function fskd(g,f0,f1)
%FSK modulation
%Example:(f0 and f1 must be integers)
%fskd([1 0 1 1 0],1,2)
%Author: Diego Orlando Barrag醤 Guerrero
%diegokillemall@yahoo.com
%Loja (ECUADOR)
%Long Live Heavy-Metal
%See also:
%http://www.mathworks.com/matlabcentral/fileexchange/loadFile.do?objectId=14328&objectType=FILE
if nargin > 3
error('Too many input arguments')
elseif nargin==1
    f0=1;f1=2;
elseif nargin==2
    f1=2;
end

val0=ceil(f0)-f0;
val1=ceil(f1)-f1;
if val0 ~=0 || val1 ~=0;
    error('Frequency must be an integer');
end

if f0<1 || f1<1;
    error('Frequency must be bigger than 1');
end


t=0:2*pi/99:2*pi;
cp=[];sp=[];
mod=[];mod1=[];bit=[];

for n=1:length(g);
    if g(n)==0; 
        die=ones(1,100);
        c=sin(f0*t);
        se=zeros(1,100);
    else g(n)==1;
        die=ones(1,100);
        c=sin(f1*t);
        se=ones(1,100);    
    end
    cp=[cp die];    
    mod=[mod c];    
    bit=[bit se];
end

ask=cp.*mod;
subplot(2,1,1);plot(bit,'LineWidth',1.5);grid on;
title('Binary Signal');
axis([0 100*length(g) -2.5 2.5]);

subplot(2,1,2);plot(ask,'LineWidth',1.5);grid on;
title('FSK modulation');
axis([0 100*length(g) -2.5 2.5]);