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clarknova

join:2010-02-23
Grande Prairie, AB
kudos:7
Reviews:
·TekSavvy DSL

[DSL] Line noise!

I have a certain wet ADSL 6/1 line with phone service on it. I have a dollar-store style splitter plugged directly into the ST516v6 modem, with a single DSL filter and phone cord going from there to the PBX, and a pair from a cat5e connecting the second splitter port to the Telus demarc.

In this configuration, the modem syncs at 928/6144, which is healthy. The SNR is usually 6.0, which I realize is borderline usable at this speed. If I ditch the splitter and voice line, connecting the modem directly to the demarc, SNR is closer to 9 or 10.

Unfortunately, I need this voice line. In fact, I have several modems and ADSL circuits at this location, and I converted the others to dry loop. I choose this as my wet circuit specifically because it had a stronger SNR than the others.

So normally, even at a SNR of 6, the internet works fine. However, Sometimes during extended telephone conversations, this modem loses sync and then re-syncs at a lower rate and will stay there indefinitely. Rebooting the modem after the phone call has ended will cause it to re-sync at a healthy 928/6144.

This re-syncing and rebooting is annoying to more people than just me. I tried another brand of DSL filter, but the result was not better, with the modem syncing around 928/5660 whether the phone was in use or not.

Being an MLPPP user, I'd really like to get a full 6144 on all my lines; it's hard to even justify a single line that syncs less than that, as my aggregate download would be about as good with that line gone altogether.

So I'm wondering if somebody can recommend a better setup. Are filters known to be noisy? Is it the line splitter? Should I be using an actual DSL splitter that I've seen at some businesses?

I'm pretty comfortable on the network side of things, but the whole analogue racket has me scratching my head.
--
db

InvalidError

join:2008-02-03
kudos:5
said by clarknova:

So I'm wondering if somebody can recommend a better setup. Are filters known to be noisy? Is it the line splitter? Should I be using an actual DSL splitter that I've seen at some businesses?

Filters should not add any noise, they should actually reduce it.

You should have your DSL splitter as close to the demarc as practical, connect your home phone wiring to the filtered side of that splitter and run a separate wire from there for the modem.

If you have only 9dB at the demarc with the rest of the home disconnected though, I doubt there is much that can be done to help your case short of Telus rolling out a remote or FTTH in your neighborhood.


clarknova

join:2010-02-23
Grande Prairie, AB
kudos:7
Reviews:
·TekSavvy DSL
said by InvalidError:

If you have only 9dB at the demarc with the rest of the home disconnected though, I doubt there is much that can be done to help your case short of Telus rolling out a remote or FTTH in your neighborhood.

If it was 9 I wouldn't have a problem, but 9 definitely turns to 6 when the line is split, and I'm guessing less than 6 when that line has voice on it.

I will try moving the filter closer to the demarc and losing the dollar store splitter. Thanks for the advice.
--
db

mactalla

join:2008-02-19
kudos:1
reply to clarknova
A 3db drop when splitting the line? That doesn't sound right to me. I'd suggest picking up a real POTS splitter. If you were local I'd give you my old unused one (my line is now split inside the demarc). If you have a recent demarc from Telus you might already have a POTS splitter.

If you want to test to see exactly which component is faulty, try working directly at the demarc and connecting things one at a time. Attaching two wires directly at the demarc will allow you to check your SNR without the dollar store splitter to show you what it should be.

And yes, bad filters can create noise on the line. But you've already tried another one and it's rare enough that getting two faulty ones is unlikely.