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Standard User Zarjaz
(knowledge is power) Sat 28-Jan-12 12:35:09
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Re: Attainable Rates dropped


[re: Bald_Eagle1] [link to this post]
 
The affected service was in the office of the factory in question. I can't remember what kind of light it was, big [censored] up in the factory/warehouse ceiling, very expensive/bright.

The big p**s take was that the punter already knew that they were causing a problem, as had been identified before by a REIN engineer previously when they had ADSL. They were declining to do anything about, and yet happy to keep moaning to their ISP.

There's no pleasing some folk. [sad]

Administrator MrSaffron
(staff) Sat 28-Jan-12 12:43:45
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Re: Attainable Rates dropped


[re: Bald_Eagle1] [link to this post]
 
Ranges of 100m are not unknown for RF problems.

Also as VDSL uses a much wider range of frequencies it may start to show up new sources of REIN. Odd that with the UK being so far behind that there is so little information from other countries on this - one could conclude that just maybe either

1. The UK is really not far behind the curve
2. We want other people to fix things
3. We enjoy moaning

Andrew Ferguson, [email protected]
www.thinkbroadband.com - formerly known as ADSLguide.org.uk
The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
Standard User Zarjaz
(knowledge is power) Sat 28-Jan-12 12:59:33
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Re: Attainable Rates dropped


[re: MrSaffron] [link to this post]
 
Ranges of 100m are not unknown for RF problems.

Easily, when airborne, even further if the source has an easy path on to the bearer network, Sky boxes for example.


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Standard User woodyblade
(newbie) Sat 28-Jan-12 13:13:38
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Re: Attainable Rates dropped


[re: Bald_Eagle1] [link to this post]
 
@Bald_Eagle1

Yeah I thought the stats looked ok from when I was looking at them.

How would I log results in Putty that's how I've been reading the more detailed stats currently?
I did attempt those scripts but don't think I've set them up correctly.

Yep knew about not mentioning the modem stats to BT, as for the quiet line test we only have cordless phones in the house so not an accurate measure, but listened to it for a minute and there was no crackling or clicks that I could hear, just a faint buzzing but I'm pretty sure that's because it's a cordless phone.
As for using the phone the SNR does drop ever so slightly 0.2 on DS, but I doubt that is anything to be concerned about, as a side note it was worse than that, the line previously dropped out on ADSL, dropping approximately 3-4db when using the phone and I'm pretty sure we never found that problem, we switched providers at the time from TalkTalk to Sky and it didn't crop up again, though the SNR still did drop when we used the phone.

----------------------------------------------------------------------

@Zarjaz

Yeah this wire connects between our old master socket (which the BT Engineer said is now inactive) to the new one, I would assume it's ordinary phone extension cable.
Yes this is fastened down with metal staples, I'll reiterate (though I know I should see line attentuation increase as well) that they really are fastened down tight to the point of crushing the wire at every point the staples are at and as mentioned one does look to have pierced the wire.

I'm not sure what you mean by this part exactly, I've never seen a small computer symbol "does the the socket where the modem plugs in have a small computer symbol on it ? If so, are these cleats or staples that have been used to fix between the two ?"

Cross talk does seem more plausible at the minute and I wouldn't be surprised if someone had it installed recently with the rubbish ADSL speeds round here, the cabinet does serve about 20 different postcodes, plus there is a Digital Region cabinet as well, installed about 3-4 months ago, so the possibility for a lot of connections.

I've not used the HH3 router since the first day it was installed, once the BT Engineer went I took it out and put my own back in.

I may have a look at phoning BT's support line but will wait and see what BT estimate in the updated data soon, ironic that the attainable rate drop happens a week before BT update the speeds on the checker.

--------------------------------------------

@RobertoS

Yeah didn't mean to explain it like that, in regards to HH3 being the only sign of fibre installs, just that I doubt there has been such a big increase in installs to cause such a drop in attainable rates.

Thanks for the replies so far as well
Standard User Bald_Eagle1
(member) Sat 28-Jan-12 14:42:17
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Re: Attainable Rates dropped


[re: woodyblade] [link to this post]
 
In reply to a post by woodyblade:
@Bald_Eagle1

Yeah I thought the stats looked ok from when I was looking at them.

How would I log results in Putty that's how I've been reading the more detailed stats currently?


These are the PuTTy settings that I used to use (manually):-

1) Open PuTTy
PuTTy_1

2) Click on Logging:-
PuTTy_2

Browse to a folder of your choice & enter a name for the log file (if one isn't already offered)

3) If you get asked about overwriting, click Yes:-
PuTTy_3

4) Type in the first xdslcmd:-
PuTTy_4

5) As soon as it has finished, type in the next command:-
PuTTy_5

6) When you have run all the commands, close PuTTy by clicking the red 'X' then click "OK":-
PuTTy_6

7) You should end up with a text file that contains ALL the relevant data:-
PuTTy_7


The resulting log file is too big to post in a forum (thousands of lines).
Either upload it somewhere & post a link to it, or PM me with your email address & I'll let you know how to get it to me so that I could plot the data for you (as a one-off).



I did attempt those scripts but don't think I've set them up correctly.

