BT upgrades means PN downgrades?

[#1]

Well for what it's worth the experts on TBB seem to be concluding that my theory is wrong anyway - at least as far as crosstalk is concerned. So basically BT are completely off the hook. It's just a coincidence.

[#2]

http://www.speedtest.net/my-result/5345474678

Well all i know is that since joining PN years ago i've had 78megs and now since the start of May i get 10megs less @ 68megs. Or 9mb/s down to 8mb/s and that now seems to be what i'm stuck with.

I haven't moved Cab because i live in a tiny town and there's only one Cab between me and the exchange. There's only 128 houses on the estate and only about half have internet. I know that because i know every single one of the people living in those homes. I think i'm the only PN member here and the rest are on BT.

My Attenuation can't have changed, so maybe it's an SNR change? Like i said i have no idea why i lost 10megs one day.

 

[#3]

This thread seems very tin foil hat to me. As I see it there are two points. The first is your sudden loss of speed. I'm with you on this as I'd find it annoying and disappointing in equal measure.

The whole BT thing is ludicrous though. Yes, who's to say that with the next free upgrade that the situation for all will not be worse? But let's be realistic.

1. A free uplift to those service levels is not likely to occur for a number of years going by the fact that this one replaces a product available for 3 to 4 years.
2. If BT did this then presumably a new tier of high speeds will be introduced least BT be aiming to homogenise their entire fibre user base, which I highly doubt and guarantee they'd not be putting everyone on a lower price it would be the opposite.
3. If such an event were to occur and, after these years you have still stuck with PN through it all, and PN have not offered anything better, then what would be stopping you from taking up the offer? It's a free market after all.

For what you pay you cannot expect to have exclusive and protected access as it isn't how the technology works. It's a shame it's this way but that's how it is. 

[#4]

Sorry, it is not possible for others speed increases to affect yours. Andrue was partially right to make you aware of crosstalk, because it is the bane of vdsl, in that if a new user joins the cab it can cause crosstalk,... but an existing users speed increase will not affect your sync speed.

To repeat what I typed earlier elsewhere.

Shouldn't make hardly any difference - DMT uses what's called a waterfill algorithm for bitloading.
Waterfill means that it does not fill all the lower tones before moving on to the next. It means it loads all available tones with 1 bit, before starting over the whole frequency to fill up with 2 bits and so on and so on.

Therefore its highly unlikely that the EU will be utilising any new frequencies that they couldn't previously use. They will just load more bits per bin across the frequencies available up to the maximum bits that tone can load depending upon the SNR.

---
The waterfill method is much clearer to see in on an adsl line which isnt subject to as much PCB and differing PSD masks that VDSL is. A prime example is here

This line is capable of much higher speeds than the technology limitations. See how none of the tones get full bit loading (despite there being sufficient SNR to fully load a bin). There's sufficient bitloading at the higher end frequencies to be able to allow the line to sync at full speed without the need for the lower tones to need to load the full 15 bits.

If DMT didnt use the waterfill method, then that line would show fully loaded 15bits for the lower tones and no loading of the higher frequencies.

The inverted U shaping up to tone 50 is the result of PSD mask.

[#5]

Well all i know is that since joining PN years ago i've had 78megs and now since the start of May i get 10megs less @ 68megs.

Sounds like it may be crosstalk.  Off the top of my head (cba to looks at stats to confirm) I think Ive lost somewhere in the region of about 25Mbps from my headline speed down to crosstalk.   There is nothing that Plusnet nor Openreach can do about crosstalk until vectoring is implemented.    Last year I did a rough analysis of lines monitored by members on my forum and the average total loss was ~20Mbps for each person.  I know its not going to be much comfort to you, but if you have 'only' lost 10Mbps, then you have in fact been let off quite lightly. 

I can tell when one of my crosstalkers reboots their connection as my line will suddenly show an increase and then fall back down again as they come back online.

Crosstalk has always been around with DSL..  I saw it on adsl2+ being first on a shiny new MSAN, then saw it drop periodically.  I lost about 4Mbps due to crosstalk on adsl2+, its not as noticeable though because losses are less.  The higher your existing speed, then the bigger those losses can be.  Its a fact of DSL technology, that those who sync at the higher speeds tend to lose the most through crosstalk.

A sudden overnight drop of ~10Mbps (unless related to G.INP or DLM) is most likely to be someone new connected on your cab who in is the same bundle of copper as you.