PASSIVE RANGE ESTIMATION USING DUAL-BASE-LINE TRIANGULATION

Modern combat systems based on active radar sensing suffer disadvantag es against low-flying targets in cluttered backgrounds. Use of passive infrared sensors with these systems, either in cooperation or as an a lternative, shows potential for improving target detection and declara tion range for targets crossing the horizon. Realization of this poten tial requires fusion of target position data from dissimilar sensors, or passive sensor measurement of target range. The availability of pas sive sensors that can supply both range and bearing data on such targe ts would significantly extend the robustness of an integrated ship sel f-defense system. We consider a new method of range determination with passive sensors based on the principle of triangulation, extending th e principle to two orthogonal baselines. The performance of single or double baseline triangulation depends on sensor bearing precision and direction to target, An expression for maximum triangulation range at a required accuracy is derived as a function of polar angle relative t o the center of the dual-baseline system. Limitations in the dual-base line model due to the geometrically assessed horizon are also consider ed. (C) 1996 Society of Photo-Optical Instrumentation Engineers.