How to find frequency from image of spectrogram?
8 visualizzazioni (ultimi 30 giorni)
Mostra commenti meno recenti
Here is what I have done so far.
[W,fs]=wavread(FileName); %this reads a wave file
[~,~,~,P]=spectrogram(W(:,end),tres,tres/2,fres,fs); %tres is time resolution %and fres is frequency resolution.
I=flipud(-log(P)); %here 'I' gives the spectrogram image in a matrix.
imshow(I,[]); %this line will display the image.
now my question is if I choose a pixel co-ordinate from the image matrix I how can I get its frequency?
0 Commenti
Risposte (1)
Wayne King
il 30 Giu 2013
Modificato: Wayne King
il 30 Giu 2013
If you output the vector of frequencies from spectrogram(), you will have the frequency information.
t=0:0.001:2;
x=chirp(t,0,1,150);
[y,f,t,p] = spectrogram(x,256,250,256,1000);
Each row of p corresponds to the frequency at the corresponding element of the vector, f. But keep in mind, that it's only as good as the frequency resolution you have. If you're looking for a technique that gives you instantaneous frequency and time behavior for a signal, it does not exist. You can only obtain information about a time-frequency rectangle of a minimum area.
0 Commenti
Vedere anche
Categorie
Scopri di più su Time-Frequency Analysis in Help Center e File Exchange
Prodotti
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!