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SNR = Expert comments please.Do I have a rubbish line?

jagger
Grafter
Posts: 411
Registered: 25-06-2007

SNR = Expert comments please.Do I have a rubbish line?

Hi guys.
My line has been flakey for a year or more now with the odd unexplained complete disappearance from broadband thrown in for free.It got fixed by BT at the exchange but was never explained to me.
So I've been digging (thanks to oldjim for the program).This is my connection for the last three days or so.The vertical lines are logs of a connection break of at least 1 minute.The snr just looks horrific to me,but I don't really know what I'm looking at.Is this as bad as it seems/feels/appears?
I include speedtests conducted over the last three weeks.You can safely ignore the big V,which was a speedtest performed just as the connection dropped.
I have a rock solid D/S attenuation of 38db and am around 3klicks from the exchange by wire.I was expecting a bit more than 2.7 megs actual.Is this my line just being rubbish?
Appreciate any comments.
11 REPLIES
Community Veteran
Posts: 38,460
Thanks: 1,028
Fixes: 62
Registered: 15-06-2007

Re: SNR = Expert comments please.Do I have a rubbish line?

Can you plug the router into the test socket and monitor it over 24 hours. You can have a phone attached as well (via a filter of course) in the test socket
Also post the stats when in the test socket
jagger
Grafter
Posts: 411
Registered: 25-06-2007

Re: SNR = Expert comments please.Do I have a rubbish line?

No can do Jim,as I have an older box without the faceplate (writing that just made me go hmmmmmmm.....)
I'll hook it up to what passes as the main socket ( it's the only one,where the telephone (dect) is connected and see what happens.
jagger
Grafter
Posts: 411
Registered: 25-06-2007

Re: SNR = Expert comments please.Do I have a rubbish line?

Ok Jim,here's where I'm at.
Hooked up to the main socket and using wireless for access.
Graph so far looks a bit different but still very high.A few breaks showing but not in the log.

Community Veteran
Posts: 26,692
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Registered: 10-04-2007

Re: SNR = Expert comments please.Do I have a rubbish line?

Quote from: jagger
'll hook it up to what passes as the main socket ( it's the only one,where the telephone (dect) is connected and see what happens.

Sorry for double checking the obvious, but was the DECT telephone plugged in using a filter?
jelv (a.k.a Spoon Whittler)
   Why I have left Plusnet (warning: long post!)   
Broadband: Andrews & Arnold Home::1 (FTTC 80/20)
Line rental: Pulse 8 Home Line Rental (£13/month)
Mobile: iD mobile (£4/month)
jagger
Grafter
Posts: 411
Registered: 25-06-2007

Re: SNR = Expert comments please.Do I have a rubbish line?

Yes Jim.Always.The one that came with my new router.
Community Veteran
Posts: 38,460
Thanks: 1,028
Fixes: 62
Registered: 15-06-2007

Re: SNR = Expert comments please.Do I have a rubbish line?

Those breaks are routerstats not getting a reply from the router in time - usually some other process on your PC getting in the way.
The results look a lot better - you haven't got the big drop over night
jagger
Grafter
Posts: 411
Registered: 25-06-2007

Re: SNR = Expert comments please.Do I have a rubbish line?

I got forgetful and switched the box off overnight but, just as you thought it was safe to........
Seems to happen around 8 o'clock.Can't think of any household systems that are active at the time.
I do live next door to a small housing estate sized electrickery substation but I can't see that dropping off in performance at prime time and hence be having some effect.
Is an snr reading that high (hovering around 16 this morning) necessarily a bad thing Jim?
Community Veteran
Posts: 38,460
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Registered: 15-06-2007

Re: SNR = Expert comments please.Do I have a rubbish line?

The SNR is high because the default margin is high,
Going back to your first graph you were seeing a drop of margin from about 15dB to about 10/11dB
The new graph shows a drop of rather less than that but we need a full overnight result to compare however the graph in your reply 3 seems to be overnight and shows no dip.
Can you confirm that this graph is from what is the nearest thing you have to a master socket and is the last graph from the same socket
grahamt
Rising Star
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Registered: 05-04-2008

Re: SNR = Expert comments please.Do I have a rubbish line?

Your setup seems to be a bit similar to mine (no proper master socket, 38dB attenuation, SNR dropping during the hours of darkness). I was also getting speeds of around 2.5-3mb/s. (I ended up being on a 'banded profile' but as your sync speed varies it looks like you're not.)
My line improved a lot after I had the bell wire snipped. (My wiring is a bit complicated so I got someone in who knew what he was doing, but if your wiring is more standard you can probably do it yourself. See http://www.kitz.co.uk/adsl/socket.htm)
I still have SNR drops at night, but my line can now sustain a sync speed of about 8mb/s (admittedly, this is on ADSL2+) and my IP profile is either 7000 or 7150.
jagger
Grafter
Posts: 411
Registered: 25-06-2007

Re: SNR = Expert comments please.Do I have a rubbish line?

Jim,
The graph in reply 3 is the main socket, and overnight, just after I'd moved the router from upstairs.
The continuation of graph in last post is below.This is current @11:05 this morning
Thanks Graham.I'll bear that in mind (not going to start snipping yet though.  Grin
Community Veteran
Posts: 38,460
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Registered: 15-06-2007

Re: SNR = Expert comments please.Do I have a rubbish line?

Moving to the main socket has made a significant improvement to the overnight noise margin.
i would also suggest removing the bell wire