Why 8 segments for pwelch?

Hi, If anyone could help me out i'd be very grateful. I'm using the pwelch function and I was just wondering why the default number of segments is 8? Is this when it is most effective, and if so, why? This is a general question for understanding

Thank you very much

Answer 1

[Rick Rosson]

The use of 8 as the default value for the number of segments is purely arbitrary. It is a perfectly reasonable value, but it is no better or worse than any other choice. In general, you can often achieve better results by choosing a custom value for the window size and the overlap amount. Remember that there is a trade off between the window size and the frequency resolution. The larger the window, the smaller the frequency increment, and vice versa.

Please try:

   nSegments = ... ;
   winSize = signalLength/nSegments;
   overlap = winSize/2;
   fftSize = winSize;

   figure;
   pwelch(x,winSize,overlap,fftSize,Fs);

for a variety of values for nSegments.