View Single Post
Old November 16th 16, 08:42 PM posted to uk.telecom.broadband
Java Jive
external usenet poster
Posts: 378
Default Estimating ADSL & VDSL Speeds From Given Distances

Thanks to both for your replies, but ...

On Wed, 16 Nov 2016 15:03:57 +0000, Graham J

Google for vdsl speed vs distance ...
- has a nice graph.

Yes, I'd found that already ...

Or: vdsl speed calculator ...

.... and kitz has something pretty similar. The problem with all of
them is that they are designed for use by people with a connection who
can read their Attenuation directly from their router, whereas I need
to calculate from distance alone, and that is where the
errors/uncertainty are worst. For example, my attenuation as measured
by my router is 63dB, which leads such calculators, working at a rate
of 13.81dB/km, to assume I'm about 4.5km from the exchange, whereas
I'm just under twice that!

Trying a few values in this suggests the speed vs distance graph is not
a straight line

No, I wouldn't expect to be, even as it tails off. Although I haven't
the background knowledge to do a detailed analysis, based on more
general scientific knowledge, my first guess would be that the
relationship is hyperbolic, where speed is proportional to 1/distance. - this gives the basis
for calculation.

Yes, I'd found that already, and it works from attenuation as
described above. One of the pages linked thence gives more of the
background of the kitz calculator, and includes a spreadsheet which
does the same 'calculation'. However, examination of the spreadsheet
code shows that all it is doing is straight-line interpolating between
points on ...
... which now gives a 404, but originally was almost certainly the
graph at ...

The problem with all such sources is that I can't 'interpolate' beyond
the end of the original data!

To whom will you be submitting your case?

Probably to funding bodies such as Highlands & Islands Enterprise,
MPs, MSPs, etc.

In a region I know of (near Holbeach St Matthew, nort-heast of Spalding)
BT are rolling out FTTP. There's no commercial need - probably there
are well under 60 houses, and it's not being extended to nearby farms
where it might be of some real use. So the only reasons I can think
it's being done is that:

1) it will demonstrate there's no commercial case, so BT will not push
it into other areas;

2) it allows BT to test all aspects of the roll-out in an area where
failure won't be noticed.

I can see that there's some point in the latter reason. So you might
adapt that to your case.

That does seem rather strange.

We know what you want is technically feasible. Evidently BT now have
"Remote nodes" which can be installed on eexisting poles. This avoids
rerouting exising cables through newly installed green cabinets. See:

Do let us know how you get on.

Thanks for the links, and I'll keep you up-to-date

On Wed, 16 Nov 2016 15:25:57 +0000, Andy Burns

As for your spreadsheet, this page has general graphs and tables of
speeds by distance, obviously it's all variable and depends on cable
quality as well as distance.

Yes, thanks, as discussed above, I'd already found that page, but I
was hoping for something I could just put in a formula, rather than
manually reading 59 values off a graph!
================================================== ======
Please always reply to ng as the email in this post's
header does not exist. Or use a contact address at: