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Re: AO40 dish



Hi Fred

>  Actually, I'd be interested in the Linux version.  I keep boxes for
> both, and would dump Windows entirely if I could.

Development is going well, sensitivity now appears equal to the real 
WSJT and its memory usage has gone down from 250+MB to about 2MB. It's 
all tied up with sliding FFTs and how you store the large amount of 
data generated in a 30 second period. It still needs a whizzy GUI.

It would be interested to have both PCs running side by side with the 
audio feeding both and doing comparisons.

>  One other thought/question I have is this:  "Has anyone used JT44
>  through AO-40, particularly during bad squint times?"  Since it
>  in theory can copy down to the negative SNRs, this might be another
>  alternative.  Certainly for those of us who are very rusty at our
> CW.

Yes, JT44 should be fine via AO-40. The delay is less than via the 
moon, but the synchronisation searching algorithm searches in time 
anyway. What would absolutely kill JT44 would be more than 5Hz of 
doppler shift in either direction in the course of one 30 second 
receive period, it could never work then. You can have doppler shift 
between reception periods, but not during.

>  Maybe the idea can be taylored to a weak signal satellite modem...

There has been discussion about a newer system than JT44 that can 
handle the frequency spreading that you get on the higher frequencies. 
Unfortunately the obvious method of having wider bandwidths also loses 
the advantages of having narrow "bins" in the FFT which is the heart of 
extracting weak signals.

>  As far as not having TVRO dishes available in Europe, I feel for
> you.  They are generally free or very low cost now in the US, and
> readily available. However, after looking at them, it shouldn't be
> too difficult to build up to about 15' diameter stressed frame
> dishes, and
>  for EME this could be better as the dishes could be made deeper than
>  TVRO dishes for better sidelobe performance.

Indeed you are right, building a dish is not the worst thing in the 
world, in fact most of the EME dishes in EU are home made (at least on 
23cms).

>  Fred W0FMS

Jonathan  HB9DRD/G4KLX
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