The study focuses on range‑free, angular‑limited sensors that only measure the direction of incoming signals, not their distance. This is highly relevant for UnderSec scenarios where inertial or direction‑only sensors detect transmitters entering a protected area, and localisation is achieved through the intersection of multiple directional bearings.

An important innovation is how the optimisation model handles obstacles. Previously detected transmitters inside the Area of Interest are treated as “obstacle‑like” sources of sensing degradation, creating angular blind zones where sensors are less effective. The algorithm then seeks configurations that still achieve strong 3‑sensor coverage (triangulation) despite these degraded regions, which is crucial when monitoring borders, perimeters or spectrum use around strategic facilities.

These concepts translate directly to UnderSec’s mission: guarding corridors, coastal segments or critical infrastructure perimeters where unknown transmitters may appear, while existing emissions and structures locally reduce sensing performance. The obstacle‑aware optimisation helps maintain robust localisation capability in such complex environments.