Bearings-Only Target Motion Analysis: Observability when the Observer Maneuvers Smoothly

Observability in bearings-only target analysis (BOTMA) is studied when the target is in constant-velocity motion and the observer maneuvers gently (a constant turn motion or a constant acceleration motion). During our study, we proved that the rendezvous routes of the observer and the target play a key role in this analysis. We establish necessary and sufficient conditions of observability and we identify the virtual (or ghost) targets giving the same bearings when the system is not observable.