摘要
干涉成像高度计是一种新体制雷达高度计,可以获得宽刈幅、高分辨率和高精度的海面高程信息。但其在轨工作原始数据量巨大,无法全部下传,而且传统用于合成孔径雷达(Synthetic Aperture Radar,SAR)数据压缩的块自适应量化算法(Block Adaptive Quantization,BAQ)会显著增加干涉成像高度计的测高误差,且数据压缩比较低。因此,在保证海面高程测量精度的前提下,大幅压缩原始数据量的在轨处理算法研究具有重要意义。基于干涉成像高度计海洋观测区域的工作时序和干涉处理方法,提出了两项改进算法:①提出一种基于目标位置估计的图像配准和去平地效应方法,相比基于轨道参数的配准和去平地效应方法,大幅降低了运算量,同时可以去除由于小角度入射导致的快速变化的平地条纹;②针对干涉成像高度计在小入射角时地距分辨率变化剧烈的情况,提出了一种插值平均的多视方法,能够降低均匀窗口多视引入的测高误差。利用天宫二号三维成像微波高度计获得的海面数据验证该方法的可行性和对测高精度的影响,实验结果表明:当在轨分辨率为300 m×300 m时,该方法数据压缩比为46.99;当地面产品分辨率为5 km×5 km时,在轨处理算法引入的相位误差标准差小于0.0049°,测高误差标准差小于0.26 cm,相对于BAQ算法,该方法具有数据压缩比高、测高误差小的优势,更适合于未来新一代宽刈幅干涉成像高度计在轨数据处理。
Interferometric Imaging Radar Altimeter(InIRA)is a new radar altimeter system,which combines synthetic aperture and interferometric measurement technologies.It can achieve two-dimensional imaging of ob⁃servation areas and wide-swath height measurement by adopting small incidence angles with short baseline.Be⁃cause the interferometric imaging radar altimeter works all time in orbit,the amount of raw data is so huge that it cannot be all downlinked.Block Adaptive Quantization(BAQ)algorithm is a commonly used data compres⁃sion method for spaceborne Synthetic Aperture Radar(SAR),but it cannot be used for InIRA because the in⁃duced error of interferometric phase can lead to unacceptable error of Sea Surface Height(SSH)measurement and its compression ratio is also quite low.Therefore,it is of great significance to study the onboard processing algorithm that compress the raw data volume under the premise of ensuring the accuracy of SSH measurement.The major contribution of our work can be summarized as:(1)a method for image registration and flat-earth re⁃moval based on target position estimation is proposed.Compared with the orbital parameter method,this meth⁃od reduces computation complexity,and can remove the rapidly changing flat-earth fringe caused by small inci⁃dence angles.(2)a multi-look method is proposed based on interpolated average,which can reduce the SSH er⁃ror compared with that using uniform window size.The ocean observation data obtained by Tiangong-2 InIRA is processed using the proposed method to verify the feasibility of the on-orbit data processing method and ana⁃lyze its influence on SSH measurement accuracy.The result shows that the data compression ratio of the pro⁃posed method is 46.99 at 300m×300m on-orbit resolution.The standard deviation of the phase error and height measurement error are below 0.0049°and 0.26 cm respectively at 5 km×5 km ground resolution.Compared with BAQ,this method has the advantages of high data compression ratio and small SSH measurement error,which is more suitable for the future new generation of wide-swath InIRA on-orbit data processing.
作者
孙圣淇
石晓进
张云华
杨杰芳
SUN Shengqi;SHI Xiaojin;ZHANG Yunhua;YANG Jiefang(CAS Key Laboratory of Microwave Remote Sensing,National Space Science Center,Beijing 100190,China;University of Chinese Academy of Science,Beijing 100049,China)
出处
《遥感技术与应用》
CSCD
北大核心
2024年第3期569-578,共10页
Remote Sensing Technology and Application
基金
国家重大航天项目,国家重点研发计划(2016YFC1401004)。
关键词
天宫二号三维成像微波高度计
在轨处理
平地效应
多视处理
数据压缩比
Tiangong-2 Interferometric Imaging Radar Altimeter
On-orbit processing
Flat earth
Multilook
Data compression ratio
