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目 录
I
I
目录
摘 要................................................................................................................................................................1
ABSTRACT...................................................................................................................................................... II
第一章 绪论......................................................................................................................................................1
1.1 研究背景及意义.................................................................................................................................... 1
1.2 国内外研究状况.................................................................................................................................... 2
1.3 本论文主要研究内容............................................................................................................................ 4
第二章 LFMCW 雷达基本原理及常用两类波信号分析............................................................................. 5
2.1 LFMCW 雷达工作原理......................................................................................................................... 5
2.2 锯齿波 LFMCW 雷达信号分析........................................................................................................... 6
2.2.1 单周期锯齿波 LFMCW 雷达信号分析....................................................................................... 6
2.2.2 多周期锯齿波 LFMCW 雷达信号分析....................................................................................... 8
2.3 对称三角波 LFMCW 雷达信号分析................................................................................................... 9
2.3.1 单周期对称三角波 LFMCW 雷达信号分析............................................................................... 9
2.3.2 多周期对称三角波 LFMCW 雷达信号分析............................................................................. 11
2.4 本章小结.............................................................................................................................................. 12
第三章 LFMCW 雷达目标识别算法研究与仿真....................................................................................... 13
3.1 MTI 算法研究与仿真...........................................................................................................................13
3.1.1 对消器原理.................................................................................................................................. 13
3.1.2 仿真实验...................................................................................................................................... 15
3.2 MTD 算法研究与仿真.........................................................................................................................17
3.2.1 MTD 算法原理............................................................................................................................. 17
3.2.2 仿真实验...................................................................................................................................... 19
3.3 恒虚警检测算法研究与仿真.............................................................................................................. 20
3.3.1 恒虚警检测算法原理.................................................................................................................. 20
3.3.2 仿真实验...................................................................................................................................... 24
3.4 多目标配对研究与仿真...................................................................................................................... 25
3.4.1 多目标配对原理.......................................................................................................................... 25
3.4.2 多目标配对实验.......................................................................................................................... 27
3.4.3 提高测量精度.............................................................................................................................. 28
3.4.4 数据分析...................................................................................................................................... 30
南京信息工程大学硕士学位论文
II
3.5 本章小结.............................................................................................................................................. 32
第四章 LFMCW 雷达算法硬件实现............................................................................................................33
4.1 数字信号处理板整体结构.................................................................................................................. 33
4.2 硬件控制模块...................................................................................................................................... 34
4.2.1 CPLD 供电模块............................................................................................................................ 34
4.2.2 AD 采样模块.................................................................................................................................37
4.2.3 W5100 以太网模块.......................................................................................................................39
4.2.4 FPGA 模块.................................................................................................................................... 41
4.3 DSP 技术概述.......................................................................................................................................45
4.4 DSP 设计技术原理...............................................................................................................................46
4.4.1 DSP 中断技术............................................................................................................................... 46
4.4.2 cache 数据缓存............................................................................................................................. 47
4.4.3 核间通信...................................................................................................................................... 48
4.5 EMIF 通信模块.................................................................................................................................... 48
4.6 LFMCW 雷达算法 DSP 实现设计......................................................................................................50
4.7 LFMCW 雷达算法实验与数据分析...................................................................................................51
4.7.1 LFMCW 雷达算法实验................................................................................................................51
4.7.2 数据分析...................................................................................................................................... 53
4.8 雷达系统外场实测.............................................................................................................................. 54
4.9 本章小结.............................................................................................................................................. 57
第五章 总结与展望........................................................................................................................................58
5.1 总结.......................................................................................................................................................58
5.2 展望.......................................................................................................................................................58
参考文献..........................................................................................................................................................60
致 谢..............................................................................................................................................................63
作者简介..........................................................................................................................................................64
摘 要
I
摘 要
目标信号识别技术是新一代线性调频连续波(LFMCW)雷达重要的技术研究课题。
在近距离探测中线性调频连续波雷达拥有比传统脉冲雷达独特的优点,使其得到广泛的
研究和应用,线性调频连续波雷达具备理论上无探测盲区、距离分辨率较高、发射功率
低、结构简单、低截获抗干扰等优点。相比于脉冲体制的雷达,
LFMCW
雷达在其理论
研究和硬软件实现方面还不够成熟和完善,但是随着国内外学者对其理论研究的进一步
深入、雷达应用技术的提高,近年来线性调频连续波雷达越来越广泛的应用于无人机探
测、汽车防撞等军事和民用等领域。
本文首先分析和介绍线性调频连续波雷达基本工作原理。例如测速测距的基本原
理,锯齿波雷达和三角波雷达的区别等。这些原理为后面的实验提供了理论依据。随后
根据对多目标的识别问题,提出一种基于互相关函数的算法,本算法相比较已有算法拥
有算法简单易理解,计算量少,距离速度精度高等特点。基于对目标识别的研究,本文
还设计出了一套 LFMCW 雷达信号处理算法,主要包括 MTI(动目标雷达信号显示)、
MTD
(动目标雷达信号检测)、
CFAR
(恒虚警信号检测)、多目标信号配对。这些信
号处理算法分别通过
Matlab
仿真验证算法结果具备较高的精度和准确性。
本文还基于研究团队自行开发的 FPGA+DSP 通用雷达数字信号处理板,完成了主
要功能模块程序的开发和上述算法验证,结果表明:本研究算法能够有效实现对多通道
目标的快速探测,具有较高的研究和应用价值。
关键词:
LFMCW
雷达;多目标识别;雷达信号处理;
FPGA
;
DSP
南京信息工程大学硕士学位论文
II
Abstract
Target signal recognition technology is an important technical research topic for a new
generation of linear frequency modulation continuous wave (LFMCW) radar. In short-range
detection, LFM continuous wave radar has unique advantages over traditional pulse radar,
making it widely researched and applied. LFM continuous wave radar has theoretically no
detection dead zone, high range resolution, low transmission power, The advantages are
simple structure, low interception and anti-interference. Compared with the pulse system
radar, the LFMCW radar is not mature and perfect in its theoretical research and hardware and
software implementation. However, as domestic and foreign scholars have deepened their
theoretical research and radar application technology has improved, linear frequency
modulation has been continuous in recent years. Wave radar is more and more widely used in
military and civil fields such as UAV detection and automobile collision avoidance.
