复合微多普勒信号的时频谐波分析方法

Time-frequency harmonic wave analysis method of composite micro-Doppler signals

在对复合微动目标的雷达回波进行时频分析时,存在时频曲线能量难以聚焦等问题,影响目标微多普勒特征提取和分析。对此,提出了时频谐波条纹的概念以及相应时频变换方法。基于复合微动包含中心运动分量和高频运动分量的假设,首先利用样条函数拟合中心分量频率曲线,构造时频变换核函数。然后,通过参数化时频变换将时域的复合微多普勒信号转化为时频平面上的谐波条纹。所提方法相比短时傅里叶变换和伪魏格纳分布等经典方法,能够明显改善复合微动目标雷达回波时频变换的能量聚集性与杂散抑制效果,仿真验证了所提方法的有效性和对低信噪比条件的适应性。

In the time-frequency analysis of the echoes from targets with composite micro-motions,there is a problem that the energy of time-frequency strip is difficult to focus,which affects the extraction and analysis of the target’s micro-Doppler feature.To solve this problem,this paper proposes the concept of time-frequency harmonic stripes and corresponding time-frequency transformation methods.Based on the assumption that the composite micro-motions include central motion components and high-frequency motion components,firstly,spline function is used to fit the frequency curve of the central motion component,and therefore construct the time-frequency transform kernel is constructed.Then,parameterized time-frequency transform is used to convert the composite micro-Doppler signal in the time domain to harmonic stripes on the time-frequency plane.Compared with traditional methods such as short-time Fourier transform and pseudo Wigner-Ville distribution,the proposed method can significantly improve the energy aggregation and spur suppression of time-frequency transform of radar echoes from composite micro-motion targets.Simulation results verify the effectiveness of the proposed method and its adaptability to low signal-to-noise ratio(SNR)conditions.