Abrupt and unwanted variations of one or more signal characteristics, such as the interval between successive pulses, the amplitude of successive cycles, or the frequency or phase of successive cycles. Note 1: Jitter must be specified in qualitative terms (e.g., amplitude, phase, pulse width or pulse position) and in quantitative terms (e.g., average, RMS, or peak-to-peak. ) Note 2: The low-frequency cutoff for jitter is usually specified at 1 Hz. 2. Random variability of data pass-through time. See timing jitter.