干涉成像雷达高度计数据BAQ压缩的FPGA实现及数据评估

Implementation of InIRA Data Compression Using BAQ with FPGA

干涉成像雷达高度计(InIRA)是一种采用短基线、小入射角、一发双收的干涉测量技术,可以获取高相干海面回波,经数据处理获得干涉相位信息,再经反演得到海面高度,其突出优越性是可以获取宽刈幅、高精度海面高程信息;但由于其原始数据量巨大,给星上大容量数据存储和下行传输带来严峻的挑战;介绍一种用FPGA实现分块自适应量化(BAQ)压缩算法的方法,对已获取的某星载干涉成像雷达高度计(InIRA)海洋回波原始数据进行处理,分析不同压缩比对测量性能的影响;同时,根据新型InIRA的数据特点对原始BAQ算法进行改进,为未来星载干涉成像雷达高度计的数据压缩提供参考依据。结果表明:压缩比为8/3时,量化信噪比可达15 dB;压缩比为8/6时,2 km分辨率时海面高度测量误差约为2.68 cm。

Interferometric Imaging Radar Altimeter(InIRA)is based on interferometric measurement technology with small incident angle,one transmitter and two receivers. Interference Imaging Radar Altimeter can obtain highly coherent sea surface echo and extract interference phase information from the echo,and then achieve sea surface height by inversion. Its prominent advantages are wide swath and high precision. However,because of the huge amount of data,it brings serious challenges to on-board high-capacity data storage and downlink transmission. This paper introduces a method with FPGA to realize Block Adaptive Quantization(BAQ)compression algorithm,which processes the original ocean echo data of a certain satellite borne Interferometric Im-aging Radar Altimeter,and analyzes the influence of different compression ratios on the measurement performance. Meanwhile,the traditional BAQ algorithm was improved according to the data characteristics of the new InIRA. It provides reference basis for data compression of future spaceborne Interferometric Imaging Radar Altimeter. The test shows that when the compression ratio is 8/3,the SQNR can reach 15 dB. At 8/6 compression ratio,the measurement error of sea surface height at a resolution of 2 km is about 2.68 cm.