MATLAB Answers

Tie to frequency using F

1 view (last 30 days)
Karl Zammit
Karl Zammit on 17 May 2021
Commented: Karl Zammit on 17 May 2021
Hi, I am trying to perform a fft on a series of runs of a vibration analysis with the following code. An empty plot seems to show up, any ideas?
%Frequency Analysis
time = xlsread('Lab-2ciii.xlsx','A1:A300');; % Time Vector
signal = xlsread('Lab-2ciii.xlsx','B1:B300');; % Signal data in Time-Domain
N = length(signal); % Number Of Samples
Ts = mean(diff(time)); % Sampling Interval
Fs = 1/Ts; % Sampling Frequency
Fn = Fs/2; % Nyquist Frequency
FT_Signal = fft(signal)/N; % Normalized Fourier Transform Of Data
Fv = linspace(0, 1, fix(N/2)+1)*Fn; % Frequency Vector (For ‘plot’ Call)
Iv = 1:length(Fv); % Index Vector (Matches ‘Fv’)
plot(Fv, abs(FT_Signal(Iv))*2)

Accepted Answer

Geoff Hayes
Geoff Hayes on 17 May 2021
Karl - are you reading the correct columns? For example, on my Mac, the time array
time = xlsread('Lab-2ciii.xlsx','A1:A300');
is empty, and the signal array
signal = xlsread('Lab-2ciii.xlsx','B1:B300');
has just a handful of elements
signal =
Both correspond to the first and second columns of your spreadsheet. I suspect you want columns E (which seems to correspond to time) and either H, K, or N...all of which have 300 elements.
  1 Comment
Karl Zammit
Karl Zammit on 17 May 2021
My bad for not commenting that the problem was solved. Thanks a lot nonetheless

Sign in to comment.

More Answers (0)

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!