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学校代码： 11059
学号：
Hefei University
毕业设计（论文）BACH ELOR DISSERTATION
论文题目：基于PWM调制的微弱信号检测
学位类别：工学学士
年级专业：
作者姓名：孙悟空
导师姓名：
完成时间： 2015年5月8号
中文摘要
工程设计领域中在强噪声环境下对微弱信号的检测始终是个技术难点。因此，全面地去研究、分析微弱信号在时域、频域等方面的特点，以及微弱信号的检测技术，都非常重要且有意义的。
本文首先介绍了在电子设备中元器件内部因为载流粒子的运动及外部因素导致系统噪声产生的原理。阐述了在分析研究微弱信号的方法中，时域分析法是目前应用范围最为广泛的分析方法，比如短时Fourier、小波变换。在此基础上，本文从工程设计的角度重点分析了PWM技术检测微弱信号的原理及实现的方法。PWM检测技术是利用PWM脉冲对微弱信号的调制, 从而达到进行频谱搬移。最后，对于调制后的信号，本文中采用带通、全波整形以及低通等三种方式实现了对待调制信号的解调，并在解调端得到最终的解调信号。
在电路仿真方面本文给出了基于Multisim软件的系统电路仿真图。通过搭建各个模块然后利用仿真电路给出了系统调制解调的各个过程及波形图。利用示波器对系统调制、解调等模块的波形检测可以发现各个模块的信号波形与理论波形基本吻合，系统的设计满足对微弱信号检测的要求。
关键词:微弱信号检测；频谱搬移；PWM调制
Abstract
The detection of weak signal in the field of engineering design is always a technical difficulty.. Therefore, it is very important and meaningful to study and analyze the characteristics of weak signal in time domain and frequency domain and the detection technology of weak signal..
In this paper, we first introduce the in Zhongyuan electronic equipment device for load flow particle's motion and external factors lead to system noise principle. In the research of weak signal analysis, time-domain analysis is the most widely used method, such as short time Fourier and wavelet transform.. On this basis, the paper analyzes the principle and the method of the weak signal detection from the angle of the engineering design from the point of view of the engineering design.. PWM detection technology is the use of PWM pulse modulation of the weak signal, so as to achieve the frequency shift. Finally, for modulated signals, this paper by band-pass, full wave shaping and low pass in three ways the treated signal modulation and demodulation, and the final demodulation signal at the end of the demodulation.
In the circuit simulation, the paper presents the simulation chart of the system circuit based on Multisim.. By building each module and using the simulation circuit, the process and the waveform of the system modulation and demodulation are given.. Using the oscilloscope system modulation and demodulation module of waveform detection can be found that each module of signal waveform and theoretical waveforms are basically consistent, the design of the system meet the requirements of weak signal detection.
.Keyword：Weak signal detection ；Frequency shift ；PWM detection
目录
前言 (1)
第一章绪论 (2)
第二章微弱信号的检测方法 (3)
2.2 时域平均 (4)
2.3 时频检测法 (5)
2.4 PWM调制检测技术 (6)
第三章 PWM调制检测系统设计 (7)
3.1 信号调制 (7)
3.2信号解调 (7)
3.2.1 带通滤波器的设计 (7)
3.2.2 全波整流的设计 (10)
3.2.3 低通滤波器的设计 (12)
第四章系统仿真及总结 (16)
4.1仿真环境简介 (16)
4.2系统仿真 (17)
4.2.1 调制电路部分 (17)
4.2.2 系统混入噪声信号图 (20)
4.2.3 带通滤波器仿真 (21)
4.2.4 整流电路 (22)
4.2.5 低通滤波器的仿真 (23)
结论 (24)
参考文献 (25)
致谢 (26)
