Positioning the AntTracker

For the tracker to position the servos relative to the compass direction of the craft, it needs to know the compass direction in degrees where the tracker antenna is pointing at rest. For convenience we call this the Heading_Source. Three possible heading sources are available:

1) Flight Computer - use this if your craft has a Flight Computer with a compass

 Align the craft's heading (where the nose points) with the direction of the tracker 
antenna, and press the Set_Home button. The tracker will use the heading of the craft 
obtained from the craft's Flight Computer via telemetry.

2) GPS - use this if your craft has a GPS, but no FC or compass

Position the tracker box such that the antenna faces the field straight ahead. Power up
the craft and tracker, and wait for a good GPS lock. The tracker's LED will flash fast. 
Walk several metres (say 5) straight ahead with the craft, place it on the ground, 
return and press the Set_Home button. The tracker calculates the compass direction of a 
vector (line) from where the craft was at the first GPS lock, to where it was when the 
Set_Home button was pressed, then use as the assumed direction of the tracker antenna. 

3) Tracker's Own Compass - use this if your craft has a GPS, but no FC or compass

Glue a suitable magnetometer anywhere on the tracker box, facing the direction of the 
antenna at rest.

Before you build/compile the tracker firmware, be sure to un-comment the appropriate #define macro according to your choice of heading source:

//#define Heading_Source 1 // GPS //#define Heading_Source 2 // Flight Computer #define Heading_Source 3 // Tracker_Compass