调频多普勒定距系统发射等幅的调频连续波，通过对发射信号与回波信号的差频进行信号处理，从而得出目标的速度信息以及距离信息。调频方式主要包括：正弦波调频、三角波调频和锯齿波调频。其特点是接收机灵敏度好、定距精度高、距离选择性好、工作电压低、抗干扰能力强、结构简单等方面。因此对其的研究具有重要的理论和现实意义。65554

    本文主要针对三角波波调频定距系统进行研究。首先分析了差频信号在静止和运动目标情况下的频谱。其次推导了系统中发射信号和回波信号混频后得到的差频信号的时域和频域数学表达式，在此基础上提出了定距方案。接着使用Matlab/Simulink软件平台进行了整个系统的仿真，对定距方案进行了论证。并研究了有源干扰电磁环境的数学描述方式，使用Matlab软件仿真了弹目接近过程中的差频信号处理流程及噪声对定距方案造成的影响。

毕业论文关键词  调频定距  差频分析 仿真    

毕业设计论文外文摘要

Title   Electromagnetic environment adaptability of frequency modulated fix-distance Doppler system                            

Abstract

Frequency modulated fix-distance Doppler system transmits frequency modulated continuous wave. By processing and analyzing the beat-note ，knowledge such as the speed and the movement of the object can be obtained. The main frequency modulating method includes sine wave FM, triangular wave FM and sawtooth wave FM. The main features of this system includes a highly sensitive receiver, better precision on distancemeasure, more option range for distance，low working requirement for voltage, better anti-jam capability, and a simple structure. Therefore, it is of great importance to conduct a research for its theoretical and practical use. 

This article will mainly discuss the fix-distance system with triangular wave FM. Firstly, the author will analyze the frequency spectrum of the beat note in both static and moving conditions. Secondly, the article will attempt to demonstrate the derivation of both time-domain and a math expression for the beat note. Further, a distance-setting program is set up which will later be expounded and proved by a simulation based on Matlab/Simulink software. Then, the author suggests a mathematical expression on describing the electromagnetic environment with active jamming. Finally, a simulation based on Matlab is carried out which examines the workflow of beat note processing while the target is approaching.  Besides, the simulation evaluates the effects of noise on the distance-setting program.

Keywords   frequency spectrum of the beat note    fix-distance Doppler system   simulation

目   录

1  绪论 1

1.1  选题的背景及科学意义 1

1.2  论文工作安排 2

2  调频定距原理及定距系统方案设计 4

2.1  调频定距系统原理 4

2.1.1  静止目标 5

2.1.2  运动目标 5

2.2  三角波调频多普勒定距系统信号处理方案 7

3  调频多普勒定距系统仿真 8

3.1  概述 8

3.2  静止目标仿真