基于窄波束和平地假设的运动补偿方向研究

The Research on the Direction of Motion Compensation According to the Narrow Beam and Flat Earth Hypothesis

窄波束和平地假设是在合成孔径雷达(SAR)运动补偿过程中常用的一种假设,其指明可以将SAR平台相对场景中任意点目标运动误差的空变近似为相同最短斜距处波束中心视线方向上相应点目标的距离空变。该文在正侧视模式和斜视模式运动补偿模型的基础上,从理论上证明了仅存在高度误差时,窄波束和平地假设运动补偿最优的方向垂直于雷达波束中心视线,说明了沿该方向进行运动补偿的原因,并用仿真实验验证了其正确性。

The narrow beam and flat earth hypothesis is a widely used assumption in Synthetic Aperture Radar （SAR） motion compensation. It proposes an approach in dealing with the space variance of the motion errors of the moving platform relative to arbitrary point targets in the scene, which is approximately considered as the space variance of the associated distance of the same range gate in the direction of radar beam center. Based on the narrow beam and flat earth hypothesis, this paper derives an implied conclusion that the optimal direction of motion compensation is perpendicular to the line of sight transmitted from the radar beam center only when the height error exists. This analysis is suitable for both broadside and squinted motion compensation models. Then, the reason of the hypothesis in carrying out motion compensation is presented in detail and its validity is confirmed by means of simulated experiments.