SNR & line quality question

zugvogel

Hello everybody,
I’d appreciate if any techies/experts could give me so advice on the following.

I’ve got an Eircom 2Mbit broadband bundle. I’m 3000 meters from local exchange, which is located in rural Kildare - all underground cable. These are my stats as I type this post.

Line State Up
Modulation DMT
Data Path Interleave

Downstream Upstream
Max Allowed Speed (kbps) 2048 256
SN Margin (dB) 11.50 23.00
Line Attenuation (dB) 39.00 22.00
CRC Error 0 1

As you can see my downstream attenuation is fine but the SN margin is pretty poor. It fluctuates quite a bit. During the day the SNR averages around 12dB but in the late evening and night it drops down to well below 10 - sometimes briefly down to 3 or 3 dB - fluctuating quite a bit.

On saying that I’ve had very few disconnects, maybe 2 or 3 in the last 6 months.

I used a very useful free tool called routerstats http://www.vwlowen.co.uk/internet/files.htm (its free) to monitor record and graph my netopia modems stats over 5 or 6 hour long periods so I have quite detailed information on all my stats.

I’ve tried all the usual stuff to see what was affecting the SNR e.g. unplugging everything and connecting my router directly into master socket and so on. As a cross check I also checked my neighbours SNR and theirs is the same as mine so I think there may be a problem with line noise.

I’d like to be able to avail of the 2Mbit to 3Mbit upgrade (whenever it happens) but given my line stats I’m not sure if my line will be able to handle it.

Do you think it would be worth my while contacting Eircom support to see if they can run any tests on the line to verify if there is a noise problem or should I leave well enough alone?

Thks,
Zug.

see attachment for snr graph

smellslikeshoes

I wouldn't call your downstream attenuation fine, its not far off the limit for a 2mbit line. In my opinion your line won't be able to give you the full 3mbit when you're upgraded.

zugvogel

SML thks for the reply.
When I put my stats in here http://www2.farina1.com/adsl/default.aspx e.g. 2048, 39 atten and 12 SNR it tells me that my line is underperforming for ADSL (appears at bottom part of page) Its says at 39BD attenuation that my line should be able for 4 or 5 MBits on ADSL(1).
This is exactly what it says...
"It would appear your line is under performing with regard to ADSL, this may be due to issues like the ring wire, unfiltered equipment and other factors. Ideally you would expect to see connection speeds of 5200Kbps or higher at your attenuation"

This would seem to tie in with whats on the ADSL reach graph here - http://www2.farina1.com/adsl/default.aspx

If you look at the bottom axis of the graph 39dB corresponds with 2900 meters (I'm at 3000) and looking at the blue for ADSL(1) over 3Mbits should be no problem.

Thats why I think its the SNR thats going to limit my capacity not attenuation.

Zug

smellslikeshoes

zugvogel wrote: »

Thats why I think its the SNR thats going to limit my capacity not attenuation.

Zug

It is always the signal to noise ratio that limits your capacity not the attenuation. As speed goes up snr goes down and it is ultimately the snr that stops every line further than a few meters from the exchange from reaching the top speed capable with the technology (if the isp is ran at top speed that is).
Bottom line is you have a poorish line and might get disconnects at 3mbit. If you are sure its nothing in the house effecting it, there really is nothing you can do about it.

zugvogel

smellslikeshoes wrote: »

there really is nothing you can do about it.

you reckon it wouldn't be worth giving eircom a call then - I thought they could run some tests on the line. Next time I see an Eircom techie around I'll mention it to him.

rc28

zugvogel wrote: »

you reckon it wouldn't be worth giving eircom a call then - I thought they could run some tests on the line. Next time I see an Eircom techie around I'll mention it to him.

