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Date: Wed, 29 Jun 2016 15:16:02 +0200
From: DK7FC <selberdenken@posteo.de>
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To: rsgb_lf_group@blacksheep.org
References: <5772DAC0.7080001@df3lp.de> <CAA8k23TGuNuOZcnJA42=EDxZgHMAVNeq9SM7=UhvTz6Noqa_FA@mail.gmail.com>
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Subject: ULF: Key down signal on the 101 km band, still on the air
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Status: O

Hi all,

Since sunday 13 UTC i'm running a carrier on 2.970000000 kHz. The ERP is 
100 nW. The antenna current is 30 mA.
The signal appears at up to 30 dB SNR in 424 uHz on my 3.5 km distant 
remote grabber, 
http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber2.html

I've done a successful test with a portable active E field receiver: abt 
15 dB in 3.8 mHz in 4.5 km distance in a quiet location: 
http://no.nonsense.ee/qth/map.html?qth=JN49IK66KU&from=JN49IK00WD
So 4.5 km is the new distance record on that band :-)
This was just for testing the receiver, which still needs some more 
input signal get get it's full sensitivity.
The actual next goal is 50% of the far field border, i.e. ~ 8 km distance.

Paul, if you are reading this: It may be worth to try to integrate the 
overall transmission time into one peak. I will continue to run the 
carrier. So far, these 72 hours are not enough to get a peak i estimate. 
But with one or two weeks integrated in one peak?? Maybe... :-)
The QRN is much lower relative to 8.27 kHz, so this may help.

There is some QSB on the 3.5 km path to my grabber. I've watched the 
phase stability over that path: It is constant, as expected: 
https://dl.dropboxusercontent.com/u/19882028/ULF/2970%20Hz%20RDF%20stabile%20Phase.jpg
Now my assumption is that the signal level drops when the forest is wet, 
although it is a loop antenna! That also means that my RX sensitivity on 
2.97 kHz is limited by the RX, not by the band noise. So the actual SNR 
could be better...

A photo of the TX transformer/coil in it's final position: 
https://dl.dropboxusercontent.com/u/19882028/ULF/20160623_234516.jpg

The 8 km distant ULF detection test is planned for this weekend. If it 
works well, i'm doing a second test in EbNaut in the same location :-)

73, Stefan