[LINK] RFI: ADLS2+ Performance

rene rene.ln at libertus.net
Thu Jul 5 17:06:42 AEST 2012

On Thu, 5 Jul 2012 15:43:55 +1000, Roger Clarke wrote:
> That's after 'Jerome', presumably in Manila, "increased the signal-to-
> noise ratio [on the DSLAM] at the exchange".
> Can anyone explain, or point to an explanation of, what that really
> means?

In short, it's highly likely that your copper phone line has become noisy 
in recent times with the result that the modem can't "hear" the DSLAM, so 
the ADSL connection drops out. 

Increasing the SNR margin on the DSLAM (or on the modem if one has a model 
that has such a setting - not many do) can overcome the noise problem but 
at the expense of sync and download speed, i.e. the connection can become 
stable, but speeds will be slower.

A detailed explanation, in pretty much layman's language, is here:

I had the same problem some months ago, and I ended up downloading 
so that I could monitor and record the SNR fluctuations - such fluctuations 
in effect show how much noise is on the line at any given time. However, on 
a quick glance at the page, it looks like it's not available for Mac. There 
may, I suppose, be some other program that runs on Macs that does the same 

NB: Some ISPs provide a variety of ADSL2 "profiles" that customers can 
set/change by logging into the ISP's web site, each profile with a 
different SNR margin. However, if the ISP doesn't provide such an option 
and noise problems start occurring, then the only option is to try to get 
customer support techs to change it. 

Also, fwiw, there's a very good ADSL troubleshooting / tips page here:


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