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uk.telecom.broadband (UK broadband) (uk.telecom.broadband) Discussion of broadband services, technology and equipment as provided in the UK. Discussions of specific services based on ADSL, cable modems or other broadband technology are also on-topic. Advertising is not allowed.

Can someone explain about noise margins?



 
 
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  #1  
Old December 5th 06, 12:01 PM posted to uk.telecom.broadband
BJH
external usenet poster
 
Posts: 15
Default 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 a

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
  #2  
Old December 5th 06, 12:36 PM posted to uk.telecom.broadband
K A Nuttall
external usenet poster
 
Posts: 39
Default Can someone explain about noise margins?

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
  #3  
Old December 5th 06, 12:42 PM posted to uk.telecom.broadband
Peter Crosland
external usenet poster
 
Posts: 1,463
Default Can someone explain about noise margins?

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 a

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... a8ba50191b51


Peter Crosland


  #4  
Old December 5th 06, 01:09 PM posted to uk.telecom.broadband
BJH
external usenet poster
 
Posts: 15
Default Can someone explain about noise margins?

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
  #5  
Old December 5th 06, 01:24 PM posted to uk.telecom.broadband
green
external usenet poster
 
Posts: 2
Default Can someone explain about noise margins?


"BJH" wrote in message
...
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



  #6  
Old December 5th 06, 01:26 PM posted to uk.telecom.broadband
green
external usenet poster
 
Posts: 2
Default Can someone explain about noise margins?


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" wrote in message
...

"BJH" wrote in message
...
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





  #7  
Old December 5th 06, 02:55 PM posted to uk.telecom.broadband
Richard Tobin
external usenet poster
 
Posts: 277
Default Can someone explain about noise margins?

In article ,
Peter Crosland 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.
  #8  
Old December 5th 06, 03:19 PM posted to uk.telecom.broadband
NoNeedToKnow
external usenet poster
 
Posts: 498
Default Can someone explain about noise margins?

On 5 Dec 2006, "Peter Crosland" 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).
 




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