音频频谱分析仪的设计

1、收稿日期:2003-10-21作者简介:郑长义(1949-,男,吉林东丰人,现任吉林师范大学信息技术学院讲师.2003年11月吉林师范大学学报(自然科学版.4第4期Journal of Jilin Normal University (Natural Science Edition Nov.音频频谱分析仪的设计郑长义(吉林师范大学信息技术学院,吉林四平136000摘要:文章介绍了用MA TLAB 的数据采集工具箱,采集音频信号的方法,同时对采集到的音频信号进行波形显示和频谱分析.文中给出了具体的硬件和一个实用程序及其运行结果.关键词:MA TLAB ;数据采集;音频信号;频谱分析中图分类号:O

2、422.2文献标识码:A 文章编号:1000-1840-(200304-0070-02音频频谱分析仪具有实际意义,如器乐标准音的标定,声乐的发声校正,使用音频频谱仪会事半功倍.该音频频谱分析仪是用电脑中的声卡通过传声器在MA TLAB6.5的数据采集工具DA TA ACQU ISITION TOOLBOX 把音频信号输入到电一组中的al (A 调的do (C 调的la =440Hz ,以它为标准求出其它各高音的频率,如钢琴中的小字一组的七个高音:cl dl el fl gl al bl 分别为:al =440Hz ,bl =al 3216=44031.1224625=493.88Hz ,gl

3、=al/216=440/1.1224625=392.00Hz ,fl =gl/216=392.00/1.1224625=349.23Hz ,el =fl/2112=349.23/1.0594631=329.63Hz ,dl =el/216=329.63/1.1224625=293.66Hz ,cl =dl/216=293.的命令窗口上.该分析仪的程序清单如下:function second ,voltage ,frequency ,magni 2tude =soundin (VoiceFrequencyFactor ,rate ;%this is a experiment that input

4、 is done using the sound card%2003,6,3;%Usage :second ,voltage ,frequency ,magnitude =soundin.%(VoiceFrequencyFactor ,rate %VoiceFrequencyFactor is set as 1/8and rate as8000,when the frequency is%below 40hz round measurement ;VoiceFrequen 2cyFactor as 1/200and rate as%44100hz ,when up 4khz%The comme

5、nts at command lines is active ,when the function is called.if nargin <2rate =8000;end ;if nargin <1VoiceFrequency =1/20;07end;ai=analoginput(winsound;addchannel(ai,1;ai.logtodiskmode=overwrite;ai.loggingmode=disk&memory;ai.triggertype=immediate;ai.samplerate=rate;actualrate=get(ai,sampler

6、ate;ai.samplespertrigger=VoiceFrequency3rate;% For zoom in x axes,that plot laterfs=actualrate; dt=1/fs;start(ai;data,time=getdata(ai;blocksize=VoiceFrequency3rate;%the default value is2205f,mag=daqdocfft(data,fs,blocksize;figure;subplot(2,1,1;plot(time,data;grid on;title(immediate trigger;xlabel(re

7、lative time%in second;ylabel(data in volts;second,voltage=ginput(5;pause;subplot(2,1,2;hold on;plot(f,mag;grid on;magnitude,frequency=ginput(5;ylabel(magnitude(db;title(frequency components of sound;xlabel(frequency(hz;delete(ai;clear ai;在MA TLAB窗口下,键入second,voltage, frequency,magnitude=soundin,即可分析

8、4KHz 以下的音频频率,如果分析4KHz以上的音频频率要给出函数的输入参数VoiceFrequencyFactor 的值,如果它的分数值很小,比如1/100,8KHz以下的波形能够看得清楚,而rate的值,即采样频繁设为44100.当按下回车键,波形出现在屏幕上,光标带上大十字,选择你喜欢的几个点,分别点击鼠标左键直到光标的大十字去掉,然后在按任一键,频谱图即出现在波形图的下面,同样光标也带上大十字选择你喜欢的几个点,分别点击鼠标左键直到光标的大十字去掉,这时返回到MA TLAB 命令窗口,即可看到各点的测量值.MA TLAB6.5是功能强大的软件,在数据采集方面有专用的工具箱.这里介绍的利

9、用电脑的声卡输入信号,也可利用声卡输出信号.除此之外,数据采集工具箱还支持各式各样数据采集卡.在仪表控制方面支持IEEE488HPIB V ISA 串口,TCPIP和UDP接口.参考文献1伍湘涛.音乐知识与名曲赏析M.北京:航空工业出版社,1993,3.2车晴.电子系统仿真与MATLABM.北京:北京广播学院出版社,2000,11.Design of Adio Spectrom AnalyzerZH EN G Chang2yi(College of Information Technology,Jilin Normal University,Siping Jilin136000,ChinaAbstract:In the paper,technique of acquisition a