Cool Tools: Certification Testers
Published: October 2008
Monitoring developments of tools used by electricians shows that many basic tools evolve as new features are added to existing products; new materials are used in their construction that make them more durable and lighter in weight; and changes in designs make them more functional, productive and easier to use.
Of course, from time to time, completely new tools are introduced or an improvement comes along that totally changes the capabilities of an entire category of tool product. The introduction of lithium-ion batteries for cordless power tools is a recent example.
A notable exception to the gradual-change-by-evolution theory is testing equipment for certification of voice/data/video (VDV) installations. These essential instruments seem to change almost as fast as computers hardware and software.
Certification tester capabilities are driven by changing technologies, and manufacturers are challenged to have appropriate testing equipment ready when new standards are implemented.
Ten gigabit Ethernet
The most recent development to influence certification testers is the new Category 6a cabling standard that defines requirements to support 10 gigabit (10G) Ethernet over twisted-pair cabling. (Ten gigabit Ethernet is sometimes referred to as 10 gigabits per second or 10 Gbps.)
“Ten gigabit Ethernet has indeed arrived, and cabling installers can ride the 10 Gbps Ethernet wave if they have the capability to test per the standard,” said David Veneski, marketing manager for certification products, Fluke Networks.
The operative standard is Amendment 10 of the Telecommunications Industry Association/EIA-568-B.2 standard (T568-B-10), Veneski said. The standard documents how to run 10G Ethernet on up to 100 meters of twisted-pair Category 6a cabling. T568-B-10 defines performance standards for deployment and testing of augmented Category 6 cabling.
According to Veneski, T568-B-10 means a test tool must be able to measure all required parameters over the frequency range of 1 megahertz (MHz) through 500 MHz, which is beyond the range of some certification tools.
“All links must be certified, and the new certification process renames some old measurement parameters and adds some new ones. Permanent link testing is not just an option. It is necessary for 10 Gbps applications, and must be performed with a permanent link adapter with reference test plugs as defined in the new standard. A portion of installed links must be tested for alien crosstalk, a new phenomenon assaulted with 10 Gbps Ethernet where a signal in one cable interferes with an adjacent cable,” Veneski said.
Dan Payerle, Ideal Industries senior product manager for datacom testing, said, because 10G Ethernet cabling must be certified to 500 MHz, installers need new Cat 6a-capable certifiers or to upgrade their existing units to make them Cat 6a compatible. There also are new accuracy requirements for Cat 6a certifiers.
“Previously, the accuracy levels were Level IIe (Cat 5e/ISO D @ 100 MHz), Level III (Cat 6/ISO E @ 250 MHz), Level IV (Cat 7/ISO F @ 600 MHz). Now there is a definition for Level IIIe (Cat 6a/ISO FA, 500 MHz),” Payerle said. “Some vendors already had Category 6 (250 MHz) and Category 7 (600 MHz+) capable certifiers, but Ideal launched a specific model, the LANTEK 6A, for Category 6a that runs at 500 MHz and is priced squarely between the Cat 6 and Cat 7 models.”
Payerle said T568-B-10 was significantly delayed because of heated debate over the issue of alien crosstalk (AXT) testing.
“Some groups wanted it to be a requirement of Cat 6a certification and others wanted to leave it as an option. In the end, it is an optional test that can be done at the discretion of the parties involved,” he said.
However, Payerle said, many manufacturers developed alien crosstalk solutions for their certifiers in advance of the standard, before knowing what the final requirements would be.
“These kits give the basic cable certifier the ability to test PSANEXT (power sum alien crosstalk) and PSAACR-F (power sum attenuation to alien crosstalk ratio—far end).
“On UTP [unshielded-twisted pair] cabling systems, many considerations need to be factored when deciding whether field testing of AXT is necessary. To date, no manufacturers are requiring AXT testing for warranty approvals of their Cat 6a systems, and it is usually done at the request of the end-user who wants to make sure that it will not be an issue down the road,” Payerle said.
Shielding and AXT
Payerle said many perceive that shielding eliminates the need for AXT because it is effective for the frequencies involved.
“In the U.S., we are seeing more manufacturers offer shielded cabling systems than ever before, and there are many inquiries from installers and end-users about the issue of shielded versus unshielded when they are considering Category 6a,” Veneski said.
