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Standard User ayeaye
(newbie) Wed 18-Apr-12 12:45:41
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Router resynch with asterisk appliance


[link to this post]
 
Hi all

I have an Atcom IP01 Asterisk box for VOIP which has a FXO module to connect to a POTS line. The phone line is either a long line or has some dodgy aluminium in it somewhere as the best synch speeds achievable are around 2.5Mbps once the SNR has been forced down (Billion 7800N router) - stats from the router:

Operational Mode ADSL2+
Upstream 694
Downstream 2552
SNR Margin(Upstream) 6.3
SNR Margin(Downstream) 2.2
Line Attenuation(Upstream) 47.6
Line Attenuation(Downstream) 71.5

With the IP01 connected through a standard filter into the master socket, it forces the router a resync immediately and it will resynch around 1.6Mbps. Double filtering is forcing a resync to about 2.2Mbps.

I suspect this is down to additional noise the Atcom unit is putting onto the line, but a second unit is also causing the same issue so in theory should rule out faulty hardware.

Is there anything other than double or treble filtering that I could try doing to minimise the additional noise / immediate resync?

Cheers
Administrator MrSaffron
(staff) Wed 18-Apr-12 13:12:52
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Re: Router resynch with asterisk appliance


[re: ayeaye] [link to this post]
 
At 71dB attenuation, your signal is so low that the noise from one switched mode power supply in the vicinity might swamp the signal.

2.5 Meg from 71dB is pretty amazing. The 1Meg is more what you would expect, and even that is higher than BT would suggest

Andrew Ferguson, andrew@thinkbroadband.com
www.thinkbroadband.com - formerly known as ADSLguide.org.uk
The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
Standard User ayeaye
(newbie) Wed 18-Apr-12 13:55:35
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Re: Router resynch with asterisk appliance


[re: MrSaffron] [link to this post]
 
Even with the SNR margin at 2.5 or so the line seems pretty stable, certainly can go weeks between reyncs. If I reset the router to defaults, a SNRM of 6 will synch at 1.7Mbps which still isn't too bad given the line stats.

Currently with O2 LLU although moving to Sky next week in preparation for fibre coming soon - looking forward to going from 2.5Mbps to just shy of 40Mbps (speed checkers reckon 52.5Mbps) - so I'm expecting a speed drop due to DLM which is why I was trying to sort out the SNR margin drop caused by this box.

I suspect you're right though - on an very marginal line, any additional noise is going to have more noticeable effects than on a short low attenuation line.

Cheers


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