Noise Margin

Kohaashi · 9 Mar 2011 at 19:36

Hi

Does anyone know what the correct noise margin I should have on my line to get the best broadband speeds while still maintaining a connection?

BT have been out and sorted the noice on the line which reduced the noise margin to 5.0 db and since then the line constantly dropped.

I have contacted Be Un Limited and they have increased the Noise Margin to 7 db and the connection now holds however speeds have reduced from 16mbps to 12mbps.

Im paying for 24mb broadband and only live a mile from the exchange.

Here's my current router stats:

Code:

                            DOWN             UP
Connection Speed 	12511 kbps 	714 kbps
Line Attenuation 	  28.0 db 	14.2 db
Noise Margin 	          7.1 db 	1.2 db

Thanks

benftl · 9 Mar 2011 at 20:00

Chadd said:
Hi

Does anyone know what the correct noise margin I should have on my line to get the best broadband speeds while still maintaining a connection?

Only you will know that, if Be have set it to 7 and you're holding a connection then 7db it is. 6db is the default so you're losing maybe half a meg to try and keep your line stable?

Your line is capable of around 15mb with that attenuation, I guess there must be a noise issue somewhere if you're only syncing at 12mb~ around the normal SNR rate.

Have you tried connecting the modem/router directly to the master socket?

Demon · 9 Mar 2011 at 20:30

I agree with benftl..

Additionally, I use DGTeam firmware on a DG834N (Just use it as a modem) on O2, it allows easy adjustment of the SNR margin and I can get my connection stable at < 2db.. But at my previous address, I'd be lucky to get a stable line at 6db..

I now always use an iPlate as well, just in case.. but did my initial stability tests plugged directly into the test socket.

Kohaashi · 9 Mar 2011 at 23:59

Thanks.

The modem/router is connected to the master socket which has just been replaced by BT so it's can't be that. We only have one socket anyway.

I have a Netgear DG834PN so I'll have a look if there's a DGTeam firmware for this like you've mentioned.

Mattus · 11 Mar 2011 at 02:38

Chadd said:
Does anyone know what the correct noise margin I should have on my line to get the best broadband speeds while still maintaining a connection?

Afraid there's no single right answer to that - it depends entirely on the line. Line quality naturally fluctuates due to time of day, weather conditions, interference, etc. - but some lines fluctuate more than others and thus need a higher noise margin to stay stable in all circumstances. Some lines are stable at 3dB or below, others need more than 6. The only way to find out is by experimenting, really.

varkanoid · 11 Mar 2011 at 09:08

I would try and check what Demon said as often this can give you an increase of about 1.5meg to 2.5meg. I dont think iPlates are sold anymore but if you can get one of those it will be easier to just fit it to your master socket providing its compatible.

If not and you feel upto it you need to check all your phone sockets including master socket to see which wires are connected. Inside the socket the wires are numbered. Wires 2 (usually blue) and 5 (usually blue/white) these are the only wires you need connected. If you have any other wires connected eg 3,4 or 6 (orange and orange/white) then you can safely remove this or snip them. These are the bell wires used when phones had analogue ringing sounds. They are not needed now and can cause noise and interference with ADSL.

For instance in my house a few years ago I was with Plusnet on 3mb speed. I disconnected the bell wires and my speed leapt upto 4.5mb.

All the iPlate does is isolate the bell wire at the master socket and hence doing the same thing as what I described above.