Acceleration vs Time; Magnitude vs Frequency

Hello, I need to plot two graphs (Acceleration vs Time and Magnitude vs Frequency) and present both of it. Here is the code that I have done (a-acceleration (Length of signal N=2048), vt=time vector (1.2048s), Fs=32768Hz)

signal = a; time=vt;

% Plot Original signal in Time Domain
 plot(vt,a);
  title('Original signal in Time Domain');
  xlabel('Time [s]');
  ylabel('Acceleration [m/s^2]');
% Plot FFT signal
N = pow2(nextpow2(length(signal)));
y = fft(signal,N);
plot(1:N,abs(y));
title('FFT');
  xlabel('Frequency [Hertz]');
  ylabel('Magnitude');

Could you help me with that? Thank you in advance!

Answer 1

[Star Strider]

Try this:

% Plot FFT signal
N = pow2(nextpow2(length(signal)));
y = fft(signal,N)/length(signal);
Fn = Fs/2;
Fv = linspace(0, 1, fix(length(y)/2)+1)*Fn;
Iv = 1:length(Fv);
plot(Fv,abs(y(Iv))*2);
title('FFT');
xlabel('Frequency [Hertz]');
ylabel('Magnitude');

NOTE — I have not tested this. It should work.

[Farrukh Karimov]

It works, but the Magnitude vs Frequency Starts from Negative Values

[Farrukh Karimov]

 As I understood, should it be like this (without "-2") ?:

Iv = 1:length(Fv);
plot(Fv,abs(y(Iv)))

[Star Strider]

Typographical error I didn’t catch.

Should be:

plot(Fv,abs(y(Iv))*2);

I also corrected it in my original Answer.