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SNR Reset and long dodgy rural lines

Uncle_Meat
Grafter
Posts: 167
Registered: 04-08-2007

SNR Reset and long dodgy rural lines

Evening folks.  Just a request to reset my target SNR and IP profile please, and a few questions for afters too.
I've on a bit of long dodgy line out here in the sticks, and it does not seem to take much to upset it (heavy rain, lightnight, strong wind) but, when it does work it can work relatively well, with 2Mb being attainable for long periods of time. However, a few disconnections or glitches and you can guess what happens. Target SNR goes up like a politicians housing allowance and my IP profile can drop like a stone.  At the moment, I'm profiled at 0.25, and currently what seems to be a target SNR of 12db which syncs at just around 1000.
Now, I've replaced my aging router and filter with a slightly newer one (DG834v4) as after the last round of storms I found my old one could barely hold a connection, let alone let it sync at anything decent (was down to 160kbps at this point) so after replacing it at least I can hold the line.
At the moment, I've tweaked the target SNR on my router to "force" 6db and I'm syncing at 2048 which seems, so far, to be stable. After all, it is dry out there... but my profile is still down in the dumps.
Finally. I notice that my local exchange is now enabled for 21CN.  Given that I'm on a relatively long line, would there be any benefit to changing over to ADSL2, given that DLM on ADSL2+ seems to be quicker to respond to line conditions? It's quite a pain, you hold a good connection for days/weeks on end and a bit of dodgy weather knackers you up for further days/weeks on end until DLM resets.
Finally, if you can reset my SNR/Profile for the time being, I take it I'm best "detweaking" my router so it does not try to negotiate a negative/zero SNR or will the reset take care of that automatically?
Cheers!
117 REPLIES
Uncle_Meat
Grafter
Posts: 167
Registered: 04-08-2007

Re: SNR Reset and long dodgy rural lines

Morning all.
Just a quicky this time, as the actress said to the bishop....

Right, I detweaked my router last night and set RouterStats going overnight to see how things were.  Target SNR is 12db and sync speed was 1300 or thereabouts, can't quite remember as I'm in work at the moment.
Anyway, there was little (+/- .5 db) deviation in SNR and all seemed fairly stable overnight.  If this keeps up, how long should I expect to wait for the target SNR to drop back down to 6db and for my IP profile to raise itself back up, as of this morning I was still only getting download speeds (BT Speedtester) of 0.13? 
Is it still worth forcing through a reset or shall be patient and let DLM slowly work things out for itself?
Finally, as before.  ADSL1 vs ADSL2/2+  Any advantages, apart from mellower DLM, on long lines (Attn 58db)?
Plusnet Staff
Plusnet Staff
Posts: 6,346
Thanks: 31
Fixes: 5
Registered: 26-11-2011

Re: SNR Reset and long dodgy rural lines

Hi Uncle_Meat,
Your analogy's did make me laugh Smiley
Quote
Just a quicky this time, as the actress said to the bishop....

Quote
Target SNR goes up like a politicians housing allowance

Anyhow, with regards to your questions;
There's already an order in place to move you to ADSL2 as BT are currently phasing out 20CN in exchanges that have 21CN in them. We're expecting this change to go through and complete on 24/04/2014. We'll be in a position to look at getting your SNR fixed to 6db or 9db.
I've managed to squeeze in an SNR Reset and I've updated your internal Speed Profile which I hope will bring your speeds up whilst we get you moved across onto 21CN. My advice would be to see how things go with this reset in place.
Chris Pettitt
Cloud Environments Engineer
PeeGee
Aspiring Pro
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Registered: 05-04-2009

Re: SNR Reset and long dodgy rural lines

Quote from: Uncle_Meat
Finally, as before.  ADSL1 vs ADSL2/2+   Any advantages, apart from mellower DLM, on long lines (Attn 58db)?

