The fefinition of phase noise
I am tatally confused by the definition of Phase noise.
I have seen a lot of different TERM for phase noise definition
1) Phase Noise
2) Spectral Density
3) Power Spectral Density
4) Spectrum
5) Single side band power spectral density
6) Auto-correlation function
It seems that they all different but related! Who has very clear reference on that? Very appreciate if any can share your understanding and reference!
Thanks!
Raymond
Phase noise is the ratio in dB between the noise level at X KHz from carrier to the total signal power.
A simple way to measure is by a spectrum analyzer. The signallooks like a skirt. Then the difference in dB between the peak to the skirt noise level at let say 100KHz is the phase moise.
The term phase noise come becouse most of the noise is created by phase noise in the active device. But there are other noise sources.
The noise in the frequency domain is power/Hz means spectral density.
Spectrum is relted to other signals in the spectrum such as harmonics etc.
Single side band power spectral density - The oscillator signal has two side skirt. So one can add the two side noise at let say 100KHz or can take only one side.
Auto-correlation function - Ergodic Stockastic process has auto correlation function- it tells how fast the signal (consists of determenistic signal and ergodic) in time is chnges. How fast the delayed signal nor correlated with the original one.
D.J