Router attenuation 'out of range' query

Here are 2 screenshots of someone elses DMT stats:

http://i24.tinypic.com/spjgax.jpg (ADSL i.e. Max - can't show the true attenuation data)

http://i24.tinypic.com/13zcy37.jpg (ADSL2+ - can show the true attenuation data)


Both of those screenshots were taken using the same router and so am I right in thinking that the real reason why routers don't show a downstream attenuation of more than 63.5 dB and an upstream attenuation of 31.5 dB is because on ADSL2+ connections, this mode enables more bits to be used for the attenuation data?

I'm a little confused though as it has been said that on ADSL Max, some routers can show the true attenuation data and some can't?

Before anyone points it out, I know that it's only a trivial question but I am interested as I myself expect to be on ADSL2+ next year and am curious if my current upstream figure of 31.5 dB will still be the same on ADSL2+

My downstream figure isn't out of range as it's 55 dB and within the 63.5 dB limit.

The ADSL standard mandates 8 bits for reporting the downstream and upstream attenuation to the exchange end. The data is stored as values 0 to 127 representing attenuations of 0 to 63.5 dB. Presumably some routers hold and display the value locally at a higher accuracy and range.

ITU-T G.992.1 para. 9.5.1

In reply to:

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The ADSL standard mandates 8 bits for reporting the downstream and upstream attenuation to the exchange end. The data is stored as values 0 to 127 representing attenuations of 0 to 63.5 dB. Presumably some routers hold and display the value locally at a higher accuracy and range

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So it's got nothing to do with whether you are on 'vanilla' ADSL or ADSL2+ then ?

I'm currently using a SpeedTouch 585 and so if I were eager enough to change my router (I'm not) to one that does show the true attenuation figures then I would need to know which models to go for.

Cheers.

the 2-wire units have an "advanced DSL diagnostics" (or some such) page with at least 3 attenuation figures, one of which is the "up to 63.5dB" figure.

I don't know if there is a difference according to whether ADSL or ADSL2+ is used - I think not. The Netgear DG834G I use only displays attenuations in integral units.

I was told it was a 'software glitch' as when trialling the original APtS our test 105's would only show up to 63.5, something was tweaked, and now they show up to 'I'm sorry that's a no !'

Thanks for the feedback everyone

p.s. I just thought.

Is it unusual to have the upstream attenuation figure affected and not the downstream attenuation figure as in my case where I have (at least) 31.5 dB upstream and 55 dB downstream ?

I would have thought that the downstream attenuation figure would be more likely to get affected first as it uses higher frequencies compared to upstream ?

Could there be a reason why this is so on my line ?

I know a few people on my street (and therefore around the same distance as me from the exchange) and none of their upstream channels are 'out of range' like mine is although they are close to the limit as they are around the 30 dB attenuation level.

Edited by deleted (Fri 26-Oct-07 20:42:21)