You may get a few extra (around 32) frequency "bins" - a bit extra speed and higher attenuation. I get up to 3.6Mb/650kb (usually 3.3Mb/600kb) on ADSL2 with 61.9/37.7dB attn., 6dB SNRM and uncapped uplink using 159 "bins", but the line is all underground. With your attn, ADSL2+ will not be used.
Plusnet Fibre (Sep 2014), Essentials (Feb 2013); ADSL (Apr 2009); Customer since Jan 2004 (on 28kb dial-up)
Using a TP-Link TD-W9980 modem-router.
Uncle_Meat
Grafter
Posts: 167
Registered: 04-08-2007

Re: SNR Reset and long dodgy rural lines

Ahh. Cheers for that Chris, I'll resist the temptation to tweak my target SNR over the next week or so in case I invoke the anger of the DLM Gods.  Let's hope the weather plays along for me too.. 
Ta for the heads up on the ADSL2 regrade, it'll be interesting to see what affect that has upon the lines around here in rural Wales. The thought of some people being able to get over 8Mb?  Witchcraft!  There'll be BTO sparkys being burned at the stake!  I realise I'll not be approaching those heady 8Mb+ heights, but if it makes things more stable that's definitely a good thing. Smiley
PeeGee. 
Well, if I get anything approaching what you get, with stability, I'll be a very happy camper indeed.  I did think that 2+ would be unattainable for me, with my line and so on, but with 2 being nice compromise between the two, a bit of a potential speed bump but a more mature DLM (ADSL2/2+ appears to have grown up a bit with DLM, as opposed to 1 that reminds me of an angsty teenager "not fair! *storms off upstairs for 3 days*  type DLM)  that'll do for me. Smiley
Uncle_Meat
Grafter
Posts: 167
Registered: 04-08-2007

Re: SNR Reset and long dodgy rural lines

Evening all.  Still having connection problems here, my IP profile is still down in the dumps after that SNR reset as the line is all over the place at the moment.  I realise that I'm being shifted to ADSL2 in a couple of days so didn't think to make that much of a fuss just yet, but here's some graphs for now from Router Stats.
One, from overnight on the 16th and another as of so far this evening.  I'm going to try going around the wiring in this place at the weekend, with being rented property and with the master socket being in the landlords part of the house I can't really go fiddling in the middle of the night, but nothing has changed here at least and the phone at least is working as well as always, and no noticeable noise when trying a quiet line test.
Any ideas folks?
Superuser
Superuser
Posts: 11,889
Thanks: 3,250
Fixes: 22
Registered: 22-08-2007

Re: SNR Reset and long dodgy rural lines

Hi,
Those are really horrible graphs!  Something is "hammering" your SNRM down into the ground.  The resynchs are each at a lower synch speed, which "restores" your SNRM, only to hammer it down again.
I take it that your router is on a (long?) extension phone socket?  If this is correct, what kind of cable connects the extension socket to the master socket?
Does the landlord have other extensions connected to the master socket?  If yes, how are they wired?  They should be daisy-chained, star connected can cause problems such as those you are seeing.
Does the landlord have phones connected to the line?  If yes are they all on filters?
How good is your relationship with the landlord?  You might need to get access to the master socket to perform some tests / inspect the extension wiring.  There should only be two wires connected (blue/white & white/blue) to pins 2 & 5.  If there is a third wire (bell wire) this can cause problems and may be disconnected.
The source of the interference could be nearly anything, I would suggest from the look of those graphs that there is a faulty power-supply-unit (mobile phone charger, laptop charger, possibly even the router power supply), plasma TV... somewhere nearby.  It needs to be identified and replaced.  You might be able to identify the source by switching off electrical equipment and look to see what happens to the SNRM line.  Typically having found the source of the noise, the SNRM will take a sharp step up.
HTH.
Uncle_Meat
Grafter
Posts: 167
Registered: 04-08-2007

Re: SNR Reset and long dodgy rural lines

Yep, they are pretty nasty..  I was going to post one from overnight until this morning but I was a bit behind getting ready to go out to work, but overnight graphs fairly similar.  After resetting the router at just after midnight, I synced at 1600 or so with 9db SNR which gradually tailed off through the early hours until a resync at 980kbps and then SNR popped bacak up to 12db or so and then started to tail off again.
It's an old farmhouse on the end of an old rural line which is overhead for quite a lot of its distance, and we have had problems with it before, all external problems with the last one being the last couple of drops being replaced due to it coming down in strong wind last December.
As for the house wiring, my router is on an extension socket, which also has the landlords cordless phone base plugged in and another long extension which goes to their sky box.  The master socket (if indeed it has one, it is an old house after all.. Might be one of those old "soap bar" junctions for all I know) I assume is upstairs as the landlord has said there's an unused socket up there.
My plan is, when I get around to it, try the router in the master socket if I can, I've got an NTE2000 here in work which I can pinch and do some strategic rewiring, see how that affects things. Just all a bit curious as things have been OK for some years now, with all this kicking off after those last couple of drops being replaced last year.
As for REIN, I've got a shedload of SW/HF band radios here, as well as a 110ft doublet antenna which, in part, runs along the eaves of the house and I've not noticed any correlation with my SNR playing up and increased background noise on the HF bands, although to be fair I've not tried too hard to pick anything out sub 1Mhz in ADSL territory.
As before, I'm supposed to be getting put on CN21/ADSL2 in the next few days, so see how things pan out once that happens.
Superuser
Superuser
Posts: 11,889
Thanks: 3,250
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Registered: 22-08-2007

