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Date: Thu, 18 Dec 2014 16:42:55 -0500
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Subject: RE: VLF: W4DEX to IK1QFK at 8822Hz
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Stunning.

Great work Paul and Dex!

Fine noise management too; 11dB @ 0.12fT and 278 uHz implies approximately
2fT/root-Hz aggregate noise?

Jim AA5BW

-----Original Message-----
From: owner-rsgb_lf_group@blacksheep.org
[mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Paul Nicholson
Sent: Thursday, December 18, 2014 4:00 PM
To: rsgb_lf_group@blacksheep.org
Subject: Re: VLF: W4DEX to IK1QFK at 8822Hz


Last night was the best reception of W4DEX so far in Todmorden.
S/N and phase in one hour steps -

  19:00 -1.4dB
  20:00  7.0dB -143.2
  21:00  7.5dB  133.9
  22:00  9.6dB  138.6
  23:00 10.8dB  116.4
  00:00 12.7dB  126.3
  01:00 12.7dB   89.4
  02:00 13.7dB  110.6
  03:00 10.3dB  115.2
  04:00 12.8dB  102.8
  05:00 13.4dB  120.6
  06:00 11.3dB  126.7
  07:00 14.1dB  140.4
  08:00 15.5dB  137.9
  09:00 10.8dB -165.2
  10:00  6.1dB -148.0
  11:00 -3.4dB

22:00 to 10:00 was 22.4dB S/N in 23.1 uHz and averaged
11.4 dB in 278uHz.

It was a strong and steady signal with no serious phase wobbles or drift.  A
beautiful line in a very narrow bandwidth spectrum,

   http://abelian.org/vlf/tmp/141218c.gif

Here's a spectrogram in a wider bandwidth

   http://abelian.org/vlf/tmp/141218d.png

I could have received a 32 character message from Dex at 17.5 bits per hour
using a rate 1/8 convolution code and coherent BPSK modulation.

And that's just using the loop receiver.  E-field reception was very good
too and if that were combined, Dex could have sent 53 characters at 28 bits
per hour!

Enough to name several cats!

Jim wrote:

 > Does this mean that ERP is now well above 150uW?

No I think the ERP is the same or only slightly improved.

Signal last night averaged just under 0.12fT and is almost the
same every night.   Last night the noise was low from 22:00
onwards which gave us a constant high S/N for many hours.

I'm very pleased with this reception.

Looks like Dex is continuing this long run,  live spectrum from Forest VA

  http://46.4.26.83/sp8822_vlf35.png

updating every 10 minutes.
--
Paul Nicholson
http://abelian.org/
--