【正文】 目 錄 中文摘要、關(guān)鍵詞 ...................................................................................................I 英文摘要、關(guān)鍵詞 ................................................................................................. II 引言 .............................................................................................................................. 1 第一章 方案論證與比較 ....................................................................................... 3 處理器的比較與選擇 ..................................................................................... 3 采樣方法比較與選擇 ..................................................................................... 3 FFT 計(jì)算方法選擇 ........................................................................................ 3 周期性判別與測(cè)量方法比較與選擇 ............................................................. 3 信號(hào)功率的計(jì)算方法比較與選擇 ................................................................. 4 低通濾波 器的比較與選擇 ............................................................................. 4 第二章 系統(tǒng)硬件設(shè)計(jì) ........................................................................................... 5 總體設(shè)計(jì) .......................................................................................................... 5 單元電路設(shè)計(jì) ................................................................................................. 5 四階低通濾波器電路設(shè)計(jì) ......................................................................... 5 前級(jí)阻抗匹配和放大電路設(shè)計(jì) ................................................................. 7 AD 轉(zhuǎn)換及控制模塊電路設(shè)計(jì) .................................................................. 10 控制器設(shè)計(jì) ............................................................................................... 12 系統(tǒng)電源電路設(shè)計(jì) ................................................................................... 13 第三章 系統(tǒng)軟件設(shè)計(jì) ......................................................................................... 13 Keil 集成環(huán)境開(kāi)發(fā) ...................................................................................... 13 系統(tǒng)主程序設(shè)計(jì) ........................................................................................... 14 觸摸屏識(shí)別程序 ........................................................................................... 15 FFT 算法的 C 語(yǔ)言實(shí)現(xiàn) ................................................................................ 16 FFT 的分析 ................................................................................................ 16 倒位序算法分析 ....................................................................................... 17 實(shí)數(shù)蝶形運(yùn)算算法 ................................................................................... 18 DITFFT 算法的基本思想分析 .................................................................. 19 第四章系統(tǒng)測(cè)試方案與預(yù)測(cè)結(jié)果 .................................................................... 21 測(cè)試方案 ........................................................................................................ 21 測(cè)試電路 ....................................................................................................... 21 兩路信號(hào)總功率測(cè)量 ............................................................................... 21 單個(gè)頻率分量測(cè)量 ................................................................................... 21 誤差分析 ....................................................................................................... 22 結(jié)論 ............................................................................................................................ 23 致謝 ............................................................................................................................ 24 參考文獻(xiàn) ： ............................................................................................................... 25 附錄 ： ......................................................................................................................... 25 附 A 元器件明細(xì)表 .............................................................................................. 21 附 B 儀器設(shè)備清單 .............................................................................................. 21 附 C 系統(tǒng)電路圖 .................................................................................................. 21 附 D 程序清單 ...................................................................................................... 21 I 音頻信號(hào)分析儀 摘要 ： 本音頻信號(hào)分析儀以時(shí)鐘頻率為 60M bps 的 Philips 32 位的高速單片機(jī)LPC2148 作為核心處理器，通過(guò)低通濾波電路和 A/D 轉(zhuǎn)換，對(duì)音頻信號(hào)進(jìn)行正確采樣分析，把連續(xù)信號(hào)離散化，然后通過(guò) FFT 快速傅氏變換運(yùn)算，在時(shí)域和頻域?qū)σ纛l信號(hào)各個(gè)頻率分量以及功率等指標(biāo)進(jìn)行分析和處理，然后通過(guò)高分辨率的 LCD 對(duì)信號(hào)的頻譜進(jìn)行顯示。該系統(tǒng)能夠精確測(cè)量的音頻信號(hào)頻率范圍為20Hz10KHz，其幅度范圍為 5mVpp5Vpp，分辨力分為 20Hz 和 100Hz 兩檔。測(cè)量功率精確度高達(dá) 95%,并且能夠準(zhǔn)確的測(cè)量周期信號(hào)的周期，是理想的音頻信號(hào)分析儀的解決方案。 關(guān)鍵詞 ： FFT； MCU；頻譜；功率 II Audio Signal Analyzer Desigin Abstrat :Audio signal analyzer is based on a 32bit processing speed MCU LPC2148controller that its clock frequency is 60Mhz ,and through the AD converter for audio signal sampling, the continuous signal discrete, and then through the FFT fast Fourier transform puting, in the time domain and frequency domain of various audio frequency signal weight and power, and other indicators for analysis and processing, and then through the highresolution LCD display signals in the spectrum. The system can accurately measure the audio signal frequency range of 20 Hz10K:Hz, the range of 55Vpp mVpp, resolution of 20 Hz and 100 Hz correspondent. Power measurement accuracy up to95%, and be able to accurately measuring the periodic signal cycle is the ideal audio signal analyzer solution. Key words:FFT 。MCU 。Spectrum 。Power 1 引 言 音頻是多媒體中的一種重要媒體。我們能 夠聽(tīng)見(jiàn)的音頻信號(hào)的頻率范圍大約是 20Hz20kHz，其中語(yǔ)音大約分布在 300Hz4kHz 之內(nèi)，而音樂(lè)和其他自然聲響是全范圍分布的。聲音經(jīng)過(guò)模擬設(shè)備記錄或再生，成為模擬音頻，再經(jīng)數(shù)字化成為數(shù)字音頻。這里所說(shuō)的音頻分析就是以數(shù)字音頻信號(hào)為分析對(duì)象，以數(shù)字信號(hào)處理為分析手段，提取信號(hào)在時(shí)域、頻域