FFT and plot amplitude spectrum
2 views (last 30 days)
Show older comments
Samaneh Arzpeima
on 6 Dec 2018
Commented: Shubham Gupta
on 10 Dec 2018
hello everybody
I got stuck on this problem and really need your help
I must plot the amplitude spectrum of a data set. my data set is the attached “momentrate.mat”. The first column is ‘time(s)’ and the second one is ‘momentrate(Nm/s)’.these 2 columns give a plot like the left figure in attached pdf file.by
plot(momentrate(:,1),momentrate(:,2))
now I need to take the amplitude spectrum of the above plot, and it should be something like the right figure in attached pdf file.
I tried the following codes
y=momentrate(:,2);
t=momentrate(:,1);
dt=diff(t)
sample_frequency= numel(t)/(t(end)-t(1))
nfft=2^nextpow2(length(y));
Y=fft(y,nfft);
Y=Y(1:nfft/2);
m=abs(Y);
f=(0:nfft/2-1)*sample_frequency/nfft;
plot(f,m);
but this won't give me anything like what I suppose to have.
Can you please tell me what is wrong?
I would appreciate if you could explain to me with simple codes.
0 Comments
Accepted Answer
Shubham Gupta
on 7 Dec 2018
You might wanna use "logarithmic plot" instead of simple plot. So last line would be
loglog(f,m);
More Answers (0)
See Also
Categories
Find more on Spectral Measurements in Help Center and File Exchange
Products
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!