It is true that snr is way more important. I have a line attenuation of 51 and snr of 25 which looks like a poor line but when I run my stats through that checker it says my line is capable of nearly 8mb- if I put in any snr figure any lower the max my line is capable of rapidly deteriorates. Try changing your router because on my other netopia2247 my snr sinks to an abysmal 7-12 and I used to get disconnects but my current router (3347) is way better and I havn't gotten any disconnects

zugvogel

rc28 wrote: »

Try changging your router because on my other netopia2247 my snr sinks to an abysmal 7-12 and I used to get disconnects but my current router (3347) is way better and I havn't gotten any disconnects

Hey rc28 that sounds like a good idea. Mine's a netopia 2247 as well. Where be the best place to get one?

Zug

rc28

zugvogel wrote: »

Hey rc28 that sounds like a good idea. Mine's a netopia 2247 as well. Where be the best place to get one?

Zug

You're in luck as that router has a problem with snr which means you're line isn't bad and is probably well capable of higher speeds. I happened to have the 3347 from when we first got bb and eircom sent us out the 2247 when we upgraded to 2mb for some reason. I wouldn't have good advice for where to buy routers and which is the best brand. Does anyone on here have any recommendations?

smellslikeshoes

zugvogel wrote: »

you reckon it wouldn't be worth giving eircom a call then - I thought they could run some tests on the line. Next time I see an Eircom techie around I'll mention it to him.

I would try a different modem as has been mentioned to see if it makes any difference but if its not the modem and is the actual phoneline there is no chance whatsoever that Eircom will do anything about it. They wouldn't even do anything about a line if there was a problem with it that stopped the user getting broadband at all so there there is very little hope in them doing it because somebody wants more than 2mbit.

zugvogel

Thks for the replies lads. I came across a couple of sites regarding problems with the netopia routers which can have problems with lines where the SNR fluctuates like mine.

http://blog.sweetnam.eu/2007/10/23/dodgy-netopia-router-this-could-be-the-reason/
http://www.boards.ie/vbulletin/archive/index.php/t-2055169617.html
http://www.theregister.co.uk/2007/10/22/zen_ar7_infineon_bt_fault/

I think it’s worth a shot trying the 3347 model or a type that doesn't use the same AR7 chip set. Maybe if I rang eircom they might be willing to do a swap for 3347 or something???

Cheers,
Zug

zugvogel

Just spent the last few hours looking at a possible replacement router for the netopia.
Thomson Speedtouch 585 comes highly recommended for users with long lines and/or unstable SNRs as does some 2-Wire models, but the SpeedTouch edges it. I think I might look into getting one of these.

Zug

zugvogel

zugvogel wrote: »

Maybe if I rang eircom they might be willing to do a swap for 3347 or something???

Just off the phone to Eircom tech support. Friendly support chap says that they don't do the Netopia 3347 model anymore and if they sent me a replacement it would only be another 2247 so that's that avenue closed

I might have to bite the bullet and buy a speedtouch 585 online from the UK. Price is £36 + £25 delivery to Ireland from DSL warehouse.

Zug

Onikage

The 3347 is 20GBP inc shipping for a refurb model on digidave uk. They have other models too, bought a 2wire and it works fine

http://www.digidave.co.uk/jshop/section.php?xSec=30&jssCart=ea7d8f47cc10073176f38b055460ebec

zugvogel

Just got upgraded to 3Mbit. All working OK. The downstream SNR on the speedtouch only dropped 1.5dB when going from 2 to 3.
SNR now is 12 to 12.5 dB

Speedtouch router is
Netopia

selfbuilder1

Hi I just got a Speedtouch 585v6 to replace my netopia in hope to improve or stablise my sn margin. The Speedtouch I got is set up for Tiscali. I have tried to set it up for eircom but it won't let me change the settings. Zugvogel can you help me with this one from your experience setting up your modem. Thanks.:(

zugvogel

Hi, when I set up my modem all I had to do was power it up, go to dsldevice.lan and enter the following information into the setup screens (This modem had the factory firmware installed - not an ISPs version).

