Far end crosstalk

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Far End Crosstalk (FEXT) is an electromagnetic interference (EMI), a type of crosstalk, introduced on UTP by close-by wires, usually running in parallel with the FEXT induced wire.

"Far End" refers to the inductance[clarify] of EMI in the end further from the end being measured on the alternate wire[clarify] in a pair.

In opposition to this, NEXT (Near End Cross Talk) is the detection of EMI on a wire whose inductance is at the same end as the measurement point[clarify]. Obviously NEXT is stronger at the other end due to attenuation[clarify] of the crosstalk signal.

Crosstalk is generally computed as the ratio in voltage between a "test signal" and the induced crosstalk signal in an alternate wire.

Professional computer network cabling must pass TIA/EIA (Telecommunications Industry Association/Electronic Industries Alliance) standards tests, generally TIA/EIA-568-B standard[clarify].