In cabling technology, crosstalk and cross-talk increase sharply with rising frequencies. This is particularly evident in data cables oflink classes D, E and F, which are used in Gigabit Ethernet and 10 Gigabit Ethernet. One of these crosstalks is alien crosstalk (AXT).
Alien crosstalk occurs between two signal-carrying data cables that are laid close together over a long distance. In this case, part of the energy fed into the data cable is emitted into other data cables via electromagnetic fields, which influence the signals there. Alien crosstalk occurs primarily between directly adjacent data cables and in connectors and, because it is a product of different signals, it is noticeable as electromagnetic noise.
Alien crosstalk can only be reduced by mechanical means. Bundling and parallel routing of data cables play a role here and should be avoided, but alien crosstalk can also be reduced by cable construction, the distance between data cables and shielding. Depending on whether the extraneous crosstalk relates to the near or far end of the cable, the terms Alien- NEXT and Alien- FEXT are used. The limit values of these two parameters are specified in the cabling standards.