I have tested heaps of gear in the market and as a rule-of-thumb, internal and external USB ADSL modems have less "reach" than external ADSL routers. It seems that they suffer from power supply problems i.e. internal and USB draw their power from the PC bus - both PCI and USB are limited in current / voltage.

External routers are plug-pack powered and seem to perform the best but are all pretty much the same - if they comply truly to Telecom specs (& haven't been tinkered with, are approved and actually match the sample that their Telepermit approval was based on).

Re house wiring, I doubt any builder / Telecom is or has installed good quality cat 5 or 6 cable into new homes - would be too expensive and more to the point, too forward thinking for a standard install :-)

Re "loading coils" - seems to me some sort of line inductance test may have been performed in which case, a 5.5km line will look like a big coil! Perhaps it was a poor explanation of the actual test performed - never heard of loading coils on a phone line - but them I have more of a RF background as opposed to this Slooow audio stuff.

Rgds, Chris...

-----Original Message-----
From: owner-adsl@unixathome.org [mailto:owner-adsl@unixathome.org]On
Behalf Of Simon Garner
Sent: Wednesday, January 14, 2004 4:58 PM
To: adsl@lists.unixathome.org
Subject: Re: ADSL modems on dodgy/long lines

On Wednesday, January 14, 2004 4:41 PM NZT,
Chris Day <chris.day@dse.co.nz> wrote:

> The type of modem you install will most probably have very little to
do
> with improving your ability to get ADSL. The problem is the actual
phone
> line length and the technology - ADSL theoretically maxs out at 5km -
as
> you have seen.

That's pretty much what I thought.

But apparently not all modems are created equal - there was an article
in the Herald a week or two back which described how some retailer had
been burned by assuming all Telepermitted DSL modems were capable to the
same distance, then found that the ones he was selling only worked to
about 3km.

http://www.nzherald.co.nz/storydisplay.cfm?storyID=3540743&thesection=bu
siness&thesubsection=technology&thesecondsubsection=information

So I'm guessing that different modem chipsets/whatever have more or less
tolerance for line quality.

> Apart from Telecom improving the quality or their lines between your
> premises and their exchange, the only other thing you could look at is

Yeah and we all know what the chances are of Telecom improving the lines
;)

> your internal house wiring. Often, homes were wired with simple
twisted
> pair which is not designed for transferring high speed data. You may
get
> a performance increase if you replace this twisted pair stuff with Cat
5
>

I should note the house is only 4 years old - it was newly built when I
first tried to get DSL - so I would expect the internal wiring to be
decent enough.

One thing I should probably add. When I was doing this four years ago,
somebody from Telecom (from this list in fact) contacted me and did some
sort of a test on the line and found there were "loading coils", which,
he said, would prevent DSL from working. Anybody know what that means?

-Simon

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