zuoye.m

很好的matlab 源代码学习资料,很好的matlab 源代码学习资料

echo off
close all
clc
t0=0.2 ;
ts=0.001
fs=1/ts
fc=300; 
t=[-t0/2:ts:t0/2];  
m=sinc(100*t);  
c=cos(2*pi*fc.*t);  
u=m.*c; 
M=fft(m,256);    
U=fft(u);
e=awgn(u,40);
E=fft(e,256);
Wp=[0.5,0.7];
Ws=[0.1,0.9];
Rp=10;
Rs=60;
[N,Wn]= Buttord(Wp,Ws,Rp,Rs) ;
[B,A]=Butter(N,Wn,'bandpass');
j=filtfilt(B,A,e);
J=fft(j,256);   
Wn=0.6;
[b,a]=Butter(64,Wn,'low');
p=j.*c;
qq=filtfilt(b,a,p);
P=fft(p,256);   
QQ=fft(qq,256)   
QQ=QQ/fs; 
L=qq.*2                         
figure(1)
subplot(3,1,1)
plot(fftshift(abs(M)))
title('原调制信号的频谱图')
subplot(3,1,2)
plot(fftshift(abs(U)))
title('已调信号的频谱图')
subplot(3,1,3)
plot(fftshift(abs(E)))
title('通过白噪声信道的已调信号频谱图')
figure(2)
subplot(3,1,1)
plot(fftshift(abs(J)))
title('加噪已调信号通过BPF后频谱图')
subplot(3,1,2)
plot(fftshift(abs(P)))
title('混频信号的频谱图')                      
subplot(3,1,3)
plot(fftshift(abs(QQ)))
title('混频信号通过低通滤波器后的信号的频谱图')
figure(3)
subplot(3,1,1)
plot(t,m(1:length(t)))
title('原调制信号的时域图')
subplot(3,1,2)
plot(t,u(1:length(t)))
title('已调信号的时域图')
subplot(3,1,3)
plot(t,e(1:length(t)))
title('通过白噪声信道的已调信号的时域图')
figure(4)
subplot(3,1,1)
plot(t,j(1:length(t)))
title('加噪已调信号通过BPF后时域图')
subplot(3,1,2)
plot(t,p(1:length(t)))
title('混频信号的时域图')  
subplot(3,1,3)
plot(t,L(1:length(t)))
title('解调后信号的时域图')