Raspberry PI running a modified version of the predict program,
coupled to camc_pic driving two RC servos (use modified version on that page for tracking),
controls a 2.4 GHz yagi antenna to track satellites.

The code and diagrams are released under the GPL license.

This project would have been much more difficult to realize without the predict program.

This project is still under _mechanical_ construction, more later when parts arrive.



the 2.4 GHz yagi
The 2.4 GHz yagi, 25 dB gain, less than 10 $, from ebay

The modified version of camc_pic that only does elevation (on x servo) and azimuth (on z servo):

The code that needs to be entered in predict.c so it can drive camc_pic:

System test, the wire points to the sat, those are 180 degrees servos, modify the code so it works for your servos,
if 180 degrees servos, flip the horizontal arm over and swing around 180 degrees when going through 180 or 360.
Calibrate with a protractor by adjusting the values in control.c.
You need a counter weight for the yagi, else the servos will draw way to much current, those should only draw current when moving.
You may consider metal gears and double ball bearing servos, I have ordered 2 from ebay, these are old servos with nylon gears, and have a lot of play in the gears.
sytem pointing test

Made a counterweight so the antenna is exactly in balance.
Satellite tracking control test video, note the fast move at about 1 minute:

return to main page (and check out the downloads link for more GPL programs and hardware)

Copyright Jan Panteltje 2013-always