Hi ELF,
Yesterday, a 12 character EbNaut message was transferred over the 3.5
km (0.00027 wavelengths) path at 22.97 Hz.
Higher noise levels caused some unsuccessful attempts but last night
was quite good and i increased the symbol length to 30 seconds. The
message took 14:24 (hh:mm) to pass over to the tree.
Capture of the signal post-processing chain and message decode attached.
73, Stefan
Am 07.02.2019 17:05, schrieb DK7FC:
Hi ELF ;-)
I'm glad to announce that since 15:46 UTC i am transmitting on ELF (the
real ELF, i.e. into the range of 3...30 Hz, ITU radio band
1 ) for the first time ever.
Here are the parameters:
TX frequency: 22.970 Hz
Wavelength of that frequency: 13060 km
Antenna voltage: 4.8 kV rms (+ a DC component of 7.5 kV)
Antenna current: 325 uA
ERP: 600 aW, or 6E-16 W
Call it QRP!
The goal is to detect the signal on my 3.5 km distant tree grabber,
whose E field is now working again. Since the E field probe is not to
far above the tree, the effective height is not as much as it should
ideally be, at this frequency, so the RX is somewhat deaf. Anyway i can
see the Schumann resonances and the 60 Hz power grid. So i hope it will
work.
A spectrogram which is centered on the frequency of interest in now
shown at
http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber2.html
(3rd window). But maybe 424 uHz FFT bin width is even to optimistic! In
a few minutes we'll see more :-) It takes about 40 minutes until a peak
could have fully developed...
73, Stefan
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12char_EbNaut_ELF_23Hz.png
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