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Lowering attenuaton and SNR

Posted: Thu Jan 26, 2012 1:09 am
by Y.sundaravej
Hi,

I have just recently signed up for the OT-20 ADSL2+ plan. My download speeds have been somewhat disappointing, hovering around 7Mbps, my attenuation is 37dB and SNR is 12.6. I'm currently using a Netgear DG834G v4. Is there any way that I could lower the noise and attenuation and increase my download speed? I was reading online not too long ago that apparently the provider could run line checks and optimise the line to reduce the noise. Is that possible? Also, is there any other better (and newer) modem-routers out there that would possibly get better out of my line than my current one?
Any help would be greatly appreciated.

Thanks,

Re: Lowering attenuaton and SNR

Posted: Thu Jan 26, 2012 4:37 am
by anurangaf
Y.sundaravej wrote:Hi,

I have just recently signed up for the OT-20 ADSL2+ plan. My download speeds have been somewhat disappointing, hovering around 7Mbps, my attenuation is 37dB and SNR is 12.6. I'm currently using a Netgear DG834G v4. Is there any way that I could lower the noise and attenuation and increase my download speed? I was reading online not too long ago that apparently the provider could run line checks and optimise the line to reduce the noise. Is that possible? Also, is there any other better (and newer) modem-routers out there that would possibly get better out of my line than my current one?
Any help would be greatly appreciated.

Thanks,
Hi Y.sundaravej,

Please try connecting only the modem directly into the main telephone socket, and monitor whether is there any improvements.
If you could try with an alternate modem to make sure that your modem is not giving any problems.
After checking all of the above please reply to 'residentialsupport@exetel.com.au' or post on this forum.

Re: Lowering attenuaton and SNR

Posted: Thu Jan 26, 2012 8:48 am
by Y.sundaravej
I currently live in an apartment unit and the modem is connected to the only telephone line available to me. So I don't think I'd be able to connect it to the main telephone line... Unless a technician Comes and install a new phone line as the current one is very old, in which case i'd have to talk to the landlord.

Re: Lowering attenuaton and SNR

Posted: Thu Jan 26, 2012 6:39 pm
by Dazzled
Back to your first question. You can't do anything about the attenuation, as it is a quality of the line. If the line were changed it might alter. The noise margin can be altered at your modem, (lower margin gives faster rate) but it will be at the expense of stability - the more you tweak, the more likely is a drop-out. Be careful.

The modem is actually a very small computer and you will need some confidence using the Linux command line, on the modem's telnet interface. There are some comments about similar Netgears at http://www.nat32.com/nat32e/htm/dg834g.htm and at http://www.kitz.co.uk/routers/dg834GT_targetsnr.htm If you use Windows you may have to first enable telnet on your computer - try the 'telnet' command in a prompt window to see if it is already set up. Microsoft have some telnet info at http://windows.microsoft.com/en-AU/wind ... -questions

PS At 12 dB, I wouldn't do it.

Re: Lowering attenuaton and SNR

Posted: Thu Jan 26, 2012 7:41 pm
by Y.sundaravej
Thank you so much on that information! I tweaked the snr down to 70 and managed to get a sync speed of about 9Mbps.
So far it's been pretty stable, no drop outs yet. If it gives me a problem though I'll just revert it back.
By the way, is 12dB really bad? Would you be able to elaborate more on how SNR works? Thanks!

Re: Lowering attenuaton and SNR

Posted: Thu Jan 26, 2012 7:50 pm
by Dazzled
Try http://www.kitz.co.uk/adsl/adsl_technology.htm and http://en.wikipedia.org/wiki/G.DMT for summaries of the theory. 12 dB margin for line noise is safe without being excessive.

Re: Lowering attenuaton and SNR

Posted: Fri Jan 27, 2012 11:12 am
by jaybee
I have a Billion 7300 that synchs 50% faster ( 6db) than my TP-Link TD8840 (12db) but the Billion drops out much more than the TP-Link so I use the latter.

Re: Lowering attenuaton and SNR

Posted: Fri Jan 27, 2012 2:15 pm
by Dazzled
I avoid Billions, so don't know a lot about their peculiarities. Some models have a coding gain option. It may be possible to raise the noise margin on yours using the telnet interface on 192.168.1.254. There is a manual of CLI commands for another Billion unit at http://billion.com.au/downloads/7500G_CLI_Manual.zip which might have some clues, otherwise see if this bloke's post is useful: http://www.computer-aid.com.au/blog/200 ... -dropouts/ Other people's info at http://forums.whirlpool.net.au/archive/637150