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Date: Wed, 01 Jun 2016 13:55:34 +0200
From: DK7FC <selberdenken@posteo.de>
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References: <1685128417.20160531153441@chriswilson.tv> <1550afb17cc-67dd-e0ec@webprd-m47.mail.aol.com> <574EAE10.3070903@posteo.de> <1876951388.20160601113904@chriswilson.tv>
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Subject: Re: LF: Earth modes and ebnaut?
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Status: O

Am 01.06.2016 12:39, schrieb Chris Wilson:
> What's my best way to generate a very very stable carrier at
> VLF?
>    
There are different philosopies as you know. But i find the really best 
(and easiest) way is to use SpecLab and (1pps + NMEA) or (1pps + NTP).
That may sound complex to you, i don't know.
Let me tell you, as i started with the Raspberry Pi, i knew absolutely 
NOTHING (!) about Raspi and Linux. I didn't start with a complex task 
but with very simple stuff....
So i would suggest to start generating a tone on the headphone output of 
your PC using SpecLab. Connect a audio PA, better build your own stuff 
instead of ebay...
Buy a large ferrite core and wind a RF transformer with say 300V rms 
output voltage. Build a dummy load with 1 kOhm and 100W. 1 kOhm is a 
typical loss resistance for a small VLF antenna, both inv-L and earth mode.
Generate the wanted frequency, without ultra stable stability in a first 
step.
Start with local tests in a range of less than 5 km. Later you can go to 
slower modes / bandwidths, where you will need the stable signal.
For te first tests, SpecLab will be stable enough without pps and you 
can easily generate any tone, QRSS, DFCW and so on.
Make sure you have the right attitude to VLF: There will not be a quick 
success over 100s of km in a week.
> I have a 10 MHz and 1PPS Trimble Thunderbolt GPS box operating 24
> hours,  7  days a week, with 10MHz, 5MHz, 1Mhz, and from 100kHz to 1Hz
> in decades, from a professionally made divider box. Can that be
> incorporated? http://www.perdrix.co.uk/FrequencyDivider/index.html
>    
The 1pps and a NTP time server program like Dimension 4 will do a good 
job. This is what i'm using on my VLF TX PC.

73, Stefan
>
> Best regards,
>   Chris  2E0ILY                          mailto:chris@chriswilson.tv
>
>
>
>    
>>
>>   Sounds interesting. I've managed about 50km with 250W and a 700m
>> long wire. But that was in 3.8 mHz, which is fast mode for VLF. But
>> it was one of the standard modes these days :-)
>>   Before TXing EbNaut i would suggest to experiment just with a
>> stable carrier and detect it in some distance. Generating an
>> absolutely stable carrier is the first step and essential for all EbNaut experiments following.
>>   The G4WGT VLF grabber may be helpful but i don't know the distances between you...
>>   Nice to see some starting activity.
>>   I have to repair (and improve) the preamp for my VLF remote
>> grabber, thus the limited performance in the moment.
>>
>>   73, Stefan
>>      
>
>