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Jitter is often measured as a fraction of UI. For example, jitter of 0.01 UI is jitter that moves a signal edge by 1% of the UI duration. The widespread use of UI in jitter measurements comes from the need to apply the same requirements or results to cases of different symbol rates. This can be d
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]
This of course means that the clock skew between two points varies from cycle to cycle, which is a complexity that is rarely mentioned. Many other authors use the term clock skew only for the spatial variation of clock times, and use the term clock jitter to represent the rest of the total clock timing uncertainty. This of course means that the ...
It is used to specify clock stability requirements in telecommunications standards. [1] MTIE measurements can be used to detect clock instability that can cause data loss on a communications channel. [ 2 ]
Instantaneous packet delay variation is the difference between successive packets—here RFC 3393 does specify the selection criteria—and this is usually what is loosely termed "jitter", although jitter is also sometimes the term used for the variance of the packet delay. As an example, say packets are transmitted every 20 ms.
For example, a 10 MHz clock has a resolution of 100 ns. To get resolution finer than a clock period, there are time interpolation circuits. [6] These circuits measure the fraction of a clock period: that is, the time between a clock event and the event being measured.
Clock recovery is very closely related to the problem of carrier recovery, which is the process of re-creating a phase-locked version of the carrier when a suppressed carrier modulation scheme is used. These problems were first addressed in a 1956 paper, which introduced a clock-recovery method now known as the Costas loop. [3]
Clock synchronization is a topic in computer science and engineering that aims to coordinate otherwise independent clocks. Even when initially set accurately, real clocks will differ after some amount of time due to clock drift , caused by clocks counting time at slightly different rates.