噪声调幅干扰仿真（含MATLAB代码）

function y=noiseAM(u0,N,wpp); 

if nargin==0 

wpp=0;u0=1; 

end 

fj=35e6;fs=4*fj; Tr=520e-6;     

t1=0:1/fs:3*Tr-1/fs; N=length(t1); 

u=wgn(1,N,wpp); 

df1=fs/N;n=0:N/2;f=n*df1;   

wp=10e6; 

ws=14e6;  

rp=1; rs=60;  

[n1,wn1]=buttord(wp/(fs/2),ws/(fs/2),rp,rs);  

[b,a]=butter(n1,wn1);  

u1=filter(b,a,u); 

p=0.1503*mean((u1.^2)) ;

figure

subplot(2,2,1),plot(t1,u1),title('噪声调制波形'); axis([0,0.05e-4,-2,2])

subplot(2,2,2), j2=fft(u1);plot(f,10*log10(abs(j2(n+1)*2/N)))

title('调制噪声功率谱');

rand('state', 0); 

y=(u0+u1).*cos(2*pi*fj*t1+2);     

p=(1/N)*sum(y.^2);

subplot(2,2,3), plot(t1,y),title('噪声调幅干扰时域波形'); axis([0,0.05e-4,-2,2])

subplot(2,2,4), J=fft(y);plot(f,10*log10(abs(J(n+1))))

title('已调波功率谱');