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Standard User mhb
(member) Mon 06-Jan-14 13:21:06
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Neighbour's BB affects mine


[link to this post]
 
For the last few months I have been experiencing a phenomenon which I do not know how best to resolve and I would welcome any advice on this matter.

To fully describe this, I need to explain that I live in a rural location some considerable distance from both my local exchange (BT and Max ADSL only) and from the cabinet which serves me. My provider is Plusnet. In order to maximise the broadband speed I receive, for several years I have manipulated the SNR (via telnet) so that normally I can achieve a stable IP of 4.5 Mbps at a SNR of around 0.5, (ridiculously low I know but nevertheless stable - for weeks at a time).

My nearest neighbouring property is opposite me on the other side of the lane. This neighbour routinely disconnects his router when not in residence. Some months ago he had a voiceline fault which BT (his provider) corrected.

The problem I have experienced ever since this repair, is that the moment that my neighbour plugs in his router, my connection resyncs with an increased SNR figure (around 1.5) and appropriately reduced IP (3.5 Mbps). Try as I might I can no longer manipulate the SNR until my neighbour unplugs his router on departure when again my connection resyncs at a higher SNR figure and once again I am able to manipulate it to restore my normal connection.

I repeat that this situation did not exist before the BT repair and so it seems likely that something they did to effect the repair is causing the problem.

So, my questions are :-
1) what might BT have done to cause this?
2) Given that even with this problem my connection speed is well above that predicted by BT (1.5Mbps presumably at a SNR of 6), what, if anything, can I or my neighbour (with whom I am on very friendly terms) do to get BT to check the efficacy of their repair?

Any advice would be welcomed.
Standard User johnjburness
(eat-sleep-adslguide) Mon 06-Jan-14 13:35:21
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Re: Neighbour's BB affects mine


[re: mhb] [link to this post]
 
The pedantic response is that there is nothing that you can do to request BT to look at it - because you are a PlusNet customer.

I would suggest that you raise a ticket with PlusNet, explaining fully the details that you have given, & see if they will progress it with BT!

I would also suggest that you carry out all the "obvious" tests to eliminate ant causes within your own property (temporarily directly connect to Test-Socket etc) - obviously, given your description, this is unlikely to be a factor but you will be asked if you have done it before they will proceed!

Regards,
John
Standard User RobertoS
(sensei) Mon 06-Jan-14 13:59:03
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Re: Neighbour's BB affects mine


[re: mhb] [link to this post]
 
I have a couple of thoughts, but confused by the re-sync at 1.5dB instead of 0.5dB. That suggests that noise has been removed from the line, not added. Which is clearly not the case. It's almost as though your "target" figure has been raised.

What value are you giving the --snr parameter? What is the untweaked margin and speed normally, and what is it when this problem is present?

Re the repair I'm wondering if it was at his master socket, and if anything there was replaced. Also is that the socket he connects his router to, and directly with an ADSL cable or using a plug-in phone extension lead? Has he by any chance also replaced his router?

My broadband basic info/help site - www.robertos.me.uk | Domains,site and mail hosting - Tsohost.
Connection - Plusnet UnLim Fibre (FTTC). Sync ~ 59.4/14.4Mbps @ 600m. - BQM

"Where talent is a dwarf, self-esteem is a giant." - Jean-Antoine Petit-Senn.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Allergy information: This post was manufactured in an environment where nuts are present. It may include traces of understatement, litotes and humour.


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Standard User mhb
(member) Mon 06-Jan-14 16:07:53
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Re: Neighbour's BB affects mine


[re: RobertoS] [link to this post]
 
Sorry but don't understand why you deduce that an increase of the SNR figure from 0.5 to 1.5 suggests a decrease rather than increase in line noise. Could you elaborate please.

I use a --snr parameter of 1 when tweaking or attempting to tweak. Usually, untweaked a SNR of 6 produces a sync speed of around 4000bps+ leading to an IP of 3.5Mbps. In fact my neighbour has today at approx. 12.30pm switched off (rather than unplugged) his router and my SNR rose to 6 without resyncing. I was then once more able to tweak it down to 0.6 and resynced at 5344bps. Since then it has auto resynced once up to 5440bps with a SNR of 0.6 and currently remains so.

