Received-SPF: neutral (google.com: 193.82.116.20 is neither permitted nor denied by best guess record for domain of owner-rsgb_lf_group@blacksheep.org)
DomainKey-Status: good (test mode)
DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws;
  s=s1024; d=btinternet.com;
  h=Received:Message-ID:From:To:References:Subject:Date:MIME-Version:Content-Type:Content-Transfer-Encoding:X-Priority:X-MSMail-Priority:X-Mailer:X-MimeOLE;
  b=a8v+jRST3cdTE+zj/p9FoZ+gPPmyUdpkmB66ogqiavuJrP4Z7UDzp9ZtLigLtzRRKEjZ8cOwPBYAIDuLojMjcjbUbt1qS7cttHrzZuL8AicZrztMuseVp+KHeN9sez3adBo7AU2MJo7WXQP2ePWXj+CXG8aX/5UxSVmRJ8x7pdY=  ;
Message-ID: <002701c6e876$ba5d4ee0$0300a8c0@lark>
From: "Alan Melia" <alan.melia@btinternet.com>
To: <rsgb_lf_group@blacksheep.org>
References: <NKEMLGOEKANPNJOBFBAFEEPCCPAA.g4wgt@tiscali.co.uk>
Date: Thu, 5 Oct 2006 13:06:40 +0100
MIME-Version: 1.0
Subject: Re: LF: Strange signal 500khz
Content-Type: text/plain;
	charset="utf-8"
Content-Transfer-Encoding: 7bit
Sender: owner-rsgb_lf_group@blacksheep.org
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org
Status: O

Hi Gary, I dont know how they work but I would suggest the digibox is
deriving a linescan rate from the received digital TV signal periodically
and it applying that to the analogue signal it generates to send to you old
set, what you are seeing are the "corrections".... a bit like a digital PLL.
Interesting......That means the signal you are receiving is probably
generated by the set's line scan circuit. It might be interesting to put a
braid breaker on the aerial to the digibox ( of the TV) and see if the coax
braid is radiating the signal.

Cheers de Alan G3NYK

----- Original Message -----
From: Gary - G4WGT <g4wgt@tiscali.co.uk>
To: <rsgb_lf_group@blacksheep.org>
Sent: 05 October 2006 12:43
Subject: RE: LF: Strange signal 500khz


Hi Alan, Markus & LF,

Here is an interesting result,

I wrote :-
 " I believe that the stepping effect is probably due to the "Freeview"
digi-box because the TV is an older analogue model & I would expect a steady
(ish) interference with no prominent stepping. I will do some tests with &
without the digi-box. "

After watching the mid-day news today whilst monitoring 500KHz using SpecLab
I switched off the digi-box & the stepped interfering line stopped, I then
switched the digi-box back on & the line returned as I expected, now I
switched the TV off leaving the digi-box on & the line stopped again. So it
is not generated solely by the digi-box but a combination of both the TV &
the digi-box being on.

Comments invited.

Regards,

Gary - G4WGT.