Calibration of Spaceborne Linearly Polarized Low Frequency SAR Using Polarimetric Selective Radar Calibrators
Calibration of Spaceborne Linearly Polarized Low Frequency SAR Using Polarimetric Selective Radar Calibrators
复制标题
DOI：
10.2528/pier11011809
复制
发表时间：
2011
影响因子：
6.7
通讯作者：
Jie Chen;S. Quegan;Xunjun Yin
中科院分区：
文献类型：
--
作者：
Jie Chen;S. Quegan;Xunjun Yin
星载合成孔径雷达（SAR）系统工作在P波段等较低频段，法拉第旋转（FR）效应对其影响很大。针对星载极化SAR数据，提出了一种在存在法拉第旋转的情况下测量系统误差（通道不平衡和串扰）的新算法。它使用四个极化选择校准器（四个极化有源雷达校准器（PARC）或可能的两个PARC和两个网格化的三面体）。理论分析和仿真结果表明，如果要准确测量串扰，优化的校准方案对相关的法拉第旋转的精度提出了严格的约束。在与校准设备相关联的允许信噪比和平均极化噪声上也存在强约束。分析表明，除非校准地点位于磁赤道，否则还需要从直接的地面-卫星视线双频系统独立测量总电子含量。
Spaceborne synthetic aperture radar (SAR) systems operating at lower frequencies, such as P-band, are signiflcantly afiected by Faraday rotation (FR) efiects. This paper presents a novel algorithm for measuring system errors (channel imbalance and cross-talk) in the presence of Faraday rotation for spaceborne polarimetric SAR data. It uses four polarimetric selective calibrators (four polarimetric active radar calibrators (PARCs) or possibly two PARCs and two gridded trihedrals). Theoretical analysis and simulations demonstrate that the optimized calibration scheme puts tight constraints on the accuracy of the associated Faraday rotation if the cross-talk is to be accurately measured. There are also strong constraints on the allowable signal-to-noise ratio and average polarimetric noise associated with the calibration devices. The analysis suggests that, unless the calibration sites are at the magnetic equator, independent measurements of total electron content (TEC) from a direct ground-satellite line-of-sight dual-frequency system are also needed.