Terry Cobb
Datacom Technologies
Enhanced-performance Category 5 cabling has become the most active project within the Telecommunications Industry Association`s (tia--Arlington, VA) TR-41 User Premises Telecommunications Equipment Committee. The Unshielded Twisted-pair (utp) Systems Task Group of TR-41.8.1 is chartered with writing an addendum for tia/eia-568a to specify additional parameters in support of new high-speed applications such as Gigabit Ethernet.
Historically, field verification has often been an afterthought in a standard. In a letter from the chairperson of the ieee 802.3 Ethernet standard committee, however, it was requested that field testing "be an integral part of a standard to require the prequalification of an installed link with a handheld tester."
At a recent interim meeting of the utp Systems Task Group, this addendum work was separated into two priorities. The first priority deals with the additional parameters of equal-level far-end crosstalk--the ratio of the attenuated signal on one pair to the crosstalk on an adjacent pair at the far end--and return loss, and with characterizing these for the installed base of cabling, along with defining their field tests.
What is now referred to as "enhanced Category 5 cabling" will be studied following this effort, and the group will address multidisturber cross-talk characteristics and cabling balance. The distinction between these two efforts is that the first will more accurately specify what has been installed under the existing tia/eia-568a standard, while the second will characterize the cabling improvements that are now available. However, debate still exists on how to identify enhanced Category 5 cabling. The completion of this addendum is scheduled to coincide with the adoption of the copper-cabling portion of the Gigabit Ethernet standard, which should be released in mid-1998.
In addition to these activities, the utp Connector Task Group of TR-41.8.1 is continuing its effort to define a test for patch cords. Significant progress has been made in understanding the effects of plug/jack interaction with the cord. The group has also proposed addressing the issue of testing zone cabling. Often, the initial cabling installation only routes cable to a consolidation point or a multiuser outlet. Today, no defined test or requirement to these intermediate points exists.
Meanwhile, the Fiber Optic Task Group has agreed to investigate a new fiber-optic connector that would be less complex than the duplex SC. It will research a connector that is comparable in size to an 8-pin modular plug.
The ratio of the attenuated signal on one pair to the crosstalk on an adjacent pair at the far end is called equal-level far-end crosstalk.
Terry Cobb is the president of Datacom Technologies (Everett, WA), a manufacturer of field-test equipment.