首先,对高速运动目标的线性调频步进回波信号建立了模型,该模型不仅考虑了目标运动造成的线性调频步进回波子脉冲信号相位变化,以及复包络时间比例发生的变化,还考虑了目标的径向运动导致子脉冲线性调频信号调频斜率的变化。然后,基于该回波模型提出了线性调频步进信号频域合成运动补偿算法,对运动目标回波信号进行精确的运动补偿。仿真结果表明,频域合成后得到的高分辨距离像副瓣电平<-40 dB,基本消除了目标高速运动对信号合成处理结果的影响。

Firstly,the model of stepped-frequency chirp echo from a high speed moving target is presented in this paper. Not only are the changes in phase and envelope between Linear FM stepped-frequency sub-pulses considered, but also the variation of frequency modulation rate caused by target's velocity is taken into account in this model. Then a motion compensation algorithm of frequency domain linear FM stepped-frequency processing is proposed based on this model. By accurately compensating the echo from a high speed moving target, simulation result indicates that the frequency domain synthesis algorithm can obtain a high resolution range image with a low sidelobe level of less than -40 dB and essentially eliminate the influence of target's high speed on the synthesis result.