摘 要

Abstract II

第一章：绪论 1

第二章：系统结构设计与方案选择 3

2.1系统结构设计 3

2.2系统方案论证 3

2.2.1整体方案选择 3

2.2.2主芯片选择 4

2.2.3EDA工具选择 4

2.2.4程序语言选择 4

2.3方案相关技术 5

2.3.1离散傅氏变换的快速算法（FFT） 5

2.3.2频率分辨率和失真度 8

2.3.3MSP430系列芯片 8

2.3.4运放LM324 10

2.4开发环境 11

第三章：信号采集模块 12

3.1设计原理 12

3.2模块设计与仿真 12

3.2.1阻抗匹配电路 12

3.2.2增益放大电路 13

3.2.3抗混叠滤波电路 14

3.2.4电平抬升电路 14

3.2.5前级调理电路 15

第四章：控制器和显示模块 17

4.1控制器模块的作用 17

4.2控制器模块的实现 17

4.2.1晶振电路 17

4.2.2键盘电路 18

4.2.3控制模块电路 18

4.3显示模块电路 19

4.4软件设计 20

4.4.1主程序设计 20

4.4.2FFT算法程序设计 22

第五章：系统实现与仿真 24

5.1系统的实现 24

5.2系统仿真 24

结论 26

参考文献 27

附录 28

附录A：总设计电路图 28

附录B：源程序 29

致谢 39

摘要

音频信号在现代社会中占据着重要的地位，所以对于音频信号的处理就变得尤为重要，音频信号的处理在语音、声呐、地震、通信系统、遥感预测、机械振动、故障诊断等很多领域均得到大量应用。随着社会和科学技术的发展，对于音频信号的运用也越来越多，对其分析处理仪器需求越来越大，功能要求也越来越高。

本课题采用TI公司的MSP430系列型号为MSP430F2418的16位单片机，实现基于离散傅氏变换的快速算法（FFT）的音频信号分析器设计。音频输入信号在通过阻抗匹配电路、放大电路、抗混叠滤波器、电压抬升等前级信号调理电路后，送入MSP430芯片中由自带的12位A/D变换对音频信号进行采样，得到正确的音频信号采样，把连续信号进行离散化，在频域对音频信号各个频率分量以及功率等指标利用离散傅氏变换的快速算法进行分析和处理，得到频谱等数据，然后再由高分辨率LCD显示分析结果。本课题通过离散傅氏变换的快速算法，其音频信号频率可测范围为100Hz-10KHz,其幅度范围为100mVpp-3.3Vpp,频率分辨率可达100Hz，检测出的各频率分量的功率之和大于96%，单个频率功率误差不大于10%，而且还可测量正弦信号的失真度。

关键字:音频信号；MSP430；FFT；功率

Abstract

Audio signal occupies an important position in modern society, so the processing of audio signal becomes more and more important. The processing of audio signal is widely used in many fields, such as voice, sonar, earthquake, communication system, remote sensing prediction, mechanical vibration, fault diagnosis and so on. With the development of society and science and technology, more and more audio signals are used. The demand for the analysis and processing instruments is becoming more and more large, and the functional requirements are becoming higher and higher.

The design of audio signal analyzer based on the fast algorithm (FFT) based on discrete Fourier transform (FFT) is realized by using 16 bit singlechip of MSP430 series of TI company as MSP430F2418. The audio input signal is sent to the MSP430 chip by the 12 bit A/D transform to sample the audio signal in the impedance matching circuit, the amplifying circuit, the anti aliasing filter, the voltage lift and so on. The audio signal is sampled, the continuous signal is discretized and the audio signal is used in the frequency domain. The frequency components and power are analyzed and processed by the fast algorithm of the discrete Fourier transform, and the data of the spectrum are obtained, and then the analysis results are displayed by the high resolution LCD. Through the fast algorithm of discrete Fourier transform, the frequency range of the audio frequency signal is 100Hz-10KHz, its range is 100mVpp-3.3Vpp, the frequency resolution can reach 100Hz, the power of each frequency component is more than 96%, the single frequency power error is less than 10%, and the distortion of the sinusoidal signal can also be measured.

KeyWord:Audio signal;MSP430;FFT;power

第一章：绪论

音频信号在现代社会扮演着越来越重要的角色，分析处理音频信号变得尤为重要，随着社会的进步、科学技术的发展，音频信号的分析处理仪器需求越来越多，功能要求越来越高。音频信号分析仪器的设计要求、设计成本、设计功能等成为市场的扩展要素。设计一款低成本而且可以随时携带的音频信号分析器是本课题的目的。