------ Originalnachricht------
Von: DK7FC
Datum: Do., 7. Feb. 2019 23:01
An: [email protected];
Betreff:Re: ELF: Carrier on 22.97 Hz
...wow, after analysing the first 90 minutes of the transmission ifound that the best SNR is achieved without sferic blanking! So thenthe hum filter and the low pass filter can be disabled too.
So far, during that noisy evening period, i'm getting about
14 dBSNR in 185 uHz.Unfortunately i temporarely overloaded the PC while doing the analysis,which caused an interruption of the stream and then all SpecLabinstances did a restart.
Now the spectrogram is generated from the unfiltered and unblankedstream and now we can already see a clear peak right on the expectedfrequency, showing about 10 dB SNR.
I intend to run the carrier at least for 24 hours, if all works
well.Not sure if and how the antenna current will drop when it starts torain. It would have been better to decouple the DC component from theantenna by using a big series capacitor but id didn't have one thatholds 20 kV or so.
More later...
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 (thereal ELF, i.e. into the range of 3...30 Hz, ITU radio band1 ) 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 tofar above the tree, the effective height is not as much as it shouldideally be, at this frequency, so the RX is somewhat deaf. Anyway i cansee the Schumann resonances and the 60 Hz power grid. So i hope it willwork.
A spectrogram which is centered on the frequency of interest in nowshown 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! Ina few minutes we'll see more :-) It takes about 40 minutes until a peakcould have fully developed...
73, Stefan
