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[Weaver]

> seems to get a lower SNR margin compared to ADSL2

I wonder if this is in part due to differences in the algorithm used for _calculating_ SNR margin?

[jeffbb]

Hi

Using ADSL2+ your attenuation goes up because you are using the higher frequencies not used in ADSL2 . There are some gains because ADSL2+ allows a minimum of one data bit . As far as speed is concerned on the longer lines the benefits become negligible to non existent.The SNR margin may well drop because of this difference in Bit loading ,that gives the slight increase in Synch rate . The real benefit is really only seen on lines of less than ~50 db.
Regards Jeff

[CurlyWhirly]

> seems to get a lower SNR margin compared to ADSL2

I wonder if this is in part due to differences in the algorithm used for _calculating_ SNR margin?

It could be, I'm not sure to be honest.

What I do know is that ADSL2+ uses twice the frequency range and, as I have a long line, this increases the attenuation.

On ADSL2 it's 52.5 dB compared to 56 dB on ADSL2+

[CurlyWhirly]

There are some gains because ADSL2+ allows a minimum of one data bit .

Thanks, I didn't know that.

[Zoe]

Hi 

The real benefit is really only seen on lines of less than ~50 db.

Jeff is definitely right about that!

Don't know what my attenuation was when I was on ADSL2 .. Coz I'd never even heard of Attenuation until I came here to Kitz 
All I know from when I was on AOL Upto 8mbps ( ADSL2 ) was that speed tests used to give me approx... 6.50mbps.

On AOL UpTo 24mbps ( ADSL2+ ) My Attenuation... Down = 35.0 | Up = 17.3

With a Noise Margin Profile of 12db .. Wasn't really getting any better than I used to on ADSL2 | approx... 6.50mbps 

However! - at the minute...
ADSL2+
Noise Margin Profile = 6db
Sync Speed... Down = 12498 | Up = 1020

Speed Tests

Few Days Ago...



Just Now...



So...
You can see that I'm only just about benefiting from being on ADSL2+
If I was to have a higher Attenuation than 35.0 - OR - Noise Margin Profile of say 9db or 12db.
Probably wouldn't be much to gain from being on ADSL2+ 


Zoe

[Weaver]

> this increases the attenuation.

There's a difference between "increasing the attenuation" and increasing the figures displayed, by which I mean that :

The software is averaging attenuation over a larger set of data points, a range that includes those data points representing higher frequencies at which the real attenuation is greater,

so

the average gets increased by the fact that there are a greater number of data points and the extra ones are high values.

So I would take the attenuation thing with a pinch of salt.

I got caught out by this when fixed rate BTW 500k was superceded by BTW IPstream MAX / DLM which suddenly showed rather different figures, displayed DS attn being about 4dB worse for my long line.

Hope that makes some kind of sense anyway. Other posters pls feel free to correct me, if I'm way off. :-)