[Lf] [Fwd: LF: Re: ADSL EMC with LF receiving?]

[Andre Kesteloot]

-------- Original Message --------
Subject: LF: Re: ADSL EMC with LF receiving?
Date: Wed, 4 Dec 2002 17:51:36 EST
From: MarkusVester at aol.com
Reply-To: rsgb_lf_group at blacksheep.org
To: rsgb_lf_group at blacksheep.org



Hi all,

most of the messages in this thread have focussed on potential
interference from the LF-TX to the ADSL connection. Being digital, I
would assume that below a certain threshold there would be no noticable
interference at all, and even above that level, error correction
protocols and adaptive channel allocation would make it relatively robust.

However, the emissions from an inadequately shielded ADSL line could be
a significant noise source for LF reception. - The background noise
level here on a quiet day is around -25dBuV/m in 1Hz, which on the
terminals of my Marconi (having -31dB efficiency) is about -107dBm/Hz or
-81dBm/4kHz. Stewart's log excerpt indicates a modem power of 12dBm, is
that power per channel? If so, the isolation between ADSL and the LF
antenna would have to be better than 93dB, which seems fairly demanding.
With small receive loops in the vicinity of the wiring, the situation
could be even worse.

As I am still using plain old analog telephony and a V.90 modem here,
this is only a rough theoretical estimate, and I wonder if somebody has
experienced any problems in actual practice.

Regards
Markus, DF6NM