A demonstration of achievable accuracy for passive location of pulsed emitter sources

This paper describes a program to investigate the achievable accuracy of an emitter location system which uses GPS as the primary source of position, velocity, and time. The method tested uses differential time of arrival (dTOA) of an emitted pulse received by two or more receivers. Two spatially separated dTOA's along with the position of the observers are used to determine the emitter position, assuming emitter altitude is known or can be inferred from its horizontal location. Kalman filtering of sequential measurements is used to improve the position solution and to detect erroneous measurements, such as might be caused by multipath and/or low sidelobe signal level. The most demanding requirement of the reference system is time accuracy, with a goal of 10 nanoseconds relative time accuracy.