Crosstalk - Network Encyclopedia
What is Crosstalk?
Crosstalk is a form of interference in which signals in one cable induce electromagnetic interference (EMI) in an adjacent cable. The twisting in twisted-pair cabling reduces the amount of crosstalk that occurs, and crosstalk can be further reduced by shielding cables or physically separating them. Crosstalk is a feature of copper cables only – fiber-optic cables do not experience crosstalk.
Near-end crosstalk (NEXT)
The ability of a cable to reject crosstalk in Ethernet networks is usually measured using a scale called near-end crosstalk (NEXT). NEXT is expressed in decibels (dB), and the higher the NEXT rating of a cable, the greater its ability to reject crosstalk.
Far-end crosstalk (FEXT)
FEXT measures the interference between two pairs of a cable measured at the far end of the cable with respect to the interfering transmitter.