Borrar filtros
Borrar filtros

Peaks of a function

4 visualizaciones (últimos 30 días)
Aaron Rosenberger
Aaron Rosenberger el 13 de Mayo de 2023
Respondida: Star Strider el 13 de Mayo de 2023
I need to calculate the frequenzy of a vibrating system.
i plotted the function and now to calculate the frequenzy i need the time between two peaks of the function.
just like:
x = max(function)
x2 = secondmax(function)
something like that ^^.
thank you very much for your help

Respuestas (2)

Stephane
Stephane el 13 de Mayo de 2023
Editada: KALYAN ACHARJYA el 13 de Mayo de 2023
There is a Matlab a function to detect peaks/local maxima: https://se.mathworks.com/help/signal/ref/findpeaks.html
You could also fit an exponentially decaying sinus if this is what you expect (https://se.mathworks.com/help/curvefit/fit.html) or do a Fourier analysis (https://se.mathworks.com/help/matlab/ref/fft.html).
  2 comentarios
Aaron Rosenberger
Aaron Rosenberger el 13 de Mayo de 2023
Thank you very much ! :).
The "findpeaks" function works for me
KALYAN ACHARJYA
KALYAN ACHARJYA el 13 de Mayo de 2023
You may accept the answer, if the answer helps to solve the issue.

Iniciar sesión para comentar.


Star Strider
Star Strider el 13 de Mayo de 2023
This is relatively straightforward —
F1 = openfig('Plot.fig', 'visible');
Lines = findobj(F1, 'Type','Line');
t = Lines.XData.';
s = Lines.YData.';
Ts = mean(diff(t));
Fs = 1/Ts;
Fn = Fs/2;
L = numel(t);
NFFT = 2^nextpow2(L);
FTs = fft((s-mean(s)).*hann(L), NFFT)/L;
Fv = linspace(0, 1, NFFT/2+1)*Fn;
Iv = 1:numel(Fv);
[pks,locs] = findpeaks(abs(FTs(Iv))*2, 'MinPeakProminence',1E-7);
figure
plot(Fv, abs(FTs(Iv))*2)
grid
xlabel('Frequency (Hz)')
ylabel('Magnitude (m)')
title('Fourier Transform')
text(Fv(locs), pks, sprintf('\\leftarrow Magnitude %.3f\\times10^{-6} m\n Freq = %.3f Hz', pks/1E-6, Fv(locs)))
.

Etiquetas

Community Treasure Hunt

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

Start Hunting!

Translated by