本文为美国加州理工大学（作者：Cindy Romero）的硕士论文，共170页。

本硕士学位论文的目标是开发一种更为真实的合成孔径雷达（SAR）仿真系统，该系统能够对目标细节进行成像，并可用于自动目标识别（ATR）。本论文是加州理工大学（Cal Poly）正在进行的SAR ATR研究的一部分，由雷神航空航天系统公司赞助，导师为约翰·萨赫里博士。合成孔径雷达利用安装在运动平台（如飞机或航天器）上的天线的前向运动，合成产生较大孔径天线的效果。用于军事ATR的大多数SAR图像都是保密的，一般公众无法获取，因此迄今为止有关ATR的所有学术研究都局限于一组运动和固定目标捕获、识别雷达（MSTAR）图像的小型数据集。由于雷达设备的不可用或合成孔径雷达数据覆盖的范围较大，有必要建立一种合成孔径雷达的图像生成方案，在该方案中，雷达平台的参数可以直接修改和控制，以用于ATR的实现。

本文主要对Matthew Schlutz在Matlab论文中模拟的合成孔径雷达成像进行了几点改进。首先，通过将天线方向图和回波发生器从Matlab移植到C++，优化了仿真，提高了代码的效率，缩短了处理时间。一种称为Blender的三维（3-D）图形应用程序用于在雷达平台成像的场景中创建并定位目标模型，向雷达平台提供高度、目标距离（从平台到目标中心区域的距离）和仰角信息。Blender允许用户从雷达平台上拍摄目标的照片，并输出从雷达平台平面到图像中每个点的距离信息。使用Blender的一个主要优点是它还能够输出图像中每个像素的距离和反射率信息。这是前几篇论文中硬编码的一个重要特征，也使得这些模拟在实际中不容易实现。

本项目中，通过在Blender中创建目标场景，就会渲染图像并将其保存为OpenEXR文件。图像以正交模式呈现，这是一种投影形式，目标平面与投影平面平行。此参数意味着模拟无法对平台运动过程中出现和消失的点目标进行图像处理。然后，回波生成程序使用从OpenEXR文件获得的距离和反射率、优化的天线方向图和其他几个用户定义的参数来产生回波（接收信号）。一旦在回波生成程序中产生了回波，然后将其读取到Matlab中，以便通过距离多普勒算法（RDA）输出最终的SAR图像。

The goal of this Master’s thesis is to develop a more realistic simulation of Synthetic Aperture Radar (SAR) that has the ability to image detailed targets, and that can be used for Automatic Target Recognition (ATR). This thesis project is part of ongoing SAR ATR research at California Polytechnic State University (Cal Poly) sponsored by Raytheon Space & Airborne Systems and supervised by Dr. John Saghri. SAR is a form of radar that takes advantage of the forward motion of an antenna mounted on a moving platform (such as an airplane or spacecraft) to synthetically produce the effect of a longer antenna. Since most SAR images used for military ATR are classified and not available to the general public, all academic research to date on ATR has been limited to a small data set of Moving and Stationary Target Acquisition and Recognition Radar (MSTAR) images. Due to the unavailability of radar equipment or a greater range of SAR data, it has been necessary to create a SAR image generation scheme in which the parameters of the radar platform can be directly modified and controlled to be used for ATR applications.

This thesis project focuses on making several improvements to Matthew Schlutz's ‘Synthetic Aperture Radar Imaging Simulated in Matlab' thesis. First, the simulation is optimized by porting the antenna pattern and echo generator from Matlab to C++, and the efficiency of the code is improved to reduced processing time. A three-dimensional (3-D) graphics application called Blender is used to create and position the target models in the scene imaged by the radar platform and to give altitude, target range (range of closest approach from the platform to the center area of the target) and elevation angle information to the radar platform. Blender allows the user to take pictures of the target as seen from the radar platform, and outputs range information from the radar platform plane to each point in the image. One of the major advantages of using Blender is that it also outputs range and reflectivity information about each pixel in the image. This is a significant characteristic that was hardcoded in the previous theses, making those simulations less realistic.

For this thesis project, once the target scene is created in Blender, an image is rendered and saved as an OpenEXR file. The image is rendered in orthographic mode, which is a form of projection whereby the target plane is parallel with the projection plane. This parameter means that the simulation cannot image point targets that appear and disappear during the platform motion. The echo generation program then uses the range and reflectivity obtained from the OpenEXR file, the optimized antenna pattern, and several other user defined parameters to create the echo (received signal). Once the echo is created in the echo generation program, it is then read into Matlab in order for it to go through the Range Doppler Algorithm (RDA) and then output the final SAR image.

1 合成孔径雷达

1.1 SAR简史

1.2 加州理工的SAR仿真研究历史

1.3 SAR几何描述

1.4 SAR工作模式

1.5 发射脉冲

1.6 接收信号

2 距离-多普勒算法

2.1 匹配滤波

2.2 距离单元徙动校正

3 已有的SAR成像仿真

3.1 基于Shultz改进二维仿真的RDA示例

3.2 Shultz在Zaharris仿真上的改进

3.3 已有二维和三维SAR仿真的局限性

4 本研究项目中的优化

4.1 Blender中的图像渲染

4.2 SAR天线方向图

4.3 回波产生

4.4 编程语言

5 三维仿真

6 其它仿真结果

6.1 方位与距离分辨力实验

6.2 坦克实验

7 验证

8 结论

8.1 未来研究工作展望

附录A 三维SAR仿真参数

附录B 天线方向图代码

附录C 回波产生器代码

附录D RDA的MATLAB代码

附录E 原始方法的代码 

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