基于条带模式 GEOSAR-TOPS 模式UAVSAR 的双基成像算法

摘要

针对基于地球同步轨道条带模式合成孔径雷达（synthetic aperture radar，SAR）发射无人机循序渐进对地扫描模式 SAR 接收组成的星机双基结构（GEO-bistatic radar with GEOSAR and UAVSAR，GEO-UAV BiSAR），提出了该工作模式下的成像算法。首先，基于泰勒展开原理推导了双基斜距，考虑到该双基斜距的空变特性，应用级数反演方法推导了具有距离空变性的点目标二维频谱。其次，考虑在小脉冲重复频率条件下由于天线转动引起的方位频谱混叠问题，提出了基于 GEO-UAV BiSAR 的成像算法。该成像算法引入 dechirp 技术解决方位混叠问题，随后通过距离压缩、距离徙动校正、方位压缩和 dechirp 技术得到清晰的成像结果。最后，仿真实验验证了该成像方法的有效性。%For bistatic synthetic aperture radar (SAR)of the geosynchronous transmitter in the strip mode and the unmanned aerial vehicle (UAV)receiver in the terrain observation by progressive scans (TOPS)mode (GEO-UAV BiSAR),a new imaging method is proposed.Firstly,the slant range model is inferred by Taylor expansion,and the point target two-dimensional frequency spectrum with the space-variant in range through se-ries reversion is further presented.Then,under the condition of the small pulse repetition frequency,the bistat-ic imaging method is proposed for the azimuth frequency aliasing caused by the steering of the antenna beam.In this imaging processing,the dechirp technology is firstly used to solve the above aliasing,and then subsequent imaging operations are carried out,i.e.range compression,range migration correction,azimuth compression and dechirp processing.Finally,simulations validate the imaging method.