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[The black Mamba]

Hi Ren
Are all the three lines with the same ISP in my thinking the results should be the same.
Regards Phil

[The black Mamba]

Hi Ren
Please check if all three lines have the new Master Socket.(speed point)

Regards Phil

[jjpearce05]

Whats the difference between low and high - my line syncs at around the "clean" low rate, not the high - the higher is higher than the estimates BT have ever shown for my line !

[Chrysalis]

gusy check my new thread, basically a whole can of worms has been opened as far as I am concerned.

My new impacted estimate is EXACTLY the same as my previous estimate, that suggests my line is in a impacted state.

Greybeard who previously took interest in my line may take interest as well.

[renluop]

Sorry if I wasn't clear in that last post of mine.

The details were the theoretical ones from the BTw estimates.

In real life they do in fact have fibre via PN and get the full whack, being 160 metres from the cab

[renluop]

I found that the harmonic mean of the estimates for my would-be connection were not that far from the old style estimates. I wonder what formula they may be using.

[Chrysalis]

ok crossposting this here as I think is relevant.

Plusnet have revealed the gains of vectoring so far arent great, considering some of us have seen speed drops of around 40mbit and 15-20 isnt uncommon, plusnet reporting gains of 10 is underwhelming, and it would seem more is at play than direct crosstalk.  After flashing the new firmware I now see some more data on my graphs which suggests BT are cutting power back in addition to crosstalk issues.

Pasting below.

I flashed my modem today with the new firmware.  The one with btagent removed and gui added.

Made some graphs, and something interesting has come to light since these graphs now show upstream data I wasnt seeing before.

They show.

Upstream attenuation lower than adjacent downstream tones (BT artifically increasing my downstream attenuation?)
Massively lower QLN on U1 tones, easy to see why, see next.
Massively reduced SNR on U1, power cutback for sure.
SNR on U2 almost as high as end of D1.  Can clearly see my U2 has more snr than adjacent downstream tones.  This is even same QLN on U2 as downstream this is a reasonable indication the downstream has power cutback on it.

[Black Sheep]

Black sheep, sorry I only just found this thread.

I actually thought you told me you never see big crosstalk before (apologies if you never said that)

I was one of those saying I think crosstalk is a big problem at least for some lines.

so if you want my opinion is 15meg crosstalk realistic on a line that synced at 80mbit? absolutely.

My line I have estimated roughly 40mbit lost to crosstalk down from 110 to just under 70. Plus 9mbit lost on the upstream from 36mbit to 27mbit.

Just seen this myself, after having taken a break from the t'internet.

I honestly can't remember saying I've, "never seen big crosstalk" ?? If I did, it may have been during my early days of VDSL faulting, when the learning curve was steep and the amount of VDSL-enabled EU's was relatively low ?? Ergo, low levels of X-Talk. I can't remember ??

I'm still awaiting the official feedback from the vectoring trials. There are 'Internal viewing only' (oo'er missus) 'docs' on our 'Intranet', showing various results at various stages on differing line lengths, but they are not the easiest of 'docs' to interpret. Lots of acronyms and jargon that I've never heard before ??

I'm sure something will happen sooner rather than later, as feedback to the Chief Engineer's Office gathers pace due to increased VDSL take-up ??

[Black Sheep]

Hi. Customers
On the provision of a new instalition from the Cab D side a high and low insulation test should be taken to the Master Socket. ( speed point )
This consistes of A and B lines to Earth plus loop resistance in ohms these results should be given to the customer in their contract with there ISP.
This test will not pick up slip pairs on an unbalanced cable but these will be corrected by the special faults group in my day.
All overhearing faults if were difficult or vague were passed to SFG.
Regards.  Phil

Hi Phil

I haven't heard of this myself. But with the 'Self-install' being very new to the business, maybe the protocols haven't filtered through to the ones that need them, ie: the engineers ??.

If the tests you mention are to be carried out from the Cab looking towards the Master Socket, then a very easy test for 'Split Pairs' would be the 'AC Balance' test. Literally two presses of a button and the results are there. A little more in-depth to perform but still do-able, would also be to test for 'Noise'. Both these tests would give an indication as to whether a 'Split pair' was in use ................ obviously, that is dependant on the fact that all the other MPF tests pass conclusively. 

