一种大斜视SAR俯冲段频域相位滤波成像算法

大斜视SAR俯冲阶段的高速下降以及加速度等特点,导致距离方位耦合严重,方位平移不变性的假设不再成立,无法得到精确的二维频谱,给成像处理带来困难.针对这些问题,本文提出一种基于频域相位滤波处理的子孔径俯冲段成像算法.采用级数反演(MSR)得到精确的二维频谱,时域校正距离走动、频域校正距离弯曲的方式实现距离和方位的二维解耦合,最后在方位频域引入高次频域相位滤波因子校正调频率的空变并结合谱分析技术(SPECAN)实现信号方位频域聚焦.整个算法只包含快速傅里叶变换(FFT)和复乘,不涉及插值,易于工程实现.点目标仿真数据和机载实测数据处理验证了本文提出算法的有效性和实用性.

A Frequency Phase Filtering Imaging Algorithm for High-Squint SAR in Diving Movement

During the diving movement for highly squinted synthetic aperture radar (SAR), the echo is coupled greatly between azimuth and range, invariance in azimuth is not accurate, which are caused by high vertical velocity and acceleration, making SAR imaging difficult to process.Due to these issues, a frequency phase filtering algorithm (FPFA) is proposed.First, the accurate 2-D spectrum can be got via the method of series reversion (MSR), the range walk will be eliminated in the time domain and in the frequency domain the range curvature removed.Then, a frequency filtering phase is leaded into frequency domain in order to correct the dependence of the FM rates.At last, the signal is focused in the Doppler domain by Spectral Analysis technique (SPECAN).As the whole procedure only involves short fast Fourier transforms (FFTs and complex multiplications without interpolation, the FPFA is computationally efficient and facilitates hardware real-time implementation.The simulated results and raw data processing validate the effectiveness of the proposed algorithm.