LF: Noise from phone lines]

Andre' Kesteloot akestelo@bellatlantic.net
Fri, 25 Jun 1999 18:22:31 -0400

Dave Sergeant wrote:

> >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