Scott Coutts

Passive Localization of Moving Emitters Out-of-Plane Multipath

Monday, August 11, 1997
11:00 AM
406 Egan

Abstract

The purpose of this work is to establish how a moving emitter can be localized by a passive receiver through the use of out-of-plane multipath signals reflected by terrain. This is a novel localization technique that assumes no a priori knowledge of the location of the multipath sources. The emitter parameters of range, heading, velocity, and altitude are estimated by exploiting the correlation between the direct-path signal and the delayed, attenuated, and Doppler modulated signals reflected by the terrain.

Two basic assumptions about the scattering properties of the terrain lead to two different maximum likelihood (ML) estimators of emitter parameters. The first assumption is that the terrain scattering is fundamentally homogeneous and the ML estimator is found to have the structure of a time-varying FIR filter. The second assumption is that the terrain scattering is fundamentally inhomogeneous and dominated by a number of discrete point scatterers. This assumption leads to a two-part estimator which first estimates the scattering parameters of azimuth, differential delay, and Doppler shift, and then estimates the emitter parameters using the scatterer parameter estimates. The Cramer-Rao lower bounds for each estimator are derived and used to study estimator performance for a number of scenarios.

The proposed estimators are successfully demonstrated using field data collected at White Sands Missile Range during the DARPA/Navy Mountaintop program. Several extensions to the basic results are considered such as localizing pulsed and self-correlated emitters, multiple emitters, and the effects of receiver motion.

Thesis Committee:
Prof. R. Raghavan (advisor)
Prof. H. Lev-Ari
Prof. D. McLaughlin
Dr. R. Fante (The MITRE Corporation)
Dr. R. Gabel (MIT Lincoln Laboratory)
Dr. J. Ward (MIT Lincoln Laboratory)