SkyBB Max..Does this make sense?

[spcdust]

Originally Posted by SkyLost1984

hold on..i just checked again, i must have read something wrong..
my downstram noise margin is 16.6 at the moment. Sorry!
Is noise margin exactly the same as SNR?

I noticed that OhNoes answered that the SNR and the Noise margin are one of the same thing but this is not my understanding of it. I Found this on the net which seems to back my thinking up but I apologies if I am mistaken and I'm happy to be corrected.

An explanation of SNR and SNR Margin *

The SNR Margin is not the same as the Signal to Noise Ratio (SNR), although it is related.

The SNR is the signal-to-noise ratio. It is the ratio between the strength of the signal and the background noise on the line and is universally expressed as a logarithmic ratio (decibels or dB).
For a given line the SNR remains essentially fixed whatever the speed you are running.

ADSL routers and modems actually report the SNR Margin, and the term used to describe this varies but is generally “SNR Margin”, “Noise Margin”, “Margin”, “Receive Margin”.

The SNR Margin is the difference between the actual SNR and the SNR required to run at a given speed.
For example, if you need 20dB of SNR to run at 512Kbps, and the actual line SNR is 45dB, then the SNR Margin is 25dB.

The main reason why SNR margins fall as the line speed increases is that the required SNR increases.
For example, if increasing the speed from 512Kbps to 2MBps raises the required SNR from 20db to 30dB then the margin left will fall from 25dB to 15dB (as 45dB-30dB = 15dB.)
The one refinement is that if it is necessary for a faster speed to use some higher frequencies then these will have inherently lower SNRs and that will also contribute to the reduced SNR margin somewhat.

The SNR Margin is there to absorb fluctuations in interference on the line, and therefore to keep the service reliable. The figure of 6dB is normally accepted as enough headroom to make the link reliable, but some lines need more - 10dB is often accepted as a safer target.

Note that the target figures in the list are a reasonable summary, but it is the "SNR Margin" that is being talked about, not the "SNR". Despite this, it also does not invalidate the point that the most important factor on the reliability of a line at a given speed is the SNR Margin.
Also, as neither the SNR or SNR Margin can be established until a line is enabled (or validated with special test gear), then the estimated attenuation has to be used to come up with a viable speed. Once a line is enabled and working, it is possible - at least in theory - to gather information about the actual SNR and SNR Margin and use that to work out the actual speed the line will be able to sustain. This is essentially what will happen with the MaxDSL launch towards the end of the year.

* The above explanation has been slightly adapted from an original post made by Steve J (nopr0700) on adsl guide forums. - Due to the fact that forum posts are often archived, I have reproduced his information on this page. Thanks Steve.

The above info can be found on this site (bear in mind the article is refering to ADSL and not ADSL2+):

http://www.kitz.co.uk/adsl/linestats.htm

spcdust

[Alphawao]

SkyLost1984, you seem to be suffering from the same syptoms as me...I was connected 7th Sep and my sync speed is stuck at 7645 but when I was with zen it was 8128. I'm 901m from my exchange (Battersea) and I was told my speed would be 12-16Mb. I need to speak to tier3 but I got no callback

Latest stats
ADSL Link Downstream Upstream
Connection Speed 7645 kbps 766 kbps
Line Attenuation 27.5 db 15.3 db
Noise Margin 16.6 db 12.2 db

My noise margin fluctuates between 14.5-16.7 db but att is stable!

P.s I'm on MAX and Sky confirmed it's MAX so yours should be the same!

[SkyLost1984]

Hi Alphawao
That does sound exactly the same as me, and exactly what I have been told by sky, glad to know its not just me.
Im gonna get on to sky today, first provisioning them try to speak to tier 3 and see what i can get sorted, hopefully something but im not holding out any hope anymore!

[SkyLost1984]

Ive managed to get sky to escalate me to tier 3. They still have no record of my line being connected, apparently its still awaiting provision. It becoming a joke now, they cant run any tests or anything cos they dont have a service id for me which bt havent given them. Whether thats true or not is another matter!

[SkyLost1984]

Finally getting somewhere, my line is now showing as active with sky and bt order tracking says the llu order is now complete...even though ive been connected for 3 days now! hopefully now i can get some proper technical support if my speeds dont improve!

[Alphawao]

Thats excellent I'm calling them today to get this sorted out too.
I'm not sure if this is the case but my llu line was provided on 7th Sept and the BT tracker said my IP MAX line ceased on the 12th. Everyone else has been asking if that screws up your line....I was thinking that somehow capped my speed to 8mb....I don't know but I'm off to call sky!

[SkyLost1984]

Well that may be true for you, but as for me, there was no adsl or isdn or anything else on this line before sky, didnt even use dial up!
I had bulldog previously, (which was cancelled 11 weeks when i registered for sky, I only did it cos i was sick of bulldog and i needed to go back to bt for the sky bb, but thats how long i been without internet at home!) and after bulldog was cancelled, i got a new bt line with new phone number and everything, so as far as im aware there shouldnt be anything on my line. Im gonna try calling and getting though to tier 3 tonight when i get home, does anyone know the best way to be put through?
A very helpful girl in tech support (Claire was her name, the only helpful one ive encountered so far) said you need a ticket raised before they will even speak to you

[Alphawao]

Ok SkyLost I spoke to Stuart (tier3) who was very understanding he checked my line to see what could be squeezed out and it looks like the killer for me is the overall length of my line. Even though samknows says I'm 901m away thats by a straight line......damm so the actual line length could be very long.

He told me I had a good quality line but its just too long, anyway Stuart check my snr/att and tweaked it abit so now my sync is 8064...well I guess I live with that!

New Stats
ADSL Link Downstream Upstream
Connection Speed 8064 kbps 768 kbps
Line Attenuation 15.5 db 12.5 db
Noise Margin 15.9 db 14.0 db

Old Stats
ADSL Link Downstream Upstream
Connection Speed 7645 kbps 766 kbps
Line Attenuation 27.5 db 15.2 db
Noise Margin 15.9 db 13.1 db

Speedtest
Download Speed: 6693 kbps (836.6 KB/sec transfer rate)
Upload Speed: 641 kbps (80.1 KB/sec transfer rate)

Cool, I also asked him about the IP Issue he said Sky have broardcast their IP range as safe so the major sites should work soon.

[SkyLost1984]

Well thats kind of good news, im on the phone on hold for tech support to try to speak to them. How did you persuade them to put you through?