A reference position used to disambiguate a single CPR-encoded frame that
has no paired opposite-format frame to decode globally against. Must be
within roughly 180 NM of the true position for airborne decode, or 45 NM
for surface decode - the caller is responsible for that precondition.
A reference position used to disambiguate a single CPR-encoded frame that has no paired opposite-format frame to decode globally against. Must be within roughly 180 NM of the true position for airborne decode, or 45 NM for surface decode - the caller is responsible for that precondition.