Hi Paul, VLF,
Now, i've optimised the resonance a bit and can run 220 mA antenna
current now! The transductor circuit is still not existing in the
system so the antenna current may vary a bit. Can be watched at
http://www.iup.uni-heidelberg.de/schaefer_vlf/VLF/TX.jpg
220 mA is equivalent to -36.5 dB.
Let's try again the same message.
f = 6470.00000 Hz
Start time: 14.05.2016 21:40:02 UTC
Symbol length: 100 s
Characters: 6
CRC 16
Coding 8K19A
Duration: 15h, 33m, 20s
Antenna current: 220 mA
Not the easiest time in the year but that's the challenge.
As soon as i go to 5.17 kHz we start to dive down the QRN! ;-)
73, Stefan
Am 14.05.2016 14:37, schrieb DK7FC:
Hi Paul,
Hmm, that's a pity. Maybe it would be useful to run a beacon,
periodically the same message in shorter symbols, maybe 40s. A single
character would be already fine, like 'R'. This would take 3:33:20 to
be sent. I could do this each 4 hours.
Or i can send a simple carrier for a few days. However i want to build
a circuit which keeps the antenna current constant, even during rain,
so the ERP stays constant!
73, Stefan
Am 14.05.2016 12:59, schrieb Paul Nicholson:
Stefan wrote:
> f = 6470.00000 Hz
> Start time: 13.05.2016 00:00:02 UTC
> Symbol length: 100 s
> Characters: 6
I haven't been able to decode this one. The average noise
was 3.7 dB higher than the previous successful message, so
there should still be a couple of dB to spare.
I've tried a wider range of phase search in case the
day/night phase change was more than expected.
So far it seems that 6.47 is more variable and unpredictable
than 8.27 which is opposite to what I'd expect.
--
Paul Nicholson
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