DSL Noise Margin

damienf1 · 15-01-2012 03:10PM #1

Hi,

I was wondering if anyone could tell me about the readings that i took for my broadband package (Eircom) i am on 8mb. Are the readings good for bad

Line Attenuation (Down/Up) 34 dB /18 dB

DSL Noise Margin: 9 dB /24 dB

Speed 8128 kbps /512 kbps

Thanks.

jor el · 15-01-2012 04:22PM

http://www.kitz.co.uk/adsl/linestats.htm
http://www.kitz.co.uk/adsl/max_speed_calc.php

Those readings are fine. 34dB attenuation is probably right on the edge of being able to support the full 8Mbps, but apart from that they're good.

Are you experiencing any problems?

Vic Vinegar · 02-02-2012 04:40PM

Hi, sorry for the mild hijacking...

What are these stats like? they don't seem too good from what little i know

relative capacity occupation: 96% 
noise margin upstream: 7.0 db
output power downstream: 19.5 dbm
attenuation upstream: 28.5 db

relative capacity occupation: 124% 
noise margin downstream: 6.5 db
output power upstream: 12.0 dbm
attenuation downstream: 40.0 db

We're supposed to be on 12mb but we are getting constant disconnects

jor el · 02-02-2012 04:45PM

http://www.kitz.co.uk/adsl/max_speed_calc.php
Your attenuation is way to high for 12Mbps, there's no way it'll be stable at that speed. The SNR margin is also very low. Your speed should be reduced to 6M or lower.

Vic Vinegar · 02-02-2012 04:48PM

jor el wrote: »

http://www.kitz.co.uk/adsl/max_speed_calc.php
Your attenuation is way to high for 12Mbps, there's no way it'll be stable at that speed. The SNR margin is also very low. Your speed should be reduced to 6M or lower.

I thought as much! i'll see about getting it reduced to 6mb or something, the router keeps disconnecting and resyncing at a lower speed each time until it's less than half of 1mb, is that normal for the line noise situation?

lucernarian · 03-02-2012 02:12AM

It's possible that the modem itself is not doing a very good job of being "rate adaptive" but the main problem is the line speed, you would be doing reasonably well to get 6mbits on ADSL1 which is what you will be reduced to if you get the speed moved down to 6mbps max. If they initially sold you up to 12 mbps on that line, possibly the line quality has deteriorated since then for some external reason.

There is another possibility, that local electrical interference is causing intermittent dropouts. I have used 17mbit ADSL2 connections with a signal margin of 6dB but I never got any dropouts. Local line conditions will vary. Still, I suspect using a different brand/model of modem would help. Along with a speed downgrade!

number_1 · 03-02-2012 01:00PM

My line stats are:

ADSL 1
Speed: 3072 kbps /384 kbps
Line Attenuation (Down/Up): 7 dB /4 dB
DSL Noise Margin: 28 dB /12 dB

There is 430m of copper wire to the exchange.

Eircom have told me that my line can't support broadband speeds higher than 5 Mbps. Does that sound correct? The above links suggest that I should have no problem receiving speeds up to 24 Mbps!

Can the Eircom line test result be wrong? If a 24 Mbps product was ordered could it work regardless of the line test result, or does the line test result mean that the line has been physically throttled to max out at 5 Mbps? ISPs don't seem to even consider providing the higher speed products due to the low line test result.

kaahooters · 03-02-2012 01:12PM

number_1 wrote: »

My line stats are:

ADSL 1
Speed: 3072 kbps /384 kbps
Line Attenuation (Down/Up): 7 dB /4 dB
DSL Noise Margin: 28 dB /12 dB

There is 430m of copper wire to the exchange.

Eircom have told me that my line can't support broadband speeds higher than 5 Mbps. Does that sound correct? The above links suggest that I should have no problem receiving speeds up to 24 Mbps!

Can the Eircom line test result be wrong? If a 24 Mbps product was ordered could it work regardless of the line test result, or does the line test result mean that the line has been physically throttled to max out at 5 Mbps? ISPs don't seem to even consider providing the higher speed products due to the low line test result.

id love to know this too, my bb is syncing at 5 mb, but, kitz says its on adsl 2 adn capable of 24mb.

eircom just lazy or really not know?

daffy_duc · 03-02-2012 01:16PM

ADSL2+ can go further faster on lower signal than ADSL1 can with the same SNR.
So keep that in mind when Eircom tells you your ADSL1 line can only do 5Mbit when an ADSL2+ can do 24Mbit on the same figures.

number_1 · 03-02-2012 01:25PM

Granted ADSL 1 has lower speeds than ADSL 2, but the links above suggest that a downstream attenuation of 7 dB should still allow speeds up to 8 Mbps on ADSL 1, not 5 Mbps.

jor el · 03-02-2012 02:30PM

daffy_duc wrote: »

ADSL2+ can go further faster on lower signal than ADSL1 can with the same SNR.
So keep that in mind when Eircom tells you your ADSL1 line can only do 5Mbit when an ADSL2+ can do 24Mbit on the same figures.

