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ADSL Mode & Modulation Settings Help

Posted: Sun Feb 14, 2010 7:37 pm
by marcus.sg
Hey everyone,

Some super simple questions for those in the know. What are the optimum settings for ADSL Mode for my Exetel ADSL2+ plan with my Billion 7300G ADSL2+ Modem.

I have the choice of these for ADSL Mode
Screen shot 2010-02-14 at 5.46.35 PM.jpg
Screen shot 2010-02-14 at 5.46.35 PM.jpg (22.38 KiB) Viewed 4475 times
and I have these as my Modulator setting choices
Screen shot 2010-02-14 at 5.46.59 PM.jpg
Screen shot 2010-02-14 at 5.46.59 PM.jpg (19.95 KiB) Viewed 4475 times
If someone could kindly explain to me what each one is and *why* I should select one over the other that would be appreciated and increase my (and anyone else who reads this) knowlegde on these setup issues.

Re: ADSL Mode & Modulation Settings Help

Posted: Sun Feb 14, 2010 8:43 pm
by Dazzled
There is a table summarising the standards at http://en.wikipedia.org/wiki/Asymmetric ... riber_Line Each standard name in the table is a link to a specific article. For most modems, let the auto function sort it out.

Re: ADSL Mode & Modulation Settings Help

Posted: Sun Feb 14, 2010 9:51 pm
by marcus.sg
So, no specific requirements from Exetel?

Will auto really do fine in most cases?

So I don't have to 'worry' about making a choices from those options then?

just askin' :)
I'm currently set to 'Open AnneX Type and follow DSLA's setting' for ADSL
and for modulation I'm currently set to 'Auto'

Is there any 'preferred' setting(s) that Exetel know about will eke out the best performance?

Downstream 7278 kbps
Noise Margin (Upstream) 14.9 db
Noise Margin (Downstream) 9.0 db
Attenuation (Upstream) 21.3 db
Attenuation (Downstream) 34.0 db

Re: ADSL Mode & Modulation Settings Help

Posted: Sun Feb 14, 2010 10:26 pm
by Dazzled
That's about average. Some modems are a bit faster than others, and you might make 8000+ kbps with another. It would not be smart to lower the noise margin or you will get drop outs. The main reason for letting the modem determine modulation automatically is so that an ADSL2 service is not constrained to ADSL1, alias G.DMT

Re: ADSL Mode & Modulation Settings Help

Posted: Fri Feb 19, 2010 1:24 pm
by CoreyPlover
I don't think Annex settings are relevant for Exetel

ADSL1 should be G.DMT modulation (i.e. ITU G.992.1)
ADSL2+ should be ADSL2+ modulation (i.e. ITU G.992.5)

The other standards (ITU G.992.2 through ITU G.992.4) and the Annex A/L/M/J variants aren't necessary and many are not supported

The most common setting would be Auto as Dazzled says (which tried ADSL2+, then ADSL2, then G.DMT, then others, in order) or ADSL Mutlimode (which tries ADSL2+ and fallback to G.DMT if that fails). Because Exetel only support ADSL2+ and G.DMT, these are all equivalent