MATLAB: How should I calculate power spectral density of signal with too high sampling rate

Question

Dear All,

I have a signal with high sampling rate (10000 Hz) and I would like to calculate power spectral density in the frequency range 0-50 Hz. Therefore, sampling rate 100 Hz would be sufficient.

My question is whether signal should be resampled by averaging 100 samples and then the spectrum should be calculated, or the spectrum should be calculated on the original signal. Should the results be the same? If not, which one would be more correct?

Best, Urban

Answer 1

I would recommend first design a filter, to filter at 100Hz, then down sample/resample, and then do PSD calculation. Actually I believe resample does that anti-aliasing for you already.

http://www.mathworks.com/help/signal/ref/resample.html

In my opinion, doing computation on the original signal is unnecessary and expensive. You may also be able to get better resolution within 0-50Hz via resample since again it's more computational friendly to zero pad a low sampling rate signal.