Message-ID: <58755576.6000702@posteo.de>
Date: Tue, 10 Jan 2017 22:43:18 +0100
From: DK7FC <selberdenken@posteo.de>
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.1.8) Gecko/20100227 Thunderbird/3.0.3
MIME-Version: 1.0
To: rsgb_lf_group@blacksheep.org
References: <5872C893.80807@abelian.org> <CAHAQVWO5rR0dkPNbxJksqPRNTOgo=DcbrxdiY0R2GDtF+dxdNg@mail.gmail.com>
In-Reply-To: <CAHAQVWO5rR0dkPNbxJksqPRNTOgo=DcbrxdiY0R2GDtF+dxdNg@mail.gmail.com>
Subject: ULF: A first local test on 970 Hz / 309 km
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Sender: owner-rsgb_lf_group@blacksheep.org
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org
Status: RO

Hi ULF,

Since a few hours i'm running 15 mA antenna current on 970 Hz, the 309 
km band. This requires to apply 5 kV to the antenna. You can see a very 
faint trace on the lower image at 
http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber2.html

Just about 10 dB SNR in 424 uHz in 3.5 km distance, or in 0.011 lambda 
distance. The receive antenna is a H field antenna that is not even 
pointing to the transmitter. Also the preamp noise is dominating the 
background noise on that frequency. So the RX is deaf on that band. 
Anyway, there is something.

The ALC into SpecLab does a very good job, it holds the antenna current 
stable during all the changes and working point drifts. The plot can be 
seen at http://www.iup.uni-heidelberg.de/schaefer_vlf/VLF/TX.png
15 mA results in an ERP of  3 nW.

My new preamp circuit is waiting for a first test together with the 
large loop. I hope to pick up the signal in at least 5 km distance with 
that preamp which is really low noise down to the lower Hz range.
An E field reeiver would be a better choise for the reception from that 
E field Tx antenna, at least in the lower near field. Maybe that will 
give another test then.

With 30 kV i could reach 0.3 uW. Not sure where this could be detected? 
And who knows the advantages of this part of the spectrum for our 
purposes!?!

Since 21:20 UTC, a 2 character EbNaut message is running. It will take 
2h, 2min, 40s. Hopefully the tree grabber is available until the message 
ends. It will shut down in a few hours due to lack of solar energy in 
these days (an improvement of this system has already been prepared and 
waits for the installation).


73, Stefan