Not quite. A line that is only capable of 5Mbps on ADSL would not be capable of much more than that on ADSL2+. The difference in speed is only apparent at low line lengths with low attenuation.

The line stats quoted though should be well capable of 8M on ADSL, or close to 24M on ADSL2+. If there's a problem with that line that is restricting the speed to 5M, then 24M is not going to be possible either.

Solair · 03-02-2012 02:51PM

You might squeeze a few extra dB of noise margin out of the line if you simplify your internal wiring.

Basically, disconnect absolutely everything except the first eircom-branded socket. Then plug your DSL splitter in there and plug your modem and cordless base station in there. With modern cordless phones, you really don't need lots of extension sockets all over the house, and they just add noise to DSL lines.

Check the line for any audible crackles too. Pick up the phone (preferably a simple non-cordless), dial any digit to silence the dial tone and listen for any loud crackles.

If the line's noisy, ring your phone provider and tell them that you occasionally can't hear people on it due to the noise. They'll then have to investigate and fix it.

It's possible the line's just too long to provide decent DSL signals. If that's the case, you might be better off looking at some of the fixed antenna wireless systems that put a little ariel on your roof. Some of them, like Nova Networks in Cork are excellent and very comparable to a good quality DSL line.

Don't go with anything that is working on 3G or WiMax other "mobile broadband" devices. They are simply not suitable for serious broadband and won't provide a good enough connection for gaming or VoIP etc.

lucernarian · 03-02-2012 05:11PM

The signal margin on those stats is very substantial. If eircom are saying it can't do more than 5 mbps, you're being limited due to capacity problems at the exchange or else eircom's testing system has simply made a mistake. There was a thread about this before where someone lived 100m from the exchange and wasn't allowed to connect at the full 8 mbps initially. Nag and pursue this, post on the Talk to: Eircom forum if necessary.

arctan · 03-02-2012 05:45PM

could be like my situation and the cable from the DP to my house is in ribbons ...

do you hav a cable that comes into the house through the concrete floor ?

I'm in an 8 meg area, but my line struggles to get 1.6 megs, copper round my way is fooked ...

even the eircom line stats say I'll only get 1.8 max .. although i'm hoping to get that tested from the socket out, soon, to verify the remote test

Vic Vinegar · 07-02-2012 05:45PM

jor el wrote: »

http://www.kitz.co.uk/adsl/max_speed_calc.php
Your attenuation is way to high for 12Mbps, there's no way it'll be stable at that speed. The SNR margin is also very low. Your speed should be reduced to 6M or lower.

We got all new cabling coming into the house now to replace the older faulty wires. The line is much improved

How are these stats now and what speed can the line support?

relative capacity occupation: 59% 
noise margin upstream: 21.0 db
output power downstream: 19.5 dbm
attenuation upstream: 14.0 db
carrier load: number of bits per symbol(tone)

relative capacity occupation: 66% 
noise margin downstream: 21.0 db
output power upstream: 12.0 dbm
attenuation downstream: 28.5 db
carrier load: number of bits per symbol(tone)

We're on 6mb at the mo but we can increase it now the line is sorted.

jor el · 07-02-2012 06:10PM

That should be good to about 16Mbps on ADSL2+, or the full 8Mbps on ADSL. The downstream attenuation is the number you want (28.5dB), and plug that into the the website linked. It'll tell you the rest.

Noise margin is also important, in that if it's less than 6dB you can have disconnection issues. At over 20dB, you're doing well. Your old margin of 6.5dB would have been OK, but not great. Could be prone to problems, especially with the high attenuation.

number_1 · 07-02-2012 09:04PM

To_be_confirmed wrote: »

The signal margin on those stats is very substantial. If eircom are saying it can't do more than 5 mbps, you're being limited due to capacity problems at the exchange or else eircom's testing system has simply made a mistake. There was a thread about this before where someone lived 100m from the exchange and wasn't allowed to connect at the full 8 mbps initially. Nag and pursue this, post on the Talk to: Eircom forum if necessary.

Persistant nagging works. Lo and behold they suddenly reckon we're able to get ADSL 2 with estimated speeds of at least 11 Mbps!

brian ireland · 04-03-2012 09:47AM

Can you have a look at this and tell me what you think. I tried to look at the Kitz site but its all double dutch to me.
My internet is slow, most youtube videos buffer three or four times during playback.
Statistics Downstream Upstream
Line Rate 1376 Kbps 256 Kbps
Noise Margin 6.8 dB 22.0 dB
Line Attenuation 63.0 dB 31.5 dB
Output Power 16.2 dBm 11.4 dBm

Thanks

Simi · 04-03-2012 05:05PM

Those stats would seem to indicate that you're either living miles from the exchange or something is very wrong with your line.

