采用双混频实现扩展目标运动参数估计和散射中心重构

Movement Parameter Estimation and Scattering Centers Reconstruction of Extend Target Using Double-Dechirping

推导了运动扩展目标在全去斜率体制下的回波信号形式,指出其为多分量多项式相位信号(mc-pps).分析了时频分析方法和多项式相位变换方法对该信号处理的不足,提出一种采用双混频实现扩展目标运动参数估计和和散射中心重构的新方法:通过对回波的双混频处理避免自相关处理带来的能量损失及分辨率降低;根据相关函数的功率谱特点,在频域抑制由多分量带来的交叉项干扰;通过循环估计减小参数估计误差的传播影响,最后利用ESPRIT超分辨估计方法提高参数估计精度.仿真结果表明该方法能有效提取目标的运动特征并能重构目标的一维散射中心.

The echo＇s mathematic model of movement target for wideband linear frequency modulated signal in STRETCH processing is deduced, which is demonstrated to be a muticomponent polynomial phase signals （mc-pps）. The defect of processing mc-pps using time-frequency analysis and polynomial phase transform （PPT） are pointed out. And then, a new algorithm of estimation movement parameter and reconstruction scattering centers of extend radar target is proposed, which can avoid loss of energy and frequency resolution of auto-correlation by using double-dechirp. According to the characteristic of power spectntm, the proposed algorithm adopts power maxima criterion suppressing crossterms and improves performance of parameter estimation by using iterative algorithm. Furthermore, the ESPRIT algorithm supersedes FFr algorithm for improving estimation accuracy. Simulation results show that the proposed method can extract movement feature and reconstruct scattering centers effectively, even when SNR is low.