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Attenuation and BT

SamP
Grafter
Posts: 51
Registered: 02-08-2007

Attenuation and BT

My exchange was enabled for broadband in 2003, and since that time I've had a downstream attenuation figure of 58 to 60 dB (measured using more than one router & checked at the master socket's test socket).  This limits the speed I can get.
My exchange is less than 400 metres away, not the 5 km or so that the attenuation figure would suggest.
Last week, BT  replaced the line between my house & the telegraph pole - I was hoping that at last I would get something like a true broadband performance.
Attenuation is now...  still  58dB.
Since the problem isn't in my internal wiring & it's not in the drop cable, where is it?
Is there any way to nudge BT to find & fix this? 
19 REPLIES
Stumpy21
Rising Star
Posts: 156
Thanks: 6
Fixes: 1
Registered: 13-06-2011

Re: Attenuation and BT

Hi
Are you sure that the nearby exchange is providing your broadband?
Check here http://www.samknows.com/broadband/exchange_search
The reason I ask is that my broadband connection is via an exchange that is further away than my closest exchange.  Shocked
Though we did have a line fault a while ago, between the exchange and the cabinet, that caused our attenuation to increase by 12db!
Derek
itsme
Grafter
Posts: 5,924
Thanks: 1
Registered: 07-04-2007

Re: Attenuation and BT

Same here I'm not on the exchange that's 1km away but the one 3km.
SamP
Grafter
Posts: 51
Registered: 02-08-2007

Re: Attenuation and BT

Quote from: Stumpy21
Hi
Are you sure that the nearby exchange is providing your broadband

Yep, I'm sure. 
My exchange wot I am connected to is 301 metres away as the crow flies  (Google Earth).
I realise BT doesn't employ crows to run cables, but even if you triple that figure to allow for cable runs along roads etc. - I shouldn't see an attenuation of 58 dB.
Does anyone know of a magic spell which will nudge BT into fixing this?
SamP
Stumpy21
Rising Star
Posts: 156
Thanks: 6
Fixes: 1
Registered: 13-06-2011

Re: Attenuation and BT

Quote from: SamP

Does anyone know of a magic spell which will nudge BT into fixing this?
SamP

Well if you go through the fault reporting system here http://faults.plus.net/ and Plusnet thinks that you have a line fault,
I believe they can nudge BT.  Grin
Derek
matt_2k34
Grafter
Posts: 1,300
Registered: 09-07-2007

Re: Attenuation and BT

indeed, the extremely crappy attenuation could be caused by something simple as a dodgy line card in the exchange or a (very poor) connection in one of the joints (including the cabinet, or termination point of the house)
what do your neighbours get? (if your at all friendly with them Wink )
Regards
prichardson
Grafter
Posts: 1,503
Registered: 05-04-2007

Re: Attenuation and BT

Either your line is made up of significant volumes of aluminium cable, or indeed there is something fishy going on.
Your line is about 1.9km long, which is accurate, as the local distribution point for all lines it serves, is 1.6km away from the exchange (cable length).
I would raise a fault, but you would be advised to make sure that you put in the notes about either this thread, or a request to check the line length estimates, along with the estimates speeds, all of which clearly show a large discrepancy.
SamP
Grafter
Posts: 51
Registered: 02-08-2007

Re: Attenuation and BT

Thank you,
I've raised a fault as you suggested referring to this thread.
Fingers crossed.
SamP
jim:quote
SamP
Grafter
Posts: 51
Registered: 02-08-2007

Re: Attenuation and BT

In order to round this thread off, here's the result of the BT Engineer's visit.
He spent about 3 hours trying to track down the source of the problem, but was unable to improve it.
He reported that the attenuation between the exchange & the cabinet was reasonable (equated to a speed of about 6 mb),  so the bulk of the loss was in the cable run from the cabinet to the telephone pole (about 300 metres).
He swapped the signal to another pair within that cable but that produced exactly the same figure.
It looks as though I have as good a Broadband connection as is practical.
SamP
Grafter
Posts: 51
Registered: 02-08-2007

