X=exported.y(:,3);
L=length(X);
time_end=exported.t(end)-exported.t(1);
Fs = L/time_end;            % Sampling frequency
T = 1/Fs;                   % Sampling period
t = (0:L-1)*T;
Y = fft(X);
figure
P2 = abs(Y/L);
P1 = P2(1:L/2+1);
P1(2:end-1) = 2*P1(2:end-1);
f = Fs*(0:(L/2))/L;
plot(1000*f(2:50),P1(2:50))
title("Single-Sided Amplitude Spectrum of X(t)")
xlabel("f (Hz)")
ylabel("|P1(f)|")