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LF: Re: Re: LF broadband QRN?

To: [email protected]
Subject: LF: Re: Re: LF broadband QRN?
From: "Dave Pick" <[email protected]>
Date: Thu, 6 Mar 2003 18:36:58 -0000
References: <[email protected]> <[email protected]>
Reply-to: [email protected]
Sender: <[email protected]>
Geri.

It's already trialling in Crieff and Campeltown (central Scotland). I don't
think it'll be radiating as far as John's QTH though!
My ADSL via telephone wires causes no problem on any band.
If there are 50 or 100Hz components it's most likely a PSU.

http://www.hydro.co.uk/broadband/

http://news.bbc.co.uk/1/hi/technology/2754203.stm

Dave
G3YXM




Hello John,

in a computer-magazine saw a new kind of cable-less modems that work
through
the regular power line. No idea on which frequencies those devices
operate,
hopefully not on 73 or 136 kHz!

Geri, DK8KW (W1KW)


----- Original Message -----
From: "John W Gould" <[email protected]>
To: "[email protected]" <[email protected]>
Sent: Thursday, March 06, 2003 1:02 PM
Subject: LF: LF broadband QRN?


>
> Since the 73kHz tests on Tuesday I have been monitoring at several times
a
> day and find a consistent and steady  noise-level that is about 20dB
below
> the signal at 138.8kHz, and about 6dB below the one at 75kHz. Its a
mains
> type of buzz, beating at times with itself.  Like most I have had this
in
> the past and put it down to RFI from switched-mode PSUs, however, it was
> only sporadic in the past so I am wondering if it's something new.  It
seems
> to be all the way up the LF band to just below the LW broadcast band
(but
> that cut-off could be a function of my aerial's resonance set at 73kHz).
>
> The only thoughts that I have is ADSL or signalling on the HV
underground
> cable somewhere beneath my garden. Certainly, ADSL will have become much
> more used locally since I last did an serious listening on LF, but I
would
> have thought the radiation would be fairly low from the balanced
overhead
> telephone lines that are at least 200m from my aerial. I would have
thought
> that the shielding around underground HV mains cables would be
sufficient
to
> stop low-level signaling causing problems.
>
> I can't see a real reason why TV related interfernce should increase
near
to
> my home.  How far away do TV's etc need to be before they cause
problems,
or
> is it more caused by the interference conducting itself along the mains
> cabling, etc.
>
> Any thoughts?
>
> 73 John, G3WKL
>
>







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