In reply to a post by Zarjaz:

I have seen 'unconfigured' FTTC DSLAM ports show 80meg sync downstream,

Yep.... also seen 80

That is promising Is that on the current 7.05MHz frequencies?

For those wanting to dream about the absolute maximums, I found another Ericsson graph about future speeds. Look at the bottom of this page and weep.

The text tells us that current VDSL2 technology at 17MHz is limited to 246Mbps (total bi-directional), and 30MHz is limited to 417Mbps.

Lookign at the graph at the bottom of the page suggests these values are available to 300M of the cabinet.

The *real* future stuff there suggests you could get to around 1Gbps almost to 150M from the cabinet. But that obviously starts to work with cabinets every other street.

I have done some digging around and found the attached news item on ISP Review http://www.ispreview.co.uk/story/2011/05/12/bt-uk-to... read the 10.55 addition. If true and Ofcom are OK then if BT use up to 17 Mhz rather than the current 7 MHz this does I think mean higher speeds for most lines.

What do others think? Is crosstalk a dead issue?

Further investigation turns up a paper on the ICT Regulations Site discussing VDSL profiles http://www.ictregulationtoolkit.org/en/Publication.2... which has various graphs showing the distance and speeds the various standards will deliver. Profile 17a seems to be the standard BT may adopt if so figure 5b shows that at 1500 feet (approx 450m) you should get 80 Mb/sec down and 38 Mb/sec up which is in line with the BT statement.

The section on impulse noise management is also worth reading but look at figure 7 which shows that VDSL2 can deliver Next Generation services up to 3000 feet from the cabinet or around 900m which is a lot further than I have seen elsewhere. Suddenly you can start to see why BT likes FTTC and VDSL2 - it can easily support VOD services to most homes without installing lots of expensive fibre.

Thanks - hadn't spotted that one.

Assuming they stick to band plan 997 (almost certain), then the spectrum from 7MHz up to 12 MHz goes to improving the upstream - which may be why they talk about increasing the uplink speeds to 20Mbps. If pricing means that most ISPs kept uplink speeds at 2Mbps, it would be a chronic waste of spectrum.

The frequencies between 12MHz and 17MHz will then be allocated to downstream, and account entirely for the extra downlink bandwidth.

Searches online for "VDSL2 profile 17a" show some product specs which suggest the distance limit for the fastest speeds (85-100MHz) is around 1000ft, or 300M. I haven't figured the cutoff point, for where speeds would be back to today's 40/10. Certainly less than 1500M though.

I'm not sure crosstalk is ever a dead issue. It will always be there, in some form, and will always need to be dealt with.

Also interesting. I wonder how much crosstalk those graphs include, because they seem to predict longer distances than any equipment seems to want to live up to.

If you look at the adverts... They say "Many of our customers are already recieving three times faster speeds" I make that out to be under 20mbps if you take an average broadband speed of 6-7mbps on ADSL. So where in that are they advertising the top speed, which by the way, a majority on this site are getting!

The main Infinity website says "at least three times" and does clearly state the headline 40mbs. In July the new Ofcom code comes in which will require that isps give reasonable estimates to each new user. BT already do that. However the advertising gives a clear impression of a high speed greatly improved speed service which, luckily, most of us who have it get.

The days of promoting headline speeds few can reach are gone for the majors at least which is why I am sceptical of the opinion that holds that an increase to 80Mbs will only for the rare user whose live on top of a cabinet similar to the way 24Mbs is for ADSL2+ users. If that was true then BT would not have announced in the way they did in my opinion.

Time will tell as they seem to want to do this before the end of 2011.

Could you link to where you found those graphs as it would be interesting to contrast them with the source I found?

There is also a technology called vectoring which can improve performance but I can find little on this as yet. Have you any sources on that.

Time will tell whether this just headline stuff or a real improvement for most users. Not that it matters too much to me as I am still delighted in getting over 20 times my ADSL speed getting 40 times seems rather academic.