Cooperative UAS Geolocation of Emitters with Multi-Sensor-Bounded Timing and Localization Error

A collection of “unmanned aerial systems” (UAS) are wirelessly networked and each is equipped with an antenna, receiver and other components resulting in a cooperative wireless sensor array that can be used for determining RF emitter location estimates. Because each UAS is independently mobile and cooperates with other array elements, the geometry of the wireless sensor array can change in a dynamic manner thus allowing for enhanced accuracy of emitter location estimates through subsequent measurements and iterative location estimate updates. UAS local timing sources and enhanced localization approaches enable time-based emitter location techniques based upon “time-of-arrival” (TOA) or “time-difference-of-arrival” (TDOA) measurements. Sensor localization errors are bounded due to the presence of individual UAS LIDAR ranging subsystems, and the use of new local time source technology likewise bounds the emitter location accuracies due to timing errors. After a review of time-based emitter location methods, two time-based geolocation methods are chosen for this investigation: a multilateration technique and the “Location On a Conic Axis” (LOCA) method. Simulation results predict the accuracy of emitter location estimates versus varying levels of realistic error in array element positioning and time measurements. A study of array size versus emitter location accuracy is also included. The simulation results are compared with the theoretical emitter location accuracy in the presence of the error sources, the Cramér-Ran Lower Bound (CRLB).