Editing Absolute phase (section)

==Signal processing==

In [[signal processing]] a [[pulse (signal processing)|pulse]] or finite wavetrain can be considered as a signal of a single frequency modulated by an envelope, or as a superposition of an infinite number of infinitesimal waves of different frequencies.{{citation needed|date=March 2021}} In the first case, one may speak of the phase of the wave with respect to the envelope as the absolute phase. In the second picture, it is a question of the relative phase of the component frequencies. For examples of physical effects due to the phase of signals with the same power spectrum.<ref>{{cite journal |vauthors=Paulus GG, Grasbon F, Walther H |title=Absolute-phase phenomena in photoionization with few-cycle laser pulses |journal=Nature |volume=414 |issue=6860 |pages=182–4 |date=November 2001 |pmid=11700551 |doi=10.1038/35102520 |display-authors=etal|bibcode=2001Natur.414..182P |s2cid=4414801 }}</ref>