Ground-Based Emitter Location in the Presence of Multipath

We address the problem of ground-based stationary emitter geolocalization in the presence of multi-path in which an emitter's signal reaches the receiver through reflection from a surface. A particle filtering algorithm is applied to estimate the location of emitting sources in which a source could be the emitter itself or a mirror image of the emitter across a reflective boundary. The receiver measures the angle-of-arrival (AOA) to each image and possibly to the actual emitter, depending on the environment. Time-difference-of-arrival (TDOA) signals are also processed by the estimation algorithm to further constrain the locations of the images and emitter. We consider only single-bounce reflections of the emitter signal and do not assume that the emitter signal itself is necessarily received. The algorithm does not assume any knowledge of the reflective surfaces. We derive an approach to incorporating both the AOA and TDOA measurements into the measurement-to-source association problem. The algorithm is evaluated within a simulated environment on a variety of different scenarios, comparing results obtained with AOA measurements only as well as with both AOA and TDOA. Both single and multiple receiver scenarios are considered. Results indicate that the algorithm performs well and handles the large uncertainty in emitter locations early in the estimation, which is challenging when using an estimator based on a single Gaussian representation of the emitter state probability density function.