Re: inquiry about homebrew az-el systems
Just think -- with TWO of them, you could compensate for the motion of the station, when operating from, say, a
boat or a vehicle under way. (Nobody say "GPS" please!)
Hi Gus, you asked for it :-) http://www.g6lvb.com/ao40mobile.htm So also here Howard sets the standard, nobody beats him - respect!
Btw: here is my 18 year old project, it still works fine after so many years: http://pa3guo.com/zb_rtr_ctrl.html
Things I learned and included in my software: - thresholds are needed to avoid the system oscillating around a target position - corrections need to be made due to overshoot (after a stop command the rotor takes time to actually stop
-- Henk, PA3GUO
On 03/08/2013 01:31 PM, PA3GUO wrote:
Things I learned and included in my software:
- thresholds are needed to avoid the system oscillating around a target position
- corrections need to be made due to overshoot (after a stop command the rotor takes time to actually stop
These are exactly the problems that can be neatly addressed with a variable speed drive rather than the classic bang-bang. If you want a fixed position, you use a control algorithm that slows the motor as it reaches it so it won't overshoot (or at least not as much) and stops at exactly the position you want.
But since you're most likely tracking a moving satellite, you can simply vary the speed of the drive to match the actual speed of the satellite and then you'll never have to stop. You'll have a small error in velocity and position but again, with the right control law those errors can be made very small.
participants (2)
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PA3GUO -
Phil Karn