# How to remove (or isolate) side peaks except main peak after FFT

8 visualizzazioni (ultimi 30 giorni)
Hyeon-Taek il 17 Apr 2024
Risposto: Star Strider il 17 Apr 2024
Hi All,
I have a data as above. This is some data from optical interferometry. After cropping the noise level (for getting dominant oscillation as best as I can), I can get the frequency data like below after FFT.
Like the fft data, there is a side peak. Sometimes more than one side peak. Also, not good the noise level as you can see. (Of course I have to get better raw data.)
Here is my questions.
Q1. How can the side peak be removed or isolated? I want to get the main peak only.
Q2. Is it available SVD function for the data?
Please let me know if whoever can let me recommend any examples for the questions. BR, Taek
##### 0 CommentiMostra -2 commenti meno recentiNascondi -2 commenti meno recenti

Accedi per commentare.

### Risposte (2)

Chunru il 17 Apr 2024
You can try "findpeaks" and using "MinPeakDistance" option.
doc findpeaks
##### 0 CommentiMostra -2 commenti meno recentiNascondi -2 commenti meno recenti

Accedi per commentare.

Star Strider il 17 Apr 2024
Using:
NFFT = 2^nextpow2(numel(signal))
and a window function (for example hann) in the fft call could improve the fft result:
FTsignal = fft((signal(:)-mean(signal(:)) .* hann(numel(signal)), NFFT)/sum(hann(numel(signal)));
Then, plot the absolute value of that result, and also use it for the argument to findpeaks. (All of this assumes that ‘signal’ is a vector.)
##### 0 CommentiMostra -2 commenti meno recentiNascondi -2 commenti meno recenti

Accedi per commentare.

### Categorie

Scopri di più su Descriptive Statistics in Help Center e File Exchange

### Community Treasure Hunt

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

Start Hunting!

Translated by