Re: Attenuation and BT

Late Update.
We've had a few problems over the last few months where the line has gone dead (on about 4 different occasions).
After the most recent one, a BT Eng found & fixed the fault - at the Exchange I think.
Since this repair, my (Downstream) Attenuation figure has dropped from 58 dB to 29 dB!  (Upstream value has gone down by a similar proportion)
I haven't a clue what he did, but at last I'm getting the sort of speeds I should have had for the last 8 years.
So now, at one and the same time, I'm feeling both very happy to finally have the performance I always though should be possible - and boodly annoyed that this could & should have been fixed years ago.
I bet the Germans have a word for this ambivalence - but it would be 40 characters long.
SamP
itsme
Grafter
Posts: 5,924
Thanks: 1
Registered: 07-04-2007

Re: Attenuation and BT

Quote from: SamP
I bet the Germans have a word for this ambivalence - but it would be 40 characters long.
SamP

Ambivalenz
x47c
Grafter
Posts: 878
Registered: 14-08-2009

Re: Attenuation and BT


Seen this sort of thing before.
Your broadband either starts to detriorate or is clearly not as good as it should be by a clear margin - in your case line attn'.
As BT don't have any guarantee of service level - due to the variability of the cables, and as the broadband is basically working its difficult to get anything 'done'.
So you have to wait until a voice fault appears - and if the broadband problems are serious enough it will appear as a voice fault - eventually.
At that point BT DO have a guarantee of service to fix it - so they do.
Even if this means they have runs out of spares and need to put in a new cable at £30K....so be it - BT picks up the bill.
And as a result the broadband problems are fixed as a "side effect" of fixing the voice call problem.
To be fair to BT they are in an impossible position.
In your case yes, there was something 'up' at the exchange end - but it might have been something in the buried cables after the street box.
Then we have to ask where is the money going to come from to pay BT to dig up and replace these cables (not laid in ducts of course!) at great expense to try and fix someone's slow broadband.  Meanwhile others with no broadband at all are foaming at the mouth at what they would perceive as a 'waste of money'.
So BT do exactly I would do, fix the worst problems, and leave the 'mostly works' alone................................
itsme
Grafter
Posts: 5,924
Thanks: 1
Registered: 07-04-2007

Re: Attenuation and BT

Quote from: x47c

Then we have to ask where is the money going to come from to pay BT to dig up and replace these cables (not laid in ducts of course!) at great expense to try and fix someone's slow broadband. 

Where you live when you walk around don't you see any BT manholes? I think you will find the users that are getting FTTC first are the ones that BT can quickly run fibre down existing ducts.
x47c
Grafter
Posts: 878
Registered: 14-08-2009

Re: Attenuation and BT

In my rural area the situation re cable ducts is that.
The street boxes are fed by cables run in ducts.
After that, the lines out to the individual houses are run in armoured cable buried direct in the ground. This cable has underground joint boxes along the roadside every few 100 yards or so where a group of houses have their supply split off.  This cable supplying this group is then run up a pole and hence either direct to the houses or via a series of poles to a house.
As to the possibility of FTTC coming and ease of installation it would depend on
a) How full are the existing cable ducts to the street boxes to enable to fibre optic to be added to them.
b) whether any of the ducts which do have ample space in them have collapsed ('tis common) which means excavations.
I would agree with you that street boxes which are not fed by cables in ducts present a major problem in terms of excavations necessary to supply them.  It's not just the cost of the physical excavation either, it's the cost of finding and avoiding the other services: gas,water, electric etc, making good after the work ie tarmacing/turfing etc.
sjrinfroyle
Grafter
Posts: 895
Registered: 08-05-2011

Re: Attenuation and BT

I presume if your attentuation has dropped to 29dB that you now sync at 8128 kbps or 7616kbps?