Re: LF: DK7FC in Todmorden at 2970 Hz

[Markus Vester <markusvester@aol.com>]

Congratulations Paul and Stefan, that is a very nice confirmation!

> stacking 13:00 to 00:00
Interesting that this worked well, as it includes the sunset terminator, and would typically be the time of highest QRN background on higher frequencies.   

> is normalised by the average power in a 20Hz bandwidth
I would think that a little more benefit could be achieved by further downweighting the days with higher noise (gain factor -2 dB / 1 dB ).

Still wondering who of you has spent more Joules on this, the transmitter or the data processing on the receive side ;-)

All the best,
Markus

-----Ursprüngliche Mitteilung-----
Von: Paul Nicholson <vlf0403@abelian.org>
An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
Verschickt: So, 26. Mrz 2017 22:43
Betreff: LF: DK7FC in Todmorden at 2970 Hz

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
--