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How do i increse SNR?

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How do i increse SNR?

Just had my re-grade from 512 to 1meg. However my SNR seams to have gone down! causing lots of disconnection’s. Is there anyway i can increase the SNR etc?

I will try wiring in directly to the Master socket later today, but any other ideas would be much appreciated.

Thanks
Si
6 REPLIES
Community Veteran
Posts: 14,469
Registered: 30-07-2007

How do i increse SNR?

Very little you can do as the bulk of the drop in signal is on the BT cable. SNR will decrease with higher speeds due to it using higher frequencies to sustain the new speed.

If connecting to the master socket (and also try the internal socket under the faceplate) results in a higher SNR then your internal wiring could be the cause and may need to be replaced with cat5 cabling rather than the normal phone cables.

Also try with no phones or ADSL filters connected a see if it makes any difference.

What is your SNR and line attenuation as both could be effecting your connection reliability.
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How do i increse SNR?

The ATEN is the same as when i was on the 512k (60) but for the life of me i can not remember what the SNR was, but its now 3! which is a problem! How does the new faceplate work which is installed by BT, is there any figures to say how much it improves?

Thanks
Si
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How do i increse SNR?

There is no set scale to how it can improve your line, or if it will at all.

It very mucg depends on the quality of your existing setup, and trial and error to see if it helps any.

SOme reports have shown benefits of upto 250%, with some gaining only 3dB. In most cases, just enough to sustain a reliable SNR, or at least one capable of sustaining a connection for 6 hours or more.
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How do i increse SNR?

Lowdown on my findings!

Background - Live in a town house (3 floors) and the master socket is ground floor. Internal wiring to bedroom (2nd floor), livingroom (1st floor), and diningroom(1st floor). The PC is connect to the diningroom socket via a filter. Phone in living room connected via filter.

PC in dining room! Keeps droping connection
ATTN 60
SNR 3.0

Move to master socket! Keeps droping connection
ATTN 60
SNR 3.0

Take off faceplate and connect at back!
ATTN 60
SNR 7.0

Surfing very happy now and speed test from adslguide

Results from broadband speed test recorded on Thursday, 23 September 2004, 12:57.

Your Connection
Direction Actual Speed True Speed (estimated)

Downstream 928 Kbps (116.0 KB/sec) 1002 Kbps (inc. overheads)
Upstream 242 Kbps (30.3 KB/sec) 261 Kbps (inc. overheads)

Hope this info helps anyone else. Just need to get a special faceplate installed by BT via Plusnet.

Si
Community Veteran
Posts: 14,469
Registered: 30-07-2007

How do i increse SNR?

SNR of 3 will be your problem - in fact anything below 10dB could produce unreliable connections. Added to this your 60dB line attenuation and I'm not surprised you have the problems you reported.

Have a read of ADSL: Understanding Line Loss and measurements which if you understand it will explain what a high line attenuation and very low SNR means in terms of signal strength and quality.
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How do i increse SNR?

As per Peters reply. Note how the SNR increased to 7dB, from 3dB.

In mathimatical terms, every 3dB (and a tiny fraction) equates to twice or half as much signal, depending on which way the figure moves.

So an increase from 3 to 7, mean that the signal is now over twice as strong as it was at 3dB.

As per peters reply, suggested/recomended SNR values are 10 and above, with most recomending a SNR of 12dB as a comfort zone. 7dB is below both of these values.

As you tested at the inner socket at the NTe5 master socket, to obtain 7dB, there is no improvment to be made out of a ADSL faceplate.

That does not mean all is lost. BT can attempt to bring your line into specification in other ways. If and when you get an engineer visit, tell him you have measured a SNR value of 7dB from the inner socket, but tell him you that isn't very accurate.

Unfortunatly, there is little you can do but hope this can be done.