A 2-D Space-Variant Motion Estimation and Compensation Method for Ultrahigh-Resolution Airborne Stepped-Frequency SAR With Long Integration Time
A 2-D Space-Variant Motion Estimation and Compensation Method for Ultrahigh-Resolution Airborne Stepped-Frequency SAR With Long Integration Time
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DOI：
10.1109/tgrs.2017.2727060
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发表时间：
2017-08
影响因子：
8.2
通讯作者：
Jianlai Chen;M. Xing;Guangcai Sun;Zhenyu Li
中科院分区：
文献类型：
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作者：
Jianlai Chen;M. Xing;Guangcai Sun;Zhenyu Li
对于超高分辨率机载步进频率合成孔径雷达，当飞行器由于大气湍流而偏离理想直线轨迹时，很大的合成带宽和很长的积分时间可能会导致二维空变（SV）运动误差。这种新型误差使运动估计和运动补偿（MOCO）变得复杂。对于运动估计，我们提出了一种联合二维SV运动误差估计方法，以同时考虑距离变化运动误差和方位变化运动误差。对于 MOCO，我们提出了一种 2-D SV-MOCO 方法。该方法通过三个处理步骤来实现：1）针对空间不变运动误差和范围变化相位误差的两步MOCO； 2) 针对范围变化包络误差的基于范围块的线性调频 z 变换 (CZT)； 3)基于方位角子孔径方法对距离相关的方位角变化相位误差进行距离块划分。最后，模拟数据和实际数据的处理验证了所提出的方法。
For the ultrahigh-resolution airborne stepped-frequency synthetic aperture radar, very large synthetic bandwidth and very long integration time may lead to a 2-D space-variant (SV) motion error when the aircraft flies off the ideally straight trajectory due to the atmospheric turbulence. This new type of error complicates the motion estimation and motion compensation (MOCO). For the motion estimation, we present a jointly 2-D SV motion error estimation method to simultaneously consider the range-variant motion error and the azimuth-variant motion error. For the MOCO, we propose a 2-D SV-MOCO method. The method is implemented through three processing steps: 1) two-step MOCO for the space-invariant motion error and the range-variant phase error; 2) range block-based chirp-z transform (CZT) for the range-variant envelope error; and 3) range block division for the range-dependent azimuth-variant phase error based on the azimuth subaperture method. Finally, processing of simulated data and real data validates the proposed methods.