How does a Netgear DG834 router work out the Noise Margin?

How does a Netgear DG834 router work out the Noise Margin?
Does it calculate the figure from the number of packets sent and
received?
Or does it ping the BT exchange?
Or what?
--
Chris

Chris <nospam@[127.0.0.1]> wrote in news:zsgifMHmlwGEFw$e@[127.0.0.1]:

> How does a Netgear DG834 router work out the Noise Margin?
> Does it calculate the figure from the number of packets sent and
> received?
> Or does it ping the BT exchange?
> Or what?

All ADSL modems have the ability to work out the Noise Margin, or SNR
(signal-to-noise ratio) margin - this is a figure that shows the amount
of signal relative to the amount of noise (interference and other noise)
on the line.

The word "margin" is used to give it some relativity - in theory,
anything above 0dB noise margin should be able to connect, but in
practice, you need at least 6dB to maintain a steady connection, due to
other factors in the real world.

So in answer to your question, when an ADSL modem begins to sync with the
DSLAM in the exchange, they both work out what the line attenuation and
SNR margin are, in both directions. This will be used on DSL Max (and is
already used by LLU providers) to allow the modem to sync at the highest
rate it can whilst maintaining a decent SNR margin (usually 6dB). I'm
afraid I don't know the exact theories of *how* it works out the figures,
but I hope this helps a bit

--
Chris Hodder
PlusNet UserGroup Member
http://usergroup.plus.net

"Chris Hodder" <(E-Mail Removed)> wrote in message
news:Xns978B69A8284Bnospaminvalid@84.92.1.12...
> Chris <nospam@[127.0.0.1]> wrote in news:zsgifMHmlwGEFw$e@[127.0.0.1]:
>
>> How does a Netgear DG834 router work out the Noise Margin?
>> Does it calculate the figure from the number of packets sent and
>> received?
>> Or does it ping the BT exchange?
>> Or what?
>
> All ADSL modems have the ability to work out the Noise Margin, or SNR
> (signal-to-noise ratio) margin - this is a figure that shows the amount
> of signal relative to the amount of noise (interference and other noise)
> on the line.
>
> The word "margin" is used to give it some relativity - in theory,
> anything above 0dB noise margin should be able to connect, but in
> practice, you need at least 6dB to maintain a steady connection, due to
> other factors in the real world.
>
> So in answer to your question, when an ADSL modem begins to sync with the
> DSLAM in the exchange, they both work out what the line attenuation and
> SNR margin are, in both directions. This will be used on DSL Max (and is
> already used by LLU providers) to allow the modem to sync at the highest
> rate it can whilst maintaining a decent SNR margin (usually 6dB). I'm
> afraid I don't know the exact theories of *how* it works out the figures,
> but I hope this helps a bit
>

Just to add my two pence worth, be careful of taking the figures too
seriously too....

I just upgraded to the latest released firmware (3.01.29) on a DG834G and my
attenuation figures have gone down (or is it up?) from 52db to 47db - I'm
not complaining of course, if this is accurate, but I wonder whether they
changed the algorithms used to work these figures out quite a bit in this
latest firmware (of course it could be more accurate - I'm hoping so
anyway!)

Andy