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Re: VO1NA on LF:

To: [email protected]
Subject: Re: VO1NA on LF:
From: Markus Vester <[email protected]>
Date: Wed, 5 Jul 2017 09:01:27 -0400
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Hi Joe,

in the past, I have used DHO on 23.4 kHz to lock 8.97 kHz VLF carriers. It was quite possible to pick up the distant signal MSK on a ferrite antenna in the presence of the strong local transmission, and SpecLabs samplerate corrector could successfully track the signal. The remaining problem was that there is no way to cure phase jumps due to soundcard glitches or buffer underruns, and for that reason (at least with the then-used Atom netbook), I never managed to produce a glitch-free multi-hour carrier. Thus I would be hesitant to go down that route for EbNaut. 

As Stefan mentioned, setting up GPS 1pps-lock with SpecLab is easy and cheap. Audio feedback will correct both DAC / ADC glitches and phase shifts from TX antenna tuning variations.

Alternatively, replacing the OCXO for your hardware DDS by a 10 MHz Rubidium source would also do the job, albeit a bit more expensive and power-consuming. 

Best 73,

-----Ursprüngliche Mitteilung-----
Von: jcraig <[email protected]>
An: rsgb_lf_group <[email protected]>
Verschickt: Mi, 5. Jul 2017 1:06
Betreff: Re: VO1NA on LF:

Hi Markus,

The oscillator is still undisciplined -- much like your's truly.
The carrier is still on with 1/3 A RF. I was considering getting
a gps module until Stefan reported on his odyssey! In the mean time
it seems like a good idea to use NAA as a reference for Spectrum Lab.
With the RX antenna connected to the pc soundcard and the sample rate
set to 96000, VLF_stations.usr gives a sharp 50 dB cutoff at 8 kHz
and not a trace of NAA. Evidently more fiddling is required.

High voltage managment has had gratifying results. The tuning coil
is starting to look elegant with its 3 pies and a solenoid. Distributing
the kilovolts over more coils seems to have cured the sparking and
ozone spewing.

Thanks for the note, Markus.


On Mon, 3 Jul 2017, Markus Vester wrote:

> Great news! Though it's high-QRN season here in central Europe, Paul will surely detect you again in England. The DL0AO grabber also covers your QRG and will hopefully be back online tomorrow. Tom and Bernd are preparing to install a second earth antenna to the northwest soon, supporting a cardioid in your direction.
> So good luck with the high voltages! Any progress on the GPS frequency lock?
> Best 73,
> Markus (DF6NM)
> -----Ursprüngliche Mitteilung-----
> Von: jcraig <[email protected]>
> An: rsgb_lf_group <[email protected]>
> Verschickt: Mo, 3. Jul 2017 16:51
> Betreff: Re: VO1NA on LF:
> Hi Stefan,
> The TX is now on 8270.007 +- a few ppb. Thanks for the
> advice and good luck to those looking for a trace of
> the weak VLF sigs!
> Joe VO1NA
> On Mon, 3 Jul 2017, DK7FC wrote:
>> Am 03.07.2017 14:52, schrieb Roelof Bakker:
>>> Hello Joe,
>>> Propagtion is a weird thing.
>> LF propagation at least :-) MF even more.
>> I find that VLF propagation is quite predictable, reproducable and
>> understandable :-)
>> 73, Stefan
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