clear all
i=10; %基带信号码元数
j=5000;
a=round(rand(1,i)); %产生随机序列
t=linspace(0,5,j);
f1=10; %载波1频率
f2=5; %载波2频率
fm=i/5; %基带信号频率
B1=2*f1; %载波1带宽
B2=2*f2; %载波2带宽
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%产生基带信号
st1=t;
for n=1:10
if a(n)<1;
for m=j/i*(n-1)+1:j/i*n
st1(m)=0;
end
else
for m=j/i*(n-1)+1:j/i*n
st1(m)=1;
end
end
end
st2=t;
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%基带信号求反
for n=1:j;
if st1(n)>=1;
st2(n)=0;
else
st2(n)=1;
end
end;
figure(1);
subplot(411);
plot(t,st1);
title('基带信号');
axis([0,5,-1,2]);
subplot(412);
plot(t,st2);
title('基带信号反码');
axis([0,5,-1,2]);
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%载波信号
s1=cos(2*pi*f1*t);
s2=cos(2*pi*f2*t);
subplot(413)
plot(s1);
title('载波信号1');
subplot(414),
plot(s2);
title('载波信号2');
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%调制
F1=st1.*s1; %加入载波1
F2=st2.*s2; %加入载波2
figure(2);
subplot(311);
plot(t,F1);
title('s1*st1');
subplot(312);
plot(t,F2);
title('s2*st2');
e_fsk=F1+F2;
subplot(313);
plot(t,e_fsk);
title('2FSK信');