The problem of observability when tracking a target with noisy angles measurements by a single observer is addressed. Necessary and sufficient conditions on the observer maneuver to ensure the target observability are developed for the constant velocity target motion case.
Mounir Ben Ghalia,
"Observability problem in target tracking via angles-only measurements", Proc. SPIE 1950, Acquisition, Tracking, and Pointing VII, (1 October 1993); doi: 10.1117/12.156601; https://doi.org/10.1117/12.156601