function FSK
clear all; 
x=randn(10,1)>0; 

fl=5000;fh=8000;fs=100000; 

ts=1/200;%碼元速率200波特 

tt=(0:1/fs:ts); 

t=[tt;tt+ts;tt+2*ts;tt+3*ts;tt+4*ts;tt+5*ts;tt+6*ts;tt+7*ts;tt+8*ts;tt+9*ts]; 

y=zeros(10,length(tt)); 

i=1; 

%對該輸入信號FSK調制 

while i<=10 

y(i,:)=x(i)*sin(2*pi*fh*t(i,:))+~x(i)*sin(2*pi*fl*t(i,:)); 

i=i+1; 

end 

t=reshape(t',length(tt)*10,1); 

y=reshape(y',length(tt)*10,1); 

subplot(211);plot(t,y); 

title('FSK信號的時域圖形'); 

%該輸入信號的頻域圖形 

n=length(y); 

r=fft(y)/n;r=fftshift(r); 

f=linspace(-fs/2,fs/2,n); 

subplot(212); 

plot(f,abs(r)); 

set(gca,'XTick',-fs/2:5000:fs/2); 

title('FSK信號的頻譜圖');