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Re: "Precision" Antenna Pointing

> I confirm your thought about plus/minus two degrees as good as amateurs
> usually can obtain.  It would be nice if ordinary antenna hardware would
> do better.  This is barely good enough for S band use even with a two foot
> dish.  Can we list here how much excess sun noise is gotten on 2400 MHz?  
> Be sure and include you antenna system and noise figure if possible.

My other hole-in-the-head, er, hobby is amateur astronomy.  In addition
to owning some exquisitly polished chunks of glass, I own a couple of
german equitorial telescope mounts.  I can routinely aim these things
to a precision measured in arc-seconds because each of the axes (RA
and declination since they're equitorial mounts) have an optical shaft
encoder connected to them.  These provide quadrature outputs with
4000 pulses per revolution.  These are connected to a small computer
with some anonymous single-chip micro running on a 9V battery; after
a calibration process which essentially computes a transformation
from the X and Y coordinates to (in this case) celestial coordinates,
it displays the current aiming.

I'd guess that the hardest part of moving this to an antenna positioning
application would likely be the mechanical aspects of coupling these
optical shaft encoders to the antenna system.


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