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#21153 - 01/27/03 10:12 PM DSL Question. CAT-5 or better?
sparky66wv Offline

Registered: 11/17/00
Posts: 2342
Loc: West Virginia
I have a loyal customer who has recently upgraded to a Digital Subscriber Line.

Even with a line filter installed, crosstalk is a problem, and I fear it is because his lines are Quad-wire instead of UTP.

Ironically, when we built his addition, I had ran RG-6 for the purpose of cable modem, but alas, it was to no avail. The network interface is on the addition side, and replacing the phone wire will be a challenge because of it.

My ignorance is mostly to blame.

He has two phone lines on quad-wire with the DSL running piggy back on line "1".

What do I need to do?

Thanks in advance...


[This message has been edited by sparky66wv (edited 01-28-2003).]
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#21154 - 01/27/03 10:38 PM Re: DSL Question. CAT-5 or better?
stamcon Offline

Registered: 03/24/01
Posts: 322
Loc: So San Francisco CA
Virgil, is the RG6 a dedicated run? I don't know if this would work, but if dedicated, could it be adapted at each end and used instead of the Cat5? Would a remote DSL modem and WiFi or powerline networking help? I don't have the answer, just suggestions.

#21155 - 01/28/03 12:29 AM Re: DSL Question. CAT-5 or better?
luciuskwok Offline
Junior Member

Registered: 12/21/02
Posts: 3
Loc: Philadelphia, PA
For DSL, you should run at least CAT-3 UTP from the network interface to the DSL modem. If it were me, I would rip out all the Quad-wire and repace it with CAT-5. I would also make sure that the cable from the wall jack to the phones are UTP. You need to use UTP to avoid cross-talk. The more twists in the cable, the better the ability to reject interference.

One thing to do if they're having problems with the DSL side is to install the DSL modem near the network interface, connect it with a short run of CAT-5, and use one DSL filter at that point. You can then connect the phones downstream of that DSL filter.

#21156 - 01/28/03 07:08 AM Re: DSL Question. CAT-5 or better?
wolfdog Offline

Registered: 10/24/01
Posts: 135
Loc: Dallas,TX
What you are describing is common setup for DSL add-on. Do you have the filters on the phone jacks?
The DSL is at a higher frequency and the filters block that from your phones,fax etc.
If you are talking about crosstalk on the voice lines, I don't think that is a DSL problem.

Here is a good site for DSL info.

[This message has been edited by wolfdog (edited 01-28-2003).]

#21157 - 01/28/03 07:21 AM Re: DSL Question. CAT-5 or better?
Scott35 Offline

Broom Pusher and

Registered: 10/19/00
Posts: 2724
Loc: Anaheim, CA. USA

The best choice for any circuit used for connecting a computer to the telco's trunk (Inside Wiring, or Subscriber's Side of the NID) is something in the twisted pairs catagories - or use shielded cables.
This would include wiring for ADSL (common type or "flavor" of Residential Digital Subscriber Line), and Analog MODEMs.
This way, you can (try to) eliminate as much RFI / EMI from falling into the phone line circuit as possible, reduce the coupled effects of two separate phone lines in one cable, plus keep the line tuned and set at a somewhat steady value.

UTP (Unshielded Twisted Pair) cable is most convenient and requires simpler installation tasks. Common types include CAT 3 UTP and CAT 5 UTP Multi Pair Cable.

STP (Shielded Twisted Pair) is more expensive and requires more work to install.
IBM's "Type 1" is an example of STP Cable.

I won't even get into Shielded Untwisted Pair cables!

Now for a few "...,But" examples!

I have seen a couple successful ADSL setups, where the "older" 4 Conductor "JK" type cable was used between the NID and the Brouter (Bridge Router - Proper name for what has become an Oxy-Moron slang term "DSL MODEM").
Having only seen about 30 minutes of Browsing time across these connections, they did manage well (don't know if the throughput died after I left, or not!).

The most significant reasons why these setups were successful are:
* Short Distance From NID To DSE (Brouter),
* No Analog Devices Coupled To The Line (via the filters normally included with DSL packages - used to connect stuff like fax machines and regular telephone sets to the circuit with the DSL connection),
* No Visible Signs Of HAM Radio Operators In Immediate Area / No Sign Of "Big or Small Yagi's" in neighbor's yards (didn't see any large HF / VHF / UHF Antennas masted atop towers),
* Relatively Decent Electrical Appliances And Circuitry.