Re: SNR Reset and long dodgy rural lines

Wow, if any one has the kit to look for REIN interference then you have!
The aspect of your SNRM plots which I do not "get" is that after each resynch at a lower speed which delivers the target 9dB SNRM the actual SNRM decays identically.  That somewhat implies that there is a constantly increasing level of REIN.  That does not seem to make sense!
If you are looking at extension wiring, it would be a good opportunity to remove the bell wire and check out for star connections.  If you need help. please ask!
Uncle_Meat
Grafter
Posts: 167
Registered: 04-08-2007

Re: SNR Reset and long dodgy rural lines

Evening all. Been away a bit so just back with an update.
Well, it still sucks.  Cheesy
I had a quick shufty around the phone wiring here, no NTE master socket as such, it's the old "Soap Bar" type box where the line comes into the house, that then goes to another rectangular connection box and then downstairs to the only phone socket in the house.  All other extensions here are "plug ins", with just one going over to the sky box and another to a wired line.  Obviously, I have my filter plugged in first on this socket.
So, thing to do next is have a peek inside the "soap bar" and see how manky the wires look, and take it from there.  Any ideas on this kind of wiring? At what point would I find the ring capacitor/bell wire in this scenario so I can disconnect and see if that helps at all?

Secondly, one for you good folk at PlusNet.  Looking at my router stats, it seems I'm still connecting via ADSL1. Can I take this to mean that the ADSL2/2+ regrade has not gone through yet, or is it just that my line is currently too dodgy to make use or attempt to connect 2/2+
Finally, are there any line tests you can try from your end of things that might give me a clue as to what might be going on? 
Earlier today I went from no connection whatsoever to 600kbps or so sync with 12db SNR with that doing it's usual fluctuations/drop as you can see on the above graphs.  Whilst this was going on, I had a couple of receivers tuned to various low frequencies (177khz, 300khz, 500khz) and also had a wander outside by where the line comes in (it comes in alongside the electrical cable btw..) with a handheld SW radio and never noticed any appreciable extra noise above the usual atmospherics you get on the HF bands.  I've currently got a radio on now connected to a 110ft doublet antenna which runs, in part, along the eaves of the house and I'm not noticing any extra buzzes, squeaks or pops that I would associate with noisy switch-mode PSUs, plasma TV or owt like that.
As interference from elsewhere, as the line runs the next property is about a mile further along the road, going towards the exchange, so nowt else immediately local kind of thing, that could affect it.

Good fun, this chasing fault stuff!
Superuser
Superuser
Posts: 11,889
Thanks: 3,250
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Registered: 22-08-2007

Re: SNR Reset and long dodgy rural lines

Goodness - rat's nest wiring!
Who provides the phone service - PN or someone else?  I think I'd be asking the phone supplier to provide a "suitable for ADSL" rectification of the not fit for purpose wiring.
I cannot answer some of your key questions. but I can provide the following advice...
1. Wiring to extensions should be daisy-chained from one socket to another and not STAR wired from a single or multiple points.
2. All "phone" type devices must be connected to the line using filters - this alone could make a significant difference to ADSL performance.
ADSL2 - what does this - http://www.kitz.co.uk/adsl/adslchecker.php - say is available?
Uncle_Meat
Grafter
Posts: 167
Registered: 04-08-2007

Re: SNR Reset and long dodgy rural lines

Yup. All the extensions are daisy chained, as before there is only the once actual socket in the house, with the extensions being plug-in ones.  However, it is quite a long bit of wire from where the line connections to the house to where the socket is.
My exchange is ADSL2 enabled, and according to support I was supposed to be getting moved over to that on the 24th.
As of now, I have no sync whatsoever, posting this whilst tethered to my mobile phone, which has a far higher connection speed than my broadband!
<a href="http://www.speedtest.net/my-result/3470538702"><img src="http://www.speedtest.net/result/3470538702.png" /></a>

