PSNEXT
Encyclopedia
Power-sum near-end cross talk (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.
Cabling bandwidths in excess of 100 MHz (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.
Category 6 cable
Category 6 cable, commonly referred to as Cat 6, is a cable standard for Gigabit Ethernet and other network physical layers that is backward compatible with the Category 5/5e and Category 3 cable standards. Compared with Cat 5 and Cat 5e, Cat 6 features more stringent specifications for crosstalk...
). 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.
Cabling bandwidths in excess of 100 MHz (Category 5 cable
Category 5 cable
Category 5 cable is a twisted pair cable for carrying signals. This type of cable is used in structured cabling for computer networks such as Ethernet. It is also used to carry other signals such as telephony and video. The cable is commonly connected using punch down blocks and modular connectors...
bandwidth) make consideration of PSNEXT more important. Gigabit Ethernet
Gigabit Ethernet
Gigabit Ethernet is a term describing various technologies for transmitting Ethernet frames at a rate of a gigabit per second , as defined by the IEEE 802.3-2008 standard. It came into use beginning in 1999, gradually supplanting Fast Ethernet in wired local networks where it performed...
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
Crosstalk (electronics)
In electronics, crosstalk is any phenomenon by which a signal transmitted on one circuit or channel of a transmission system creates an undesired effect in another circuit or channel...
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.