BT FTTC 76/20 downgrade to new 52/10 package? DLM reset

Any definitive answer as to whether DLM will be reset in the process?

Also, is there any reason why BT chose 52 instead of 50?

Edited by smsmasters (Fri 15-Apr-16 15:55:44)

My thoughts on this, given that it will have been defined by engineers and tweaked by product management and marketing/advertising.

The original products were 80 and 40 ... One being twice the other.

In the electronics and communications industry when fitting something between two points it is quite normal to use a ratio rather than the mid point. In the case of two items being separated by a factor of two, the intermediate will often be the square root of 2 (1.414) times the lower. And thus 1.414 time the intermediate will give the upper.

So, 40 x 1.414 = 56.6 and 56.6 x 1.414 = 80

Put the product management spin onto 56.56 and they would say 55 looks to be a nicer number.

The marketing/advertising side has taken the 80 down to 76 to allow for the difference in sync and download speed, - a difference of 4 and similar with 40 being marketed at 38, two lower. It ten follows that a 55 product would need to be around 2.5 lower and thus the figure of 52.

Edited by MHC (Sat 16-Apr-16 13:11:50)

In reply to a post by MHC:

The marketing/advertising side has taken the 80 down to 76 to allow for the difference in sync and download speed

That's actually due to ASA regulations, i.e. advertised headline speeds, or 'up to' speeds, must be consistently achievable by at least 10% of the service's customers, which is why 24 meg ADSL2+ is usually advertised at around 17 meg.

I know that, why do you think I referred to ADVERTISING.

It's not "to allow for the difference in sync and download speed", it's to allow for the sync speeds achieved by 10% of the user base, download speed doesn't factor into the decision.

Rubbish, the sync speeds that were the problem when quoted by ISPs. It is the achievable download speeds which are always below sync.

In reply to a post by MHC:

It is the achievable download speeds which are always below sync.

Yes, but advertising departments always quoted maximum sync speeds, they weren't quoting download speeds to account for overheads and only lowered their advertised sync limits when the ASA got involved with the 10% rule.

Actually Oliver, MHC is right on this one. The major ISPs easily meet >10% users on max sync for FTTC and the 'up to' speeds are an attempted calculation of download speed after overheads. (I think BT came up with the figures and everyone copied blindly...) Congestion is effectively ignored because off-peak speeds are sufficient to substantiate an ‘up to’ claim.

partial DLM reset.

It seems if the line is banded it wont be removed as reported by multiple user's on kitz. but interleaving state will be reset.