atcomsystems.ca/forum Forums Wiring - Telecom Carriers - Trunks & Services Telecom Service & Providers dsl over broken/problem pair

Hello,
I've heard different stories about people having no dial tone and voice service after a severe storm, but their dsl service was still running.
I have also found on the web a story from a bell tech about a customer who was able to use his dsl service (albeit very poor speed), with a pair that was open and no dial tone, and the cable had to be replaced.
Can anyone explain how it is possible, and don't hold back on the details, please.
If this is the wrong forum I appologize.
Thanks,
Ak

DSL runs out of the voice range and it's data, so if you had one side open (in theory) you could get NDT and yet have degraded DSL service. Same goes for noise or any other poor line condition. I've never tried it, but you could go to the DEMARC and open one side and see if you could still get sync on your DSL modem. I would think a lot would have to do with your distance from the DSL (CO) source too.

Welcome to the board and please complete your profile.
Thanks,
Bill

Ak

Ive seen it both ways with DSL.
You may pass voice frequency OK and not have data.

Ive seen data and no voice frequency.

When reporting trouble to VERIZON it takes them two or three attempts to resolve the service issue.
Make sure you isolate the trouble at the demarc or what they call their demarc.
You may have to take your dsl modem to that point to make a proper test for trouble reporting to call the kettle black.
It will take some effort to x-shoot just where the problem is and with whom lies the problem of the dsl ckt.

So what you're both saying is you really only need one wire, to transmit voice or data, on a very basic level i.e. it will work but not very well with only one wire? I guess you would have to have the side carrying the current, to be working? or does it not matter since the dsl modem has its own power source to modulate and demodulate??

I'll do my profile asap, but wanted to see if anyone could shed any light on this, first, as it's been bugging me ever since I heard of it!

Thanks for your answers and helping me to understand something I thought should not work.
Ak

1 wire ? (1 conductor?) no.

--------------------------
1 pair or tip/ring.
a circuit, ok

Voice will not work, properly, and I put that in there on purpose, there is the very slight chance you could have an open tip that is grounded on your side of the CO which you could talk over, although it would be noisy. DSL "may" work with just one good side and again I think proximity to the CO may have something to do with it. You are correct in that if the ring side were open the voice wouldn't work, period.

OK just for grins, I opened one side of my line and the DSL still worked, however I am close to the CO.

When you say "an open tip that is grounded on your side of the co", do you mean between a modem and any telco box/equipment before it hits the co, rather than between a telco box/equipment and the co?
If proximity to the co is a big factor, then this was the right neighbourhood, as the telco guy repairing the lines said that the line which fed the neighbourhood came straight from the co, and then was distributed via the box on the pole, which was affected by the lightening. It is a very "old" neighbourhood.

In other neighbourhoods, I understand the dsl tone/signal is added not at the co, but at a telco box (i think they call them "slams"?). could this be a factor as to how this single wire situation might work in other cases/situations, where the modem is not close to the co, or the open tip is not on the modem side of the co?

I don't mean to harp on this issue, but I find it really odd, and interesting.
Ak

Which side did you open? negative or positive?

I'm talking voice.

To your other question I opened both, one at a time. I didn't loose DSL signal on either side, speed seemed a little better with the ring side only verses the tip side only, but I'm sure that means nothing. Even the private line data will work with one side of a pair open (not the whole transmit or receive).

Just to clarify, there is no negative. Telephone voice circuits are battery and ground. To me negative means negative battery. You can go from the ring side of a telephone circuit other side to ground and it will work, but it will be noisy since the ground is not filtered.

That's amazing, to me. I would have imagined that ack/rts/cts etc would choke if everything had to be done with only one wire, not just slow down.

Did you go to a website which measures your throughput?

What do you mean by "private line data"?

No I didn't check the speed. Private line data is a dedicated point to point, or multipoint 4 wire data circuit.

Heck you can run a phone line over barbed wire can't ya Justbill !

You bet and did. :thumb:

DJ, I'll presume to answer that one ---- yes, until 1956 the local area had an independent that had magneto ringing --- and, unless you paid extra, you either talked via one side ground or the top strand of barbed wire ---- just don't leave the pasture gate open.

As for the topic :shrug:

If you can't talk on it, what do I know?

KLD

Actually had a wire that went up and over gates. At least that's what I heard.

Yeah, there was one down by the creek low water crossing north of Jarbalo. The farmer was complaining of a noisy line --- his field hand had attached the electric fence so it went over the gate. Guess keeping the cows in was more important than a phone call.

:shrug:


KLD

I had thought of the telegraph, but didn't think voice could be done, and really didn't think data could be done.
That's funny about the barbed wire phone, but I'll bet the barbed wire didn't have to contend with things like 23:54:23.817524 10.0.0.2.1072 > 10.0.0.1.5001: S 577076198:577076198(0) win 65535 flying back and forth, and resending if one sequence got messed up...
Thanks to everyone for enlightening me, I knew this was the place to find my answer.
Ak

Ken,
Actually had line to ground when I started working for the phone company. Out in the sticks were some lines we called "farm lines" owned by the farmers. This was open wire of course and in some cases one side and ground. Lots of times the farmers would run there service over barbed wire after an ice storm until they could pay the phone company to put it back together. Just thought I'd throw that little tid bit in there.
Bill

AK, maybe my two cents will help to clear the air. Rember that DSL is a signal, as in a TV channel. You know that you can lose certain channels with cable TV for any reason. It's very simmilar with DSL, since it is just a "channel" on the cable pair that brings in phone service.

The DSL signal is sent using the dedicated voice pairs in the cable. The pair is a metallic path from point A to point B. Since DSL is a signal and not really a circuit, as with the telephone line itself, it uses the copper pair as a private antenna so to speak. The DSL signal simply wiggles it's way to the premises over the cable pair.

If one side of the pair has a fault, it's still possible that the DSL can ride on half a pair. It's as if a water pipe's diameter got cut in half. Slower flow, but it still gets there.

Now, when voice works and DSL doesn't, that's strictly an issue with the head or terminal ends. If the voice circuit is good, then DSL amost has to work unles the distance is too far out.

Thanks, Ed, feel free to toss in anything else you can think of. I know nothing about the phone system, so this is a great learning experience.
Ak

I think the signal vs. circuit explanation was about as good as you can get. Clear and simple.

Ok Ed
You enlightened us with how DSL works via barbed wire ! . Here is a new challange ! Explain to a "Novice" PCM Theory ! In less than 3 words ! I can . :toast:

Here's about as much as I know about it:

Pulse Code Modulation.

That's all folks!