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SNR & Loop Attenuation

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21 Dec 2005 22:43 #29582 by spies
Replied by spies on topic SNR & Loop Attenuation
In your telephone point there are 3 wires, only 2 are required if you have a microfilter for each phone, that will generate the ring pulse.

You need to find and disconnect the bell wire, i think it's orange.

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21 Dec 2005 22:51 #29584 by kensharp
Replied by kensharp on topic SNR & Loop Attenuation
Oh right, that's handy to know! :)

I'll give it a go. Thanks.

Vigor 2800G : Firmware 2.8.1
Extremely useful: Draytek Syslog from Router Tools and Wireshark (previously Ethereal).

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22 Dec 2005 21:44 #29616 by fredbloggstwo
Replied by fredbloggstwo on topic SNR & Loop Attenuation
have a look here http://www.telephonesuk.co.uk/wiring_info.htm

I think the theory goes that any noise on the house wiring will be picked up and propagated by the bell wire, whereas the A and B wires are a balanced pair and should cancel out any locally generated noise. If you have extensions off the Master socket, you can use microfilters to regenerate the bell signal as described on the web site above.

Haven't tried it meself purely haven't got around to doing so so I would be interested in any improvement (or otherwise ) that you get.
Cheers, Mike

Mike

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27 Apr 2006 17:33 #33095 by walker_jr
Replied by walker_jr on topic SNR & Loop Attenuation
I have found that the equipment often performs a lot better than the raw figures available at the beginning would suggest.

In my case I'm only 400m from the exchange, and I have a SNR of 40.5 and loop attenuation of 13.0, but bizarrely the BT speed checker reckoned my line was only good for 6.5M. However, the line went in and I got 8M (and no retrains) - so take the online information with a big grain of salt!

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30 Aug 2008 23:37 #51714 by fab-itrescue
Replied by fab-itrescue on topic Big SNR Small Loop Attn = NOT Always Good !
Recently had mega problems with a client on an enta ISP (enta = good, BT = bad) and the SNR was around 8 to 15, the loop attn was always 50+. Now I used to recon on double figures for SNR was desirable. but after lots and lots and lots of screwing around by BT to finally get better than 64kbps upspeed & 1200kbps downspeed, enta suggested LOWERING the SNR to increase the UPspeed! The SNR didn't change in the end but after lots of messing the speed increased.

But the idea of reducing the SNR to increase the speed is interesting . . .

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08 Sep 2008 11:18 #51808 by fab-itrescue
Replied by fab-itrescue on topic ADSL Firmware for Poor Quality Lines
I've got a 2600VG running (barely) on SNR 15 and Loop Att 55.

It can connect at around 380Kbps Up & 1880Kbps Down, but after a short while the Up drops to just 64Kbps, with no change in the DownSpeed. Corrected & Uncorrected Blocks are in the 1,000s after just a few hours running a site to site VPN.

The Firmware is 2.5.8.3 with ADSL Firmware 41e2be2c.

In the release notes it says this is the regular ADSL Firmware for the UK but there is an alternate for High dB - ADSL Firmware 43e2eaa1.

Can anyone suggest if this would help and if so how to get it into my router?

Regards

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