Envelope-to: dave@picks.force9.co.uk
Delivery-date: Sun, 06 Nov 2005 15:38:19 +0000
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From: "Alan Melia" <Alan.Melia@btinternet.com>
To: rsgb_lf_group@blacksheep.org
References: <003b01c5e25f$31822370$f500a8c0@Dell5150>
Date: Sun, 6 Nov 2005 15:35:39 -0000
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Subject: Re: LF: Fuzzy lines
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Hi Dave, It was too noisy to look for them last night. There is nothing I
can see there in daylight (well almost ...1525z) on a 30 sec slow Argo
screen. There is a lot of "snow" on it due to 50Hz dimmer interference I
think. I do run the level out of my RXs quite high (into the LINE inputs on
the soundcard) so I can hear signals on the computer speakers. I do get IMDs
with strong signals and try to use a 300Hz filter in the RX IF to remove
most of them.

Cheers de Alan G3NYK

----- Original Message -----
From: "Dave Pick" <dave@picks.force9.co.uk>
To: <rsgb_lf_group@blacksheep.org>
Sent: 05 November 2005 23:18
Subject: RE: LF: Fuzzy lines


Markus

Interesting. The frequencies are right. I could understand the Rugby one
because that's loud here but neither DCF39 nor Lessay are loud enough to
intermod locally so where does that product get generated?

Dave G3YXM


  _____

From: owner-rsgb_lf_group@blacksheep.org
[mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of
MarkusVester@aol.com
Sent: 05 November 2005 22:04
To: rsgb_lf_group@blacksheep.org
Subject: Re: LF: Fuzzy lines


Dear Dave and LF,

this seems to be an intermodulation between DCF39 (abt 0.1Hz wide due to the
data telegrams every 10s) and Loran C. The lines in you screenshot are
138830.03 - 142 * 50000 / 6731 = 137775.21 (Lessay, Soustons, Sylt, Rugby)
and
138830.03 - 158 * 50000 / 7499 = 137776.56 (Sylt, Lessay, Verlandet).
The latter one is a little surprising because Rugby does not appear to be
dual rated.

Laurence KL1X saw similar DCF ghosts in December 2003, which appeared every
time the path was open from Germany to Alaska. For a while we speculated
about possible ionospheric crossmodulation, but then Laurence confirmed that
the spurs were caused by periodic triggering of his noise blanker on the
Pacific Loran pulses. We also found a faint hint of a Sylt + DCF39
combination in one of Alan's screenshots.

Hope this helps...

73 de Markus, DF6NM