Drift (telecommunication)

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In telecommunication, a drift is a comparatively long-term change in an attribute or value of a system or equipment operational parameter.

The drift should be characterized, such as "diurnal frequency drift" and "output level drift."

Drift is usually undesirable and unidirectional, but may be bidirectional, cyclic, or of such long-term duration and low excursion rate as to be negligible.

Source: from Federal Standard 1037C and from MIL-STD-188

Drift is also common in pseudo-synchronised streaming applications, such as low-latency audio streaming over TCP/IP. Normally both ends of a streaming connection would stay in-sync with a master clock, TCP/IP does not provide this 'master clock' mechanism. Therefore applications running fixed clocks will drift apart over time and glitches will occur. This is usually fixed by performing jitter or drift control by slightly altering the clock speed at one end of the connection.