signal processing

spectrogram

h = figure;
Nwin=2048;
Twin=Nwin*dt;

[dum,f,t,p] = spectrogram(y,Nwin,0,[],1/dt,'yaxis');

surf(t,f,10*log10(abs(p)),'EdgeColor','none');

periodogram

making an envelope

envelope

downsample

upsample

diff