Noise Margin Problem

Been lurking around for a while, but never had a problem except for the last 2-3 months. I would say it started when they renovated the police station/house and changed it into more of a police office, I come off the last pole on the line and they come off 3 poles back.

Been with Demon for 6 years and never had any real problems, except the time that speeds where dire. Noise Margin was around 6db +/- and sync was 8128kbps, Modem DG834N (previously DG834GT).

But recently my Noise Margin has creep up to 15.9db and sync has dropped to 4800kbps. Plugged into the master socket, tried 3 different filters, different cable from socket to router, checked no ring wire connected, changed router (DG834GT), all to no avail, stats where around the same (0.2db better with the DG834GT).

Full Stats : Downstream Upstream
Connection Speed 4800kbps(8128) 448kbps(448)
Line Attenuation 13.0db(11.5) 5.5db(6db)
Noise Margin 15.9db(6db) 23.0db(24db)
(Full Speed Stats)

Connection has always been solid, never lost my connections to my knowledge, except a reboot or power cut.
RouterStats been running for 5hrs(since last reboot) with a nice straight line across graph. Router Commander running as well has 1 downstream error (S.Frame) in that time.

Will it drop back down to 6db itself?
How long does this take?
Or do I get it reset?

Thanks for any advice.

The obvious immediate problem is the high downstream noise margin of 15.9dB, but for that to have got that high implies deeper ones.

It is also possible that when the trouble started you made things worse by all the trying to improve it that you did. Many of us have fallen into that trap and caused the noise margin to rise.

It should drop back in 3dB stages at 10-14 days per step if you leave it alone, and preferably switched on 24/7. Keep RouterStats running so we can see what the margin is doing over each 24 hours. A knowledgeable poster here recommends 30-second intervals, but I prefer 5-second as a reconnection could occur in less than 30 seconds and all you see sometimes see is the result, not the behaviour around the critical time. Plus short spikes will show, where they probably won't at 30 second sampling.

In your case I'd be very interested in the detail. Also a good idea to alter the vertical scale of the graph to perhaps -3 to plus 20, to pick up the small variations better.

You could try asking Demon for a reset, but I think we should do the above for a week first, so we see weekdays and weekends, as there is no point in talking them into that if the same thing might occur again staright away.

For a bit more information on the system see my Noise Margin, High Noise Margin, and other Troubleshooting pages.

Thanks for the reply RobertoS

It is also possible that when the trouble started you made things worse by all the trying to improve it that you did. Many of us have fallen into that trap and caused the noise margin to rise.

Your possibly correct, I probably didn't help matters. Will leave it alone for the time being and see if anything improves. So it could take 30+ days to drop to 6db if there is no other problems.

Router is always on 24/7 and RouterStats is running, Noise Margin dropped to 15.3db earlier this evening, but had gradually risen to 15.8db by 23.00hrs.

what is it like in the test socket, rather than just the master faceplate ?

The SNR margin is high but at that attenuation it could be that high at 8128 sync

Sorry Yarwell my mistake, my terminology not quite up to scratch

The reading where take from the test & faceplate socket with similar values.

Thanks,

Here are the last 3 days Noise Margin graphs up midnight Friday.

6/09/2011
7/09/2011
8/09/2011
9/09/2011

All other stats have been unchanged
Connection Speed 4800 Down 448 Up
Line Attenuation 13.0 Down 5.5 Up
Noise Margin 16.3 Down 22.0 Up

Noise margin seems to be continuing to rise.

Noticed a few peaks on the graphs, rising to about 17 db.
Is this expected or does it indicate a problem?

On the 7/09 graph in the evening, I removed an extension wire that was no longer used from the faceplate, to see if that will help. But since then not touched anything.

The green line on one of the graphs is when I rebooted the computer.

Today my WAN uptime restarted itself, but at the time the graph show nothing, but the logs said disconnection 9:25:05, connected 9:25:16

Thanks

Interesting graphs, as some of the behaviour is normal and some the opposite of what I would expect. I need to go through them again and make a few notes before going into detail, but overall there doesn't seem to be a current problem with the noise, so long-term things look good.

I've quite a lot to do here, so if I don't get back to you tomorrow, and the graphs continue in that fashion, you should be able to get your ISP to request an SNR reset. That's probably what I will recommend anyway.

