[amsat-bb] Re: thought for a neat product, anyone seen one?

[Mark Vandewettering]

I have the same rig, and much the same idea.  I haven't gotten very  
far along with this idea, but
here's where my thinking takes me.  I've implemented Miller's "Plan  
13" algorithm in Python, and
currently use it to plan all my satellite operations.  On any  
reasonable laptop, it runs many times
faster than real time, even while running in Python, so it seems like  
overkill to carry a laptop
with you to do satellite operations.  The laptop is expensive, bulky,  
and hard to use in the field
while aiming an antenna by hand, has limited battery life, etc.    
Clearly, a more limited computer
can do all that we really need.     If you look at G6LVB's latest/ 
greatest antenna tracker:

http://www.g6lvb.com/Articles/LVBTracker2/index.htm

you can see that he does all that you want using just a PIC  
microcontroller.   My own personal
bias is against the PIC though: I prefer the Atmel AVR chips, and in  
particular have been having
a great deal of fun with the Arduino microcontroller board.  I suspect  
that if I back ported my
Python code into C and put it on the Arduino, I could still get an  
update rate approaching 1Hz,
which should be good enough for the purposes we desire.   The Arduino  
also has a nice little
piggyback ethernet board.   Here's what I imagine the usage is.  While  
at home, you plug this
thing into your home network.  It then contacts celestrak or whatever,  
and automatically downloads
the TLE for current amateur satellites.  You can then disconnect the  
rig from your home network, and
it's ready to carry into the field.  A couple of buttons on the box  
allow you to cycle through
satellites, giving the elevation and azimuth of the satellite.  The  
Arduino also has a serial port
which we can hook to the FT-817, and use it to control the 817 with  
doppler.  It would be a pretty
simple project, requiring three modules (arduino, ethernet shield and  
display) and a few extra
buttons etc...   Total cost probably around $100 or so.  Could  
probably run off batteries for days.

I probably won't get back to working on this until after the first of  
the year, but if anyone
is interested, some enthusiasm might further motivate me to get the  
software working.

	Mark