安恒公司电缆标准为设计人员、施工人员和客户带来了信心安恒新闻中心

Bob Jensen，福禄克网络公司的标准发展与技术经理，同时兼任电缆工业协会（TIA）住宅电缆标准主席，对 TIA 570B 标准做出了展望。

TIA 570B 标准将为住宅电缆和网络定义技术标准，因此所有涉及施工的参与者，包括设计人员、集成商、施工人员、建筑人员以及消费者对于电缆施工将会更具信心。Jensen 谈到 TIA 570B 电缆标准将可以确保用户得到他们所期望的，整个网络系统也将会按照他们所预期的运行。

Raising The Bar

Fluke Networks' integral role in TIA 570B

By Mike Llewellyn

For Bob Jensen of Fluke Networks, the custom installation business is all about making sure customers get exactly what they've paid for. To that end, he says Fluke Networks, a member of the Telecommunications Industry Association (where Jensen is chair of the Residential Cabling Standard), has been hard at work with its fellow TIA affiliates hammering out a network testing standard. The product of their labors, to be known as TIA 570B, will be available in the coming months. TIA 570B will define technical standards for residential cabling and networks that all points of the custom install business can feel confident in, including designers, integrators, installers, builders and, last but not least, consumers.

"This is not just a certification, this introduces various methods of testing a full system," says Jensen. "What we need to do is make sure that the customer is getting what they've asked for and that the whole system is really going to perform for them. There's a lot of information within this standard on designing out a system, what kind of cabling you need to put in the various areas of a home or a multi-dwelling units, whether that is copper twisted or fiber, etc."

Although the standard is, of course, designed as an aid to the customer, Jensen says 570B serves especially well as a guide for installers. "It talks about installation requirements, keeping the twists of the pairs up to a certain point," reports Jensen. "That's where we find [that] a lot of problems happen, where people either missed on a connection when they punch it down or they've used the wrong tool. Also, that they may not be keeping the twists all the way up to the connection point."

Testing One, Two, Three

Jensen says one of the key points of the standard is the inclusion of field test requirements and for the field test requirements. "We go all the way from a visual examination of the cabling, checking for kinks and knots, making sure you're keeping correct separations from the electrical wiring because that can play havoc with your cabling system. Then we go to the next stage, which is called verification testing," he explains.

Verification testing happens when the sheet rock is still down off the walls, when installers still have a chance to terminate cable. "At that point they can actually test the cable to make sure that they have full continuity, and if they have full continuity they're in pretty good shape," says Jensen. "But what we also want to do is make sure that the cabling is going to work after the sheet rock is put up, because in many cases you'll find that a nail can go through a cable and cause a short."

After the sheet rock is up, the standard calls for installers to use a wire mapper to verify continuity once again. "Fluke Networks offers something called the MicroScanner Pro," notes Jensen, "and we also came out just recently with the Intellitone 200, which is a toner and probe that does this digitally."

According to Jensen, these are not necessarily eventualities that installers always test for. "What we've been finding is that in many cases, installers do something we call 'wire and walk,' which is where they just wire it up and walk away," he says. "One of the goals of this standard has been to try to see if we can get both manufacturers and field installers to start verifying that they actually have good cables once they're placed inside the wall, and what we're envisioning is that it's going to help them out in the long run, because they won't have to go back an do a truck rollback if there's a problem. They can actually pull out records and say 'This was tested on such and such a date and everything was good.'"

Jensen expects that installers may even be able to earn extra money using the standard. If a customer calls an installer complaining of faulty wiring, Jensen says the installer can take advantage of the documentation the standard offers. "So if someone calls up and says their cabling is bad, [installers] can look at the records and say 'No, it's really good. We tested it at such and such a date, and if we come out there to take a look at this, we're going to have to charge you time and materials.' So it can actually help out their businesses in a big regard."

The central goal of the standard is simply to make sure cabling is installed properly. "So after the cabling is installed in the building or in the home, after they go and put up the sheet rock, and do all the insulating and so forth, we go back again at the finish stage, because you can even occasionally change performance characteristics just by moving some of the connectors around," says Jensen.

Once installers are at the finish stage, they are called upon to test the system in one of two ways, through qualification or characterization. The simpler of the two, qualification, is a test of the cable to make sure it can handle the type of network that's expected to run across it. The preferred test, however, is a characterization of the system.

"A characterization is a full certification of the cable," says Jensen. "The difference between the two is that a full certification of the cable requires testing it to the parameters of things like attenuation, its near-end cross-talk, its far-end cross-talk, etc. There are so many different parameters that get tested out even to 250 MHz. And you have to take a look at the full sweep of the frequencies."

The drawback to a system characterization is that "a full certification of cable gets to be a bit expensive, and the testers are quite expensive as well," admits Jensen.

570B: The Making Of

Jensen says Fluke Networks is in a great position to be one of the key supporters of the standard because of the company's presence and reputation in the industry (other supporters include Leviton, Genesis Cable, Grayfox and GE Interlogix). "Fluke Networks has always been interested in ensuring the quality of the cabling installed in a building," he says. "And we see very big benefits for both manufacturers and installers because it's going to bring them more business. Adhering to the standard is time well spent on the job because, while testing may run two hours of time to ensure a system is working properly, you can make sure the builder is asking you back to do more work for them."

"The first standard for residential cabling, as I recall, was back in 1991, and it looked at telephony and data

networking within a home. They were concentrating on ISDN more than anything else at that point in time," explains Jensen. "But networks have progressed significantly, as you've seen modems coming out with the DSL services and more people employing Ethernet-type services within their homes. So in 1999, we produced the second edition of that standard, which was 570A. When that came out, again it focused a lot on data networks and video systems. But it was still voice, data and video-centric."

An expansion of the field of coverage was called for. "We now want to take a look at systems of whole-home audio, control systems and security systems. So what we have now is a standard that has a bunch of addendums to it that are going to take care of a whole residence as well as multi-tenant facilities," Jensen explains, noting that the standard is also due to be updated and revised every five years.

A new standard to cover a entire home or building has been a long time coming, and Jensen says he's eager to see 570B released. He says, "We're getting into a well-rounded standard that installers can actually pick up and use, as well as for designers and builders out there."