function Md_m=Modulate(Md_f,phcode,fd,i)

global nn;
global fs;
global F_if ;
phcode = phcode;
fd = fd;
Loop_time = i;
CA_Code = CAcode(phcode,fd,Loop_time);

% t = [(i-1)*nn:i*nn-1]/fs;
% Phase_signal = 2*pi*(F_if+fd)*t;
% Carr = cos(Phase_signal);

CA_Mapping = CA_Code;

if Md_f == 1
    Md_m = CA_Mapping;
else
    Md_m = -CA_Mapping;
end