A few things to consider would be:
  • What type of interference is falling onto the telephone line circuit,
  • How intense the noise is,
  • What Analog stuff is connected to the DSL circuit,
    and probably the most important;
  • Does the noise come in on the Telco's Trunk, meaning does the noise originate on the telco side of the NID.

As mentioned before, try relocating the DSE closer to the NID, then see what the results are.

Check around for crappy connections on anything possible (POTS circuits and AC Power circuits).

Also remember that each Passive device connected to the POTS circuit will affect the signal's power - and can bring in noise (or even create noise) if not correctly designed or connected.

I'll add more later if you like - and if you can add a little more info, that would be cool!

Scott35 S.E.T.

p.s. edited to fix spell-eeng again!

[This message has been edited by Scott35 (edited 01-28-2003).]
Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!

#21158 - 01/28/03 08:15 AM Re: DSL Question. CAT-5 or better?
strangedog Offline

Registered: 08/23/02
Posts: 30
Loc: Dayton, Ohio
Before you rip out everyting try this:

Split off all other lines at the network interface from the run that feeds the DSL 'Modem'. Place a filter on all the other lines right there. If a phone shares the "home run" to the DSL Modem place a filter at that point as well.

Plan B is to pull a dedicated cat 5 Line from the network interface to the DSL 'Modem'. Again place the filter at the network interface rather than letting the DSL signal run throuout the house.

Plan C involves locating the modem on a shelf near the network interface and using something like this powerplug network to distribute the signal. You could locate a router next to the modem and use the powerplug bridge to distribute the net to the entire house, or you could place the bridge between the modem and computer.

Let us know how it works out.

PS I reccomend a router for all DSL applications, the software provided by your telco for PPPOE is crap (PPPOE is the protocal used in DSL)
It is best for a leader to be both feared and loved. But since this usually cannot be done, it is safer to be feared.

#21159 - 01/28/03 04:19 PM Re: DSL Question. CAT-5 or better?
ThinkGood Offline

Registered: 08/07/02
Posts: 1084
Loc: Milwaukee, WI
Since we're on the subject of eliminating interference from telephone lines, has some good suggestions.

#21160 - 01/28/03 06:15 PM Re: DSL Question. CAT-5 or better?
George Offline

Registered: 02/23/02
Posts: 380
As I recall, the phone company came out and did something to the line near my house when we got DSL. The phone company might have messed something up.

If you turn the DSL modem off and still get cross talk, the DSL is not the problem. (DSL should cause line noise not cross talk.

I would test the line where the phone comes into the house. Our phone box has test jacks in it for each line. With 2 phones you can test for line noise on the Phone company side.

#21161 - 01/28/03 06:46 PM Re: DSL Question. CAT-5 or better?
stamcon Offline

Registered: 03/24/01
Posts: 322
Loc: So San Francisco CA
George, this might be what the phone company did with your line. My line had a load coil on it and they had to remove it.

"A load coil is an inductor placed on the local loop by the phone company, they are placed starting at 3000 feet in 6000 feet intervals to suppress exactly the signal that DSL modems need to transmit high speed data on -- high frequency. The effect of a load coil is similar, from the perspective of the DSL equipment, to adding 20k feet to the line length. No DSL equipment now works through load coils. A Load coil is the major source of DSL Disappointment during the installation phase of DSL.
Here is a good site on load coils, and this one as well

#21162 - 01/28/03 07:40 PM Re: DSL Question. CAT-5 or better?
Bjarney Offline

Registered: 04/10/02
Posts: 2561
Loc: West-Southern Inner-Northeast ...
Cat. 3 unshielded cable should be fine—it's rated for 10Mb/s and residential ADSL is ~1Mb/s.

I’d try temporarily running cat. 3 {or 5 but that should be overkill} across the floor between rooms and see if that fixes the problem before I’d attempt tearing out or replacing anything.

The signal gets far more abuse between central office and subscriber before it sees customer-premises wiring.

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