I would like to understand how the Paparazzi autopilot
manages crossing UTM Zones. I have studied the source code and cannot see that
this is catered for, unless one uses the Lat/Long supplied by the GPS. I am
reluctant to do that as the conversion of lat/long to UTM loads the processor
(it is not a trivial computation). As I understand, the Nav function in
Paparazzi works with a coordinate system based on a georef point whose (x.y) is
set to be zero. All waypoints, aircraft position etc are then assigned coordinates
relative to this point. This is a fantastic way of working – just needs
to be able to handle receiving a UTM eastings value from the GPS which is in a
different zone.
Hence please if someone can explain how this is managed in Paparazzi
it would be much appreciated.