Theoretical: Why use trapz to calculate absolute power?

Hi everybody,

This more of a theoretical question and since I'm not an engineer I apologize in advance for any trouble understanding my question. I've recently seen a script that first calculated the power using pwelch method and then used trapz to calculate the integral between two frequency bins, like:

[Pxx W] = pwelch(data, window, overlap);
Pow1 =  [Pow1 ; trapz(Pxx(2:6))];

Does anyone know the possible reason to take the integral of the frequencies when you are interested in power? And does this represent something different?

Thanks,

Eric

Answer 1

[Vinod Sudheesh]

The "pwelch" function returns the power spectral density (PSD) estimate. To compute the power contained in a frequency range, the PSD should be integrated over the required frequency range.