Re: [amsat-bb] Dish aiming

[Roy Welch <rdwelch@xxxxxxxxxx>]

Assuming that the rotor controller interface uses an 8 bit A/D converter
that divides the AZ 360 degrees into 0-254 segments, then the AZ accuracy
can be about +/- 1.4 (360/254) degrees regardless of the control box to
rotor accuracy.  The EL accuracy from the same arrangement would be 180/254
or 0.7 degrees.  Then on top of that the accuracy in actual pointing would
depend on the linearity of the resistance of the rotor position
potentiometer, gear lash, etc.

David Guimont wrote:
> 
> >
> >Seems like lots of folks have high hopes for the microwave parts of P3D.
> >BUT ... are the average rotators/elevators sufficiently accurate to use
> >with the narrow beamwidth of dishes etc ?
> Hello Richard,
> 
> No problem on the rotors, Richard.....
> 
> I think the problem MAY be with the accuracy of the program that directs
> the rotors...the many programming gurus we have on here can comment on that
> statement.
> 
> I've done some experimenting....Very easy to bias the EL with a positive
> forward weight with the antenna.....Accuracy is about 1/2 degree....And
> with a little work it is easy to bias the AZ with a pulley and a
> weight.....Same error then on the AZ.
> 
> Remaining, of course, is the antenna alignment, but I'm hoping that can be
> done with some experimenting, and minor re-alignment.  We have a mico-guru
> here in town, and am hoping I can get him to educate me....There was a time
> when I could barely breathe "up" on 435, but feel pretty comfortable there
> now....Live and learn I guess...
> 
>         73 de Dave, wb6llo@amsat.org
> 
>                             Disagree; I learn.
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-- 
73, Roy

Internet: w0sl@amsat.org
Home Page: http://home.swbell.net/rdwelch
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