Message-ID: <54946F68.4090806@abelian.org>
Date: Fri, 19 Dec 2014 18:33:12 +0000
From: Paul Nicholson <vlf0403@abelian.org>
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Subject: Re: VLF: W4DEX to IK1QFK at 8822Hz
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Overnight 2014-12-18/19:

The carrier was detectable in IK1QFK's on-line receiver at
Cumiana from around 23:00 to 05:00 with a gap around 03:00.

It barely shows up on a spectrogram though,

  http://abelian.org/vlf/tmp/141219a.png

although if you know it's there you can see it.

I swept a range of times and bandwidths and found the optimum
with

  http://abelian.org/vlf/tmp/141219b.gif

which gives S/N of 14.8dB in 43 uHz.   It was by far the
strongest peak in the 23400 neighbouring frequency bins of a
1Hz wide spectrum centered at 8822 Hz.

  http://abelian.org/vlf/tmp/141219d.gif

In fact it was the strongest in a 2Hz band (46800 bins) except
for one interference line at 8822.618 Hz that is always there.

With such a clear signal this must surely count as a new distance
record of 7173km for detection of amateur VLF signals.

I could not find anything in the signal from DL4YHF at
Bielefeld.   It seemed quite noisy there last night and the
receiver was suffering from broadcast intermod.

Another strong steady signal at Todmorden

  http://abelian.org/vlf/tmp/141219c.png

 From 00:00 to 08:00 it averaged 12.6dB S/N in 278uHz, 0.14fT.
That's enough signal to send 27 characters at a rate of 22
information bits per hour.

--
Paul Nicholson
http://abelian.org/
--