%
%混頻
%

function y1=hunpin(x,f,w1,w2);
fs=100e6;                               %采樣頻率100M
Ts=1/fs;
T=0.00003;                             %脈沖重復周期30微秒
t=0:Ts:T-Ts;
N=length(x);
y=x.*cos(2*pi*f*t);

n=50;                                  
Wn=[w1,w2];                          
b=fir1(n,Wn);                          %濾波器系數
y=[y,zeros(1,25)];
y1=filter(b,1,y);
y1=y1(26:length(y1));