弹载前斜视SAR BP成像算法与实现

摘要

Azimuth resolution of missile borne synthetic aperture radar (SAR)is determined by traj ectory and squint angle.Based on acquired range between missile and target during each pulse interval,back projection (BP) algorithm implements azimuth coherent accumulation by converting range into phase compensation value.Because no theoretical approximation is used,BP algorithm is applicable to imaging with large squint angle or imaging with nonlinear trajectory.To meet the requirements of missile borne real-time SAR imaging,a sort of SAR imaging processing method based on each arrived pulse is introduced.The time domain processing method is a revision of BP algorithm,which can start computing on arrival of each pulse and is suitable to missile borne SAR with characteristics of short time delay,real-time fast imaging.The efficiency was validated by SAR imaging simulation and aircraft borne experiments under large squint angle circumstances.%弹载合成孔径雷达(SAR)的方位成像能力受飞行弹道和观测角的影响.后向投影(BP)算法建立在每条回波脉冲对应的弹目斜距已测知,通过斜距将回波信号反向投影至成像区域进行相干累加,实现目标区域的精确成像,在原理上不存在任何理论近似,因此适用于弹载大斜视角或者非线性航迹等复杂成像几何下的成像聚焦处理.为满足弹载实时SAR成像处理的要求,提出一种逐脉冲SAR实时成像算法.该方法是在BP算法基础上改进的时域处理算法,具备逐脉冲实时处理的特性,适合弹载条件下的延迟时间短、实时率高、快速成像的特点.仿真和机载试验表明,该方法可以有效进行大前斜视角的SAR成像,实现SAR实时成像处理.