how do i normalise frequency axis after computing fft ?
5 vues (au cours des 30 derniers jours)
Afficher commentaires plus anciens
pavan sunder
le 14 Jan 2016
Modifié(e) : Star Strider
le 14 Jan 2016
i have a 10 hz signal. i want to specify the cutoff for my filter. what is the normalized cut off for 50 hz signal? plz mention the formula used for normalization.
0 commentaires
Réponse acceptée
Star Strider
le 14 Jan 2016
Modifié(e) : Star Strider
le 14 Jan 2016
If you have a 50 Hz sampling frequency, the Nyquist frequency — in this instance the normalising frequency if you are designing a digital filter — is 25 Hz. So if you want a 15 Hz cutoff for a lowpass filter for instance, the normalised frequency, ‘Wn’ would be:
Fs = 50; % Sampling Frequency (Hz)
Fn = Fs/2; % Nyquist Frequency (Hz)
Fc = 15; % Cutoff Frequency (Hz)
Wn = Fc/Fn; % Normalised Cutoff Frequency (Dimensionless)
So Wn = 15/25 = 0.6
EDIT — For fft scaling, the best documentation is in the R2015a fft version. See specifically the code between the first two plot images.
0 commentaires
Plus de réponses (0)
Voir également
Catégories
En savoir plus sur Matched Filter and Ambiguity Function dans Help Center et File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!