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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.
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.
Jitter period is the interval between two times of maximum effect (or minimum effect) of a signal characteristic that varies regularly with time. Jitter frequency, the more commonly quoted figure, is its inverse. ITU-T G.810 classifies deviation lower frequencies below 10 Hz as wander and higher frequencies at or above 10 Hz as jitter. [2]
Reference clock jitter translates directly to the output, but this jitter is a smaller percentage of the output period (by the ratio above). Since the maximum output frequency is limited to f c l k / 2 {\displaystyle f_{clk}/2} , the output phase noise at close-in offsets is always at least 6 dB below the reference clock phase noise.
Jitter is the undesired deviation from true periodicity of an assumed periodic signal in electronics and telecommunications, often in relation to a reference clock source. Jitter may be observed in characteristics such as the frequency of successive pulses, the signal amplitude , or phase of periodic signals.
The phase of each transmit pulse is different from the previous and future transmit pulses. This phenomenon is called phase jitter. In order for MTI to work, the initial phase of both transmit pulses must be sampled and the 180 degree phase rotation must be adjusted to achieve signal cancellation on stationary objects.
The averaging method yields an autonomous dynamical system ˙ = (,,) =: ¯ which approximates the solution curves of ˙ inside a connected and compact region of the phase space and over time of /. Under the validity of this averaging technique, the asymptotic behavior of the original system is captured by the dynamical equation for y ...
A phase-locked loop or phase lock loop (PLL) is a control system that generates an output signal whose phase is fixed relative to the phase of an input signal. Keeping the input and output phase in lockstep also implies keeping the input and output frequencies the same, thus a phase-locked loop can also track an input frequency.