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Standard User PhormFree
(learned) Mon 17-Jan-11 13:35:43
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Noise Margin: a clueless numptie enquires. . .


[link to this post]
 
Heigh-ho. Sorry to be a nuisance, but if someone could explain how "noise" is, er, regulated (if such be the word), that'd really be appreciated.

I'm on a slowish broadband connection due to being a long way from the exchange. My ISP is Newnet. My connection is wireless. My router is a Netgear DG834 v2.

Because of various dconnectvitiy problems in the past, I relocated the ro;uter to a position next to the BT master socket, to make it first in the queue, as it were, in the house's phone wiring. This seemed to work OK. I also fiddled about with glue, cardboard and silver paper (how sad is that?) to make a, er, parabolic reflector to sit atop the router's stubby antenna. Weirdly, that also works well: signal strength to the top of a three storey house ranges from very good to excellent.

Now. . . back in November, connectivity probs started all over again. And the line speed never seemed to stay one thing or another. According to BT, however, there was no line fault. (Though three days later, not one but *four* BT Openreach vans were in o;ur village, digging up the road in different places. Coincidence?)

Figuring that I ought to know *something* about my line stats, I downloaded the little RouterStats Lite application. Its graphs chart connection speed and noise margin.

During the past three weeks, my Internet connectivity has been pretty hopeless. Here's a typical example from the Routerstats log yesterday:

Mon 27 Dec 2010 09:54:23, Noise Margin= 12.4, Sync Speed= 1568
Mon 27 Dec 2010 09:54:38, Noise Margin= 12.4, Sync Speed= 1568

Mon 27 Dec 2010 12:21:57, Noise Margin= 12.9, Sync Speed= 1568

Mon 27 Dec 2010 12:22:12, Noise Margin= 6.6, Sync Speed= 1568

Mon 27 Dec 2010 12:22:28, Noise Margin= 2.2, Sync Speed= 1568
Mon 27 Dec 2010 12:22:42, Noise Margin= 3.9, Sync Speed= 1568
Mon 27 Dec 2010 12:22:57, Noise Margin= 0.5, Sync Speed= 1568
Mon 27 Dec 2010 12:23:12, Noise Margin= 0.1, Sync Speed= 1568
Mon 27 Dec 2010 12:23:27, Noise Margin= 0.1, Sync Speed= 1568
Mon 27 Dec 2010 12:23:42, Noise Margin= 0.1, Sync Speed= 1568
Mon 27 Dec 2010 12:23:57, Noise Margin= 0.2, Sync Speed= 1568
Mon 27 Dec 2010 12:24:12, Noise Margin= 0.0, Sync Speed= 1568
Mon 27 Dec 2010 12:24:27, Noise Margin= 0.2, Sync Speed= 1568
Mon 27 Dec 2010 12:24:42, Noise Margin= 0.2, Sync Speed= 1568
Mon 27 Dec 2010 12:24:57, Noise Margin= 0.3, Sync Speed= 1568
Mon 27 Dec 2010 12:25:12, Noise Margin= 0.4, Sync Speed= 1568
Mon 27 Dec 2010 12:25:27, Noise Margin= 0.6, Sync Speed= 1568
Mon 27 Dec 2010 12:25:42, Noise Margin= 0.7, Sync Speed= 1568
Mon 27 Dec 2010 12:25:57, Noise Margin= , Sync Speed= 0
Mon 27 Dec 2010 12:26:12, Noise Margin= , Sync Speed= 0
Mon 27 Dec 2010 12:26:27, Noise Margin= , Sync Speed= 0

In other words, things start off OK then, whilst I'm in the middle of something, the connection vanishes and that's it. When I click on the toolbar icon, it says 'Local Only' connection. And there's no way of getting anything more.

I really don't understand this Noise Margin business. It seems the lower it drops, the higher the chance I have connectivity problems. So. . . my numptie question is this:

* Is the Noise Margin a reflection of something that *my* router causes, or of something, somewhere, caused by *my* internal phone wiring?

Or is it something to do weith some arcane equipment at the BT Exchange??

Help appreciated (and sorry if this is a daft question. . .)
Standard User yarwell
(sensei) Mon 17-Jan-11 14:02:17
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Re: Noise Margin: a clueless numptie enquires. . .


[re: PhormFree] [link to this post]
 
it looks like you connect with a noise margin of 12 dB and then some noise comes along and reduces it to the point where it disconnects.

