  This letter deals with the problem of clutter edge detection and localization
in training data. To this end, the problem is formulated as a binary hypothesis
test assuming that the ranks of the clutter covariance matrix are known, and
adaptive architectures are designed based on the generalized likelihood ratio
test to decide whether the training data within a sliding window contains a
homogeneous set or two heterogeneous subsets. In the design stage, we utilize
four different covariance matrix structures (i.e., Hermitian, persymmetric,
symmetric, and centrosymmetric) to exploit the a priori information. Then, for
the case of unknown ranks, the architectures are extended by devising a
preliminary estimation stage resorting to the model order selection rules.
Numerical examples based on both synthetic and real data highlight that the
proposed solutions possess superior detection and localization performance with
respect to the competitors that do not use any a priori information.