Veneski believes shielded cable is a largely misunderstood topic.
“Shielded cable can offer greater immunity to interference and reduce alien crosstalk,” he said. “But there is no guarantee that shielded cable will offer better performance. It depends on connection techniques and the degree of care used during installation. Shielded cable comes in several forms. There can be a shield that surrounds all four-wire pairs. There can be individual shields around each wire pair. There may also be a combination of the two where each pair has a shield surrounded by a larger shield around all four pairs.”
Veneski said if an incorrectly grounded shield is installed, it can cause more problems than it solves.
“Whether dealing with the more familiar unshielded-twisted pair or one of the variants of shielded cable, a final certification test is still the way to tell if the link will perform as expected,” he said. “If shielded cable is used for 10 Gbps links, the send test for alien crosstalk is also required.”
Testing mixed fiber systems
Payerle estimated the ratio of copper to fiber in mixed systems hasn’t changed significantly, but believes 10G could change that.
“Fiber requirements for 10 Gbps are not much different than those for 100 Mbps or 1 Gbps Ethernet, so it is very possible that fiber may start to see a cost advantage when 10 Gbps is considered,” he said. “Of course the cost of the active equipment is the biggest factor in the copper versus fiber decisions, so in the end, it may come down to the equipment manufacturers. With Category 6a required for 10 Gbps applications and its inherent costs in terms of materials and installation time, 10 Gbps may be the application that starts to initiate change.”
Veneski said Fluke Networks sees the use of optical fiber as definitely on the rise, particularly in long-haul, campus and vertical cabling environments. Fiber to the desktop and fiber’s use in residential settings is still rare.
“For electrical contractors, there is a growing opportunity in commercial installations that use a mix of both cable types,” he said. “Fiber optic cabling is seeing increased use in data centers and connections between buildings in business parks and similar sites. The final connections to desktop PCs and retail terminals are almost always copper. An installer equipped to test and certify both is in a very strong position.”
Veneski added that some electrical contractors have been reluctant to move into fiber installation because of the cost and complexity of optical time domain reflectometers (OTDRs). Newer test tools have gotten around these obstacles by making the OTDR look and behave like the more familiar copper certification test tools.
“Last year, Fluke Networks introduced a compact OTDR module for the DTX CableAnalyzer, which snaps into the back of an existing DTX certification tool,” he said. “For the installer, this offers three immediate advantages. First, the investment in tools already purchased is leveraged into a new use model. Second, installers familiar with copper test tools will be able to transfer that knowledge to fiber testing. Third, the contractor can bid on new business for a small portion of what it would have cost to buy stand-alone test equipment.”
Power over Ethernet
The Institute of Electrical and Electronics Engineers (IEEE) 802.11n is a new, still-unfinished IEEE standard for wireless local area networks (LANs), Veneski said. It is backward-compatible with 802.11b and 802.11g, but it includes many advances in radio frequency (RF) technology and protocols.
The two biggest features of 802.11n are its ability to support bit rates in excess of 100 Mbps and cover its ability to cover more area with RF signal, Veneski said. These features will make wireless LANs more popular for primary workstation connectivity and for leading-edge applications, such as voice over wireless LAN (VoWLAN). The IEEE standard in process specifies speeds as high as 600 Mbps, although the maximum bit rate in the foreseeable future will be 100 Mbps and 200 Mbps. Even at these lesser speeds, it is possible for the maximum total traffic on the wired portion of the network to be approximately 400 Mbps.
For installers, this means the wired portion of a network supporting 802.11n will need to be certified to 1 gigabit Ethernet.
“Many 802.11n access points are also designed to take advantage of power over Ethernet [POE], and at higher wattages than currently seen today,” Veneski said. “This creates a new challenge for installers, who must perform a thorough wiremap test to be certain the installation conforms to TIA standards. Some PoE manufacturers are designing unique cable and pin-out configurations. Without a thorough wiremap test to ensure compliance with each vendor’s design, the ability to safely power up the access point is uncertain, and in many cases the wiremap test must be made with the power turned on.”
Veneski said Fluke Networks’ DTX CableAnalyzer has an AC wiremap test that can accurately perform wiremap tests even on a link with an active (power-on) PoE supply.
GRIFFIN, a construction and tools writer from Oklahoma City, can be reached at 405.748.5256 or firstname.lastname@example.org.