Any uses for cat3

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rexowner

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Location
San Jose, CA
Occupation
Electrician
Rampage_Rick said:
While it's true that you can get gigabit to work over CAT5e, the actual 1000Base-T spec is for 4 bidirectional 250MHz channels. CAT5e is only spec'd to 100MHz, though many manufacturers do go higher. Cables can be tested up to any frequency that is supported by the test equipment, but such measurements are meaningless without the context of applications and cabling standards. Bandwidth is defined as the highest frequency up to which positive power sum ACR (Attenuation to Crosstalk Ratio) is greater than zero. I have in my hand some cable that's marked "Draft 5e" and tested to 350MHz. Should be good for 1.4 gigabit, no?

No, because Hz (cycles/second) is not equal to baud (symbols per second). 1000BASE-T works fine on 100MHz
cable because more than one bit can be transmitted
in each cycle by using a PAM (Phase Amplitude Modulation) code.
 

wireguru

Senior Member
LV grider said:
FCC has a minimum standard for premise wiring which requires at least cat3. The old school quad with no twisted pairs is out, yet i still see some tract builders letting their alarm guys install the stuff

The Alarm guys are installing what is required for their application not the phone guys application.


when i posted that, i meant the builders are having their alarm guys run quad for the phones while theyre in there.
 

wireguru

Senior Member
mdshunk said:
I'd like to see what you call complex, then. :grin: You must work on some real Jim-dandy's!

One particular Nortel system I get to do MAC work on (Meridian, not Norstar :grin: )takes up about a 4x16 foot footprint, and has a pretty big encyclopedia set for a manual.

i saw a bigger nortel yesterday. it was a DMS500 switch, and was 4 or 5 rows about 30' long. It was brown and smelled like burning.
 

Rampage_Rick

Senior Member
rexowner said:
No, because Hz (cycles/second) is not equal to baud (symbols per second). 1000BASE-T works fine on 100MHz
cable because more than one bit can be transmitted
in each cycle by using a PAM (Phase Amplitude Modulation) code.
Upon further reading I see your point. The confusion lies in the fact that 1000Base-T and 1000Base-TX are different specs. 802.3ab (Base-T) uses the same symbol rate as 100Base-TX but manages 3 bits per symbol and over all 4 pairs. TIA/EIA-854 (Base-TX) is the one that specs 250Mhz over 2-pair (CAT6) and is all but dead, but many people add the X in error.

Learned something new today... I'm more of a PSK guy anyways... :grin:
 
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LV grider

Member
wireguru said:
when i posted that, i meant the builders are having their alarm guys run quad for the phones while theyre in there.

Understood and respected. In that case the builder is relying on faulty information by assuming the security installer knows what the phone guy needs when he finally gets the phone call and arrives. Usually that is the same time as the painters are putting on the final interior coat and the security guy has drank all the funds he created selling a product to service another subcontractors WAG needs.
 

nakulak

Senior Member
I still find a lot of uses for cat3 - phone lines and also tying stuff down on my pickup to take to the dump. :grin:

I don't know why nobody likes cat6, I love the stuff.
 

LV grider

Member
nakulak said:
I still find a lot of uses for cat3 - phone lines and also tying stuff down on my pickup to take to the dump. :grin:

I don't know why nobody likes cat6, I love the stuff.

Is your love for CAT6 based on application or possible profit margin?

Are you sure you are really using CAT6 or CAT5e?
 

nakulak

Senior Member
cat6 is cat6 there's no mistaking it

it takes a beating its not for pansies it has intrinsically 2x the bandwith of cat 5e, right ?
 
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rexowner

Senior Member
Location
San Jose, CA
Occupation
Electrician
nakulak said:
cat6 is cat6 there's no mistaking it

it takes a beating its not for pansies it has intrinsically 2x the bandwith of cat 5e, right ?

Twice the bandwidth does the user no good. Physical
layers (e.g. Gigabit Ethernet) either work or they don't,
and data networking and other applications work just
fine on Cat5e.

As Rampage_Rick pointed out, one physical layer
(1000BASE-TX) which used Cat 6 was dead on
arrival, because there was the same speed available
that ran on Cat-5 or better (1000BASE-T).

I worked for a major manufacturer of computer network
equipment for 10 years, and when you look at what the
installed base is for Cat-5(e) vs Cat 6 or higher, and
what the trends are, it is completely obvious that if
you want to sell equipment, you are not going to orient
it to Cat 6 or higher. Simply put, the world has been
populated by Cat-5, and the next major upgrade is
not going to be a Cat-#. IMO, the likelihood of there ever
being a useful mainstream application for Cat-6 or Cat-7
is approaching zero. There are things like datacenter
10-Gigabit Ethernet, but at that point, the large majority
of end-users want to go fiber anyway.

If someone really wants to future-proof an installation
that doesn't have raised ceilings/floors/cabletrays,
e.g. in a residence, some form of raceway and junction
boxes is the way to go. It is a lot of labor to provide the
requisite support etc, but I've put ENT-type raceways
(e.g. Carlon Resi-gard) in a number of homes here in
Silicon Valley where the owners wanted to have whatever
is called for in the future. It is not for everyone, but
it certainly provides a useful upgrade path, albeit
at a pretty high cost to install.

As far as the beating issue, I try to be careful, but at
some point it's not uncommon for my CAt5e to get
stepped on etc, and I've never had a problem. Quality
definitely varies by brand though, and what I get from
my regular distributor is much better quality and easier
to work with than what the orange or blue stores sell.
 
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grich

Senior Member
Location
MP89.5, Mason City Subdivision
Occupation
Broadcast Engineer
rexowner said:
... I try to be careful, but at
some point it's not uncommon for my CAt5e to get
stepped on etc, and I've never had a problem. Quality
definitely varies by brand though, and what I get from
my regular distributor is much better quality and easier
to work with than what the orange or blue stores sell.

Our facility standardized on Belden 1700A (1701A plenum) CAT5e cable in the mid '90s, and it's still all I order. We have temporary jumpers get stomped on, pulled hard around corners, etc., and no problems either. The pairs are bonded, which make it a pain to terminate, but I think that's what makes it what it is...the impedance of the pair is going to remain stable under abuse. No problems passing Gig-E thru it.
 

LV grider

Member
Awful big words

Awful big words

This thread has gone from "are there any uses for Cat3" to "how many big words can I use to sell Cat5 when it isn't needed".

Is this a tech spec board or lingo to use when trying to upsell a customer board?:smile:
 
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