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RE: Auto Doppler on FO-20



> Hi Guys,
> Automatic doppler correction software on a P.C. ,  like 
> Fodtrack tunes your
> radio to  maintain a doppler corrected signal "at the 
> satellite".  If you
> do it "by ear" you are correcting at your end of the link. 
> Fodtrack works
> brilliantly if both QSO partners have it fully implimented.

All's well and good, but there are a couple of hitches, like it increases
the cost of satellite operation considerably, particularly for portable
stations.

Firstly, you need a rig capable of being computer controlled.

Secondly, if you're portable (like me), you need a notebook to run the
software on.  However, it is true that secondhand notebooks can be fairly
inexpensive.  What is the minimum processor requirement?

> Graham Ratcliff VK5AGR wrote an excellent paper on the subject for the
> Amsat-UK Colloquium 1998 with a full description and a very simple CAT
> interface. I built a few interfaces and several of regulars 
> on the Amsat
> VHF net had fun trying it out on FO-20 and 29.  I expect that 
> this type of
> auto correction will be just whats wanted when working P3D on 
> the higher
> frequencies.

I would like to try it, but that will have to wait until it becomes feasible
(both technically and economically) for my minimalist style of operation.
:-)

> The article may be archived somewhere on the net.  If anyone 
> knows where
> perhaps they can post it to the bb.

It's on the AMSAT-NA site.  It is quite a good article, and maintaining a
constant frequency at the satellite is the proper way to do things, as
that's the only point that's common to everyone.

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