clc;clear;close all;
N = 10;             
Tb = 3;            
fc1 = 6;            
fc2 = 5;            
fs = 150;           
t = 0:1/fs:Tb-1/fs;  
m = randi([0 1],1,N);
c1 = sqrt(2/Tb)*sin(2*pi*fc1*t);
c2 = sqrt(2/Tb)*sin(2*pi*fc2*t);
message = [];
fsk = [];
time = [];
for i = 1:N
    if m(i)==1
        msg = ones(1,length(t));
        signal = c1;
    else
        msg = zeros(1,length(t));
        signal = c2;
    end
    message = [message msg];
    fsk = [fsk signal];
    time = [time (i-1)*Tb+t];
end
figure; 
subplot(4,1,1);
stem(0:N-1,m,'filled');
title('Binary Data');
xlabel('Bit Number');
ylabel('Bit');
axis([0 N-1 -0.5 1.5]);
grid on;
subplot(4,1,2);
plot(time,message,'LineWidth',1.5);
title('Message Signal');
xlabel('Time (s)');
ylabel('Amplitude');
axis([0 N  -0.2 1.2]);
grid on;
subplot(4,1,3);
plot(time,fsk,'LineWidth',1.5);
title('BFSK Modulated Signal');
xlabel('Time (s)');
ylabel('Amplitude');
grid on;
demod = zeros(1,N);
for i=1:N
    r = fsk((i-1)*length(t)+1:i*length(t));
    x1 = sum(r.*c1);
    x2 = sum(r.*c2);
    if x1>x2
        demod(i)=1;
    else
        demod(i)=0;
    end
end
subplot(4,1,4);
stem(0:N-1,demod,'filled');
title('Demodulated Data');
xlabel('Bit Number');
ylabel('Bit');
axis([0 N-1 -0.5 1.5]);
grid on;
disp('Original Bits:');
disp(m);
disp('Recovered Bits:');
disp(demod);
if isequal(m,demod)
    disp('Demodulation Successful');
else
    disp('Demodulation Failed');
end