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J
Jitter
Distortion in transmission that occurs when a signal
drifts from its reference position. Jitter can be caused by variations in the timing or
the phase of the signal in an analog or digital transmission line. Jitter typically
results in a loss of data because of synchronization problems between the transmitting
stations, especially in high-speed transmissions.
Jitter is inherent in all forms of communication because
of the finite response time of electrical circuitry to the rise and fall of signal
voltages. An ideal digital signal would have instantaneous rises and falls in voltages and
would appear as a square wave on an oscilloscope. The actual output of a digital signaling
device has finite rise and fall times and appears rounded when displayed on the
oscilloscope, which can result in phase variation that causes loss of synchronization
between communicating devices. The goal in designing a transmission device is to ensure
that the jitter remains within a range that is too small to cause appreciable data loss.
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