FFT results correct for following filtering?
3 views (last 30 days)
Show older comments
I have inductive measurement data that i want to filter with a lowpass, so first i want to get the frequency spectrum to know what to filter out.
I used the following code to do the FFT motivated by an answer to a question i was reading here.
%% FFT
load('CH0.mat');
load('t.mat');
L = numel(CH0);
Ts = mean(diff(t));
Fs = 1/Ts;
Fn = Fs/2;
CH0FT = fft(CH0-mean(CH0),[],1)/L;
Fv = linspace(0, 1, fix(L/2)+1)*Fn;
Iv = 1:numel(Fv);
CH0abs = abs(CH0FT);
plot(Fv,mag2db(CH0abs(Iv)*2));
As you see it look like this:
Usually i would expect a peak at a certain frequency so i could filter the other frequencys out but here is just a big peak near zero and also the frequencys are smaller than i would expect.
Do you see any mistakes or is it just the way my sensor measures? How would you filter it? I also attached the data. Thank you!
0 Comments
Accepted Answer
Star Strider
on 4 May 2021
That signal and ‘CH0’ here are apparently quite noisy with a large low-frequency component. Consider using a lowpass filter if you only want to isolate the low-frequency component (likely 0 to 0.001 frequency units here).
0 Comments
More Answers (0)
See Also
Categories
Find more on Multirate Signal Processing in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!