Date: Fri, 25 Jun 1999 01:30:03 -0400
From: "Dave Sergeant" <sergeantd@compuserve.com>
Subject: Re: LF: Noise from phone lines
To: rsgb_lf_group@blacksheep.org
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>From Dave G3YMC

An associated topic, not yet having hit us in the UK yet, but imminent, is
the ADSL system for putting high speed internet at 1.5Mb/s down normal
telephone lines. An excellent, though fairly technical, article on this and
associated techniques appears in the IEE Electronics and Communications
Engineering Journal, June 1999 issue, entitled 'High Speed Copper Access: a
tutorial overview'.

The article in particular discusses interference problems, to and from,
amateur transmissions, and indicates that the designers do indeed take
these interference problems seriously.  Unfortunately they have not heard
of 136kHz and state that amateur interference is not an issue with ADSL
which only uses frequencies up to 1MHz or so!  Some of the scenarios
considered for the much faster (26Mb/s) VDSL system which is much further
down the line for deployment however make me think that we will have big
problems if these systems take off!

I have not seen such open discussion of amateur matters in any official
papers from the proponents of the PLT (data over mains) systems, which as
we know have been shown to have serious QRM problems for the amateur bands.
I wonder if the two parties do talk to each other!!

73s Dave G3YMC