The "Noise Margin" is actually the "signal to noise ratio in excess of that required to sustain a defined error rate" so if you get more noise the signal to noise ratio (SNR) drops and you lose the connection, prompting a resync.

Is it any better in the test socket, behind the master faceplate ?

Phil

MaxDSL - goes as fast as it can and doesn't read the line checker first.

MaxDSL diagnostics
Are your kids pirates ? Limewire, Bearshare, Kazaa, BitTorrent, eMule are all tools of the trade.

Edited by yarwell (Mon 17-Jan-11 14:31:29)

Standard User RobertoS
(sensei) Mon 17-Jan-11 14:23:19
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Re: Noise Margin: a clueless numptie enquires. . .


[re: PhormFree] [link to this post]
 
This page doesn't help find what is causing the problem but I hope it will explain for you how noise margin works.

My broadband basic info/help site - www.robertos.me.uk
My domains,website and mail hosting - Tsohost. Internet connection - O2 Standard.


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Standard User PhormFree
(learned) Mon 17-Jan-11 17:49:50
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Re: Noise Margin: a clueless numptie enquires. . .


[re: RobertoS] [link to this post]
 
MANY thanks to Roberto and Phil for the fast response. First, to Roberto:

That's an incredibly helpful resource you've provided. It's so comprehensive, I'm taking my time to go through it -- so apologies for not replying sooner.

To Phil: you must be psychic -- after posting my query, I decided to disconnect, remove the face plate, and plug directly into the hidden (test) socket. So for the past few hours (we had to go out) it's been connected up like that, and still is. RouterStats Lite is a bit confusing because obviously, when the computer goes to sleep, so too does the application. When the computer comes alive again -- even though the router hasn't been turned off during the computer's sleep period -- the Noise Margin stats are then different than before, although the connection speed is the same.

Currently, fingers crossed, there's no severe deterioration in the Noise Margin, but I obviously can't immobilise all the phone extensions in the house so will have to swap back soon. (Oh, and no, there's no bell wire in the socket; I removed it a year or two back.)

I guess the essence of my problem (!) is that I thought noise could be introduced to a line due to external as well as internal factors -- but that if I connected the wireless router to the first point of call, as it were (the master socket) then it couldn't be affected by noise in the wiring system elsewhere in the property -- and especially not by our Sky Plus box, which is on the next floor up.

I'll see what happens after tea when I unplug from the test socket and go back to the master socket.

Meantime. . . are there *other* stats I ought to be looking at, with a view to identifying this recurring connection problem? I understand that there's a 'full' version of Routerstats available for my particular modem, but I haven't used it due to a basic techno-fear (sad, I know) of being assailed with all kinds of data about which I haven't a clue. . .

Thanks again to you both.
Standard User RobertoS
(sensei) Mon 17-Jan-11 18:03:06
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Re: Noise Margin: a clueless numptie enquires. . .


[re: PhormFree] [link to this post]
 
Noise from inside your premises gets onto the line down the active lines as well as the bell wire, and hits the modem/router where it hurts. That's why using the test socket eliminates it, whereas just using the external socket on the router has relatively little effect.

Is the Sky+ box filtered? If not, it should be, and if it is see if the behaviour changes with it disconnected. Possibly double-filter it. That can help if it is a particularly noisy one.

See Miscellaneous Nasties in the Troubleshooting section of my website for a few other things to consider. Also check and post what colour wires are connected to which terminals on the back of the faceplate, and it would be worth doing the same at every extension as well. There can be issues there.

The full RouterStats does have quite a few other things that may be useful to you, but I've always struggled with it for some reason. As others have no problem it must be me.

My broadband basic info/help site - www.robertos.me.uk
My domains,website and mail hosting - Tsohost. Internet connection - O2 Standard.
Standard User PhormFree
(learned) Mon 17-Jan-11 20:23:17
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Re: Noise Margin: a clueless numptie enquires. . .


[re: RobertoS] [link to this post]
 
Many thanks, Roberto. I will check. After my last post, I did unplug from the test socket and go back to the master socket. . . since which time, it's been a case of wondering why do I bother paying for broadband? (Only joking, but you'll understand the frustration.)

