Can someone explain about noise margins?

Hi all

I've just changed from a fixed 512k connection to 8M connection, I assume
this is what is called ADSL Max? I won't bore anyone with my reasons for
changing other than it got me away easily from Legend Communications (who
won't release MAC codes).

My noise marging with the 512K connection tended to be around 15dB

Since my new speed went 'live' today I've noticed that the noise margin has
dropped to 6dB.

I assume this is a function of the different connection type?

My current figures are:

Downstream
Noise Margin: 6dB
Output Power: 20dBm
Attenuation: 35dB

Upstream
Noise Margin: 26dB
Output Power: 10.5dBm
Attenuation: 17.5dB

Upstream: 448Kbps
Downstream: 6816 Kbps

Any comments/explanation on the above figures would be greatly appreciated.

--
Regards
Barry

BJH wrote:

> I've just changed from a fixed 512k connection to 8M connection, I
> assume this is what is called ADSL Max? I won't bore anyone with
> my reasons for changing other than it got me away easily from
> Legend Communications (who won't release MAC codes).

Ugh. Legend. Nightmare. Enough said.

> My noise marging with the 512K connection tended to be around 15dB
>
> Since my new speed went 'live' today I've noticed that the noise
> margin has dropped to 6dB.

BTW aim to keep the s/n ration at 6dB or above. They do this by
lowering the sync speed until the line is stable. S/N ratio is an
indicator of stability, so they target this value initially at 6dB, and
increase it in stages, if the disconnection rate doesn't improve. They
also set Interleave on problem lines.

As long as your line is stable, 6dB is fine. And you're probably
getting the best speed possible from your line.

--
K A Nuttall
www.yammer.co.uk
Re-type the e-mail address how it sounds, remove .invalid

> I've just changed from a fixed 512k connection to 8M connection, I
> assume this is what is called ADSL Max? I won't bore anyone with my
> reasons for changing other than it got me away easily from Legend
> Communications (who won't release MAC codes).
>
> My noise marging with the 512K connection tended to be around 15dB
>
> Since my new speed went 'live' today I've noticed that the noise
> margin has dropped to 6dB.
>
> I assume this is a function of the different connection type?
>
> My current figures are:
>
> Downstream
> Noise Margin: 6dB
> Output Power: 20dBm
> Attenuation: 35dB
>
> Upstream
> Noise Margin: 26dB
> Output Power: 10.5dBm
> Attenuation: 17.5dB
>
> Upstream: 448Kbps
> Downstream: 6816 Kbps

You are getting close to the theoretical maximum of 7MB. The up to 8MB is a
myth because with overheads etc. the real up to is about 7.1MB or
thereabouts,

> Any comments/explanation on the above figures would be greatly
> appreciated.

Quite a good explanation of ADSL MAX can be found here.

http://portal.plus.net/support/broad...afa8ba50191b51


Peter Crosland

On Tue, 5 Dec 2006 11:42:11 -0000, Peter Crosland wrote:

> You are getting close to the theoretical maximum of 7MB. The up to 8MB is a
> myth because with overheads etc. the real up to is about 7.1MB or
> thereabouts,

Thanks Guys, that's good. I had a heart stopping moment about 15 mins ago
when the router 'lost' the connection.

I was logged on with the Legend user ID and password, but all I had to do
was switch off for a few minutes and reconnect with the new UserID and
password.

Now all fine and thanks again for the very clear explanations.

--
Regards
Barry

"BJH" <(E-Mail Removed)> wrote in message
news:1pe0d4131a8pu$.(E-Mail Removed)...
> On Tue, 5 Dec 2006 11:42:11 -0000, Peter Crosland wrote:
>
>> You are getting close to the theoretical maximum of 7MB. The up to 8MB is
>> a
>> myth because with overheads etc. the real up to is about 7.1MB or
>> thereabouts,
>
> Thanks Guys, that's good. I had a heart stopping moment about 15 mins ago
> when the router 'lost' the connection.
>
> I was logged on with the Legend user ID and password, but all I had to do
> was switch off for a few minutes and reconnect with the new UserID and
> password.
>
> Now all fine and thanks again for the very clear explanations.
>
> --
> Regards
> Barry

dont sweat it m8

mine goes every other day but alwsy comes back with an on/off router like
you did

bt "remotely stabilised mine" - from s/n of 6.6-7.5 - line going every
couple of hours

to sn above 10 sometimes 14 and a couple of days out of it

so they can "tweak" things

speed is down a bit but not fatal

i can only get 2.something meg but it will do me



"green" <(E-Mail Removed)> wrote in message
news:1yddh.132864$(E-Mail Removed)...
>
> "BJH" <(E-Mail Removed)> wrote in message
> news:1pe0d4131a8pu$.(E-Mail Removed)...
>> On Tue, 5 Dec 2006 11:42:11 -0000, Peter Crosland wrote:
>>
>>> You are getting close to the theoretical maximum of 7MB. The up to 8MB
>>> is a
>>> myth because with overheads etc. the real up to is about 7.1MB or
>>> thereabouts,
>>
>> Thanks Guys, that's good. I had a heart stopping moment about 15 mins ago
>> when the router 'lost' the connection.
>>
>> I was logged on with the Legend user ID and password, but all I had to do
>> was switch off for a few minutes and reconnect with the new UserID and
>> password.
>>
>> Now all fine and thanks again for the very clear explanations.
>>
>> --
>> Regards
>> Barry
>
>

In article <45755b13$0$8717$(E-Mail Removed)>,
Peter Crosland <(E-Mail Removed)> wrote:

>> Upstream: 448Kbps
>> Downstream: 6816 Kbps
>
>You are getting close to the theoretical maximum of 7MB. The up to 8MB is a
>myth because with overheads etc. the real up to is about 7.1MB or
>thereabouts,

The figures quoted also include those overheads, so he is still over a
megabit away from the maximum. If he had a perfect line, it would show
the downstream as 8128Kb/s.

-- Richard
--
"Consideration shall be given to the need for as many as 32 characters
in some alphabets" - X3.4, 1963.

On 5 Dec 2006, "Peter Crosland" <(E-Mail Removed)> wrote:

>http://portal.plus.net/support/br....

or maybe (since the pn_session information is meant to be unique)
http://portal.plus.net/support/broad...ax_guide.shtml
(which will fit on newsreaders a bit better without wrapping/breaks).