Disconnect all sky boxes, phones etc. from the the line and reset your dsl modem/router. Then check your stats again to see if they've changed any. If not, that's the best your gonna get sorry.

Gipo3 · 04-03-2012 07:22PM

What about this?
Vodafone day cant get speed increase??

Current(kbps) Down 3072, Up 384;
Max Rate(kbps) Down 7968, Up 1048;
Noise Margin Down 22.3db, Up 24db;
Attenuation Down 27db, Up 47db;
Power Down 19.6dbm, Up 11.9dbm

brian ireland · 04-03-2012 07:44PM

Simi wrote: »

Those stats would seem to indicate that you're either living miles from the exchange or something is very wrong with your line.

Disconnect all sky boxes, phones etc. from the the line and reset your dsl modem/router. Then check your stats again to see if they've changed any. If not, that's the best your gonna get sorry.

That was a test with everything disconnected but the Mac.

lucernarian · 05-03-2012 12:18AM

brian ireland wrote: »

That was a test with everything disconnected but the Mac.

Disconnect everything else from the line itself, not the router.

exaisle · 20-07-2012 12:08PM

I have a faceplate ADSL filter connected and my SNR is 15.4dB. Without the filter connected, it's 11.2dB.

Am I right in thinking that the filter is reducing the noise on the line(ie filtering part of bandwidth out that includes noise, hence a better ratio)?

I'm quite a distance from the exchange so attenuation is 55dB but I'm happy enough with a 2mb connection....as long as its stable.

Solair · 20-07-2012 03:12PM

Yeah the higher the SNR margin the better.

It's measuring how much louder the signal is compared to the background noise on the line.

* 6bB. or below = Bad and will experience no line synchronisation and frequent disconnections.
* 7dB-10dB. = Fair but does not leave much room for variances in conditions.
* 11dB-20dB. = Good with little or no disconnection problems
* 20dB-28dB. = Excellent
* 29dB. or above = Outstanding (you actually live in the exchange)

BigGeorge · 25-09-2013 07:31PM

Folks - sorry to drag up an old threat but am having intermitent BB problems & need to eliminate. There has been fibre works going on in the area at the same time

Stats off the router ( zyxel p660hw-t1 v3) are :

DSL Mode: ADSL_G.dmt Speed: 4352 kbps /512 kbps Line Attenuation (Down/Up): 59 dB /31 dB DSL Noise Margin: 6 dB /21 dB
Any suggestions great appreciated

bealtine · 25-09-2013 07:44PM

BigGeorge wrote: »

Folks - sorry to drag up an old threat but am having intermitent BB problems & need to eliminate. There has been fibre works going on in the area at the same time

Stats off the router ( zyxel p660hw-t1 v3) are :

DSL Mode: ADSL_G.dmt Speed: 4352 kbps /512 kbps Line Attenuation (Down/Up): 59 dB /31 dB DSL Noise Margin: 6 dB /21 dB
Any suggestions great appreciated

Didn't you read the last post before yours?

Your noise margin is 6db meaning disconnects, get onto your supplier

BigGeorge · 25-09-2013 08:00PM

There is a crackle on the line, I need to have a look at the wiring in the house to make sure that the filters are all in place

bealtine · 25-09-2013 08:21PM

BigGeorge wrote: »

There is a crackle on the line, I need to have a look at the wiring in the house to make sure that the filters are all in place

disconnect all extensions and all phones except for the main socket and measure from that again, if the noise margin goes up you'll know if the problem is with your extensions inside the house or not

BigGeorge · 26-09-2013 11:30PM

OK, so

Called Eircom tech support who did a line test & said that the line was only capable of delivering 4MB, not 5, & did a line test. he said he turned the speed down to 4MB & I quickly saw that the noise increased to 7dB - he confirmed this from the line test. Better but not good

So, I took your advice, disconnected absolutely everything & plugged the modem directly into the master socket with everything else cut off. results are now:

Speed: 3872kbps /384 kbps
Line Attenuation (Down/Up): 56 dB /31 dB
DSL Noise Margin: 6 dB /26 dB

At least I now know that the wiring in the house is not at fault. I can see the nearest green cabinet - it is 150m away & the fibre cabinet has just been installed besides the old one. It is a new line installed by Eircom 20 months ago. What do I do next?

bloodyhawk · 27-09-2013 03:58AM

What in the world, could someone help me on this?
My SNR Margin: Just dropped from 15.0 dB 21.3 dB to 14.0 dB 14.3 dB

bloodyhawk · 27-09-2013 04:02AM

My Attainable Net Data Rate: Also dropped from 35.974 Mbps 137.364 Mbps to 34.388 Mbps 115.376 Mbps I have no idea whats going on. Does anyone perhaps know why this has happened?

I am on E-fiber 70mb by the way.

DSL Noise Margin

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