The present a new technique for localizing multiple narrowband sources by a
passive sensor array based on dimensionality-reducing time-varying preproc
essing of the sensor outputs. The technique allows a significant reduction
in the number of receivers required for the implementation with only two re
ceivers sufficing in the extreme case. The estimation method we use is base
d on approximating the corresponding maximum likelihood estimator by a comp
utationally simpler generalized least squares (GLS) estimator that is prove
d to be both consistent and asymptotically efficient. Simulation results co
nfirming the theoretical results are included.