Well done, Stefan and Markus and Paul!
Still waiting for the gps module to arrive. The renewed VLF
licence was issued today.
73 Joe VO1NA
On Wed, 20 Sep 2017, DK7FC wrote:
Hello Markus,
That's great, impressive work! I confirm the message. A kind of challenge
just for you, right? :-)
A new series of VLF experiments at 300 mA on all frequencies from 8270 Hz
down to DC will start in the near future...
Be prepared!
73, Stefan
Am 20.09.2017 19:03, schrieb Markus Vester:
Today I finally managed to decode Stefan's 15 character transmission, using
DL0AO data from four days, September 10 to 13. This was quite a
challenge...
Two tail ends were missing, due to a TX modulation failure on Monday 12:56
UT, and lost data since Wednesday 12 UT due to a forced reboot of the RX
PC.
To make use of all available SNR, it was necessary to include both
available channels (West cardioid and East-West earth loop), which is
equivalent to a weighted sum of E- and H-field antennas. The complex
antenna weighting factor had to be optimized separately for each day. Then
the four days were again optimally weighted and summed up.
Using the known message, SNR contributions from the four days could be
evaluated separately:
day Eb/N0
dB power
Sun 0910 -6.21 0.239
Mon 0911 -6.01 0.251
Tue 0912 -2.98 0.502
Wed 0913 -5.13 0.307
stacked +0.97 1.250
Stefan, thank you for this message!
Best 73,
Markus (DF6NM)
-----Ursprüngliche Mitteilung-----
Von: DK7FC <[email protected]>
An: rsgb_lf_group <[email protected]>
Verschickt: Di, 12. Sept 2017 14:01
Betreff: Re: VLF: 15 charaters on the 67 km band...
I'd like to shorten that transmission experiment a bit. For a decode from
Paul or Jacek it may take 2 weeks of daily transmissions. DL0AO however
will likely get a decode today, if all works well. After the decode from
DL0AO i'd like to stop the test because my new stacked coil is already
completed, at least it allows a transmission on 8270 Hz. My larger 3 layer
coil allows 700 mA antenna current, the new one allows just 300 mA, i.e.
-7.4 dB. Anyway i'd like to test that new coil for the first time. I intend
to run DFCW-60000 near 8270.005 Hz. This will allow to see a trace in a 47
uHz spectrogram, for Mike and Luis and DL0AO and maybe even a few more
stations. Each 'dit' will take 16 hours.
I'll start in the end of the week but for the newcomers it would make sense
to start a RX spectrogram a few days earlier.
An announcement of the carrier transmission will follow during the week...
73, Stefan
PS: Markus, if you can decode the message, you can tell it, it's no secret.
Am 09.09.2017 20:27, schrieb DK7FC:
VLF,
Another EbNaut message which is even more challenging to decode:
*f = 4470.005000 Hz
Start time: 10.September.2017 05:00:00 UTC (daily repetition)
Symbol period: 20 s
Characters: 15
CRC bits: 14
Coding 16K21A
Duration: 11h01min20sec
Antenna current: 155 mA*
Markus, if you decode it (after stacking 2...3 days), pse don't
tell the message here (but your decode details pse). It will be
interesting to see if Paul can get it too. Paul, will you try? Or
are you still testing the E field antenna?
73, Stefan
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