Hi ULF,
Since yesterday (10.Sep), 11 UTC, i'm running a new experiment on the
101 km band. It is in 31.2 km distance to my transmitter-site.
The last experiment did not produce satisfying results due to various
reasons.
Now i improved the loop cross section area, the loop orientation, GPS
reception (for the 1 PPS + NMEA reference signal). Furthermore the
recording sample rate was reduced to 32 kS/s which allows about 3 days
of stereo recording.
I'm still using the Raspberry Pi2 for therecording. The system consumes
just 150 mA from a 12V battery. 3x 7 Ah lead acid batteries are in use now.
The transmission contains stable carriers and a short DFCW-12000
message, "73". The transmission can be followed on my 3.5 km distant
forest grabber at
http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber2.html ,
as usual.
Relative to the last experiment, the average QRN has dropped
significantly now, another advantage. So i'm quite optimistic to get a
good result!
The next experiment in about 60 km distance is already in preparation.
Then i will use my new coil which is still in preparation. The last
measurement, after completing the 3rd stack, showed a resonance
frequency of 4.27 kHz. So it should have 2.8 H now...
In the next experiment, i will use 100 mA antenna current, again a about
6 dB stronger signal.
The current experiment will stop on Tuesday afternoon. Results can be
expected in the end of the next week.
73, Stefan/DK7FC
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