I am trying to understand how to interpret a spectrogram image plot: (1) what does the yellow band and its corresponding color code with a high positive value indicate? There are so many yellow bands in comparison to blue. The legend shows that the yellow bands have higher positive values, so is that higher frequency?
(2) I used the following code to generate the spectrogram. The X axis contains 50 data points because the method splits the signal into segments of length 50. I arbitrary used 10 into the spectrogram function. Is there a specific rule as to how to determine the number of points?
x(1) = rand; for n = 1:500 x(n+1) = 4*x(n)*(1-x(n)); end specto=spectrogram(x,10,0,256); %using 256 fft points with no overlap logspecto=(20*log10(abs(specto)));