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Re: VLF: 300 mA on 8270 Hz

To: [email protected]
Subject: Re: VLF: 300 mA on 8270 Hz
From: DK7FC <[email protected]>
Date: Fri, 22 Sep 2017 13:26:43 +0200
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Hi Mike,

Am 22.09.2017 11:52, schrieb Mike Dennison:
I would certainly like to try to receive you again on VLF, Stefan.
But I understand that EbNaut cannot be seen on a spectrogram. Is that
Yes, correct. At least as long as the SNR is as weak as it usually is on RX sites a few 100 km distant. On my tree grabber which is just 3.5 km distant you can see the signal in the spectrogram:
   I don't have GPS timing (though I expect to have it by the
New Year). I do have excellent frequency accuracy and the computer
clock is synched to an NTP server and is kept within 0.5mS.
That sounds good.
Also you are locking SpecLab to GBZ which is normally a 24/7 available reference.
So you are already now able to decode EbNaut.
Is there anything I can receive during this test? Or should I wait
for a simpler transmission?
A simpler transmission, i.e. a carrier is better for starting. Did you get a result from my recent carrier transmission? The current transmission is 6 dB weaker. But somehoe propagation wasn't really good during the last weekend... You said you wanted to buy a new PC. This is a good step: To have a permanent running spectrogram, or 2 or 3. I know you are having a blog where you post some reception results from time to time. So you seem to be skilled enough to build up a website and maybe even run a test wise VLF grabber, like Eddie does from time to time. A grabber is also helpful to check the current situation (QRM, QRN, availability) by other people. Also it would be helpful to build a separate antenna just for VLF reception. Just build an active vertical. A 5m or 8m pole for example will give you enough capacity and signal energy to observe the ultra low frequencies.
73, Stefan

Mike, G3XDV


My new VLF coil is now in operation. It is designed to run 300 mA. The
first station where i like to transmit some messages is 8270 Hz, just
because 36 km it is the easiest band on the VLF frequencies available
for us. The idea is to transmit at least 100 hours on each band down
towards DC, just to proof the design. Does someone like to join the
experiments, RX or TX wise?

I'm going to start a first transmission tomorrow morning using EbNaut:

*f = 8270.005000 Hz
Start time: 22.September.2017  06:00:00 UTC
Symbol period: 24 s
Characters: 12
CRC bits: 16
Coding 16K21A
Duration: 11h,31min,12sec
Antenna current: 300 mA*

73, Stefan

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