针对存在频谱混叠的窄带雷达微动信号平动补偿问题,从高阶和低阶频谱混叠两种情况出发,给出了一种平动补偿方法。在对两种频谱混叠情况分析的基础上,针对高阶混叠将混叠的瞬时频率近似为线性调频锯齿波信号,通过对频率以及调频率的估计,实现信号混叠程度的快速降阶。对于低阶混叠,首先将时频图在频率维周期扩展,再基于形态学图像处理方法提取出无模糊的瞬时频率曲线,最后对其进行多项式的最小二乘拟合完成平动补偿。仿真实验验证了所提方法的有效性以及对不同的信号形式和噪声的鲁棒性。
A translational compensation algorithm of micro-motion with spectrum aliasing for narrow-band radar is proposed. It is done in high-order and low-order spectrum aliasing cases. Based on the analysis of these two aliasing cases, the translational can be fast degraded by approximating the aliasing frequency as a linear fre- quency modulation saw-tooth wave in high-order spectrum aliasing cases. To deal with the low-order spectrum aliasing, the time-frequency image is expanded in frequency, and then the time-frequency curve without frequen- cy ambiguity can be extracted based on morphological image processing. Finally, the least-square fitting of poly- nomial is utilized in the curve for translational compensation. Simulations are given to validate the effectiveness and robustness of the proposed algorithm.