Abstract
ABSTRACT
Compared to the camera, radar has more advantages. For example, it can detect distant targets day and night without being influenced by fog, clouds, and rains, which means that it has the capability of all-weather and all-time, and the ability to penetrate. Therefore, radar application is also popular in the field of security. Currently, the security perimeter surveillance radar is widely used in airport security zone detection, protection of pipelines and oil fields, as well as integration with the existing prison security video system.
Security radars generally use LFMCW (Linear Frequency Modulated Continuous Wave) system. LFMCW radar has a good distance and speed resolution, high reliability, small blind distance and good anti-jamming performance. So it is widely used in radar range and velocity measurement.
This thesis is based on Ka-band radar project on security, studied some LFMCW radar baseband signal processing algorithms. The main research work is as follows:
First, introduced the background and current research situation of LFMCW radar, followed by a detailed analysis of its basic principles and signal model. Also, the advantages and disadvantages of LFMCW radar were introduced. Based on the above research and the specific requirements of Ka-band security radar, the baseband signal processing solution was proposed, among which several important radar signal processing modules were mainly studied, including moving target indicator (MTI), moving target detection (MTD), constant false alarm rate (CFAR) processing, and multi-target pairing. Simulations using MATLAB were done for each module in order to compare the performances of different algorithms. In MTI part, an adaptive novel MTI filter has been designed by applying Genetic Algorithm. In the process, an innovative fitness function and penalty function are used, and the simulation result shows that the designed filter has good performance. In MTD part, the paper compared two different kinds of filter designing algorithm based on FFT and FIR. As for CFAR processing, various one-dimensional two-dimensional scene processing algorithms were analyzed and compared. In multi-target pairing section, four algorithms are introduced: pairing method in frequency domain, MTD-pairing method in frequency domain, variable cycle method, and the method of adding a flat slope. Subsequently, completed the integration of the various algorithm modules and the
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Abstract
simulation of the whole LFMCW radar system, and verified the simulation results.
Another work that has been done is the field testing of the whole radar system. At the same time, two sets of data collected from different outfields was imported into the software MATLAB to verify the reliability of the actual performance of the simulated system. The final results show that the whole system works well, and it has achieved the measurement of multi-target speed and distance parameters.
Keywords: Linear Frequency Modulated Continuous Wave radar, Moving Target Detection, CFAR processing, Multi-target pairing, Field test
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目录
目 录
第一章 绪论 .............................................................................................................. VII
1.1 LFMCW的主要优缺点 .................................................................................. 1 1.2 LFMCW雷达研究状况与发展动态 .............................................................. 2
1.2.1历史概况 ................................................................................................ 2 1.2.2当前发展动态 ........................................................................................ 3 1.3论文背景及任务需求 ...................................................................................... 3 1.4论文内容安排 .................................................................................................. 4 第二章 Ka波段LFMCW安防雷达系统设计描述 ................................................... 5
2.1 LFMCW雷达的基本原理 .............................................................................. 5 2.2 LFMCW雷达信号分析 .................................................................................. 8 2.3 毫米波LFMCW雷达的优点 ...................................................................... 11 2.4 Ka波段LFMCW安防雷达系统设计要求 .................................................. 11
2.4.1 信号处理系统功能 ............................................................................. 12 2.4.2 信号处理系统参数 ............................................................................. 12 2.4.3 信号处理系统实现方案 ..................................................................... 13 2.5 本章小结 ....................................................................................................... 13 第三章 LFMCW雷达信号处理算法分析 ............................................................... 14
3.1 动目标显示（MTI） .................................................................................... 14
3.1.1杂波模型分析 ...................................................................................... 14 3.1.2 MTI改善因子（If） ........................................................................... 15 3.1.3 传统MTI滤波器设计 ........................................................................ 17 3.1.4 自适应MTI滤波器设计 .................................................................... 19
3.1.4.1 遗传算法（GA）简介 ............................................................. 19 3.1.4.2 使用遗传算法（GA）设计自适应MTI滤波器 .................... 20 3.1.4.3 自适应MTI滤波器仿真实例 .................................................. 22
3.2 动目标检测（MTD） .................................................................................. 24
3.2.1 基于FFT的MTD滤波器组 ............................................................. 25 3.2.2 FIR实现MTD滤波器组 .................................................................... 27 3.3 恒虚警（CFAR）检测技术 ......................................................................... 28
3.3.1 引言 ..................................................................................................... 28
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3.3.2 CFAR检测技术的基本原理 ............................................................... 28 3.3.3瑞利杂波环境下的CFAR检测 .......................................................... 30 3.3.4 一维恒虚警（CFAR）检测 ............................................................... 32
3.3.4.1 单元平均恒虚警算法（CA-CFAR） ...................................... 32 3.3.4.2 选大、选小恒虚警算法（GO、SO-CFAR） ......................... 36 3.3.4.3 有序统计恒虚警算法（OS-CFAR） ....................................... 38 3.3.4.4 一维CFAR处理性能分析 ....................................................... 39 3.3.5 二维恒虚警（CFAR）检测 ............................................................... 43
3.3.5.1 二维矩形参考滑窗 ................................................................... 44 3.3.5.2 二维十字形参考滑窗 ............................................................... 45 3.3.5.3 二维矩形十字形参考滑窗性能对比 ....................................... 45
3.4 LFMCW雷达距离-速度去耦合算法分析 ................................................... 46
3.4.1 对称三角LFMCW雷达距离速度耦合问题分析............................. 47 3.4.2 频域配对法去耦合 ............................................................................. 48 3.4.3 MTD-频域配对法去耦合 .................................................................... 50 3.4.4 变周期对称三角LFMCW目标识别法 ............................................ 51 3.4.5 对称三角加平坦斜率LFMCW目标识别法 .................................... 54 3.5 本章小结 ....................................................................................................... 55 第四章 Ka波段LFMCW安防雷达系统仿真 ......................................................... 57
4.1 Ka波段LFMCW安防雷达信号系统算法流程 .......................................... 57 4.2 仿真参数设计 ............................................................................................... 58 4.3 信号处理流程仿真 ....................................................................................... 59 4.5 本章小结 ....................................................................................................... 64 第五章 Ka波段LFMCW安防雷达系统外场测试 ................................................. 65
5.1 外场测试条件 ............................................................................................... 65 5.2 外场测试效果 ............................................................................................... 65 5.4 外场测试数据算法验证 ............................................................................... 66
5.4.1 场景一 ................................................................................................. 66 5.4.2 场景二 ................................................................................................. 69 5.5 本章小结 ....................................................................................................... 71 第六章 结束语 ........................................................................................................... 72 致 谢 ........................................................................................................................... 73 参考文献 ..................................................................................................................... 74
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目录
攻读硕士学位期间取得的成果 ................................................................................. 77
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