clear;clc;
f1=50;f2=1500;fs=4000;
N=128;
n1=(0:N-1);
I1=sin(2*pi*f1/fs*n1)+sin(2*pi*f2/fs*n1);
I2=randn(size(I1));
I=I1+I2;
figure(1);
subplot(221);plot(n1/fs,abs(I1));grid;
title('纯净信号时域波形图');xlabel('时间');ylabel('幅值');
subplot(222);plot(n1/fs,abs(I));grid;
title('加噪信号时域波形图');xlabel('时间');ylabel('幅值');
subplot(223);plot(n1*fs/N,abs(fft(I1)));grid;axis([0 2000 0
80]);
title('纯净信号频域波形图');xlabel('频率');ylabel('幅值');
subplot(224);plot(n1*fs/N,abs(fft(I)));grid;axis([0 2000 0
80]);
title('加噪信号频域波形图');xlabel('频率');ylabel('幅值');
w1 = 2*pi*50/fs;
wp = 2*fs*tan(w1/2);
w2 = 2*pi*1000/fs;
