fsk.m

4fsk调制信号的详细过程

Rs=2400;%码元速率
Ts=1/Rs;%码元间隔
n=5;%一个码元采样数
fs=n*Rs;%采样速率,每码元采样5个点
%s=[0,0,0,0,0,0,0,0,0,0,0,1,1,0,1,0,1,1,1,0,1,0,1,0,1,0,1,0];
s=[0,0];
s_length=length(s);%序列长度
m_length = fix(s_length/2);%码元个数
t=[1/fs:1/fs:1/fs*m_length*n];
y=zeros(1,m_length*n);
f=zeros(1,m_length);


%********************************************************
for i=1:1:m_length
   b1 = s(2*i-1);
   b2 = s(2*i);
   if((b1 == 0) & (b2 == 0))
        f(i) =750;
    elseif((b1 == 0) & (b2 == 1))
        f(i) =1500;
    elseif((b1 == 1) & (b2 == 1) )
       f(i) =2250;
    elseif((b1 == 1) & (b2 == 0) )
        f(i) =3000;
        end
end
%***************************************************************
%对该输入信号FSK调制
i=1;
while i<=n*m_length 
y(i)=sin(2*pi*f(ceil(i/n))*t(i));
i=i+1; 
end 

%*****************************************************************
figure(1)
subplot(2,1,1);plot(t,y);
title('4FSK信号的时域图形');