A signal can be either power signal or energy signal. Is EEG signal is a power or energy signal? I see in some example computation of both power spectrum and energy spectrum as feature? how is that possible
EEG is a energy signal. In fact not any practical signal is power signal.
If I'm not mistaken, the EEG units from a typical electrode montage is several micro-volts differential with respect to the electrode montage.....as you trace back this voltage differential respect to the electrical montage channels. As you may interpret this voltage differential and consider the time element and cortical sources of this voltage differential you can then extrapolate the power &/or energy.
For transparency reasons, I share that my answer below is based on my understanding of this source: http://www.matel.p.lodz.pl/wee/i12zet/Signal%20energy%20and%20power.pdf
Judging by the formulas and explanations power and energy simply refer to whether the squared magnitude of the signal (amplitude in the case of EEG) is calculated over a finite (power) or infinite (energy) time window. These can be calculated independent of whether the signal is classified as a power or energy signal.
It is indeed rather that the classification of the signal depends on the relationship between the energy and power values for that signal (see source).
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