define frequency of signal from fft output
2 visualizaciones (últimos 30 días)
Mostrar comentarios más antiguos
Ngoc Lam
el 29 de Sept. de 2014
Comentada: YAMASANI MANOJ REDDY
el 21 de Ag. de 2018
what is the relationship between the sampling frequency Fs and frequency of signal of FFT function in matlab? assUme that, we have a signal with spectrum as follow picture. with Fs= 44.1Khz, I know that X-axis is not the frequecy of signal, right? How to define the frequency of this signal with followed spectrum? for example, at the point X-axis = 10000, with Fs= 44.1Khz, how to define frequency of signal at that point?
0 comentarios
Respuesta aceptada
Rick Rosson
el 29 de Sept. de 2014
Editada: Rick Rosson
el 29 de Sept. de 2014
dF = Fs/N;
f = dF*(0:N-1)';
Más respuestas (4)
Ngoc Lam
el 30 de Sept. de 2014
Editada: Ngoc Lam
el 30 de Sept. de 2014
1 comentario
Rick Rosson
el 30 de Sept. de 2014
The sampling rate in your code is
Fs = 500/(4*pi);
which is approximately 40 samples per second. By the Nyquist Sampling Theorem, the maximum frequency that you can represent without aliasing is Fs/2 or approx 20 Hertz. Your signal, however, contains components at 50 Hertz and 100 Hertz, which are well above the maximum.
Rick Rosson
el 30 de Sept. de 2014
Please try:
Fs = 1000;
dt = 1/Fs;
N = 12000;
t = dt*(0:N-1)';
x = sin(100*pi*t) + 2*cos(200*pi*t);
X = fftshift(fft(x))/N;
dF = Fs/N;
f = -Fs/2:dF:Fs/2-dF;
plot(f,abs(X));
1 comentario
Syed Masoud Shah kakakhel
el 23 de Mzo. de 2017
Editada: Syed Masoud Shah kakakhel
el 23 de Mzo. de 2017
kindly @Rick Rosson can u comment...variables like what is N?? kindly will be more helpful..m waiting for response
Ver también
Categorías
Más información sobre Spectral Measurements en Help Center y File Exchange.
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!