are long-term random variations of the significant instants of a digital signal
from their ideal positions. Phase variations with a frequency content above 10 Hz
are considered jitter
, while those with a frequency
below 10 Hz are referred to as wander.
Wander variations are those that occur over a period
greater than 1 s (second). Jitter
, swim, wander, and drift
have increasing periods
of variation in that order.