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What's in a certification? Network managers and technicians are always anxious to make sure their cabling plant is certified for Category 5 (or Category 3, or some other cable type). Until now, there have been no standards for certifying the transmission performance of the installed information channel. Existing specifications for transmission performance of UTP cabling systems apply only to the components of the cabling system such as cable and connectors.
Behind The Categories In the early 1990s, the Telecommunications Industry Association/Electronic Industry Association (TIA/EIA) introduced the concept of categorizing cable and connectors according to the transmission performance at different spectral bandwidths. Telecommunications System Bulletin (TSB) 36, 40 and 40A provided the transmission performance requirements for cables and connectors for Category 3 (for performance up to a spectral bandwidth of 16 MHz), Category 4 (for performance up to 20 MHz) and Category 5 (for performance up to 100 MHz). The TSB specifications provided for the cables and connectors only as components of a transmission channel and not as specifications for the channel itself.
A prelude to TIA/EIA 568A, Standards Proposal 2840 (SP2840) was introduced as an Informative Annex and contained mathematically derived specifications for Near End Crosstalk (NEXT) and attenuation for an installed channel of a given configuration. This annex specifically declared that the numbers derived were not to be used as a specification for certifying a channel.
Pressured by the market, instrument vendors adopted Annex E of SP2840 as a threshold specification for pass/fail testing of Category 5 despite the absence of a standard. Due to mass confusion in the user community over so-called Category 5 certifications, the TIA/EIA published a fact sheet in March 1994 that admonished the test set vendors for misleading users and unequivocally spelled out that a standard for the transmission path's performance did not exist, and furthermore, that the accuracy of the test sets were suspect.
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