Lexicon Jitter
(from the English: to jitter = to tremble). Temporal uncertainty in the arrival of events. See also Phase Noise. Particularly used in the transmission of digital signals, where the temporal events represent the signal edges of the transmitted signal.
Jitter, if it exceeds a certain level, can prevent correct detection of the received signal and lead to data errors. Therefore, for a given transmission system, an upper limit is set for the allowed jitter. This upper limit depends on the data rate and the modulation method used. The higher the data rate, the less jitter is allowed.
If a clock is also recovered from the transmitted digital signal, then the quality of this clock can be affected by the jitter. That is, the recovered clock may itself be subject to jitter. An important property of a clock recovery circuit is therefore its jitter suppression, that is, its ability to still produce a clean clock despite jitter in the received signal. This is particularly significant when a low-jitter clock is required, for example for A/D conversion or D/A conversion.
Jitter is often specified in terms of time, indicating by how much the event (e.g. the signal edge) may be too early or too late.
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