far end crosstalk (wiring) (FEXT)
The long-distance cross-talk attenuation refers to the end of the line, at the receiver end of the transmission path. The signal fed into a line is reduced by the cable attenuation at the line end.
The crosstalk of this signal on another line is called Far End Crosstalk (FEXT). Since the cable attenuation dampens the interference level, this is lower at the end of the cable. The FEXT value is therefore length-dependent.
For the far-end crosstalk attenuation (FEXT), a distinction is made between the input/output FEXT, I/OFEXT, and the equal level FEXT, Equal Level Far End Crosstalk ( ELFEXT). These two FXTEXT values are related to each other via the attenuation: ELFEXT = I/O-FEXT - Attenuation.