[amsat-bb] Re: U-110 Rotor Setup
ko6th.greg at gmail.com
Tue Jul 3 20:49:23 PDT 2012
Joel Black wrote:
> @KO6TH: I like your approach. Let me see if I got my head wrapped
> around your design - serial interface to the FODtrack board which then
> controlled your controller? That's pretty cool.
Well, sort of. FODTrack has two different Az/EL rotor interfaces which
you can choose from. One uses a parallel port, and talks to a bit of
custom analog hardware to directly sense the rotor position and turn
on/off the motors. The other uses the serial port, and was intended to
be used with the Yaesu controller of the day. What I did was to build my
own controller that emulated enough of the Yaesu serial protocol for the
FODTrack software to talk to it via the serial port. So, I wasn't using
the analog FODTrack controller board hardware at all.
A fundamental decision that needs to be made early on is what type of
feedback your rotors give. There are two kinds - analog (potentiometer),
and digital (index switch). The analog type can be controlled much more
precisely, but the interface is more complicated. The digital types
(which are what I have), have a resolution of around 5-10 degrees.
Fortunately, 10 degrees is plenty accurate for most uses, so I went with
what I had. Others have added Pots to their digital rotors, and I
suppose one could add an index switch to an otherwise analog rotor too.
Just decide which way you want to go up front, then work out the rest
By the way, I've long ago retired the FODTrack software, and now use
Predict on my Linux box. I had to tweak the code a little (yea Open
Source!), to output the same Yaesu commands as what FODTrack spit out.
Alternatively I could have modified the controller. Either way, it's
still working great.
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