[clug] ADSL2+ speeds (Sakari Mattila)

smattila at tpg.com.au smattila at tpg.com.au
Thu Feb 12 13:36:25 GMT 2009

We had similar problem, very  stable line attenuation, but 0 - 12 dB 
varying SNR. After writing with big enough letters, the ISP contacted
Telstra, who contacted a subcontractor. He changed the pair the
telephone was using and now all is well. There is big difference between 
pairs in  big cables. There is cross-talk between the pairs. Now it
is running 6.1 Mb/s over ca. 3 km line (City exchange) in the ADSL 

Phone lines are build for 300 - 3400 Hz signals and now people are 
using the lines for 0 - 20 MHz frequencies.

In our case the strange thing was, that the analog phone line was 
perfect and interference was some high-frequency source within the 
same cable. 

In fact, there is not much point using ADSL2+ on longer than 3.5 km 
cables. In theory somebody may eek out a few kilobits per second
up to 7 km thought ADSL2+, which is too long distance for ADSL.

BTW. New telephone connection may be better or worse than the
existing connection. May use different trunk cable. I has been happy 
with "3"  1 - 6 GB per month 3G connection. Not fast, about 2 Mb/s
at best, in theory 3.6 Mb/s. Reliable, but depends on other 3G
users. It is uncapped and about $ 110 per GB when over the limit.
One trick to know and avoid: "3" RF-modem can make alternative
GSM connection, uncapped. Very expensive to use and only indication 
is the color of the light in the USB stick.

Sakari Mattila, Canberra

Alex Satrapa <grail at goldweb.com.au> wrote:

> There were a few instances in the past where I've had customers report  
> a fault on a line, and the NDC/whoever tech inspecting the problem was  
> able to solve it by switching to a different pair between the exchange  
> and the nearest post.

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