One of the most important cable measurements is Near-End Crosstalk (NEXT). It’s signal interference from one pair that adversely affects another pair on the same end. Crosstalk occurs between adjacent wire pairs (“pair-to-pair NEXT”). In addition, all other pairs in a UTP cable can also contribute their own levels of both NEXT and Far-End Crosstalk (FEXT), multiplying the adverse effects of interference onto a transmitting or receiving wire pair. These compounded levels of interference can prove crippling. So check your NEXT ratings on any CAT5e and CAT6 cable you purchase.
NEXT measures an unwanted signal transmitted from one pair to another on the near end.
PS-NEXT measures the unwanted signals from multiple pairs at the near end onto another pair at the near end.
FEXT measures an unwanted signal from a pair transmitting on the near end onto a pair at the far end. Full-duplex operation is taken into account where signals are generated simultaneously on both ends.
PS-ELFEXT measures the total sum of all interference from pairs on the far end onto a pair on the near end without the effects of attenuation.