Jitter

In electronics and telecommunications, jitter is the deviation from true periodicity of a presumably periodic signal, often in relation to a reference clock signal; in clock recovery applications it is called timing jitter. It is a significant, usually undesired factor in the design of almost all communications links, and may be caused by electromagnetic interference and crosstalk with carriers of other signals. It can make a display monitor flicker, affect the performance of processors in personal computers, add clicks to audio signals and cause loss of transmitted data between network devices. Jitter can be quantified as root mean square or peak to peak displacement, and the unit interval expresses it as a fraction of the transmission unit period. Random jitter is unpredictable timing noise that typically follows a normal distribution, while deterministic jitter is predictable, reproducible and bounded. In computer networking the term can also refer to packet delay variation.