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Re: LF: DK7FC in Todmorden at 2970 Hz

To: [email protected]
Subject: Re: LF: DK7FC in Todmorden at 2970 Hz
From: DK7FC <[email protected]>
Date: Mon, 27 Mar 2017 21:57:32 +0200
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Hello Paul, ULF,

Thank you for working out the signal so clearly. The accurate frequency matching is an ID in itselfe. Most impressing. It was an exciting and unique experiment taking months from the beginning to the 8.7 wavelength distance detection. It was the big goal! Pure 70 hours of coil winding for that 6.1 H coil. A first 'amateur' ULF detection between DL and UK ! Somehow historic, but just shared in a small group. But someone will write about it in a blog, so the story will find its way to the www... I'm putting your nice spectrum plot into my ULF folder, seen as a reward for the 'efforts'.
Hm, what next? :-)
After repairing the coil i would like to try to transfer a message. Let's see how the QRN behaves down there during the summer time. Will the band be unsuable or is it just slightly affected? Based on 14 dB in 25 uHz we could try: http://abelian.org/ebnaut/calc.php?sndb=14&snbws=0.000025&snmps=&code=16K25&sp=30&crc=18&nc=3&submit=Calculate
Maybe this decodes in just a week :-)

73, Stefan

PS: I'm going to risk 200 mA in the next attempt.


Am 26.03.2017 22:41, schrieb Paul Nicholson:
Stefan wrote (10th March):

> Since 16:56 UTC  i'm running 180 mA antenna current
> on (2970 + 7/(24*3600)) Hz, i.e. on 2970.000081 Hz

After coherently stacking 13:00 to 00:00 for 9 days in a
bandwidth of 25.25 uHz I get a clear signal at significance
of around 5 sigma:

 http://abelian.org/vlf/tmp/170326a.png

The peak has S/N 14.0 dB in 25.25uHz, which is -66 dB in
2.5kHz bandwidth.   Signal azimuth is east with the expected
phase angle between E and H antennas.

The days used were 11th to 16th plus 18th to 20th.  Attempting
to include the 17th, or 21st to 23rd reduced the S/N.
Leaving out any of the nine stacks days also reduces the S/N.

The amplitude of each daily contribution is normalised by
the average power in a 20Hz bandwidth around the signal
frequency.

No other bandwidth or daily time range produces a stronger
peak.   14:00 to 19:00 in 55.5 uHz gives about 12dB S/N.

So far, no attempt has been made to compensate for night time
phase delay.

Distance is 881.2 km, approximately 8.7 wavelengths.

--
Paul Nicholson
--





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