基于非均匀FFT的超宽带合成孔径雷达高效成像算法

Efficient imaging algorithm based on non-uniform fast Fourier transform for ultra-wide band synthetic aperture radar

超宽带合成孔径雷达(ultra-wideband synthetic aperture radar,UWB-SAR)成像算法中后向投影算法(back-projection algorithm,BPA)和可扩展的Omega-K算法成像精度很高,但成像处理中的复数插值操作带来了较大的运算负担。非线性调频变标算法(nonlinear chirp scaling algorithm,NCSA)不存在复数插值处理,成像效率较高,由于级数展开处理存在近似,SAR图像存在一定的距离方位耦合副瓣。提出了一种新的UWB-SAR成像算法,通过对SAR距离脉压后的距离时域数据进行非均匀傅里叶变换,去除距离方位的耦合。图像消除了距离方位耦合副瓣,具有较好的质量。随着成像点数的增多,本文算法成像效率接近NCSA成像效率。仿真结果验证了该算法的正确性。

In the ultra-wideband synthetic aperture radar（UWB-SAR）imaging algorithms the back-projection al- gorithm（BPA）and the extended Omega-K algorithm（EOKA）have high imaging accuracy. But the complex interpola- tion operation in the imaging process brings about heavy computational load. The nonlinear chirp scaling algorithm （NCSA） does not need a complex interpolation process and has a higher imaging efficiency. Due to the approximation in the series expansion process, SAR images contain certain range and azimuth coupling sidelobe. This paper presents a new UWB-SAR imaging algorithm. The proposed algorithm does non-uniform FFT on the range-time domain data af- ter range compression to cancel the range and azimuth coupling. The images delete the range and azimuth coupling side- lobe and have high quality. As the data number increases the proposed algorithm imaging efficiency is closer to NCSA imaging efficiency. Simulation results verify the correctness of the proposed algorithm.