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In signal processing, phase noise is the frequency-domain representation of random fluctuations in the phase of a waveform, corresponding to time-domain deviations from perfect periodicity . Generally speaking, radio-frequency engineers speak of the phase noise of an oscillator, whereas digital-system engineers work with the jitter of a clock.
Thus, noise at f 1 is correlated with f 2 if f 2 = f 1 + kf o, where k is an integer, and not otherwise. However, the phase produced by oscillators that exhibit phase noise is not stable. And while the noise produced by oscillators is correlated across frequency, the correlation is not a set of equally spaced impulses as it is with driven systems.
Oscillator phase noise, random fluctuations of the phase of an oscillator; Barkhausen effect or Barkhausen noise, in the strength of a ferromagnet; Spectral splatter or switch noise, caused by on/off transmitter switching; Ground noise, appearing at the ground terminal of audio equipment; Synaptic noise, observed in neuroscience
The group delay and phase delay properties of a linear time-invariant (LTI) system are functions of frequency, giving the time from when a frequency component of a time varying physical quantity—for example a voltage signal—appears at the LTI system input, to the time when a copy of that same frequency component—perhaps of a different physical phenomenon—appears at the LTI system output.
The more phase noise the oscillator exhibits, the wider the bandwidth of each harmonic. Phase noise is a noise in the phase of the signal. Consider the following noise free signal: v(t) = Acos(2πf 0 t). Phase noise is added to this signal by adding a stochastic process represented by φ to the signal as follows: v(t) = Acos(2πf 0 t + φ(t)).
One definition of signal-to-noise ratio is the ratio of the power of a signal (meaningful input) ... circuits, where voltage and current are in phase, ...
Different types of noise are generated by different devices and different processes. Thermal noise is unavoidable at non-zero temperature (see fluctuation-dissipation theorem), while other types depend mostly on device type (such as shot noise, [1] [3] which needs a steep potential barrier) or manufacturing quality and semiconductor defects, such as conductance fluctuations, including 1/f noise.
A signal sent by an ideal transmitter or received by a receiver would have all constellation points precisely at the ideal locations, however various imperfections in the implementation (such as carrier leakage, low image rejection ratio, phase noise etc.) cause the actual constellation points to deviate from the ideal locations. Informally ...