实验报告 语音信号实验 数字信号处理 DTFT 采样 量化 频谱.doc

clear;close all;
f=10;
t=0::9/f;
x1=sin(2*pi*10*t+);
fs=40;
t1=0:1/fs:9/f;
x2=sin(2*pi*10*t1+);
subplot(3,1,1);plot(t,x1);title('原始信号');
subplot(3,1,2);plot(t,x1);hold on;stem(t1,x2,'g');title('采样过程');
subplot(3,1,3);plot(t1,x2);title('采样后信号');
X1=fft(x1);
X2=fft(x2);
clear;close all;
f=10;
t=0::9/f;
x1=sin(2*pi*10*t+);
fs=40;
t1=0:1/fs:9/f;
x2=sin(2*pi*10*t1+);
X1=fft(x1);
X2=fft(x2);
subplot(211);plot(t,abs(X1));title('原始信号频谱');
subplot(212);plot(t1,abs(X2));title('采样后信号频谱');
clear;close all;
f=10;t=0::9/f;
x1=sin(2*pi*10*t+);
fs=5;t1=0:1/fs:9/f;
x2=sin(2*pi*10*t1+);
X1=fft(x1);X2=fft(x2);
subplot(611);plot(t,abs(X1));title('5Hz原始信号频谱');
subplot(612);plot(t1,abs(X2));title('5Hz采样后信号频谱');
fs=40;t1=0:1/fs:9/f;
x2=sin(2*pi*10*t1+);
X1=fft(x1);X2=fft(x2);
subplot(613);plot(t,abs(X1));title('40Hz原始信号频谱');
subplot(614);plot(t1,abs(X2));title('40Hz采样后信号频谱');
fs=200;t1=0:1/fs:9/f;
x2=sin(2*pi*10*t1+);
X1=fft(x1);X2=fft(x2);
subplot(615);plot(t,abs(X1));title('200Hz原始信号频谱');
subplot(616);plot(t1,abs(X2));title('200Hz采样后信号频谱');
clear;close all;
fs=22050;
ws=[4800 5200]*2/fs;wp=[4600 5400]*2/fs; %通带和阻带边界频率
Rp=1;Rs=30;Nn=128; %通带波纹和阻带衰减以及绘制频率特性的数据点数
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