You could have a look here. It MIGHT help to simplify things:-

Step-by_step


As for using the phone the SNR does drop ever so slightly 0.2 on DS, but I doubt that is anything to be concerned about

Yep, that's all I get since the engineer replaced a section of drop wire.
I would guess that is normal?

HTH,


Paul.

Edited by Bald_Eagle1 (Sat 28-Jan-12 14:44:09)

Standard User Zarjaz
(knowledge is power) Sat 28-Jan-12 15:37:30
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Re: Attainable Rates dropped


[re: woodyblade] [link to this post]
 
Yeah this wire connects between our old master socket (which the BT Engineer said is now inactive) to the new one, I would assume it's ordinary phone extension cable.
Yes this is fastened down with metal staples, I'll reiterate (though I know I should see line attentuation increase as well) that they really are fastened down tight to the point of crushing the wire at every point the staples are at and as mentioned one does look to have pierced the wire.

I'm not sure what you mean by this part exactly, I've never seen a small computer symbol "does the the socket where the modem plugs in have a small computer symbol on it ? If so, are these cleats or staples that have been used to fix between the two ?"

Sounds as though the engineer has extended the internal wire and shifted the NTE, rather than fit a data extension kit. In this instance, staples are acceptable.

Standard User woodyblade
(newbie) Sat 28-Jan-12 16:01:27
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Re: Attainable Rates dropped


[re: Bald_Eagle1] [link to this post]
 
@Bald_Eagle1

Ran those commands in Putty and got a 330KB file, what software would I use to plot the data, GNUPlot?
I'll send you an PM about sending the file over.

EDIT: Managed to get those scripts working now, it was me skim reading over things (it'll get me in trouble one day), didn't set the system path correctly, now I just need to work out how to set them to record data for set times, can't work that bit out (or I may have missed it in the instructions again).

Ok got it set to run every minute via Windows Scheduler, how can I hide the command prompt from appearing everytime?

@Zarjaz

Ok no problems, guess the wire is fine so I'll have to assume the problem if any is external, as the modem is the first point after the wire into the house.
Yet another unknown to how this line works.

Edited by woodyblade (Sat 28-Jan-12 17:02:52)

Standard User Bald_Eagle1
(member) Sat 28-Jan-12 20:23:50
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Re: Attainable Rates dropped


[re: woodyblade] [link to this post]
 
In reply to a post by woodyblade:
@Bald_Eagle1

Ok got it set to run every minute via Windows Scheduler, how can I hide the command prompt from appearing everytime?


Which version of windows are you using?
Standard User woodyblade
(newbie) Sat 28-Jan-12 22:08:58
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Re: Attainable Rates dropped


[re: Bald_Eagle1] [link to this post]
 
I'm running Windows 7.
Standard User WWWombat
(committed) Sat 28-Jan-12 23:12:49
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Re: Attainable Rates dropped


[re: woodyblade] [link to this post]
 
Sorry I'm a bit late on this... I haven't had a chance to look through this thread so far.

My glance at the before/after "pbParams" data suggests that:
- The attenuation hasn't changed, so it doesn't look like anything catastrophic has happened to the line
- The power levels have gone up slightly, suggesting that the signal level ought to have gone up slightly
- The SNRM levels have gone down significantly.
- The sync speeds haven't changed

Because the sync speed hasn't changed, the SNRM levels can only have gone down because noise has increased. I don't think it has anything to do with the time of day of the last sync, as you still managed to get to the full sync speed anyway. The increased power means that *something* has noticed this, and tried to compensate; the higher signal level means that noise has probably increased more than the simple difference in SNRM levels.

The questions then are:
- What is the cause of this noise?
- Does it affect the line all the time?
- Does it affect all frequencies?

The more that this noise happens 24x7, the more likely it is to be crosstalk than REIN. The more it is spread over all frequencies, the more likely it is to be crosstalk too (but a little less certainly).

Before attributing things to REIN, and starting a lengthy investigation, perhaps we should consider whether the drop can feasibly be attributed to crosstalk.

My (currently) favourite documents on Vectoring give some good graphs on the impact of crosstalk (so you can then see how good Vectoring is at fixing it). One is found here (look at graphs on page 14 and 15 for 0.4mm cable), and the other is found here (page 9 for 0.5mm cable).

A favourite quote in there is "In an environment where several VDSL2 systems are in the same cable binder, it is FEXT (far-end crosstalk) that severely limits the performance." Just as a reminder that crosstalk is significant... and that the interference comes more from the cabinet-end, so it doesn't have to be a close neighbour to have an effect.

How significant? The graphs suggest, for 0.5mm cable, a speed drop from 80Mbps to 55Mbps (at 3000 feet, or 1000 metres). Or for 0.4mm cable, a speed drop from 70Mbps to 52Mbps (at 1800 feet, or 600 metres.

So that kind of drop *is* possible, but it probably requires more than one crosstalk-ing line.

Probably the first questions I'd ask are:
- How far are you from the cabinet?
- How much does the speed vary over a few days? Are there sharp changes in variation, or just sudden drops & increases?
- Was the drop from 70-80 down to 52 a sudden one, or could it have been spread over weeks?
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