2.m

一个简单的modulation的例子,关于AM,FM,载波等

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%Digital Modulation
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Lb=16000
BI = round(rand(1,Lb));
%
Nbits=2;
len_BI=length(BI);
len_Bc=len_BI/Nbits;
Bc=zeros(1,len_Bc);
for n=1:Nbits
Bc=Bc+2^(Nbits-n)*BI(n:Nbits:end);
end
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%Gray coding-only used for Nbits=2
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
for i=1:len_Bc
    if Bc(i)=2
        Bc(i)=3
    elseif Bc(i)=3
        Bc(i)=2
    end
end
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%Mapping to 4-QAM
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%