function fdh(filename);
Data = load(filename);
s = 500; %number of sampled points
dt = 60; %time sampling rate msec
t = Data(1:s,1); %time
y = Data(1:s,2); % yellow button
g = Data(1:s,5); % green button

Y = abs(fft(y));
G = abs(fft(g));
w = ((2.*pi.*(1./dt).*(1:s))./s).*1000;

figure;
subplot(2,1,1);
plot(t,y,'-y',t,g,'-g');
xlabel('time [msec]');
subplot(2,1,2);
plot(w,Y,'-y',w,G,'-G'); grid on;
xlabel('frequency [Hz]');
