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基于阵列技术的机载前视线性调频连续波(FMCW)合成孔径雷达(SAR)能对载机前方区域高分辨成像,且能满足机载SAR小型化的需要。针对前视成像若不考虑载机运动时信号模型不完整和系统应用受到制约的问题,提出基于载机运动特征的FMCW SAR前视成像。分析了前视FMCW SAR与脉冲SAR信号收发模式等问题的异同,建立了基于载机运动特征的前视FMCW SAR信号模型。分析了载机运动的影响,并重点讨论了载机运动引入的多普勒频率偏移。结合距离-多普勒(RD)算法流程给出了多普勒频率偏移的补偿方法并进行了仿真研究。结果表明,载机运动会引起点目标航线向主瓣展宽、旁瓣畸变以及目标位置的搬移,通过补偿可有效消除载机运动的影响。
Based on the array technology, the airborne forward looking frequency-modulated continuous wave (FMCW) synthetic aperture radar (SAR) is capable of high-resolution imaging of the aircraft in front of the area and can meet the needs of miniaturization of airborne SAR. In view of the problem that the forward-looking imaging does not consider the incomplete signal model and the system application is restricted when the carrier is moving, the forward-looking FMCW SAR imaging based on the characteristics of the carrier is proposed. The similarities and differences between forward-looking FMCW SAR and pulse SAR signal transmission and reception modes are analyzed, and a forward-looking FMCW SAR signal model based on the characteristics of aircraft carrier is established. The influence of carrier motion is analyzed, and the Doppler frequency offset introduced by carrier motion is discussed. Combined with the distance-Doppler (RD) algorithm flow, the compensation method of Doppler frequency offset is given and simulated. The results show that the movement of the carrier will cause the movement of the target route to the main lobe, the distortion of the side lobe and the moving of the target position. The compensation can effectively eliminate the influence of the movement of the carrier.