How is Plusnet estimated line speed calculated

[#1]

Quote

Estimated line speed:     4.0 - Checked on 2010-12-09 04:04:44 Current line speed:     3500

Fact is that to achieve an IP profile of 4000kbps I would need a sync rate in excess of 4544kbps and given my current stats are
Noise Margin:    5.9  dB
Connection Rate:  4160  Kbps
with no line drops for 27 days and a noise margin which hasn't moved outside the 4.7 - 6.9dB range  since the 19th November

[#2]

Hi Jim,
The estimate is derived from the BT availability checker.
Jojo

[#3]

You just knew what the next questions were don't you 
How does that calculate it and why has it increased whereas my attenuation hasn't changed
Note sync speed hasn't dropped below 4000 since mid September and the maximum ever was 4480kbps
Just to add - if the BT value is sync speed then it needs to be clearly differentiated from Current Line Speed which is the IP profile and typically 500+ kbps lower

[#4]

Radial Distance Calculator   if memory serves......
Attenuation figs can also vary , due to  Router chipset & how their read data line data.
Your attenuation will be higher if your paired an IFTN router chipset to your IFTN DSLAM.  On the other hand a Trend chip would lower it , but at loss of stability
thx f9o

[#5]

Router and reported attenuation haven't changed either

[#6]

Hi Jim,
The figures from the availability checker is apparently sync rate and not profile speed.
Jojo

[#7]

In which case the Plusnet information needs clarifying.
Do you want me to raise it under feedback or will you cover it with the relevant department

[#8]

Just changed phone product and I was amused by this - a bit pessimistic isn't it

[#9]

It does make one wonder.
When my daughter started with PN broadband the estimate was 6000, actual 6500. A few weeks ago she added Homephone, and the estimate is now 3500, actual 7000. 

[#10]

Maybe BT's  TCP/ATM calcs are out of wack.....?
One wonders if they've been fiddling around due to FTTC.....

[#11]

That was my thought in this thread http://community.plus.net/forum/index.php/topic,89742.0.html
My estimate ( on ADSL2+) changed from 13Mb to 3.5Mb and now back to 15Mb. The initial change coincided with FTTC going live on my cab.
My line's been pretty constant at 8Mb on 20CN.

[#12]

BT Calculate the speed you will get by throwing 3 darts at the dart board its simple
Puddy

[#13]

must be a funny dartboard then with a lot of 2's and 3's 

[#14]

No it's the thrower. First dart hits a number, number two and three go outside. The average of all three is then taken and adjusted down by a DLM factor. Surely you knew that.