Gus and the group: Lots of birds going up in the next year. Success rate not 100% as it's rocket science oftentimes on a budget. Hopefully we'll get a few out of it. The Arduino IDE install supports PPM. The nice thing about that platform is that configuration is doable for just about all forms of hardware that you might drive with it and scaling can be done in software for the various different bits of kit.
I am sure that with the appropriate development environment and having the hardware on hand IN a well equipped lab, it should be a weekend project to get running.
The hard bit in my opinion is how to mount the antennas to the az/el clockwork. Will require a little woodwork/metalwork to finish.
Everyone who does this will have a problem with some phase of it. Needs to be simple and repeatable.
Norm n3ykf