Username: eircom
Password: broadband1
Encapsulation: PPPoE
Multiplexing: LLC Based
VPI: 8 VCI: 35
Primary DNS: 213.94.190.194
Secondary DNS: 213.94.190.236

But I guess you know this already. It could be that your modems firmware was modified by Tiscali, limiting the amount of configuring users can do. One option could be try return it to the factory default settings and then try and set the above parameters by redoing the modem setup – on my modem interface (dsldevice.lan) there’s options to do both of these. If that doesn’t work you may need to download and flash it with Thomson’s own version of the firmware for the 585v6. This link looks to have a firmware for the 585v6 http://www.thomson.net/GlobalEnglish/SelfService/dsl-modems-download/Pages/default.aspx
If you can get it working I would expect it to stabilise your SNR and possibly improve it by 1 to 1.5dB.
That any help

Zug

Samba

smellslikeshoes wrote: »

I would try a different modem as has been mentioned to see if it makes any difference but if its not the modem and is the actual phoneline there is no chance whatsoever that Eircom will do anything about it. so there there is very little hope in them doing it because somebody wants more than 2mbit.

Thats interesting, Im on the same modem with the following stats i've tried plugging in directly via a filter etc but there has been little or no change.

Could the fact that im plugging direclty into an old ISDN box have anything to do with my poor stats?(I cant see how this could make much difference)

Max Allowed Speed (kbps) 6144 512
SN Margin (dB) 12.00 15.00
Line Attenuation (dB) 30.50 13.50
CRC Errors 0 1

They wouldn't even do anything about a line if there was a problem with it that stopped the user getting broadband at all

Neither of the two DSL lines were fit for BB when we initially applied. Some complaints were made to specific people in Eircom and whaddya know soon after we had 2 working DSL lines in the house. It's all about how you complain and who you complain to that will ultimately decide how an issue is dealt with.

In general you are right though they will generally have little time for entertaining I want broadband complaints.

Im just wondering is it possible my line could sync up at faster speeds with a better router? Or is this speed fixed at the exchange?

I ask because on both lines have the exact same sync speed using that Netopia model as do other people I know with the same model, I gather it can effect SN but what about Sync speeds?

smellslikeshoes

Samba wrote: »

Thats interesting, Im on the same modem with the following stats i've tried plugging in directly via a filter etc but there has been little or no change.

Could the fact that im plugging direclty into an old ISDN box have anything to do with my poor stats?(I cant see how this could make much difference)

Max Allowed Speed (kbps) 6144 512
SN Margin (dB) 12.00 15.00
Line Attenuation (dB) 30.50 13.50
CRC Errors 0 1




Neither of the two DSL lines were fit for BB when we initially applied. Some complaints were made to specific people in Eircom and whaddya know soon after we had 2 working DSL lines in the house. It's all about how you complain and who you complain to that will ultimately decide how an issue is dealt with.

In general you are right though they will generally have little time for entertaining I want broadband complaints.

Im just wondering is it possible my line could sync up at faster speeds with a better router? Or is this speed fixed at the exchange?

I ask because on both lines have the exact same sync speed using that Netopia model as do other people I know with the same model, I gather it can effect SN but what about Sync speeds?

Your line is performing well for your line attenuation, you aren't realistically going to get very much more from it.

selfbuilder1

Thanks Zugvogel for your help. I managed to upgrade the firmware getting rid of the Tiscali settings but boy was it a pain. Alot of googleing finally worked. My SN margin is now a steady 17 which it was never before. Usually it went from 0 to 15 with the netopia. Still waiting for my upgrade to 3mb from eircom which was due to happen this weekend but nothing as yet. Thanks again.:)

zugvogel

Excellent SB1. I wouldn't be surprised if a lot of people had problems with disconnects/resyncs after the upgrade as their lines are pushed to their limit because the 2247 Netopias don't seem to be able to hold a steady SNR at all on certain lines (like yours and mine).