Hmmm
Superuser
Superuser
Posts: 11,889
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Registered: 22-08-2007

Re: SNR Reset and long dodgy rural lines

Hi Uncle_Meat,
I think we need to take this one back to basics and check out some not asked / not answered questions.
You said that the master socket in in the landlord's part of the house.  Who "owns" the phone service - you or the landlord?  I take it that you "own" (pay for) the BB service - I can conceive that possibility that you do not though "own" the phone service, which could make this even more difficult to fix.
Can you describe in detail the wiring from the over-head drop on to the "property", through to the master socket / extensions etc. to the point where the router is?  Consider how wired to the sockets (rear connected / from face plate / via socket doublers) / wire type / shape / pinned down / hanging loose / coiled up and where the filters are.  Ideally it should be now worse than somewhat like...

< drop wire into property > - [ master socket ] - < phone grade wire from / to back plates > - [ extension socket ] - [ ADSL filter ] - < standard router cable > - [ router ]
                                               \ [ ADSL filter ] - [ phone ]                                                         \- [ phone ]

There should be no star connections (more than one extension wire from one connection box).  Extension wires from the MASTER socket only need two wires connecting (blue/white on pin 2 and white / blue on pin 5).  Older installations might have more than 2 wires and be of a different colour.  If this is the case, then I'd want to try to get BTOR to update the installation before trying to fix the BB issues.
You state that you cannot synch - do you still have a dial tone?  If not then that fault needs rectification first.  Is your modem still trying to force a 6dB SNRM?  If this cannot be attained, then the modem will never synch.
You have not posted a full set of router stats, thus your line attenuation is not known to forum members.  Chris said that you are to be moved to 21CN - this does not assure you of ADSL2/2+ operation.  Depending on your line characteristics (which sound bad) you might find that the line will only support ADSL(1) modulation.
Plusnet Staff
Plusnet Staff
Posts: 6,346
Thanks: 31
Fixes: 5
Registered: 26-11-2011

Re: SNR Reset and long dodgy rural lines

Just to chip in here, the order doesn't look to have gone through correctly so I've re-placed it for you. Please allow 5 working days for this to complete.
Chris Pettitt
Cloud Environments Engineer
Uncle_Meat
Grafter
Posts: 167
Registered: 04-08-2007

Re: SNR Reset and long dodgy rural lines

Righto, where do I start. Cheesy
Yep, the line is owned by the landlord and I just pay for my BB service upon it. The drop comes into an upstairs spare bedroom into an old "soap bar" type junction box.  Cable from this junction box runs along the skirting board into another oblong junction box and then downstairs to the only phone socket in the house, which I assume must be the master socket, but it's not a more modern NTE5 removable faceplate one.   All extensions are wired as "plug ins" to this socket, just two which is to a sky box and a phone handset, both of which are filtered at the end of the extensions as well as having a pigtail filter plugged into the socket. I've tried replacing filters around (I work in a computer shop, lots of filters for me to pinch from work and play with) with no noticable difference.
Line attenuation, when things where working OK was 58db down, however since this has been playing up even more the last time I checked it was 63.5db, and with the DG834v4 I've read somewhere that this could be even higher but the router will only report a maximum of 63.5.  Saying this, even when it was reporting 63.5 I could still hold 2Mb for periods of time with a reasonable SNR.  
At the time I had no sync whatsoever, I could still get a dialtone and make/receive calls with no noticable cracking or noise on the line. I asked my landlord if he had noticed any deterioration or problems with the phone, but he only uses it rarely and has yet not noticed owt wrong.  Also, where I had been tweaking SNR on my router, I've "detweaked" since all this had been playing up and just allowed the router to connect with default settings.
As for ADSL 1/2/2+, I was more curious if that had gone through yet.

My plan is, when I get around to it, is to have a look inside those junction boxes first armed with some deoxit and a toothbrush, it's an old building and the internal wiring must be decades old.  So, try that first and, if no luck, try persuading my landlords service provider that the line is fundamentally iffy and can they ask BTO to pop in and fit a nice, modern NTE5 box.

As before, it's not been quite right ever since BTO replaced 2 drops that came down in a storm last December, so I still suspect that but before I can point towards that for certain I'd like to make sure everything from the junction to my router is behaving itself first.

*final edit*  Cheers for that Chris, however I think I need to get this line diagnosed first!  Any available diagnostics from your side of things that might help in nailing this down?