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Re: ULF: Ground loop night transmission 3.0

To: [email protected]cksheep.org
Subject: Re: ULF: Ground loop night transmission 3.0
From: DK7FC <[email protected]>
Date: Thu, 18 Apr 2019 14:10:49 +0200
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RR, thanks. Can you say something about the noise (QRM/QRN) situation relative to the recent test at 2970 Hz? Assuming equal noise conditions, the signal could be 3 dB weaker for a message decode. And i calculated a 3 dB weaker signal ( G = 40 * lg(2470/2970) = -3.2 dB).
I remember Jims plot from the email of the 7th, June 2017, attached. Two
markers, showing the consideration that a lower frequency could work
even better than 2.47 kHz on our path? But it's not the best time in the
year to try :-)
Fortunately the SNR is well at IK1QFK. That gives an impression of what
can be expected in ~ 450 km distance.
For a next test at lower frequencies i better concentrate on carrier
transmissions again.
Hmm, looking at that plot, i see that 970 Hz could work 40 dB better
than 2.47 kHz. The plot is based on a constant ERP i guess. At 970 Hz
the signal should be 20 dB weaker than at 2970 Hz, assuming equal
antenna current and equal skin depth (loop size). Maybe we find an
advantage, a higher loop size at that frequency. But even with 20 dB
less ERP the signal would be better detectable than at 2970 Hz?? Or do i
misunderstand something here? If not, then it is worth a try!!! That
would be dreaming^4.
Ideas?

73, Stefan


Am 18.04.2019 10:15, schrieb Paul Nicholson:
Nothing decoded in Todmorden.

> it is 'CFM'.

No significant correlation either, best carrier Eb/N0 -9.6dB.

--
Paul Nicholson
--

Attachment: FDTD Plot , updated, (E field), by Jim_2.jpg
Description: JPEG image

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