Raw CPR fields from the even-format (F=0) frame.
Raw CPR fields from the odd-format (F=1) frame.
Which frame is more recent - determines which frame's latitude zone the result is reported in.
The resolved position, or undefined if the two frames fall in different latitude zones (the pair cannot be combined) or the result is physically impossible.
Resolves an absolute position from a paired even and odd airborne CPR frame (ADS-B BDS 0,5 / 2,0 - type codes 9-18 and 20-22), per DO-260B SS A.1.7.3. The two frames must be close enough in time that the aircraft could not have crossed a latitude zone boundary - in practice, no more than about 10 seconds apart, since airborne position is broadcast at roughly 2 Hz. Enforcing that window is the caller's responsibility; this function only performs a zone-consistency check as a lightweight guard, which cannot by itself detect a same-zone false positive from a pair spanning too wide a gap.