Definitions
Historically there have been two conflicting yet widely used definitions for phase noise. The definition used by some authors defines phase noise to be the power spectral density (PSD) of a signal's phase, while the other definition is based on the PSD of the signal itself. Both definitions yield the same result at offset frequencies well removed from the carrier. At close-in offsets however, the two definitions differ.
The IEEE defines phase noise as where the "phase instability" Sφ(f) is the one-sided spectral density of a signal's phase deviation. Although Sφ(f) is a one-sided function, it represents "the double-sideband spectral density of phase fluctuation". The phase noise expression ℒ(f) is pronounced "script ell of f".
Read more about this topic: Phase Noise
Famous quotes containing the word definitions:
“The loosening, for some people, of rigid role definitions for men and women has shown that dads can be great at calming babies—if they take the time and make the effort to learn how. It’s that time and effort that not only teaches the dad how to calm the babies, but also turns him into a parent, just as the time and effort the mother puts into the babies turns her into a parent.”
—Pamela Patrick Novotny (20th century)
“What I do not like about our definitions of genius is that there is in them nothing of the day of judgment, nothing of resounding through eternity and nothing of the footsteps of the Almighty.”
—G.C. (Georg Christoph)