That redoes the initial 10-day training, and in so doing sets the noise margin back down to 6dB. Connection speed should rise dramatically, and throughput not long after.

I shall be away from early Monday till late Thursday.

Edited by RobertoS (Sat 10-Sep-11 15:38:37)

Thanks RobertoS for the advice, much appreciated.

Will leave RouterStats running next week and see if there is any improvement. If not then I will contact Demon and get them to request a SNR reset.

Thanks

Post deleted by MrSaffron

While above post appeared helpful in suggesting the police station work may have disturbed the telecoms infrastructure, the inclusion of a link to a sales site for line testers suggests another low paid human spam operator.

Well after running for a week nothing had changed. So last night I changed the router to the old DG834GT. Connection speed increased, noise margin(down) dropped and Line Attenuation(down) dropped.

ADSL line is on Fastpath and has been all the time.
Connection Speed 4960Kbps(Down) 448Kbps(Up)
Line Attenuation 11.0db(Down) 5.5db(Up)
Noise Margin around 14.0-15.0db (Down) 24.0db(Up)

Only thing now is Noise Margin is constantly jumping, DG834GT Graph, compared to the previous router, DG834N Graph.
So is this acceptable or should I put my other router back on?

Suppose I should give my setup. Phoneline comes into house through wall and terminates at master socket where it comes through. Filter fitted to master socket, ADSL cable goes to Router, 5m of foil shielded RJ11 to RJ11 cable. Another filter fitted to phone outlet of filter, then a two socket adapter fitted to this phone outlet, one cable going to phone and the other to a AIO printer.
I did try a double phone and modem adapter with surge protection, in the master socket, and done away with the filter on the ADSL line and a filter in each of the phone outlets, but this increased the Noise Margin marginally.

Have sent a request to Demon to try and get the Noise Margin reset. But awaiting a reply.

Thanks

In reply to a post by Scottish_Pete:

Well after running for a week nothing had changed. So last night I changed the router to the old DG834GT. Connection speed increased, noise margin(down) dropped and Line Attenuation(down) dropped.

ADSL line is on Fastpath and has been all the time.
Connection Speed 4960Kbps(Down) 448Kbps(Up)
Line Attenuation 11.0db(Down) 5.5db(Up)
Noise Margin around 14.0-15.0db (Down) 24.0db(Up)

Only thing now is Noise Margin is constantly jumping, DG834GT Graph, compared to the previous router, DG834N Graph.
So is this acceptable or should I put my other router back on?

Suppose I should give my setup. Phoneline comes into house through wall and terminates at master socket where it comes through. Filter fitted to master socket, ADSL cable goes to Router, 5m of foil shielded RJ11 to RJ11 cable. Another filter fitted to phone outlet of filter, then a two socket adapter fitted to this phone outlet, one cable going to phone and the other to a AIO printer.
I did try a double phone and modem adapter with surge protection, in the master socket, and done away with the filter on the ADSL line and a filter in each of the phone outlets, but this increased the Noise Margin marginally.

Have sent a request to Demon to try and get the Noise Margin reset. But awaiting a reply.

Thanks

Are there no LLU providers in your exchange ?samknows checker will tell you if you don't know already.
If there is any llu such as be/02 i personally would not be having a upto 8mbit ip stream service, with such a short line you should get around 22mbit maybe more, never mind an upto adsl max product that is subject to bt DLM the downstream sync appears to be Capped at 4800 why i don't know that would also account for the high snr which has been deliberately raised to effectively cap the connection Demon are the ones to be asking,
it sounds as if there is some type of fault that affects your line attenuation but i would doubt that it will lie between your master socket and exchange could be the equipment at the exchange failing,

Unfortunately on a market 1 exchange, so stuck with BT Wholesale and any upgrade will be in the dark and distant future.

Thanks,

I found that the DG834GT always gave me a jumpy graph.
My best move was to get the old style BT office hub.
Made my line jump from 2.something connection to 5 something connection
I live in the sticks outside of Kilmarnock and the BT engineer was surprised to see that the hub had now gave me a 5mbps profile

I loved my DG834GT - it was a lovely router, and was only *replaced when I was able to start getting faster speeds that needed a draft-n router.
The router was easily tweaked, and was good fun to use.
Ok, GT had to be replaced due to becoming faulty [under warranty]. I sold the sealed/un-opened replacement on Amazon.

Only a pity that it couldn't go fasssterer.