基于参数化解调的旋转目标微多普勒频率提取方法

旋转运动是航天领域中最为常见的微运动,如卫星天线转动、弹道导弹自旋运动等。旋转目标的微多普勒特征对雷达目标识别具有重大影响。针对旋转目标不同散射点的微多普勒频率相互重叠、难以提取的问题,提出了基于参数化解调的旋转目标微多普勒频率提取方法。由点散射模型得到旋转目标的微多普勒信号解析形式。考虑到旋转目标微多普勒信号具有正弦频率调制特征,构造了基于正弦模型的参数化解调算子,优化微多普勒频率参数,使解调信号在载波频率处的频谱值达到最大。为了估计多个散射点的微多普勒频率参数,提出了参数迭代估计方法,在每次迭代中只估计当前最强散射点的微多普勒参数,将相应信号分量从原始信号中剔除,消除对后续分量估计结果的影响。仿真和实验结果表明:基于参数化解调的旋转目标微多普勒频率提取方法与传统时频峰值检测方法相比,能更精确地提取相互交叉的旋转目标微多普勒频率,为最终实现雷达空间目标识别提供了理论基础,能应用于卫星天线、弹道导弹等目标的监测、识别。

Micro-Doppler Frequency Extraction for Rotating Targets Based on Parameterized Demodulation

In the field of spaceflight, the rotating motion of a target is one of the most common micro motions, such as the rotation of the satellite antenna and the spinning motion of the ballistic missile. The micro-Doppler (m-D) signatures of these rotating targets play important roles in radar space target recognition. Since the m-D frequencies of different scattering points usually overlap in the time-frequency domain, it is difficult to extract them by use of traditional methods. To address this issue, this paper proposes a novel m-D frequency extraction method for rotating targets based on parameterized demodulation. Firstly, according to the theory of point scatter model, the analytical expression of the radar echo signal from a rotating target is obtained. Given the fact that the obtained signal model is featured by sinusoidal frequency modulation, a parameterized demodulation operator based on the sinusoidal model is constructed and the parameters of the m-D frequency are optimized to ensure that the spectrum of the demodulated signal reaches the maximum value at the carrier frequency. To estimate m-D frequency parameters of multiple scattering points, an iterative parameter estimation scheme is proposed. For each iteration, only m-D parameters of the current strongest scattering point are estimated and then the corresponding signal component is removed from the original radar echo signal to eliminate the influence on the parameter estimation of other components in subsequent iterations. The simulation and experiment show that compared to the traditional time-frequency peak detection method, the proposed method can accurately extract overlapped m-D frequencies of rotating targets, laying the foundation for radar space target recognition. The method has a promising application prospect in monitoring and identifying the targets such as satellite antenna and ballistic missile.