Simulate BFSK or FSK technique.

// BFSK or FSK --> Binary Frequency Shift Keying.

t=[0:0.01:4.4*%pi];
A=5;
wc=5;

Vm=A.*squarewave(t);
Vc=A.*cos(wc.*t);
fc=wc/(2*%pi);


subplot(5,1,1);
plot(t,Vm, 'black');

subplot(5,1,2);
plot(t,Vc, 'black');

df=0.5;
subplot(5,1,3);
Vf=A.*cos(2.*%pi.*(fc+Vm.*df).*t);
plot(t,Vf, 'black');
legend('df=0.5');


df=1;
subplot(5,1,4);
Vf=A.*cos(2.*%pi.*(fc+Vm.*df).*t);
plot(t,Vf, 'black');
legend('df=1');


df=1.5
subplot(5,1,5);
Vf=A.*cos(2.*%pi.*(fc+Vm.*df).*t);
plot(t,Vf, 'black');
legend('df=1.5');

// Output
                              BFSK or FSK --> Binary Frequency Shift Keying