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
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