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Re: VLF: Carrier on 8270.005 Hz, VLF stuff here and there

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Subject: Re: VLF: Carrier on 8270.005 Hz, VLF stuff here and there
From: DK7FC <[email protected]>
Date: Sat, 04 Nov 2017 18:59:47 +0100
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Hi Markus, VLF,

Am 04.11.2017 13:19, schrieb Markus Vester:
Hi Stefan,

unfortunately I will be here only for a few days, and won't have the opportunity to rig up any kind of useful VLF RX-antenna.
Pity. But then, we can try the daytime carrier to your home QH the next weekend maybe.

The DL0AO grabber is online again. Interestingly, this time better SNR was achieved from the E-field antenna than from the western cardioid.
Do you expect a change of the angle of the downcoming wave, to steep to be detected by the E field antenna, i.e. no ground/skywave cancellation? Or maybe there is just more noise coming from W. Indeed there were thunderstorms in EA/CT. Paul will be able to cancel them out by 'turning' the loop minimum onto them.
 The DF9RB images near the bottom are from Bernd's netbook, which is currenly connected to an unsued former telefone line at the same site in Amberg. You can see that samplerate correction had not been working properly before 2 UT.
Ah yes, thanks, i can see my signal. It is very strong on the E field antenna, as you say. Also on the old telephone line. But it seems the QRM is a bit higher there :-)
I would use that telephone line for ELF transmit experiments, without (!) doing any calculations before, except the output transformer for the PA of course :-)

Good luck for your attempt to reach RC4HAA!
Thanks. As you maybe see, there are only a few wishful pixels, no significant signal. The PPS still has a problem and maybe the antenna input level is a bit low. But i need to present a success to mobilise more motivation to improve the system...
Today i will run another carrier, same antenna current. But it is on the air since 16:30 UTC now, 3 important hours earlier. Maybe that helps.
I like the spectrograms very much but the single character EbNaut experiments are just more meaningful. With just 5 dB SNR in 47 uHz i can transfer one character in 12 hours. Whereas with just one pixel at 5 dB SNR into a 47 uHz spectrogram (even using a Hanning window) you see nothing!! If there are multiple decodes but the right character under them, i can repeat the experiment and it will show a single decode with just the right character the next day. This worked impressingly well in the recent 5170 Hz experiment with RN3AUS. It is the method to use when exploring new regions of RF spectrum down towards DC! And it can be interesting to experiment with the decoder because you can come very close to the decode limit...
When Paul has optimised his H field, i bet he will catch me on 970 Hz.
Great stuff!

73, Stefan

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