From: MarkusVester@aol.com
Message-ID: <12a.1c772615.2b1fe0f8@aol.com>
Date: Wed, 4 Dec 2002 17:51:36 EST
To: rsgb_lf_group@blacksheep.org
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Subject: LF: Re: ADSL EMC with LF receiving?
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<HTML><FONT FACE=arial,helvetica><FONT  SIZE=2 FAMILY="SANSSERIF" FACE="Arial" LANG="2">Hi all,<BR>
<BR>
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.<BR>
<BR>
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.<BR>
<BR>
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.<BR>
<BR>
Regards<BR>
Markus, DF6NM<BR>
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