Jitter

Jitter is the deviation from a true periodicity of a signal or timing of events. In electronics, telecommunications, and data networks, jitter describes variations in the arrival times of signal edges or in the spacing between sequential events. It is a measure of timing instability and can affect the reliability and quality of communication and processing systems.

There are several types of jitter. Clock jitter refers to phase or frequency variations in a clock signal used to time digital circuits. Data jitter describes irregularities in the timing of digital data transitions. In networks, jitter is the variation in packet arrival times, or inter-packet spacing, which can occur even when average latency is stable.

Jitter is typically quantified by statistics such as peak-to-peak deviation or root-mean-square deviation of timing, and in networks by the variation in latency between consecutive packets. In practice, small amounts of jitter are common and tolerable in many systems, while large or inconsistently timed jitter can cause errors, degraded audio or video quality, artifacts, and reduced system performance.

Causes of jitter include clock instability, variable propagation delays, queueing and processing delays in networks and devices, routing changes, wireless interference and multipath propagation, and contention for shared resources. Effects depend on the application: in digital communications, jitter can increase bit error rates and cause symbol misalignment; in streaming media, it can lead to buffering, stuttering, or dropped frames.

Mitigation strategies focus on smoothing and synchronization. Jitter buffers in streaming systems absorb timing variations, while clock recovery and distribution networks reduce clock jitter. Quality of Service controls, traffic shaping, and synchronization protocols such as NTP and PTP help manage network and timing jitter. Robust system design also aims to minimize processing delays and use stable oscillators.