In reply to a post by adslmax:

BT Openreach should have two FTTC's cabinet in halfway between in houses will be no problem at all. Reason is BT doesn't want two cabinets in same area. And a silly to put cabinet long distance away from some houses who unable to get VDSL because too long over 3km away. So, putting two cabinets each 1.5km rather than 3km away will solves it.

To put an FTTC cabinet 1.5km nearer the far houses would mean also putting a PCP there for those lines. That's a rather major task.

On top of which the last few houses on the first cab would get very upset when the next house down their street got 80/20 from the new one.

The only way it works fairly with a 3km gap would be to put the new one 2km from the first and feed both ways for 1km. Making it even more expensive and non-viable.

Also opening up a national demand never to be more than 1km from a cabinet.

In reply to a post by RobertoS:

In reply to a post by adslmax:

because too long over 3km away. So, putting two cabinets each 1.5km rather than 3km away will solves it.

To put an FTTC cabinet 1.5km nearer the far houses would mean also putting a PCP there for those lines. That's a rather major task.

It also belies the statistics, and simple mathematics.

The Sagentia report indicates that there are about 2% of lines that have a D-side length of more than 1.5km. This 2% of lines is the starting point of the market for this product.

If there are 300 lines on a cabinet (the national average), then on average, only 6 lines exist out beyond 1.5km. @adslmax is making a lot of fuss (an awful lot of fuss) about a very small group.

In some cases, there's a good chance the long lines are roughly in the same direction - so a cab would work. For the kind of size we're talking, that 2% doesn't merit a full FTTC cabinet as we see them today - something sized like the FTTRN node would do ... which we know BT are already working on; part of the target market gets dealt with that way.

In other cases (especially the very rural), the long lines are more likely to radiate in all directions, so you'd need more than 1 cabinet to cope with them (it would more likely require at least 6 cabinets to fully surround the original). That becomes even more of an economic problem.

If BT find it hard to make a cabinet of 300 lines commercially viable, adding 6 cabinets for 6 long lines is never going to work.

It is almost certainly a very small group that this is going to work with.

If ADSL1 was available in the first instance if that helped to limits the affect on the co-located VDSL2 lines would be appreciated. The proposal makes a lot of sense.

In reply to a post by MrSaffron:

Most likely most people lost both wires in their pair and this person was the lucky one

No, this was the strange thing, even the local paper reported on the hundreds that lost their phone connection but unusually most still had an internet connection!

Sounds more like a blown line card, or subrack, in the exchange.

In reply to a post by WWWombat:

Sounds more like a blown line card, or subrack, in the exchange.

The big delay we faced waiting for the repair was the road where the lightning struck is a main route in/out of St Ives or a better description is 'the main route' for St Ives! The Highways restricted Friday and Saturday working to avoid impacting the holiday makers, so on the Monday night the road was closed and they did an overnight cable replacement, so it was definitely a fried cable!
So in summary a fried cable, hundreds lost their telephone service but most still had internet......

As a follow-up, I found another NICC document that describes the use of DSL systems:
http://www.niccstandards.org.uk/files/current/ND1405...

Section 6.9.1.2 describes the use of ADSL2+ in a cabinet, with the phrase "The [DSLAM transmit power] mask for all Annex (A, B, I, J, and M) is not supported by the ANFP without downstream spectrum shaping" - so we definitely will see power shaping/reduction applied at the cabinet.

The document includes a graph (figure 25) that shows the standard ADSL2+ power mask overlaid over the power shaping masks that apply to VDSL2 at the cabinet.

Even without the dips associated with the power cutback, it can be seen that the maximum power at the cab, for the bulk of the frequency range, is about 10 dBm/Hz lower than the maximum power from the exchange.

That's going to hit the speeds available too: I reckon that is worth 2 bits on every tone up to about 1.2MHz, then 1 bit up to 1.4MHz; equivalent to losing approx 4Mbps.

And, If I've read it correctly, the ADSL (not 2+) power mask allows that variant to be transmitted from the exchange at 3 dBm/Hz higher than ADSL2+ (which might explain why, on long lines, restricting the modem to ADSL does better than allowing use of ADSL2+). That too wouldn't be allowed at the cabinet, and would be brought back down to the VDSL2 levels.

Nobody knows the availability or pricing of this yet.

My pcp is serving quite a few on 1.5km plus more on 1km because of its stupid position

nice info, by the way I think adsl2 is best for long lines providing the dsl modem works properly on it.

When i was on ukonline, the sync speed was lower and stability was worth with adsl2+ than adsl2, my adsl2 sync was as good as adsl1 but had the benefit of SRA.