How to plot average (mean) signal of 231 signals and plot the frequency response of that mean signal?

Hi all, I would like to plot an average signal of 231 signals in time domain and plot the frequency response graph. Here is my code and I would appreciate if somebody gives me any idea how to solve it.

signal = a; % acceleration
time=vt;  % time
% Plot Original signal in Time Domain
subplot(211); 
plot(vt,a(:,1:231,1)); % for sensor 1
  title('Multiple signal in Time Domain(Healthy-Sensor1)');
  xlabel('Time [s]');
  ylabel('Acceleration [m/s^2]');
%FFT plot
Fs=32768; %Sampling frequency
N=2048;
y = fft(a(:,1:231,1),N)/length(signal);
Fn = Fs/2;
Fv = linspace(0, 1, fix(length(y)/2)+1)*Fn;
Iv = 1:length(Fv);
subplot(212);
plot(Fv,abs(y(Iv))*2);
title('FFT(Healthy-Sensor1)');
xlabel('Frequency [Hertz]');
ylabel('Magnitude');

Answer 1

[Image Analyst]

I don't think you can use fft like this:

y = fft(a(:,1:231,1),N)/length(signal);

fft() is for 1-D signals, not 2-D signals or 3-D signals which is what a(:,1:231,1) is. I think you have to call mean() on one direction of the a signal, then fft that one 1-D mean signal. Please attach a and vt in a .mat file if you want more help.

[Farrukh Karimov]

Thank you for your help. However, the file size is more than 5mb, so here is a link on google drive

https://drive.google.com/file/d/0B7GxFIsnZHu4Z0lKT2V1b2ZKbGM/view?usp=sharing Thank you again!