SAR雷达成像算法的研究

SAR雷达成像算法的研究

摘要

合成孔径雷达(SAR)是一种置于运动平台(如飞机和卫星等)的成像雷达，具有全天时、全天候、远距离成像的特点，因此可以大大提高雷达的信息获取能力，近年来在军事和民用方面都得到了广泛的发展和应用。机载合成孔径雷达成像仿真技术在机载SAR 的研究与发展中具有重要作用。

本文首先介绍了二维SAR成像的基本原理，分析了二维SAR距离和方位向上的分辨率以及距离徙动特性，从脉压理论和合成孔径原理出发，分析了SAR高分辨率成像的距离高分辨率和方位高分辨率理论，说明距离分辨率取决于信号带宽，方位分辨率则取决于载机与固定目标相对运动时产生的具有线性调频性质的多普勒信号带宽决定，并通过脉压技术实现方位高分辨成像。然后介绍了两种成熟的合成孔径雷达成像算法：距离-多普勒算法、线频调变标算法，并在Matlab环境里进行仿真实现。最后应用距离-多普勒算法完成了机载正侧视合成孔径雷达对地面固定目标模型的成像仿真实验，得到了比较理想的仿真图像。

关键词:合成孔径雷达，距离-多普勒算法，线频调变标算法

Research of Imaging Algorithm for SAR

Abstract

Synthetic aperture radar(SAR)is placed in moving platform such as airplane and satellite, and can obtain image reflecting dispersion characteristic of the objects．Because SAR is free of weather influence, and works in both day and night, and it can g reatly improve radar’s capability of gaining information, it is widely applicated and well developed in both civilian and military fields in recent years. Imaging simulation technology plays an important role in the research and development of airborne SAR.

This thesis discusses the fundamental theory of planar SAR, analyzes planar SAR resolving ability in range and azimuth dimensions and the characteristic of Range Cell Migration(RCM). According to pulse compression theory and SAR principle, the paper firstly gives an analysis on the principle of high-resolution SAR imaging, then, notes that the SAR range resolution is dependent of signal bandwidth, while SAR azimuth resolution is dependent of the bandwidth of the LFM-featured Doppler signal generated from the relative movement between aircraft carrying the radar and the fixed ground target, thus, high azimuth resolution can be realized through pulse compression. This thesis also introduces two kinds of mature SAR imaging method, Range-Doppler algorithm and Chirp-Scaling algorithm, which have been simulated and realized under Matlab environment. Finally, the imaging simulation test of airborne sideway SAR to the fixed target on the ground is carried out by using the Range-Doppler algorithm, accordingly the ideal simulating images have been obtained.

KEY WORDS:Synthetic Aperture Radar, Range-Doppler algorithm, Chirp-Scaling algorithm

目录

摘要 ........................................................................................................................................... I Abstract .................................................................................................................................... II 1 绪论 . (1)

1. 1 研究背景和意义 (1)

1. 2 SAR研究概况 (1)

合成孔径雷达分类 (2)

合成孔径雷达应用 (3)

本文研究内容 (3)

2 SAR成像与高分辨率基本原理 (4)

引言 (4)

2.2 二维SAR成像基本原理 (4)

2.2.1 二维SAR原始数据的录取 (4)

2.2.2 距离徙动 (6)

2.3 线性调频信号和脉冲压缩原理 (9)

2.3.1 线性调频信号 (9)

脉冲压缩原理 (10)

2.4 雷达分辨率 (12)

实孔径侧视雷达成像及成像空间分辨率 (12)

实孔径侧视雷达成像 (12)

2.4.1.2 实孔径侧视雷达空间分辨率 (13)

2.4.2 SAR 空间分辨率 (14)

2.4.2.1 距离向分辨率 (14)

2.4.2.2 方位向分辨率 (16)

2.5 本章小结 (19)

3 SAR 仿真成像 (20)

3.1 引言 (20)

3.2 合成孔径雷达成像算法 (20)

3.2.1 距离—多普勒成像算法 (20)

3.2.2 线频调变标(Chirp—Scaling)成像算法 (26)

3.3 本章小结 (29)

4总结与展望 (30)

致谢 (31)