In my opinion, you dont need elevation for any existing AMSAT nor do you need an OSCAR array since we have no HEO birds and LEO's are so close, there is 6 to 10 dB right there. And with nmodest beams, the beamwidth is wider than the inaccuracy in the rotator. My design simply used the 1 RPM rotatino of the motor to keep track of position and after each pass, or on edmand, it woiuld drive CW (or CCW) into the stops, zero the counter and then consider that zero and count from there. Tilt the beams up modestly to 15 degrees and you have plenty of gain. When the LEO satellite is above that it is 6 to 10 dB closer and plenty strong enough. And when it is below 15 degrees it is far away on the horizon and still totally within the main beam of the modest beam.
Some rotors use a microswitch feedback system, where there is a
momentary "click" every few degrees.? It's pretty easy to build a
system that counts clicks and controls a set of relays based on it.?
I did this 20 years ago with a Basic Stamp-II.? Should be fairly
trivial to port to an Arduino, especially since you wouldn't have to
deal with a 360 degree coordinate system in a system that was
limited to mostly 8 bit math due to a lack of variable space.? That
was fun...? See http://home.wavecable.com/~ko6th/ at the top of the
page.? (Yeah, the site desperately needs an update...? The current
software version is 1.4.)
The rotors I used had a resolution of 6 degrees for Azimuth, and 10
degrees for Elevation, which is well within the beamwidth of the
antennas.?
Greg? KO6TH
Russ Ramirez wrote:
Tim,
I had some success with this with an Alliance Tenna rotor a
few years ago, but the older (Arduino Mega based) K3NG rotator
controller would "hunt" in terms of Elevation because these
old rotors generally do not have position feedback in the form
of a potentiometer the way the Yaesu rotors do. The G-5500(DC)
setup is hard to beat.?
Anyone
have a simple interface for a low budget TV rotor (RCA) to
allow SatPC32 to control azimuth? I do have intentions of
obtaining a GS-5500 but that is a few months down the
road....meanwhile I have an Alaskan Arrow still in box
that I want to use until I can get the sat antenna pack
from Amsat....
Any
Raspberry Pi or Arduino interfaces? It's beyond my level
to try to program something myself.
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