Theoretical: Why use trapz to calculate absolute power?

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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

回答(1 个)

Vinod Sudheesh
Vinod Sudheesh 2015-4-1
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.

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