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中国物理学会期刊

运动目标的多维度微运动特征提取研究

CSTR: 32037.14.aps.73.20231691

Research on multi-dimensional micro-motion feature extraction of moving targets

CSTR: 32037.14.aps.73.20231691
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  • 微多普勒特征提取作为一种常用的时频分析工具, 对微动目标特征的提取重构具有重要意义. 为了更好地研究多运动的微多普勒效应, 提出了一种运动姿态分类方法. 按照目标频移是否随时间变化可以将运动姿态分为频移时变运动和频移时不变运动. 频移时变运动包括平移、翻滚和振动. 针对这种运动应分析对比不同时间对应的瞬态频移, 频移时不变运动主要为旋转运动. 本文通过微多普勒效应理论结合电磁波频域模型, 实现3D运动目标微动特性提取的仿真建立目标, 分析不同环境条件例如晴天阴天、有无湍流对探测的影响, 为后续实验研究奠定理论基础. 开展基于收发同置系统的多特征运动目标的微多普勒频移探测实验, 实验结果表明, 不同目标位置上频移的幅度、正负性和谱线宽度旨在反演目标形状、运动姿态、运动方向和速度. 利用FFTshift函数对一维数据进行解调分析, 实现三维时间-频率-强度关系的研究. 本研究实现了对目标宏观形状特性的测量以及微观运动信息的提取, 为雷达探测和识别奠定基础.

     

    The micro-Doppler effect is a physical phenomenon generated by the micro-motion of objects and their components, which have a significant influence on improving radar detection and resolution capability and also enhancing the radar imaging and target recognition performance. The extraction of micro-Doppler frequency, as a commonly used time-frequency analysis tool, is of great significance in extracting and reconstructing the signal with micro-motion targets. The micro-motion characteristics for moving targets can be verified by using simulation through combining the theory of micro-Doppler effect with the frequency domain model of electromagnetic waves. The simulation research on the micro-motion characteristics of a three-dimensional target is conducted by using the finite element method. The influences of environmental conditions such as relative humidity, visibility, and the presence or absence of turbulence on echo intensity and time-frequency relationship are investigated theoretically. The simulation results indicate that parameters such as relative humidity and visibility, which affect the atmospheric attenuation coefficient, can reduce echo intensity and the period of time-frequency curve. By triggering off beam drift in the transmission path, turbulence can lead to “frequency shift deformation” of the time-frequency curve, degrading the extraction of target motion attitude. A motion attitude classification method is proposed in order to study the micro-Doppler effect better. According to whether the frequency shift changes with time, the motion attitude can be divided into frequency shift time-invariant motion and time-variant motion. Frequency shift time-variant motion includes translation, rolling and vibration. Vibration and rolling are motions that periodically change with time, requiring the comparison of instantaneous frequency shifts at any three times within a cycle. Translation is a time-variant motion with irregular frequency shifts over time, which involves studying instantaneous frequency shifts at any three times. Transient frequency shifts should be analyzed and compared at different times for these motions. The frequency shift time-invariant motion is mainly rotation obtained experimental results indicate that the amplitude, plus-minus, and spectral width of frequency shift at different positions are aimed at inverting the target shape, attitude, direction and velocity. Demodulating one-dimensional data obtained from the FFTshift function can obtain the time-frequency-intensity relationship. This multi-parameter analysis method is a multi-dimensional processing method widely used in the fields of radar, sonar, and communication. The above research is conductive to the measurement of target macroscopic shape properties and the extraction of microscopic motion information, which lays the foundation for radar detection and recognition.

     

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