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FIFTH ANNUAL
ASAP '97 WORKSHOP


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3-D Emitter Localization
Using Out-of-Plane
Multipath

Scott D. Coutts
MIT Lincoln Laboratory
244 Wood Street
Lexington, MA 02173-9108
tel: (781) 981-5789
email: scoutts@ll.mit.edu

Abstract The ability to estimate the range, heading, and velocity of an airborne emitter by a single passive receiver using out-of-plane multipath was demonstrated at the 1996 ASAP Workshop. Progress on this topic has been made in several areas. First, the maximum likelihood estimator that is based on a homogeneous clutter assumption was expanded to include emitter altitude estimation. The Cramer-Rao lower bounds were determined and jammer localization results using Mountaintop data collected at White Sands Missile Test Range are presented. The second major area of progress is the design of an estimator based on an inhomogeneous clutter assumption. This approach uses correlation techniques to obtain time-difference-of-arrival (TDOA), and frequency-difference-of-arrival (FDOA) estimates for the emitter direct-path signal and the delayed and Doppler shifted replicas reflected by some number of dominant scatterers. The TDOA and FDOA estimates were combined with emitter and scatterer azimuth estimates to form a minimum-variance unbiased estimator of emitter location parameters. The covariance of the emitter parameter estimates was determined and localization results using Mountaintop field data are presented. Comparisons of both the inhomogeneous and the homogeneous estimation approaches are presented along with localization results from several Mountaintop jamming scenarios. Localization performance versus emitter power was studied by artificially increasing the noise floor of the Mountaintop data sets. Similarly, performance versus signal bandwidth was studied by using lowpass filters to reduce the bandwidth of the Mountaintop data. Pulsed and self-correlated emitter waveforms were also considered.

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