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For example, UI is used to measure timing jitter in serial communications or in on-chip clock distributions. This measurement unit is extensively used in jitter literature. Examples can be found in various ITU-T Recommendations, [1] or in the tutorial from Ransom Stephens. [2]
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]
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.
PPS signals are used for precise timekeeping and time measurement. One increasingly common use is in computer timekeeping, including NTP.Because GPS is considered a stratum-0 source, a common use for the PPS signal is to connect it to a PC using a low-latency, low-jitter wire connection and allow a program to synchronize to it.
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 ]
If the clock arrival times at individual registers are viewed as variables to be adjusted in order to minimize the clock period while satisfying the setup and hold inequalities for all of the paths through the circuit, then the result is a Linear Programming problem. [3] In this linear program, zero clock skew is merely a feasible point - the ...
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.