基于FFT音频信号频率和失真度分析仪.doc

音频信号频率和失真度分析仪 摘要 音频信号分析仪利用频谱分析原理来分析被测信号的频率、频谱及波形。常用的频谱分析方法有：扫频法、数字滤波法、FFT法。这里基于FFT方法的音频信号分析仪设计方案，通过快速傅里叶变换(FFT)把被测的音频信号由时域信号转换为频域信号，将其分解成分立的频率分量，在此基础上对其进行各种分析。Altera Cyclone II 系列FPGA嵌入高性能的嵌入式IP核(Nios)处理器软核，代替传统DSP芯片或高性能单片机，实现了基于FFT的音频信号分析。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。并在频域对信号的总功率，各频率分量功率，信号周期性以及失真度进行了计算。并在FPGA中嵌入了数字低通滤波器，代替传统有源模拟滤波器实现了性能优异的音频滤波。 关键词：频谱分析；时域分析；频域分析；数字滤波；信号失真 Audio Signal Frequency And Distortion Analyzer Abstract Audio signal frequency and distortion analyzer to analyze the theory using the measured spectrum of the signal frequency, spectrum and waveform. Spectral analysis methods commonly used: sweep algorithm, digital filtering, FFT method. Here use a method based on FFT audio signal frequency and distortion analyzer program, through the fast Fourier transform (FFT) to the audio signal from the measured time domain signal into frequency domain signal, established its decomposition components frequency component, in this based on their various analysis. ?? ?The design is based on Altera Cyclone II family of embedded high-performance FPGA embedded IP core (Nios) soft core processor instead of the traditional high-performance DSP chip or microcontroller to realize FFT-based audio signal analysis. System control and operation by the core, programmable amplifiers, filtering, and sampling and other modules. And the total frequency domain signal power, the power at each frequency, the signal periodicity and the distortion is calculated. FPGA embedded in a digital low pass filter, instead of the traditional active analog filters to achieve a high performance audio filter.  Key words: spectrum analysis; time domain; frequency domain; digital filter;Signal distortion 目录 1 绪论 1 1.1 音频信号分析仪的国内外发展背景 1 1.2 音频信号分析仪的现状 2 1.3 论文研究的内容和意义 3 1.4 章节结构安排 4 2 音频信号分析理论基础 5 2．1 数字信号处理基础 5 2.1.1 傅立叶变换 6 2.1.2 信号的采样 8 2．2 音频信号分析 9 2.2.1 时域分析 10 2.2.2 频域分析 11 2.2.3 失真分析 12 3 方案的选择与论证 15 3.1 整体方案选择 15 3.2 采样和滤波 15 3.3 信号周期性判断及周期测量 15 3.4 正弦信号的失真度测量 16 3.5 信号功率的计算 16 3.6