I've edited the recent RouterStats log to delete duplicate entries on the time intervals, but here's the picture (bearing in mind that all was stable at a reported Noise Margin of 9.0 / Sync Speed of 1888 prior to the change-over at 17:02 today):

Jan 2011 17:02:04, Noise Margin= 9.0, Sync Speed= 1888
Mon 17 Jan 2011 17:02:19, Noise Margin= 9.0, Sync Speed= 1888

Mon 17 Jan 2011 17:22:50, Noise Margin= 8.8, Sync Speed= 1888
Mon 17 Jan 2011 17:23:05, Noise Margin= 8.8, Sync Speed= 1888

Mon 17 Jan 2011 17:57:37, Noise Margin= 8.6, Sync Speed= 1888
Mon 17 Jan 2011 17:57:52, Noise Margin= 8.8, Sync Speed= 1888
Mon 17 Jan 2011 17:58:07, Noise Margin= , Sync Speed= 0
Mon 17 Jan 2011 17:58:22, Noise Margin= , Sync Speed= 0
Mon 17 Jan 2011 17:58:37, Noise Margin= , Sync Speed= 0
Mon 17 Jan 2011 17:58:52, Noise Margin= 12.1, Sync Speed= 1376

Jan 2011 18:04:52, Noise Margin= 12.1, Sync Speed= 1376
Mon 17 Jan 2011 18:05:07, Noise Margin= 12.1, Sync Speed= 1376
Mon 17 Jan 2011 18:05:22, Noise Margin= 12.0, Sync Speed= 1376
Mon 17 Jan 2011 18:05:37, Noise Margin= 5.1, Sync Speed= 1376
Mon 17 Jan 2011 18:05:52, Noise Margin= 1.1, Sync Speed= 1376
Mon 17 Jan 2011 18:06:07, Noise Margin= 0.6, Sync Speed= 1376
Mon 17 Jan 2011 18:06:22, Noise Margin= 0.9, Sync Speed= 1376
Mon 17 Jan 2011 18:06:37, Noise Margin= 0.9, Sync Speed= 1376
Mon 17 Jan 2011 18:06:52, Noise Margin= 0.9, Sync Speed= 1376
Mon 17 Jan 2011 18:07:07, Noise Margin= 0.9, Sync Speed= 1376
Mon 17 Jan 2011 18:07:22, Noise Margin= 0.2, Sync Speed= 1376
Mon 17 Jan 2011 18:07:37, Noise Margin= 0.0, Sync Speed= 1376
Mon 17 Jan 2011 18:07:52, Noise Margin= 0.0, Sync Speed= 1376
Mon 17 Jan 2011 18:08:07, Noise Margin= 0.2, Sync Speed= 1376
Mon 17 Jan 2011 18:08:22, Noise Margin= 0.2, Sync Speed= 1376
Mon 17 Jan 2011 18:08:37, Noise Margin= 0.3, Sync Speed= 1376
Mon 17 Jan 2011 18:08:52, Noise Margin= 0.3, Sync Speed= 1376
Mon 17 Jan 2011 18:09:07, Noise Margin= , Sync Speed= 0
Mon 17 Jan 2011 18:09:22, Noise Margin= , Sync Speed= 0
Mon 17 Jan 2011 18:09:37, Noise Margin= , Sync Speed= 0


Mon 17 Jan 2011 18:09:52, Noise Margin= 12.3, Sync Speed= 992
Mon 17 Jan 2011 18:10:07, Noise Margin= 11.4, Sync Speed= 992

Mon 17 Jan 2011 18:26:38, Noise Margin= 11.3, Sync Speed= 992
Mon 17 Jan 2011 18:26:55, Noise Margin= 11.4, Sync Speed= 992
Mon 17 Jan 2011 18:27:13, Noise Margin= -, Sync Speed=
Mon 17 Jan 2011 18:27:23, Noise Margin= 11.3, Sync Speed= 992
Mon 17 Jan 2011 18:27:42, Noise Margin= , Sync Speed=
Mon 17 Jan 2011 18:27:59, Noise Margin= -, Sync Speed=
Mon 17 Jan 2011 18:28:12, Noise Margin= , Sync Speed=
Mon 17 Jan 2011 18:28:27, Noise Margin= , Sync Speed=
Mon 17 Jan 2011 18:28:43, Noise Margin= -, Sync Speed=
Mon 17 Jan 2011 18:28:53, Noise Margin= 11.3, Sync Speed= 992
Mon 17 Jan 2011 18:29:12, Noise Margin= , Sync Speed=
Mon 17 Jan 2011 18:29:27, Noise Margin= , Sync Speed=
Mon 17 Jan 2011 18:29:42, Noise Margin= , Sync Speed=
Mon 17 Jan 2011 18:29:57, Noise Margin= , Sync Speed=
Mon 17 Jan 2011 18:30:12, Noise Margin= , Sync Speed=
Mon 17 Jan 2011 18:30:27, Noise Margin= , Sync Speed=
Mon 17 Jan 2011 18:30:39, Noise Margin= 11.2, Sync Speed= 992
Mon 17 Jan 2011 18:30:57, Noise Margin= , Sync Speed=
Mon 17 Jan 2011 18:31:50, Noise Margin= , Sync Speed=


