Innovative techniques are proposed for investigation in a Phase I effort to determine passive RF surveillance and targeting sensors and associated methodology for Performing rapid and accurate measurments of range/location of threat RF emitters. The essential physical constraints to be observed are sensor compatibility with, and portability of the associated range determination/processing equipment on, an airborne platform. The innovative techniques outlined in this proposal offer very promising alternative options for realizing passive RF ranging systems that satisfy these constraints. These techniques will be evaluated analytically in the proposed Phase I effort design analyses will be performed to define the tradeoffs in the practical implementations within the dynamic environment of airborne platforms with variable attitude, position and associated rates and other significant considerations. Definitive sensor configurations, sensor processing schemes/techniques, computational algorithms and operating modalities will be firmed up, and design and implementation latitudes will be established, complete with performance predictions, and a plan for proof-of-method experiments and a hardware development program for Phase II .