直升机载调频连续波旋转式SAR信号分析与成像算法研究

摘要

该文研究基于调频连续波(Frequency Modulated Continuous Wave, FMCW)的直升机载旋转式合成孔径雷达(ROtating Synthetic Aperture Radar, ROSAR)成像，提出一种直升机载FMCW-ROSAR成像的新方法。该方法首先利用等效相位中心原理，将收发分置天线系统的回波信号等效为“自发自收”单基系统。在此基础上，给出了其精确的2维频谱同时分析了载机在发射信号和接收信号过程中天线连续运动的影响产生多普勒频移及其补偿方法；然后运用高效的逆Chirp-Z变换校正了距离徙动空变性。整个算法只包含快速傅里叶变换和复乘操作，不涉及插值，易于工程实现。仿真结果验证了分析结论的正确性和算法的有效性。%A novel helicopter-borne Frequency Modulated Continue Wave (FMCW) ROtating Synthetic Aperture Radar (ROSAR) imaging method is proposed. Firstly, by performing the equivalent phase center principle, the separated transmitting and receiving antenna system is equalized to the case of system configuration with antenna both for transmitting and receiving signals. Based on this, accurate two-dimensional spectrum is obtained and the Doppler frequency shift effect induced by the platform’s continuous motion while radar transmits and receives signals is analyzed in detail and compensated. Then, efficient inverse Chirp-Z transform is applied to correct the range-variant Range Cell Migration (RCM). With only FFT and complex multiplication and no interpolation, the proposed method can be efficiently implemented. Finally, correctness of the analysis and effectiveness of the proposed algorithm are demonstrated through simulation results.