中段弹道目标宽带回波仿真与速度补偿

Wideband echo simulation and velocity compensation of midcourse ballistic target

中段弹道目标的主要特征是高速平动和微动。因此测量得到的目标多普勒频移值是模糊的,而且同时被目标微多普勒调制。这给估计目标微多普勒带宽和提取目标微多普勒参数造成了困难。在充分考虑目标运动特征的条件下,首先研究和建立了目标的宽带雷达回波数学模型。然后提出了基于简化分数阶傅里叶变换(simplified fractional Fourier transform,SFRFT)的速度补偿方法。推导了方位向信号起始频率和调频斜率的估计误差方差,证明了算法的有效性。仿真结果表明,该方法能够给出精确的参数估计结果,并能对平动多普勒频率进行准确补偿。即使在信噪比较低的情况下,该方法仍表现出较好性能。该方法为目标微多普勒参数的提取提供了前提条件。

Midcourse ballistic target（MBT）possesses two motion features of high velocity and micro-motion.Hereby,the measured Doppler shift is ambiguous and modulated by the micro-Doppler components.That makes it difficult to estimate the micro-Doppler bandwidth of MBT and extract its micro-motion parameters.Taking the motion features of MBT into account,its wideband echo mathematical model is established and investigated at first.Then,the velocity compensation technique is put forward based on simplified fractional Fourier transform（SFRFT）.In order to prove the asymptotic validity of the method,the parameter estimation error variance of initial frequency and slop of the signal in azimuth is derived.Simulation results show that the advanced method can present accurate parameter estimation and perform effective compensation for translation Doppler shift.Even in low signal to noise ratio case,the simulated outcomes prove it still work well.This technique provides the precondition for micro-Doppler feature extraction.