音频信号分析仪设计

文档编号:CK096   文档字数:11603,页数:32

 摘  要
 本系统基于快速傅立叶变换(FFT)算法，以AT89S52单片机和FPGA为控制与数据处理核心，结合必要的外围电路，实现对频率范围在200Hz~10KHz音频信号频率成分的分析 。以单片机为主要控制器件，由信号调节、信号采样和DFT算法处理等部分组成。信号调节与12位A/D配合，保证了测量精度。信号采集后存储到FPGA内部的RAM中，将旋转因子量化存储到FPGA的ROM中，利用地址发生器将采样信号与旋转因子在一定的时序下相乘累加，高速精度地完成了DFT算法。系统由控制与运算核心、程控放大器、滤波和采样等模块组成。通过对程控放大器增益的调整将系统可测电压(峰-峰值)的动态范围确定为100mV~5V； 通过改变模数转换器的采样频率，实现频率分辨力100Hz；频谱分析结果可按序存储，并使用点阵式液晶屏实时显示；通过对频谱数据特征的提取判断信号的周期性，并实现对信号的失真度分析。另外，可通过点阵式液晶屏以图形方式显示信号各频率分量及其相对大小。
关键词：频域分析、FFT、频率分量、分辨力、周期性
 
Abstract
The system is based on fast Fourier transform (FFT) algorithm to AT89S52 MCU and FPGA for the control and data processing core, combined with the necessary external circuit, the frequency range of 200Hz ~ 10KHz audio signal frequency component analysis.To MCU as the main control device, the signal conditioning, signal processing, sampling andDFT algorithm components.Signal conditioning and 12-bit A / D with guaranteed accuracy.After signal acquisition to the FPGA's internal RAM memory in the rotation factor to quantify the ROM to store FPGA, the use of address generator and twiddle factor will be sampling the signal timing under certain multiply accumulate, high-speed precision DFT algorithm is completed.System control and operation by the core, programmable amplifiers, filtering, and sampling and other modules.Through the programmable gain amplifier to adjust the system can measure voltage (peak - peak) of the dynamic range defined as 100mV ~ 5V; by changing the ADC sampling frequency, to achieve frequency resolution 100Hz; spectrum analysis results can be stored sequentially,and use real-time dot matrix LCD display; by spectral data feature extraction determine the periodic signal, and to realize the distortion of the signal analysis.In addition, through the dot matrix LCD screen to graphically display the signal of each frequency component and its relative size.
Keywords: frequency domain analysis, FFT, frequency components, resolution, periodic  
 

目 录
摘要......................................................................III
一 前言....................................................................1
    1.1音频信号及音频分析....................................................1
    1.2选题的背景与意义......................................................1
    1.3音频分析仪器现状......................................................2
    1.4研究的基本内容与基本要求..............................................3
二 音频信号分析仪的方案设计与论证..................................4
    2.1方案比较与选择........................................................4
    2.2系统实现框图..........................................................6
三 理论分析与计算.......................................................7
   3.1前级电路参数分析及A/D位数选择.........................................7
   3.2采样率及采样点数确定...................................................7
   3.3功率谱测量方法.........................................................8
   3.4周期性判断方法.........................................................9
   3.5失真度测量原理........................................................10
四 主要电路功能与实现................................................11
   4.1程控放大器的实现......................................................11
   4.2 A/D采样..............................................................11
   4.3 滤波器的设计与实现...................................................12
   4.4总功率测量电路........................................................13
   4.5 FPGA部分.............................................................14
   4.6 单片机部分...........................................................14
五 系统软件部分........................................................19
六 系统误差分析........................................................21
七 结论...................................................................22
八 总结...................................................................23
致谢.......................................................................24
参考文献..................................................................25
附录.......................................................................27

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