Advice on my connection stats - Good or Bad?

I have just taken the following readings rom my DG834G MkII

Downstream
---------------------------------
Connection Speed 1152kbps
Line Attenuation 49 db
Noise Margin 1 db

Upstream
---------------------------------
Connection Speed 288kbps
Line Attenuation 26 db
Noise Margin 28 db

Im a bit concerned about the downstream Noise Margin. A mate of mine says
its a good reading, but Im inclined to think its maybe a bad one : ( I have
never seen it as low as 1 db..... It would normally be around 8 - 15 db, if
I remember correctly.

Is it good or bad ???

Connection is stable, and has been up for many days.....

Thanks in advance.

On Tue, 13 Sep 2005 20:00:52 +0100, "Sass"
<(E-Mail Removed)> wrote:

>Downstream
>---------------------------------
>Connection Speed 1152kbps
>Line Attenuation 49 db
>Noise Margin 1 db

on the verge of failure.
Try it in the test socket
http://www.clarity.it/telecoms/adsl_faceplate.htm#part3

poor margin result for a decent attenuation

>Upstream
>---------------------------------
>Connection Speed 288kbps
>Line Attenuation 26 db
>Noise Margin 28 db

that's good.

Phil
--
Tiscali - dialup speeds at Broadband prices, see
http://bbs.adslguide.org.uk/postlist...&Board=tiscali

AOL - the unlimited ISP of choice for heavy downloaders.

In an earlier contribution to this discussion,
Sass <(E-Mail Removed)> wrote:

> I have just taken the following readings rom my DG834G MkII
>
> Downstream
> ---------------------------------
> Connection Speed 1152kbps
> Line Attenuation 49 db
> Noise Margin 1 db
>
> Upstream
> ---------------------------------
> Connection Speed 288kbps
> Line Attenuation 26 db
> Noise Margin 28 db
>
> Im a bit concerned about the downstream Noise Margin. A mate of mine
> says its a good reading, but Im inclined to think its maybe a bad one
> : ( I have never seen it as low as 1 db..... It would normally be
> around 8 - 15 db, if I remember correctly.
>
> Is it good or bad ???
>
> Connection is stable, and has been up for many days.....
>
> Thanks in advance.

I think your router is lying! It can't possibly work with a downstream noise
margin of 1dB.

I would be worried at anything under 10dB.
--
Cheers,
Tim
______
Please reply to newsgroup. Reply address is invalid.

On Tue, 13 Sep 2005 22:12:53 +0100, "Tiscali Tim" <(E-Mail Removed)>
wrote:

>I think your router is lying! It can't possibly work with a downstream noise
>margin of 1dB.

it can, that's 1 dB more than it needs to sustain a certain error
rate. If the noise is up and down it'll drop but if its consistent or
of 1 is the worst case it could hang on in there.

Phil
--
Tiscali - dialup speeds at Broadband prices, see
http://bbs.adslguide.org.uk/postlist...&Board=tiscali

AOL - the unlimited ISP of choice for heavy downloaders.

"Tiscali Tim" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...

>
> I think your router is lying! It can't possibly work with a downstream
noise
> margin of 1dB.
>
> I would be worried at anything under 10dB.
> --
> Cheers,
> Tim

It seems you were right... A full reboot of the router and its now showing
25db : ) Panic over!

"Barry" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
>
> "Tiscali Tim" <(E-Mail Removed)> wrote in message
> news:(E-Mail Removed)...
>
>>
>> I think your router is lying! It can't possibly work with a downstream
> noise
>> margin of 1dB.
>>
>> I would be worried at anything under 10dB.
>> --
>> Cheers,
>> Tim
>
> It seems you were right... A full reboot of the router and its now showing
> 25db : ) Panic over!

Yep you were right Tim. Just got back home.... Barry popped over earlier
and rebooted the Netgear and it came up with a more reasonable 25db.

Thanks to all. (You beat me to it Barry!)

In an earlier contribution to this discussion,
Phil Thompson <(E-Mail Removed)> wrote:

> On Tue, 13 Sep 2005 22:12:53 +0100, "Tiscali Tim" <(E-Mail Removed)>
> wrote:
>
>> I think your router is lying! It can't possibly work with a
>> downstream noise margin of 1dB.
>
> it can, that's 1 dB more than it needs to sustain a certain error
> rate. If the noise is up and down it'll drop but if its consistent or
> of 1 is the worst case it could hang on in there.
>
> Phil

I'm not so sure! My belief is that what some routers calls noise margin,
others calls SNR. In other words, it needs to be able to discriminate
between the requisite number of levels *within* this margin in order to
work.

In the recent past, I've had a lot of problems with my 3Com wireless
router - which ultimately turned out to be a noisy power supply. When the
problem was present, the reported margin would start at about 14dB when
everything was cold, and then drop - with an associated increase in CRC
errors and reduction in throughput - as it warmed up. When the reported
margin got below 10dB it would die altogether and refuse to synch any more.

[FWIW, not it's running on a non-3Com non-switch-mode power supply, it's
consistently reporting 19dB or more.]
--
Cheers,
Tim
______
Please reply to newsgroup. Reply address is invalid.

On Wed, 14 Sep 2005 11:19:08 +0100, "Tiscali Tim" <(E-Mail Removed)>
wrote:

>I'm not so sure! My belief is that what some routers calls noise margin,
>others calls SNR. In other words, it needs to be able to discriminate
>between the requisite number of levels *within* this margin in order to
>work.

IIRC the noise margin or SNR margin has its 0 dB pont defined as the
SNR that gives a bit error rate of 1E-7 at the operating speed. So it
should work at 0 or above 0 and indeed below 0 with increased errors -
have seen -5 reported though the kit usually triggers a retrain fairly
quickly.

Lot of variability in the equipments ability to hang on at low SNR,
and if the actual SNR (rather than the margin) is variable then
reliability will be poor with single digit margins. More is always
better.

Turns out is was a Netgear anyway, they seem to claim margin reduces
with time until rebooted, so its hard to know what reality is.

Phil
--
Tiscali - dialup speeds at Broadband prices, see
http://bbs.adslguide.org.uk/postlist...&Board=tiscali

AOL - the unlimited ISP of choice for heavy downloaders.

Sass wrote:
> I have just taken the following readings rom my DG834G MkII
>
> Downstream
> ---------------------------------
> Connection Speed 1152kbps
> Line Attenuation 49 db
> Noise Margin 1 db
>
> Upstream
> ---------------------------------
> Connection Speed 288kbps
> Line Attenuation 26 db
> Noise Margin 28 db
>
> Im a bit concerned about the downstream Noise Margin. A mate of mine
> says its a good reading, but Im inclined to think its maybe a bad one
> : ( I have never seen it as low as 1 db..... It would normally be
> around 8 - 15 db, if I remember correctly.
>
> Is it good or bad ???
>
> Connection is stable, and has been up for many days.....
>
> Thanks in advance.

If, as you say your connection is stable, then the figures are broken.
Don't worry about it as many routers do give conflicting results to that
which are really present. Use them as a baseline to keep tabs on any
deviation but nothing else.

If they were as bad as what they look you service would most probably
fail every night as well as intermitently during the day & not be as
stable as what you say..