%射頻噪聲干擾信號(hào) good!
function y=RFnoise(N,wpp)
 
Tr=520e-6;           %脈沖重復(fù)周期
fs=120e6; 
t1=0:1/fs:Tr; 
if nargin==0
 N=length(t1); wpp=7.246;
end
u=wgn(1,N,wpp); %產(chǎn)生高斯白噪聲0dBw             % randn(1,N)
df1=fs/N;n=0:N/2;f=n*df1;
%j2=fft(u);           %噪聲信號(hào)頻譜分析 
%figure,
%subplot(2,1,1),plot(t1,u),title('高斯白噪聲');
%subplot(2,1,2), plot(f,(abs(j2(n+1)*2/N))),title('功率譜');
 
wp=[30e6 40e6];       %加濾波器 fj0=35M Bj=10M?
ws=[28e6 42e6]; 
rp=1; rs=60; 
[N1,wn]=buttord(wp/(fs/2),ws/(fs/2),rp,rs); 
[b,a]=butter(N1,wn);;
%phi=2*pi*rand(1,N);R = raylrnd(u);
y=filter(b,a,u);;       % figure,psd(y)  mean((u1.^2))=1(平均功率為1W)
%y=R.*cos(2*pi*35e6.*t1+phi);
J=fft(y);;             %噪聲信號(hào)頻譜分析 
figure,subplot(121),plot(t1,y),title('射頻噪聲干擾信號(hào)'),xlabel('t(單位：s)'),ylabel('幅度/v)');
subplot(122),plot(f,(10*log10(abs(J(n+1))))),title('頻譜圖'),xlabel('t(單位：Hz)'),ylabel('功率/dB)');;