mod_ask.m

基带数字信号通过成形滤波（选用升余弦滚降函数）然后进行载波调制

function s_ask=mod_ask(data,sample,M,fb,fc)

%clear;clc;
%M=2;N=20;
%data=randint(1,N,M);
%data=[1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 ];
%sample=16;

Tc=1/fb;


deltat=Tc/sample;

t=(-(4*sample-1):1:(4*sample))*deltat;
for i=1:length(t)  
   if(t(i)~=0)
       if t~=Tc/2;
           h(i)=sin(pi*t(i)/Tc)*cos(pi*t(i)/Tc)/(pi*t(i)/Tc)/(1-4*t(i)^2/Tc^2);
       else
           h(i)=sin(pi*t(i)/Tc)/(pi*t(i)/Tc);
       end
   end
   if(t(i)==0)
       h(i)=1;
   end
end



g=[];
for i=1:length(data)
    g=[g data(i) zeros(1,sample-1)];
end;
%figure
%subplot(2,1,1);plot(g);

delay=3*sample;
g=[g zeros(1,delay)];


s=filter(h,1,g);
pulse=s(delay+1:end);

%subplot(2,1,2);plot(pulse);

fs=fb*sample;ts=1/fs;

t=[0:length(pulse)-1]*ts;
c=cos(2*pi*fc.*t);

s_ask=pulse.*c;

%s_ask=s_ask/max(s_ask);

%figure
%plot(s_ask)