Are You a Data Commander?
by Steve Lampen
Today’s headline recalls Commander Data, the
android on the TV series "Star Trek: The Next Generation."
I recently toured Paramount Studios and saw workers
building the sets for the coming Star Trek movie "Nemesis."
I also had a chance to see some of the sets for the "Enterprise"
TV series.
Why was lowly Lampen invited? Because almost every
scene on the ship has video monitors in the background. In the past,
where they could have maybe one or two active monitors and the rest
were back-lit transparencies, now viewers want to see things moving
on all the screens.
Some sets have more than 30 live screens. This means
there’s more than a few feet of cable running everything. They
wanted some opinions from this cable guy on the best way to do all
this. And this got me to thinking about the world you live
in.
Data details
I’ve discussed Category 5 data cables, especially
when used to run audio or other non-data signals. I’ve only
talked in passing about using them as data cables, which is what
they’re designed to do. After all, this column is Wired
for Sound, not Wired for Data.
But the difference between those two titles is getting
pretty fuzzy. A lot of sound is running as data. Some is running
as AES digital audio, which is more "digital" that it
is "audio." Other audio systems are using data formats,
such as Ethernet, a trademark of Xerox Corp., to run multichannel
audio, such as Peak Audio’s Cobranet. Or they’re running
digital on fiber optic cable, such as Klotz’s new Vadis system.
I would bet it’s pretty hard to walk into any
broadcast facility, including many small radio stations, without
seeing a bunch of computer monitors piled on top of that old audio
console. Hard-drive, server-based systems, especially those replacing
music and spots, are getting cheaper and cheaper. Of course, these
are computers that just happen to run audio.
So more than a few of your installations look surprisingly
like those Star Trek sets, with a pile of computers, monitors, hard
drivers, servers, keyboards and lots of other control devices. The
difference, of course, is that the Star Trek stuff is a set, designed
to fool you into believing it’s actually working. Yours, on
the other hand, had better work. Your station depends on
it.
So it’s about time we talked in detail about
data. If you are the data commander for your station, you probably
have installed Cat-5 or 5e, or maybe even the new Category 6. In
this and future columns, we’ll look at these and the data applications
that run on them.
Of course, there was life before Category 5. There
was a 4 and a 3. Even a 2, 1 and a 0.
Category 3 is still around, and for good reason. Last
July, an FCC law went into effect. All telephone wiring, even into
homes, must now be a minimum of Category 3. The reason is obvious:
what’s running down these cables often is a whole lot more
than telephone calls.
Basic Internet access, 56K, ISDN, DSL, XDSL, even
T1 now are common on these cables. These can run into the megahertz
in bandwidth, a lot more than the 3500 Hz of a phone call. So the
emission of signals off of old phone cables can be substantial.
Category 3 was the first attempt to build a data cable
out of a telephone cable. Once Cat-3 was in use, earlier cable designs
were specified as Category 2, 1 or 0, also called POTS ("plain
old telephone service") lines.
Don’t go looking for Cat-2 or lower standards.
Most are no longer even recognized, at least as "data"
carriers. Category 3 has a bandwidth of 16 MHz.
Then came Cat-4 and, soon after, Cat-5. Category 4
has a bandwidth of 20 MHz. Cat-5 is 100 MHz.
So it should be no surprise that TIA/EIA, which sets
the standards for data cables, has eliminated Category 4. And the
price differential between Cat-3 and Cat-5 is getting slim enough
that many installs are now using Cat-5 for running not only computers
but phone lines as well.
Crazy? Like a fox! Putting in an all-Cat 5 install
means it doesn’t matter which line is the phone and which the
computer.
Want to change your office to a different view? If
it’s all Category 5, no problem. If you put in Category 3 for
the phone, that’s pretty much all it will ever be.
Putting in all Cat-5 means that you can upgrade your
external data delivery with little or no problems. Unless you want
to put in something better, like Cat-5e.
Here’s a little riddle that only data "experts"
would understand: When is Enhanced Category 5 not enhanced?
A little recent history will explain. Back in the
distant past, when Cat-5 was first ratified, some manufacturers
thought they could do better. They started to bring out cables that
were tested to way more than 100 MHz, some to 350 MHz.
Other manufacturers decided they were going to get
on the bandwagon. They also brought out 350 MHz cables, or even
400 MHz – at least, they said their cables worked to these
high frequencies. The serious ones actually gave data on attenuation,
crosstalk and other parameters out to these frequencies. These cables
commonly were called Enhanced Category 5 cables.
Cat-5e
When the TIA/EIA agreed on the standard for an enhanced
cable, it was ratified as Category 5e. That means the Enhanced cables,
and you will note I use a capital E, may or may not be Category
5e, because they predated the specification. The earlier Enhanced
cables simply meant "better than Category 5."
So if you want Category 5e, you’d better ask
for Category 5e.
What exactly is Category 5e, and how is it different
from Cat-5 and the coming Cat-6? We’ll get to that next time,
Data Commanders!
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