noiseam.m

产生噪声调幅干扰信号

%噪声调幅干扰 
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);  %产生高斯白噪声6dBW% 
df1=fs/N;n=0:N/2;f=n*df1;  
%加滤波器 生成带限高斯白噪声
wp=10e6; %调制噪声带宽10M
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); %带限 p=0.1503 mean((u1.^2))
%figure,subplot(2,1,1),plot(t1,u1),title('高斯带限噪声');
%subplot(2,1,2), j2=fft(u1);plot(f,10*log10(abs(j2(n+1)*2/N))),title('功率谱');% good!

rand('state', 0);

y=(u0+u1).*cos(2*pi*fj*t1+2);         % 功率：p=(1/N)*sum(y.^2) =0.5728
                        %  or  J=10*log10(abs(fft(y,512))); fftshift( 

%figure,subplot(121), plot(t1,y),title('噪声调幅干扰时域波形'),xlabel('t(单位：s)'),ylabel('幅度/v)');
%subplot(122), J=fft(y);plot(f,10*log10(abs(J(n+1)))),title('功率谱'),xlabel('t(单位：Hz)'),ylabel('功率/dB)');%???
%clear all; clc;
clc;