PSNEXT

Power Sum Near End Cross Talk, or PSNEXT, is the algebraic sum of near end crosstalk (NEXT) of three wire pairs as they affect the fourth pair in a four-pair cable (e.g. Category 6 cable). The specification was developed to directly address the effect of transmissions on multiple adjacent pairs on the pair being tested and is relevant to all connecting hardware and associated communications cables. ^{[cite web |url=http://www.superiormod.com/smp/pages/support/White%20Paper%20-%20RJ21X.pdf |title=Component Level PowerSum Compliance and RJ21X Connectivity Solutions (Superior Modular Products White paper)|accessdate=2008-09-13 |format=PDF |work= ]}

Cabling bandwidths in excess of 100MHz (Category 5 cable bandwidth) make consideration of PSNEXT more important. Gigabit Ethernet through Cat-6 uses all four wire pairs simultaneously and bidirectionally. The additional wire pair usage and growing bandwidth increase the need to keep NEXT in check.

PSNEXT is a way of measuring NEXT in the ends of cables due to their close proximity. The (cited) SMP white paper states that the testing process for PSNEXT consists of measuring all pair-to-pair crosstalk combinations and then summing all of the values for each pair.

References