I do not know what the engineers did to repair my neighbours line and for the moment I cannot ask him. Other than the fact that his BT router, which has not changed, is plugged into a socket via the cable that came with it, I know nothing more.

Hope this helps your deliberations.
Standard User mhb
(member) Mon 06-Jan-14 16:24:45
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Re: Neighbour's BB affects mine


[re: johnjburness] [link to this post]
 
Yes, thanks for this advice. It is just that I would prefer to have a few ideas in mind as to possible causes before consulting Plusnet who I would not expect to be too readily willing to bring in BT given the speeds which I get anyway.
Standard User RobertoS
(sensei) Mon 06-Jan-14 16:32:35
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Re: Neighbour's BB affects mine


[re: mhb] [link to this post]
 
In reply to a post by mhb:
Sorry but don't understand why you deduce that an increase of the SNR figure from 0.5 to 1.5 suggests a decrease rather than increase in line noise. Could you elaborate please.
smile
Note that I did say the rise didn't make sense on the face of it.

Have a read of this page. It might help you see why I said there was an implication of less noise.

That apart, I think I can explain the rise. At the point when he switches on, there is a burst of noise getting onto the line from his system. Your router therefore loses sync and re-syncs at about 0.6dB but at a lower speed because of that noise.

Once his router establishes sync, after yours has completed its re-sync, the noise it is creating falls a little, but not to zero. So the SNRM on yours rises by about 1dB giving you the 1.5dB or so you observe when you check the stats.

Which explains the effect, but doesn't give us any clue as to what the engineer has done that causes the problem in the first place. Not nice frown.

My broadband basic info/help site - www.robertos.me.uk | Domains,site and mail hosting - Tsohost.
Connection - Plusnet UnLim Fibre (FTTC). Sync ~ 59.4/14.4Mbps @ 600m. - BQM

"Where talent is a dwarf, self-esteem is a giant." - Jean-Antoine Petit-Senn.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Allergy information: This post was manufactured in an environment where nuts are present. It may include traces of understatement, litotes and humour.
Standard User mhb
(member) Mon 06-Jan-14 17:16:06
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Re: Neighbour's BB affects mine


[re: RobertoS] [link to this post]
 
Okay, I can now follow your logic and it seems credible to me. However, as you say, it gets us no further in diagnosing a possible cause for me to use in an attempt to get Plusnet to cajole BT to revisit their repair work. Though, many thanks anyway for your time and effort.
Standard User RobertoS
(sensei) Mon 06-Jan-14 17:40:06
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Re: Neighbour's BB affects mine


[re: mhb] [link to this post]
 
I do remember several years back now when the chap across the road went from dialup to broadband. The day he did so, I started to lose about 500kbps when his router was on, from simple cross-talk.

Not obviously comparable to your case, but there may be a connection.

My broadband basic info/help site - www.robertos.me.uk | Domains,site and mail hosting - Tsohost.
Connection - Plusnet UnLim Fibre (FTTC). Sync ~ 59.4/14.4Mbps @ 600m. - BQM

"Where talent is a dwarf, self-esteem is a giant." - Jean-Antoine Petit-Senn.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Allergy information: This post was manufactured in an environment where nuts are present. It may include traces of understatement, litotes and humour.

Edited by RobertoS (Mon 06-Jan-14 17:40:38)

Standard User Zarjaz
(knowledge is power) Wed 08-Jan-14 22:58:14
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Re: Neighbour's BB affects mine


[re: mhb] [link to this post]
 
before consulting Plusnet who I would not expect to be too readily willing to bring in BT given the speeds which I get anyway.

I think you are right there. You are forcing the service to be unstable with your tweaking, now if, when it's all working at the default 6db snr you still have an issue, then maybe they'd get someone out.

As to causes .... cross talk, or maybe a rectified split pair with your neighbours line for a short length.

Standard User eckiedoo
(committed) Thu 09-Jan-14 07:14:18
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Re: Neighbour's BB affects mine


[re: mhb] [link to this post]
 
It may seem simplistic; have you tried the Quiet Line Test, both when you know your neighbour's system is operational and when it is not?

Has your neighbour observed any problems at his end?

Does he have any idea of what BT did?
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