  We present novel solutions to the problem of direct localization of multiple
narrow-band and arbitrarily correlated sources by partly calibrated arrays,
i.e., arrays composed of fully calibrated sub-arrays yet lacking inter-array
calibration. The solutions presented vary in their performance and
computational complexity. We present first a relaxed maximum likelihood
solution whose concentrated likelihood involves only the unknown locations of
the sources and requires an eigen-decomposition of the array covariance matrix
at every potential location. To reduce the computational load, we introduce an
approximation which eliminates the need for such an eigen-decomposition at
every potential location. To further reduce the computational load, novel
MUSIC-like and MVDR-like solutions are presented which are computationally much
simpler than the existing solutions. The performance of these solutions is
evaluated and compared via simulations.
