Parallel port add-on to set the direction of an antenna. it could be used for most any antenna, but I did it for the hdtv antenna (http://www.instructables.com/id/Yet-another-dtv-antenna/).
Note: This instructable requires programming. I did not include my code for legal reasons.
Warning: Please be careful with this project. Not properly hooking wires correctly could cause shock and or even death. You could also damage your computer and other electronic parts. Please get a professional electronics technician to help if you are not sure what to do. . Please use a breadboard first before doing any soldering. Get expert help if you are not sure.
Get needed tv station degree from input.
Get current angle from compass.
If compass angle less than tv station degree then use stepper motor to turn in that direction till correct direction is achieved,
otherwise go the opposite till correct degree is achieved.