需求分析 (52)
5.2 硬件设计 (52)西峪水库
5.2.1 模拟预处理板卡设计 (53)
5.2.2 PXI系统 (54)
5.3 软件设计 (55)
5.3.1 上位机执行流程 (56)
5.3.2 程序模块 (57)
5.4 硬件实验和分析 (60)
5.4.1 硬件实验 (60)
5.4.2 调试问题及分析 (65)
5.5 本章小节 (66)
结论 (67)
参考文献 (69)
攻读学位期间发表的论文、专利 (73)
哈尔滨工业大学学位论文原创性声明和使用权限 (74)
致谢 (75)