[kitz]

Ive posted about this else-where but I feel it also needs to be added here.

When BT first brought out the 'impacted info', my own line data still showed the same estimated speed for impacted. Both lines of data were the same.   Over the past few weeks, my max headline speed has now dropped due to cross-talk, meaning that anytime now Im expecting this to have a real impact on my connection speed.    Suddenly some-time over the past week, for the first time the checker is returning a different set of speeds under 'impacted'.   They definitely were not there last year - Ive checked many times in the past.   

Is it a co-incidence that impacted figures of 63Mb now have appeared only when the possibility to affecting my connection speed through cross-talk.   My clean is still showing at 80Mb, but impacted goes down as low as 53.8 Mbps.

[waltergmw]

Re replies 38 & 39, can anybody enlighten me as to how such tests can be performed everywhere when there appear to be so many subcontractors who have no more than an inverter-powered modem without any access to port 2 ?

Surely there can be little point in the noble Black Sheep and his flock placing their seal of approval on the relatively small number of lines they can be involved with, leaving a nasty but undefined mess elsewhere.

I would also like to know what End User commercial conditions are applied to any achieved repairs of impacted lines.

Kind regards,
Walter

[Black Sheep]

Nail on head, Walter. This is as much a bug-bear with genuine engineers as it is EU's and ISP's alike. There's always been, shall we say 'Issues' raised, up the management tiers as to why our headline product was being a) Installed by the junior members of staff ie: the ex-MOD guys, and b) Allowed to be repaired by severely under-trained engineers, some of whom still have only an analogue SA9083 as their means of testing.

In BTOR's defence, our then CEO (Liv) addressed the tools issue, and has made massive headway in getting engineers kitted out with the necessary. The Contractors ?? Can't comment on that as I have no dealings with them.
However, even with the right kit you still need to have a healthy understanding of the electrical principles to decipher what the instruments are telling you.

We do have some good apprentices coming through the ranks, but we have far more staff that require a better understanding of our job. I lay that particular blame firmly at the 'BT training' door.   

[waltergmw]

@ BS,

As well as electrical principles, perhaps we could also include a detailed understanding of DLM logic**, the effects of using Huawei and ECI modems on the "opposite" MSAN equipment and the changes which are quite obviously included within each new updated modem firmware release on both platforms.

"Simples" it is NOT !!!!

** Just as a trivial example, who can tell me why some VDSL services are capped (banded ?) at integer sync speeds whilst others wander about just as the spirit takes them at any sync speed they select ?

Oh, and don't forget the joys of self install by EUs provided with standard dongle filters and who can't even recognise what a ring wire is; let alone the benefits of an integral filter faceplate.
(E.g a Sky self install with a BT Wholesale estimated 42.4 Mbps but actually achieving 13 Mbps.)

Kind regards,
Walter

[Black Sheep]

I have to say, I don't know anybody who has a full understanding of DLM logic. Not even our resident brain-boxes have the complete picture on that one, but I take your point about 'awareness'. The only addendum I would add to that, is if the engineer has comprehensively ensured that the MPF is as good as it can be, then DLM activity is nothing to do with us ..... see: RFI, REIN, EMI etc etc .

I personally do not think self-install is a good idea, and won't be as big as some think. I probably get one a fortnight whereby the EU has 'No synch'. They have usually moved into a new premises and inadvertently plugged a micro-filter into an integrated filter. This should of course, be resolved via the 'Fault reception' front desk, but it isn't. I shan't mention which ISP tends to be the guiltiest regarding this, suffice to say they are the ones that are pushing the self-install product more than any other.
The same example would probably follow during a VDSL install with some EU's ??

Lets be reasonable here though, these ISP's aren't in business for nothing. They will (as they always do) be working on 'percentages' as a business model, in as much as most EU's will manage a self-install if they choose to, thus enjoying a cheaper 'Customer experience' . The rest will need help to maximise their installation, and will have to pay for it.
 
Cheers Walter.