On Sunday, May 31, 2015 at 7:32:20 PM UTC+2, Andy Blackburn wrote:
I bet you could do a good enough job without a lot of trig. You need position, velocity vector and some measure of curvature. You could probably do the horizontal and vertical parts separately. The cone part is just relaxing the distance that constitutes a collision conflict progressively with each increase in projection time/distance.

Of course the proof is in how FLARM behaves so they are doing something like what I described.

How the calculations fit in processing time available is a question for the likes of Dave Nadler who understand these issues intimately.

9B

On the 'Classic' platform, we do a lot of the calculations in (our) fixed-point integers, plus use lookup tables and other tricks. A bit harder to code and test, but *very* fast on the AVR processor.

Urs
FLARM