Paul and Dex,

Thanks for great data.  

The phase data is interesting as always; especially since models still lag
empirical data. In the absence of accurate analytical modeling tools for VLF
propagation, the lightning geolocation community has had significantly
better success with continuous (multi-year) refinement of path-specific
amplitude/phase (empirical) databases, providing empirical phase/amplitude
characteristics for each path as a function of time of day and season, and
allowing spatial interpolation between paths. Wondering if Paul's archived
data might be a valuable resource in this regard. Lightning community
publications (available on the web) show substantial merit of this technique
at short and medium ranges; their systems do not characterize long paths.

73,

Jim AA5BW



    

-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Paul Nicholson
Sent: Saturday, December 13, 2014 3:40 PM
To: [email protected]
Subject: Re: LF: Re: 8957 Hz

W4DEX at Todmorden and Bielefeld (DL4YHF) in 1 hour steps

  Start     Todmorden       Bielefeld
            S/N    Phase    S/N     Phase
  21:00     8.9dB  -16.9    0.6dB
  21:30    10.7dB  -29.0    1.1dB
  22:00     7.7dB  -51.0   -5.3dB
  22:30     4.1dB  -73.3   -3.4dB
  23:00     8.9dB  -84.6   -1.4dB
  23:30    10.8dB  -81.7    1.3dB
  23:45     9.9dB  -73.8    3.9dB    80.6
  00:00     7.9dB  -77.2    8.1dB    91.1
  00:30     8.7dB  -94.4   12.0dB   110.4
  01:00     9.8dB -101.6    7.2dB   137.5
  01:15     9.0dB  -93.7    6.2dB   145.5
  01:30    10.0dB -105.4    1.3dB
  02:00     9.1dB  -81.4    2.2dB
  02:15     9.3dB  -82.4    6.8dB    90.5
  02:30     8.7dB  -70.9    7.3dB   101.1
  02:45     9.2dB  -68.1    4.3dB   117.2
  03:00     8.9dB  -69.0    3.2dB

Signal from Dex was quite steady in the UK and I was hoping for a good
result from Bielefeld but the signal only appeared
doubtfully above noise for about an hour.   It showed a positive
Doppler (shortening path length) of about 20uHz.

  http://abelian.org/vlf/tmp/141213a.gif

The background after blanking was a bit lower than it was on the 2nd when
this was received

  http://abelian.org/vlf/tmp/141202j.gif

but the blanker was having to work hard last night.  This creates a 'long
tail' in the distribution of Fourier bin amplitudes and the peak at 8957
last night is not as significant as it looks.
Attempts to improve the S/N with narrower bandwidth and compensation for
Doppler didn't improve things, which makes it more doubtful.

Sadly, not the unequivocal detection I was hoping we would see.

W4DEX very strong at Forest (near Lynchburg) VA, range 254 km

  http://abelian.org/vlf/tmp/141213b.png

Much of the time over 20dB S/N in 0.83mHz and reached 24dB at
01:00 UT.   Phase was pretty steady too:

   UT     S/N      Phase
  18:40  13.6 dB   148.7
  19:00  12.0 dB   156.4
  19:20  11.6 dB   162.9
  19:40  12.4 dB   178.4
  20:00  12.8 dB   166.8
  20:20  15.0 dB  -175.6
  20:40  11.3 dB  -173.9
  21:00  13.7 dB  -159.0
  21:20  14.3 dB  -142.8
  21:40  16.1 dB  -148.8
  22:00  15.4 dB  -149.0
  22:20  17.9 dB  -141.9
  22:40  18.8 dB  -146.0
  23:00  19.0 dB  -144.5
  23:20  17.6 dB  -158.2
  23:40  21.5 dB  -156.8
  00:00  22.0 dB  -148.7
  00:20  22.4 dB  -159.6
  00:40  22.9 dB  -153.9
  01:00  24.5 dB  -155.8
  01:20  23.4 dB  -157.5
  01:40  22.1 dB  -158.4
  02:00  22.7 dB  -151.8
  02:20  21.2 dB  -146.3
  02:40  20.5 dB  -146.1
  03:00  21.9 dB  -147.7
  03:20  20.9 dB  -134.4
  03:40  18.6 dB  -141.7

--
Paul Nicholson
--