%
%?Example?of?sound?aliasing
%
clear?all;

fc?=?1.8e3;???????????????%?tone?freq
Fs?=?1e3*8;???????????????%?sample?freq
Ts?=?1/Fs;????????????????%?sample?time
timelen?=?3;??????????????%?sample?file?length

n?=?0:ceil（timelen/Ts）-1;
x?=?0.9*cos（2*pi*fc*n*Ts）;

disp（[‘tone?freq?=?‘num2str（fc）‘?sampling?frequency?=?‘num2str（Fs）]）;
wavplay（xFs）;

%
%?downsampling
%
d2=3/4;
disp（‘press?any?key?to?continue‘）;
pause
disp（[‘tone?freq?=?‘num2str（fc）‘?sampling?frequency?=?‘num2str（Fs*d2）]）;
x_d2?=?0.9*cos（2*pi*fc*n*Ts/d2）;
wavplay（x_d2（1:floor（length（x_d2）*d2））Fs*d2）;

d3=1/3;
disp（‘press?any?key?to?continue‘）;
pause
disp（[‘tone?freq?=?‘num2str（fc）‘?sampling?frequency?=?‘num2str（Fs*d3）]）;
x_d3?=?0.9*cos（2*pi*fc*n*Ts/d3）;
wavplay（x_d3（1:floor（length（x_d3）*d3））Fs*d3）;

%
%?write?wav?files
%
%wavwrite（xFs16‘output01.wav‘）;
%wavwrite（x_d2（1:floor（length（x_d2）*d2））Fs*d216‘output02.wav‘）;
%wavwrite（x_d3（1:floor（length（x_d3）*d3））Fs*d316‘output03.wav‘）;

%
%?show?plot
%
Xw?=?fft（xlength（x））;
L?=?0:length（Xw）-1;
figure（1）;
subplot（211）;
plot（Fs*L/length（Xw）/1e3?20*log10（abs（Xw）））;?grid;
xlabel（‘Frequency?KHz‘）;?ylabel（‘Gain?dB‘）;
title（[‘Tone?Freq?=?‘num2str（fc）‘?Sampling?Freq?=?‘num2str（Fs）]）;
subplot（212）;
stem（1:30x（1:30））;
xlabel（‘n‘）;?ylabel（‘Magnitude‘）;

Xw_d2?=?fft（x_d2length（x_d2））;
L_d2?=?0:length（Xw_d2）-1;
figure（2）;
subplot（211）;
plot（（Fs*d2）*L_d2/length（Xw_d2）/1e3?20*log10（abs（Xw_d2）））;?grid;
xlabel（‘Frequency?KHz‘）;?ylabel（‘Gain?dB‘）;
title（[‘Tone?Freq?=?‘num2str（fc）‘?Sampling?Freq?=?‘num2str（Fs*d2）]）;
subplot（212）;
stem（1:30x_d2（1:30））;
xlabel（‘n‘）;?ylabel（‘Magnitude‘）;

Xw_d3?=?fft（x_d3length（x_d3））;
L_d3?=?0:length（Xw_d3）-1;
figure（3）;
subplot（211）;
plot（（Fs*d3）*L_d3/length（Xw_d3）/1e3?20*log10（abs（Xw_d3）））;?grid;
xlabel（‘Frequency?KHz‘）;?ylabel（‘Gain?dB‘）;
title（[‘Tone?Freq?=?‘num2str（fc）‘?Sampling?Freq?=?‘num2str（Fs*d3）]）;
subplot（212）;
stem（1:30x_d3（1:30））;
xlabel（‘n‘）;?ylabel（‘Magnitude‘）;

?屬性????????????大小?????日期????時間???名稱
-----------?---------??----------?-----??----

?????文件??????13275??2006-02-17?14:54??DSP-Mitra\demos\demos.htm

?????文件?????228842??2004-09-17?15:16??DSP-Mitra\demos\image_demo_1\blackwhite.png

?????文件?????463972??2004-09-17?12:18??DSP-Mitra\demos\image_demo_1\tulips.PNG

?????文件?????225814??2004-09-17?12:18??DSP-Mitra\demos\image_demo_1\tulips_BLUE.PNG

?????文件?????221998??2004-09-17?12:18??DSP-Mitra\demos\image_demo_1\tulips_GREEN.PNG

?????文件?????210874??2004-09-17?12:18??DSP-Mitra\demos\image_demo_1\tulips_RED.PNG

?????文件?????138349??2004-09-18?17:57??DSP-Mitra\demos\image_enhance\filtered_image.png

?????文件?????155232??2004-09-18?17:58??DSP-Mitra\demos\image_enhance\noisy_image.png

?????文件??????17408??2004-09-19?18:04??DSP-Mitra\demos\image_enhance\Thumbs.db

?????文件????3102964??2004-09-17?15:21??DSP-Mitra\demos\music_synthesis\other\nonLinear_bells.wav

?????文件????2431792??2004-09-17?15:21??DSP-Mitra\demos\music_synthesis\other\phyMod_string_major.wav

?????文件????1232452??2004-09-17?15:21??DSP-Mitra\demos\music_synthesis\other\specMod_major.wav

?????文件????1904676??2004-09-17?15:21??DSP-Mitra\demos\music_synthesis\other\wavetable_piano_oldsong.wav

?????文件????2123088??2004-09-16?16:40??DSP-Mitra\demos\music_synthesis\twinkle\nonLinear_horn_twinkle.wav

?????文件????2044296??2004-09-16?16:41??DSP-Mitra\demos\music_synthesis\twinkle\phyMod_guitar_twinkle.wav

?????文件????1980708??2004-09-16?16:41??DSP-Mitra\demos\music_synthesis\twinkle\specMod_twinkle.wav

?????文件????1351716??2004-09-16?16:39??DSP-Mitra\demos\music_synthesis\twinkle\wavetable_piano_twinkle.wav

?????文件???????2066??2004-09-19?17:12??DSP-Mitra\demos\sound_aliasing\aliasing.m

?????文件???????2063??2004-09-16?17:17??DSP-Mitra\demos\sound_aliasing\aliasing.m.bak

?????文件??????97064??2004-09-19?18:28??DSP-Mitra\demos\sound_aliasing\aliasingmusic.wav

?????文件??????33122??2004-09-19?18:26??DSP-Mitra\demos\sound_aliasing\aliasingspeech.wav

?????文件?????????25??2004-09-19?17:11??DSP-Mitra\demos\sound_aliasing\batch\aliasing.bat

?????文件???????6084??2004-09-16?17:17??DSP-Mitra\demos\sound_aliasing\Fig01.png

?????文件???????5655??2004-09-16?17:18??DSP-Mitra\demos\sound_aliasing\Fig02.png

?????文件???????5986??2004-09-16?17:17??DSP-Mitra\demos\sound_aliasing\Fig03.png

?????文件?????970244??2004-09-05?14:58??DSP-Mitra\demos\sound_aliasing\music.wav

?????文件??????48044??2004-09-19?17:11??DSP-Mitra\demos\sound_aliasing\output01.wav

?????文件??????36044??2004-09-19?17:11??DSP-Mitra\demos\sound_aliasing\output02.wav

?????文件??????16044??2004-09-19?17:11??DSP-Mitra\demos\sound_aliasing\output03.wav

?????文件??????14848??2004-09-16?17:18??DSP-Mitra\demos\sound_aliasing\Thumbs.db

............此處省略268個文件信息