Jan 2011 20:01:53, Noise Margin= 12.3, Sync Speed= 992
Mon 17 Jan 2011 20:02:08, Noise Margin= 12.4, Sync Speed= 992
Mon 17 Jan 2011 20:08:17, Noise Margin= , Sync Speed=
Mon 17 Jan 2011 20:08:32, Noise Margin= , Sync Speed=
Mon 17 Jan 2011 20:08:47, Noise Margin= , Sync Speed=
Mon 17 Jan 2011 20:09:02, Noise Margin= , Sync Speed=
Mon 17 Jan 2011 20:09:23, Noise Margin= , Sync Speed=
Mon 17 Jan 2011 20:10:43, Noise Margin= , Sync Speed=
Mon 17 Jan 2011 20:10:58, Noise Margin= 12.3, Sync Speed= 992
Mon 17 Jan 2011 20:11:13, Noise Margin= 12.4, Sync Speed= 992
Mon 17 Jan 2011 20:11:28, Noise Margin= 12.4, Sync Speed= 992
Mon 17 Jan 2011 20:11:43, Noise Margin= 12.4, Sync Speed= 992
Mon 17 Jan 2011 20:11:58, Noise Margin= 12.3, Sync Speed= 992

At the above Noise Margin / Sync Speed it wasn't possible to access the Internet (Local Only') so I disconnected and tried again. Bizarrely, however, it has re-connected at the same as before, only this time I can get both Local and Internet connections. (Or perhaps it's not bizarre, I dunno.) But the loading time for this site was just so sl-oooo-w. . .

No need to wade through all the stats above, youj can probably see the pattern at a glance. So it does seem to prove that everything's going to pot now that the router is plugged back into the Master Socket. Iy yi yi yi.
Standard User RobertoS
(sensei) Mon 17-Jan-11 20:37:20
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Re: Noise Margin: a clueless numptie enquires. . .


[re: PhormFree] [link to this post]
 
I think you will see a difference on the graph between the log lines with 0 speed and margin and those with blank speed and margin. At a guess, the blank ones will show a red drop line and the zeros will stay at the normal colour.

Are you still connecting wirelessly to the router? If so, connecting wired will almost certainly eliminate the blank/red line ones. That is usually the wireless link bombing out.

Click the InSSIDer link on my Useful Links page and download it. Have a look at the wireless activity around you. In particular your channel and overlaps with it, and the strengths of the various signals.

You want to aim for the least overlap.

My broadband basic info/help site - www.robertos.me.uk
My domains,website and mail hosting - Tsohost. Internet connection - O2 Standard.
Standard User PhormFree
(learned) Tue 18-Jan-11 12:07:10
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Re: Noise Margin: a clueless numptie enquires. . .


[re: RobertoS] [link to this post]
 
Bob: just a quickie thank you for that link. I've DL'd and installed inSSIDer 2.0 and it's up and running. I'm 3 floors above the point where the router connects to the master socket; inSSIDer is reading the Netgear WG111v2 USB connected to this computer. It reports no other wi-fi activity anywhere, just this home network.

What was intriguing, even though I don't pretend to understand it, was the RSSI graph reading minus 68, Channel 11. I've moved the Netgear WG111 to a slightly different position and the RSSI is now steady at minus 52. Which, er, must be some sort of improvement!

I've also re-checked the RouterStats Lite graphs but the lines are only solid red or solid blue. Further to your advice, I've also installed another ADSL filter on the line used by the Sky Plus box, so now there are two in place.

I'm going to see how things progress today, alternating between the master socket and the test socket.

Once again, sincere thanks for your help and advice, and apologies for intruding on your time.
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