Well, most exciting stuff to read each hour these days.
-4.8 dB is better than i expected. 1 character in a single night is in
reach! Furthermore i'm running a carrier with 1.2 A antenna current
since 19:20 UTC. That's QRO of 1.58 dB. The wx forecast shows
strong rain coming closer to Heidelberg. It will rain in a few hours.
During the carrier transmission in the last days i observed that the
current drops down by 6 dB in heavy rain. I need the transductor again.
A few minutes ago i tried to turn the small coil inside the main coil a
bit, to reduce the L and rise the resonance frequency a bit. Hopefully
this helps to lower the detuning from the coming rain...
Now, could i do this night? I'm most curious about the message
detection. I like the whole EbNaut detection process very much,
meanwhile.
On the other side i admit that a 24+ hour carrier may be even more
useful because you can generate a spectrum peak that can give an
impression about the signal strength (of a 3rd night), and it was
requested by Markus and Jacek and Jim. With a carrier you can even
determine the day and night phase and the best time period for a night
time transmission.
Anyway, it is better to run daytime carriers during the weekends so i
will start the carrier tomorrow in the evening.
Today i'd like to try that first east to west VLF TA transmission.
Let's try:
f = 17470.1000 Hz
Start time: 07.Dec.2017 22:00:00 UTC
Symbol period: 60 s
Characters: 1
CRC bits: 6
Coding 16K21A
Duration: 08:32 [hh:mm]
Antenna current: 1 A
I just checked that this would be the path to Forest,VA:
http://k7fry.com/grid/?qth=FM07II52&from=jn49ik00wd
73, Stefan
Am 07.12.2017 18:12, schrieb Paul Nicholson:
Ah, ignore the last message. I just noticed a mistake
I made with the sample rate!!!
Forest, Virginia gives Eb/N0 = -4.8 dB on the 3 char
message, which is -37.30 dB in 1Hz.
Only something like 1 in 300 chance of that Eb/N0 with random noise.
Combining the two results, this is quite likely your signal.
So, this is looking interesting.
--
Paul Nicholson
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