Chang Yonglei, Li Pingxiang, Yang Jie, Zhao Jinqi, Zhao Lingli, Shi Lei
State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Wuhan 430079, China.
School of Remote Sensing and Engineering, Wuhan University, Wuhan 430079, China.
Sensors (Basel). 2018 Jan 30;18(2):403. doi: 10.3390/s18020403.
The GaoFen-3 (GF-3) satellite is the first fully polarimetric synthetic aperture radar (SAR) satellite designed for civil use in China. The satellite operates in the C-band and has 12 imaging modes for various applications. Three fully polarimetric SAR (PolSAR) imaging modes are provided with a resolution of up to 8 m. Although polarimetric calibration (PolCAL) of the SAR system is periodically undertaken, there is still some residual distortion in the images. In order to assess the polarimetric accuracy of this satellite and improve the image quality, we analyzed the polarimetric distortion errors and performed a PolCAL experiment based on scattering properties and corner reflectors. The experiment indicates that the GF-3 images can meet the satellite's polarimetric accuracy requirements, i.e., a channel imbalance of 0.5 dB in amplitude and ±10 degrees in phase and a crosstalk accuracy of -35 dB. However, some images still contain residual polarimetric distortion. The experiment also shows that the residual errors of the GF-3 standard images can be diminished after further PolCAL, with a channel imbalance of 0.26 dB in amplitude and ±0.2 degrees in phase and a crosstalk accuracy of -42 dB.
高分三号（GF-3）卫星是中国首颗设计用于民用的全极化合成孔径雷达（SAR）卫星。该卫星工作在C波段，拥有12种成像模式以适用于各种应用。其中提供了三种全极化SAR（PolSAR）成像模式，分辨率高达8米。尽管SAR系统的极化校准（PolCAL）是定期进行的，但图像中仍存在一些残余失真。为了评估该卫星的极化精度并提高图像质量，我们分析了极化失真误差，并基于散射特性和角反射器进行了极化校准实验。实验表明，高分三号图像能够满足卫星的极化精度要求，即幅度通道不平衡为0.5 dB，相位为±10度，串扰精度为-35 dB。然而，一些图像仍包含残余极化失真。实验还表明，经过进一步的极化校准后，高分三号标准图像的残余误差可以减小，幅度通道不平衡为幅度0.26 dB，相位为±0.2度，串扰精度为-42 dB。
