FSK-2

fs = 20;
Ts = 1/fs
L = 10- Ts;
t = 0:Ts:L;


f = zeros(1,200);
f(1:100) = 2;
f(101:200) = 5;
signal = sin(2*pi*f.*t);
N = length(signal);


X_mags = abs(fftshift(fft(signal)));
bin_vals = [0 : N-1];
N_2 = ceil(N/2);
fax_Hz = (bin_vals-N_2)*fs/N;
subplot(2,1,1)
plot(fax_Hz, X_mags)
xlabel('Frequency (Hz)')
ylabel('Magnitude');
title('Double-sided Magnitude spectrum (Hertz)');
axis tight
subplot(2,1,2)
plot(t,signal)