Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[waltergmw]

Gentlefolk,

We have been grinding on with a long-lasting difficulty for an EU who should have a near-perfect VDSL service as estimated by both BT Wholesale and Openreach (See below on the estimator data).

The last Openreach engineer spent a long time swapping pairs from PCP 76 all the way to the house which did improve matters as shown on the bit loading graph; but in so doing has left a very nasty bridge tap on the Hlog graph.

Out next problem is convincing the (uninformed) case handler that there is a bridge tap and then get it fixed.
He still insists that the Wholesale estimator tells him there is no bridge tap !

Kind regards,
Walter

[WWWombat]

That certainly looks like a bridged tap.

With the first dip at around tone 100-110, one formula tells you the extra wire is about 340ft in length.
Another method, when looking at the dips at tone 100 and 1,000 (with 3 sub-dips inbetween), suggests a length of roughly 100m.
Could that relate to something in the house or premises? or the length of the drop wire?

Persuading BT, though, isn't so easy.

The usual way would be through the consequences the bridged tap causes - ongoing SNR variation and disconnection problems, or significantly low speed.

Unfortunately, the downstream doesn't seem to help you there. While you get troughs in the Hlog (and signal), you also get troughs in the QLN ... so the bitloading stays relatively even ... so the sync speed isn't particularly affected.

Upstream is different, perhaps affected by the way UPBO works to adjust upstream power. There are dips in Hlog, but no difference in QLN, so there are significant dips in the bitloading. Upstream is slower than it would otherwise be ... but I don't think Openreach have fault threshold in this direction. And, as it reaches 10Mbps anyway, it might be hard to persuade anyone of a fault worth pursuing.

[waltergmw]

Thanks very much indeed WWWombat for that useful information.

The EU is, not unreasonably, peeved that he is paying for a premium rate VDSL service but not getting it - particularly on the upstream.

We had noticed a degree of reluctance, prevarication and unfamiliarity - not helped by the BT Wholesale estimator clearly showing that there is NO bridged tap!
That is compounded by statements that the line test does not show a fault.

All of which, despite many hours of chats, leaves the EU nearly incandescent!

I've never understood why the estimator shows the "Left in jumper" against ADSL offerings either - when it's clearly a VDSL function.

Kind regards,
Walter

[Moderator edited to fix a typo.]

[waltergmw]

We are now told that BT Retail are unable to communicate with Openreach but we have been rewarded with this link to raise a complaint direct to Openreach !

https://www.formwize.com/run/survey3.cfm?idx=505d0401000108

[burakkucat]

I've never understood why the estimator shows the "Left in jumper" against ADSL offerings either - when it's clearly a VDSL function.

Sorry Walter but there are also jumpers, for G.992.X (a.k.a. ADSL) exchange based services, which can be "left in".

[waltergmw]

@ BKK,

So surely we need BT Wholesale to differentiate between ADSL and VDSL jumpers ?
In this case we know that a VDSL service is running so they are bound to be PCP jumpers, even if the ADSL ones are still in place but isolated by the low pass filters in the FTTC.

Compared to the size of the BT network I've only seen a tiny number of services but they have all been associated with services where I know VDSL is installed.
However I have also seen some VDSL services where the jumpers have NOT been recorded.

Kind regards,
Walter

[waltergmw]

We are most impressed with the speed that the Openreach complaints team have reacted !
However as any oversight by the Openreach engineer can only be fixed by the Openreach team we are less impressed with their response :-

________________________________________________________________________________

"Hi xxxxxx,

Many thanks for getting in touch with us. I'm sorry to hear you're having trouble with your broadband.

Please let your communications provider know as they are best placed to run tests and if needed, arrange for an Openreach engineer to attend.

I'm sorry to redirect you.

Kind regards

Andy

Openreach Complaints Team

If no further assistance is needed, this case will close in 1 working day."

___________________________________________________________

As we have only been given 1 day we are about to express this sentiment to the complaints department and include the Hlog graphs as proof of the situation.

After that, the next email will be addressed to Clive Selley, CEO Openreach

[burakkucat]

I am somewhat amused by the Wikipedia page for the "Curate's Egg".

In the example section it quotes Malcolm Turnbull [1], Australia Federal Communications Minister describing the state of the Telstra copper telecommunications network in 2015, thus --

The copper network is undoubtedly very good in parts, very poor in parts, and probably very adequate for most of it. But it is like any linear network: it will have good bits and bad bits... It's like the Curate's egg; it's good in parts.

[1] https://www.crikey.com.au/2015/08/25/a-big-risky-project-turnbull-says-nbn-cost-will-be-settled-soon/

[WWWombat]

Thanks very much indeed WWWombat for that useful information.

I appear to have concluded that the line was running at 10Mb upstream, but there's no such data. I was obviously confused with a previous thread I was looking at. Sorry.

What sync speeds were being reached before and afterwards?

[waltergmw]

The line stability was quite variable and at one stage seemed to have been constrained by a 40 / 10 profile.
Most of the time download sync speeds of 49.8  now up to 57.5 Mbps.
The line is still well below the Openreach and BT W range B figures:-

Estimated down speed: 77.68 Mbps
Estimated up speed: 20 Mbps

whilst the next door neighbour within 10 m of this EU regularly obtains 68.5 Mbps with the same estimates too.

Here's the latest picture after the bridge tap disappeared.

[Moderator edited to remove the PDF file and replace with a PNG file of the same image.]