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Date: Sun, 11 Oct 2015 02:18:43 +0200
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Subject: Re: LF: QRSS/DFCW transmission with a Raspberry Pi
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Hi Dimitris,

Am 10.10.2015 22:58, schrieb Dimitrios Tsifakis:
>> BEV! That's it. Can you build a beverage antenna on your new QTH? Maybe 3
>> Lambda on 630m? :-) You know, i would do so! :-)
>>      
> Hmm, that's about 2 km of wire, my place is not big enough, but the
> people around me seem to be quite friendly, so I guess it's possible.
> What sort of wire would you use for this?
>    
Well i'm not an expert on beverage antennas. Not at all. I even never 
built one :-)
But i expect the wire diameter, i.e. the wire losses are not critical. 
There are some interesting new pages about DX antennas on 630m in the 
web. Worth to study.
What is your new locator?
I would start to place the wire, and play with the termination 
resistance. I guess that 5m above ground is a good choice? Or maybe it 
doesn't matter so much because the skin depth on 630m is larger then on 
80m/160 anyway? So maybe it is not necessary to lift the wire at all? It 
will depend on the ground conductivity. So i would lay the isolated wire 
just on the ground and start that way. Interesting.
Some simulations could be helpful as well.

>> Well, the C-file for WSPR is already existing. So the Pi can be told to
>> transmit on a certain frequency for a certain duration and then on another
>> frequency for another durartion and so on. So QRSS /DFCW could be "just"
>> some adaption/modification to the existing code.
>>      
> I have butchered the pi wspr code and I can now arbitrarily produce
> any frequency I like using the GPIO4 pin. That's the hard bit. Now I
> need to produce the character to morse code translation code and add
> the features you requested. Stay tuned!
>    
Wow, that sounds fast, i'm impressed.

73, Stefan