BT ADSL speed checker

When ADSL started (and the limits were stricter) BT's speed checker claimed
that my house could only have 512k ADSL

Eventually it claimed that I could have up to 2Mbs (when I was actually
on 1M).

A month or so ago I upgraded to 2Mbs and it seems rock solid (a consistent
~18dB signal/noise)

I see today that the BT checker says "no 2Mbs, might get 1Mbs". This seems
an unusual change (in that they are generally relaxing limits)! It does
not seem to reflect current reality and it seems I am lucky I grabbed 2Mbs
when I did!!!!

In article <ddcsdc$6cs$(E-Mail Removed)>,
Brian McIlwrath <(E-Mail Removed)> writes:
> When ADSL started (and the limits were stricter) BT's speed checker claimed
> that my house could only have 512k ADSL
>
> Eventually it claimed that I could have up to 2Mbs (when I was actually
> on 1M).
>
> A month or so ago I upgraded to 2Mbs and it seems rock solid (a consistent
> ~18dB signal/noise)
>
> I see today that the BT checker says "no 2Mbs, might get 1Mbs". This seems
> an unusual change (in that they are generally relaxing limits)! It does
> not seem to reflect current reality and it seems I am lucky I grabbed 2Mbs
> when I did!!!!

The BT checker is more like a weather forecast. It's a prediction of
what might happen based on the information available to it. It tends to
err on the pessimistic side, and is not kept updated with what
eventually happens - like you getting 2 Mbps on the line.

Perhaps the degree of pessimism they apply equates to about 10 dB, and
the current prediction for your line was out by at least 8dB. Earlier
predictions were no doubt based on earlier info, which may even have
been further out in the opposite direction. Or the pairs might have been
swapped at some point along the line - one can never be quite sure.

It's a pity that the automated ordering process that many ISPs use
rely so heavily on what is just an educated guess.

--
Tim Clark

Tim Clark <(E-Mail Removed)> wrote:

: Perhaps the degree of pessimism they apply equates to about 10 dB, and
: the current prediction for your line was out by at least 8dB. Earlier
: predictions were no doubt based on earlier info, which may even have
: been further out in the opposite direction. Or the pairs might have been
: swapped at some point along the line - one can never be quite sure.

: It's a pity that the automated ordering process that many ISPs use
: rely so heavily on what is just an educated guess.

I see from further research that BT have a limit of 43dB in 2Mbs ADSL and,
on that basis, the line checker is perhaps now correct (as, according to my
router) attenuation is 46dB (but with a good S/N which varies between
16 and 20dB and a solid 2Mbs connection).

I am still pretty certain that the Checker was certain that I could get
2Mbs at some times in the past - and that it has now swung to the opposite
extreme in thinking that 1Mb is not at all certain.

As ISPs *DO* rely on it so much it is a pity that BT don't provide a facility
for it allow users to input corrections!

On Fri, 12 Aug 2005 12:28:39 +0000 (UTC), Brian McIlwrath
<(E-Mail Removed)> wrote:

>As ISPs *DO* rely on it so much it is a pity that BT don't provide a facility
>for it allow users to input corrections!

with a mechanism to stop eejits typing in 11 dB attenuation 40 dB
noise margin then calling out BT when the 8M service doesn't work on
their 8 km line :-)

Phil
--
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