Splendid work, Stefan! Thanks for the details of what must have been the first
amateur VLF message across the globe.
It seems the VLF TX on this end is behaving itself again, thanks to
your guidance. It was good to have some company from Riccardo on Paul's
spectrograms. A bit of tinkering is still needed here before EbNaut can
be attempted again.
73
Joe VO1NA
On Tue, 12 Nov 2019, DK7FC wrote:
Свернуть
Hi Joe,
Yes, the carrier transmissions were done to get an impression if and when the
path is stable and if this is reproducable over a few days. I transmitted
carriers for a few hours and later i tried to decode EbNaut '*' messages with
different start times and symbol lengths.
The results were plotted in an Excel sheet (attached) and we found that, when
stacking 4 days, that a 3 hour long transmission starting at 17.55 UTC would
give the best SNR of about 12.5 dB. One week later, the situation would be
different since the path is very dynamic and the sunrise/sunset times are
changing permanently. It looks a bit weird but in the end we managed to
decode a 1 char, a 2 char and a 3 character EbNaut message.
The antenna current was 1.2 A. I had some PA problems, EMC and so on. The
antenna should have managed 3 dB more signal.
Meanwhile the special licence for that band expired.
73, Stefan
