Chen-
> I have a time signal, and if I calculate
time-frequency
> spectra distribution, I'd like to draw a figure in which
> x axes is time, y axes ia frequency, like the figure in
> the attached file. does matlab provide a function to draw
> this kind of figure.
> I am looking forward to seeing your answer.
Suggest to check out spectrogram() function. This link shows an example figure
plot:
http://www.mathworks.com/access/helpdesk/help/toolbox/signal/spectrogram.html
And this link has some mention of gray-scale version:
http://www.mathworks.com/matlabcentral/fileexchange/1553
-Jeff