This chapter was written, in part, by Henry Heidary of Hughes Aircraft Corporation (now Raytheon Systems), Fullerton, CA.
Several types of passively acquired sensor information can be combined through data fusion. For example, the raw signals themselves, direction angles, or angle tracks may be selected as inputs for a data fusion process. The signals, sensor data, and communications media available in a particular command-and-control system often dictate the optimum data fusion technique. This chapter addresses data fusion architectures applicable to multiple-sensor and multiple-target scenarios in which range information to the target is missing but where the target location is required.