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Standard User joconnell
(experienced) Thu 14-Jun-12 10:07:46
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Downstream SNR keeps dropping


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Ever since I've been using a Billion Bipac 7800N router at home, I've noticed that my ADSL line's downstream SNR decreases over a number of days from 4 down to 1, then drops the ADSL connection and spends quite a while re-connecting. I noticed the dropped connection on Tuesday night when I had no internet access at around midnight - a quick check of the ADSL status on the router's status page at that point confirmed that the router was indeed reconnecting to ADSL and taking it's time about it.

I checked the SNR last night and it's now 3 and ADSL is connected.

Can anyone explain the above behaviour? Is it normal?
Standard User john2007
(legend) Thu 14-Jun-12 10:13:33
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Re: Downstream SNR keeps dropping


[re: joconnell] [link to this post]
 
I'd say not normal, a drop overnight and a rise in the morning is typical.

Run RouterStats http://www.vwlowen.co.uk/internet/files.htm if possible. A graph may help in diagnosis.
Standard User joconnell
(experienced) Thu 14-Jun-12 10:43:16
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Re: Downstream SNR keeps dropping


[re: john2007] [link to this post]
 
In reply to a post by john2007:
I'd say not normal, a drop overnight and a rise in the morning is typical.

Run RouterStats http://www.vwlowen.co.uk/internet/files.htm if possible. A graph may help in diagnosis.

Thanks for that, I'll give it a go


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Standard User joconnell
(experienced) Thu 14-Jun-12 22:31:40
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Re: Downstream SNR keeps dropping


[re: joconnell] [link to this post]
 
Well I'm running Routerstats since 22:05 tonight and at about 22:14 the graph drops to zero for noise margins and sync speeds momentarily before recovering back to the previous level around a minute later. I didn't notice any drop in the ADSL connection though i.e. I was browsing normally

Is this expected?
Standard User camieabz
(sensei) Thu 14-Jun-12 23:07:41
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Re: Downstream SNR keeps dropping


[re: joconnell] [link to this post]
 
Most people reboot in the quiet hours to get a high sync / low SNR. If you reboot in the busy times (7.30pm ish) you might get a more stable sync.

~ Camieabz ~

All Connection Data ~ Some plusnet links

mod'er·a'tion n.
Synonyms: temperance, restraint, modesty.
Standard User RobertoS
(sensei) Sat 16-Jun-12 23:07:59
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Re: Downstream SNR keeps dropping


[re: camieabz] [link to this post]
 
Uh?

If you really mean SNR then fine. But do you, or do you mean SNR Margin? That's what 90% of readers will think you mean, and of course that isn't true.

When's the "quiet time" anyway?

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

"Where talent is a dwarf, self-esteem is a giant." - Jean-Antoine Petit-Senn.
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Standard User camieabz
(sensei) Sun 17-Jun-12 01:05:11
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Re: Downstream SNR keeps dropping


[re: RobertoS] [link to this post]
 
SNR - Signal to noise ratio.

Quiet time for me is 4am to 6.30am if I were being pedantic, but generally 2am to 8am will do.

~ Camieabz ~

All Connection Data ~ Some plusnet links

mod'er·a'tion n.
Synonyms: temperance, restraint, modesty.
Standard User RobertoS
(sensei) Sun 17-Jun-12 10:16:19
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Re: Downstream SNR keeps dropping


[re: camieabz] [link to this post]
 
Wierd - that's the opposite of what most people experience. So I think those times would give most people a low sync and high day-time noise margin, particularly in the winter. I.e. stability rather than speed.

I seem to remember this being discussed before about your line?

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

"Where talent is a dwarf, self-esteem is a giant." - Jean-Antoine Petit-Senn.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Standard User camieabz
(sensei) Sun 17-Jun-12 12:48:53
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Re: Downstream SNR keeps dropping


[re: RobertoS] [link to this post]
 
Here's my experience. The target SNR is 3.0dB. In the busy times it drops to as low as 2.5dB, but in quiet times rises to 3.6 dB. If I reboot at 3.6dB it resets at 3.0 / 3.1dB and the sync increases. However, if the busy time is very busy the SNR drops to below 2.5dB and might trigger a disconnection. Then it resets to 3.0 / 3.1dB but at a lower sync (more stable). Then in the quiet times it pops back up to 3.6 or more. smile

I did mention to the Plusnet handler that it was a bad time to switch to ADSL2+ and train the line (Jubilee, Euro 2012, Olympics). I got a really decent sync on Friday morning, only to get a disconnection when the country decided to go online around the time of the England match. No idea why, since it's on FTV telly, but those are the trends I'm seeing.

~ Camieabz ~

All Connection Data ~ Some plusnet links

mod'er·a'tion n.
Synonyms: temperance, restraint, modesty.

Edited by camieabz (Sun 17-Jun-12 13:23:42)

Standard User ClaretMatt
(newbie) Sun 17-Jun-12 13:14:47
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Re: Downstream SNR keeps dropping


[re: camieabz] [link to this post]
 
Mine wanders around by 3-4 db and there doesn't seem to be any rhyme or reason for it. Had BT on the fault for 8 weeks last year and every section of my copper was changed, all joints checked, lift and shift, tie pair modify and no change.

So I just live with it I guess
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