一种去除回波频谱调制的直升机SAR成像方法

摘要

Since radar signals are modulated by rotor blades shadowing and helicopter vibration, the helicopter-borne synthetic aperture radar (SAR) imaging is difficult. Therefore, modulation reasons are analyzed and investigated based on time-frequency method. The modulation phase errors are extracted from the dechirped data and then compensated to remove modulation. Subsequently, the phase gradient autofocus is performed to achieve a high quality SAR image. The method has great reference value to the helicopter-borne SAR imaging.%直升机机载合成孔径雷达(Synthetic aperture radar,SAR)信号受到主旋翼遮挡和直升机振动的调制,给合成孔径成像造成很大影响.本文采用时频分析方法对调制产生的原因和特征进行分析和研究,提出利用去斜后的方位相位误差作补偿,再进行相位梯度自聚焦(Phase gradient autofocus,PGA)处理,实现调制雷达回波的高质量SAR成像.实测数据表明,本方法较好地解决了回波调制情况下的成像问题,对直升机平台SAR成像具有重要的参考价值.