This article first analyzes and introduces the basic working principle of LFM continuous
wave radar. For example, the basic principle of speed and distance measurement, the
difference between sawtooth wave radar and triangle wave radar. These principles provide a
theoretical basis for subsequent experiments. Then, based on the recognition of multiple
targets, an algorithm based on cross-correlation function is proposed. Compared with existing
algorithms, this algorithm has simple and easy-to-understand algorithms, less calculation, and
improved distance and speed accuracy. Based on the research of target recognition, this paper
also puts forward a set of LFMCW radar signal processing algorithm design scheme. Mainly
includes MTI (moving target radar signal display), MTD (moving target radar signal
detection), CFAR(constant false alarm signal detection), and multi-target signal pairing. These
signal processing algorithms were verified by Matlab simulation to have high accuracy and
accuracy.
Based on the FPGA +DSP general radar digital signal processing board developed by the
research team, this paper has completed the development and algorithm verification of the
above main function module programs. The verification algorithm shows that this algorithm
can effectively achieve the rapid detection of multi-channel targets High research and
application value.
Key words: LFMCW radar; Multitarget recognition; radar signal processing board; FPGA;
DSP
第一章 绪论
1
第一章 绪论
1.1 研究背景及意义
雷达的主要技术是利用飞机、汽车、船舶自身发射的无线波或电磁波快速确定某区
域目标、定位、实时显示、跟踪及目标运动参数。雷达系统是一套高科技电子系统,它
在各国的军事和民用领域扮演着重要的角色,它好比是国家的千里眼,为国家国防安全
保驾护航。近来经过数十年的不断发展,雷达除了最早应用在军事工业领域和民用领域,
也越来越应用于气象预报、地质资源探测、船舶导航、汽车防撞、交通测速等民用电子
技术领域
[1,2,3]
。
雷达根据发射电磁波信号不同,电磁波段不同可分为很多种。例如线性调频连续波
雷达、脉冲雷达、激光雷达、超视距雷达等。毫米波雷达因其具有探测精度高,技术成
熟等诸多优点被广泛应用。毫米波雷达又可分为连续波体制雷达和脉冲体制雷达,连续
波雷达主要是采用连续波调频信号作为发射信号的雷达,脉冲雷达是采用脉冲信号作为
发射信号的雷达,连续波雷达理论上无距离盲区,探测距离较近被广泛应用于交通测速、
军用战场监视、汽车辅助系统(ADAS),探测低慢小目标等多种领域。连续波雷达又
可分为单一频率连续波和调频连续波两种,其中简单的单一频率连续波雷达只能对目标
进行测速,不能测距。调频连续波雷达不仅可以对目标测距,而且能够准确区分多个固
定目标和多个运动目标。调频连续波雷达是在连续周期内发射调频信号的连续波雷达,
通过将线性调频回波信号与连续波发射信号混频得到差拍连续波信号的频率,进而得到
目标运动参数。其中线性调频连续波雷达(
Linear Frequency Modulated Continuous Wave
,
LFMCW)在民用领域应用最为广泛。本文基于线性调频连续波雷达对目标识别算法处
理。其相比于脉冲雷达主要优点表现为
[1]
:
(1)距离分辨率高
分析得到雷达距离分辨率为
C/2B
,雷达距离分辨率与发射信号带宽
B
呈反比关系,
带宽 B 越大,距离分辨率越好。LFMCW 雷达带宽一般达到几百兆赫兹甚至更高,而脉
冲雷达的距离分辨率与周期是线性关系,追求更高的距离分辨率要求采样频率就越高。
相对于脉冲雷达,
LFMCW
雷达处理的是回波信号与本振信号混频得到的差拍信号,差
拍信号的频率一般较低,在工程信号处理的硬件系统中 ADC 的要求就会降低,实现较
为简单。
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