Signal Processing Stack Exchange is a question and answer site for practitioners of the art and science of signal, image and video processing. It only takes a minute to sign up.
Sign up to join this community
In the context of signal averaging to reduce uncorrelated noise:
Is it possible to perform signal averaging from just the magnitude spectrum of certain signals? Or that would only work if we know also the phase information of those signals. In that case, what would be the requirement for the signals to average, regarding phase information? I guess they both have to be somehow "related" to the same "starting point".
The short and most common answer is that you can average without phase but there are cases where you can average phase as well.
Cross correlation between two signals where one has a delayed component of the other that is of a "long" duration can exploit complex averaging.
Spectral analysis using the periodogram averages magnitude or magnitude squared.
There are numerous examples of where you do or don't use complex averaging. It depends on the problem being solved and is typically going to be relatively obvious if you should or shouldn't. If you expect the phase to evolve in a predictable way over your observations, you can use that to your advantage.
