舰船目标三维转动SAR成像仿真研究

SAR Imaging Simulation for Three-Dimensional Rotations of Ship Targets

机载合成孔径雷达(SAR)对海面舰船目标侧视成像时,雷达与目标间的相对运动既包含载机与舰船的平移运动,也包含舰船在复杂海况下的横滚、俯仰和偏航等三维转动,运动形式会造成图像模糊。为了解决三维转动引起的成像散焦不清晰问题和提高系统的稳定性,在短时远距的典型条件假设下建立了舰船目标成像的距离-多普勒模型,并重点分析舰船横滚、俯仰和偏航的三维转动对所成图像的影响。采用时频分析方法成像,并进行仿真。仿真结果验证了成像模型的正确性及时频分析成像方法的优越性,提高了系统的性能。

The rotations of ship targets as well as the relative movement between the airborne radar and the ships on the sea surface bring great difficulties to imaging process.In order to deal with the defocusing problems under three-dimension rotation condition,this paper establishes the range-doppler（RD） model for SAR-ISAR ship imaging under the condition that the range is very long and the observation time is short.Based on this model,the effects on the image brought by rolling,pitching and yawing of the ships are discussed.As a traditional algorithm,the FFT method can not acquire clear images when the ship experiences irregular rotation.In this paper,the FFT method is replaced by time-frequency analysis to obtain the target image in range-doppler domain.Several time-frequency methods including WVD,CWD and SPWVD are studied.The simulation proves the accuracy of RD model and the advantages of time-frequency analysis.