R. Rajagopal et al., SIGNAL SUBSPACE BEAMFORMING IN THE PRESENCE OF COHERENT INTERFERENCESAND UNKNOWN CORRELATED NOISE FIELDS, Signal processing, 63(1), 1997, pp. 17-33
In a realistic passive sonar scenario, the desired signal will be rece
ived in the presence of coherent interferences and spatially correlate
d noise fields. In this paper beamforming algorithms are developed for
this scenario. Two types of signal subspace beamformers based on diff
erent optimality criteria, are developed. They are (i) optimum-interfe
rence notch beamformer, and (ii) optimum-interference plus noise rejec
tor, The beamformers are first developed for the narrowband data model
and then extended to the wideband case. Projection matrices onto the
signal subspace are computed by using Q-R decomposition instead of the
computationally intensive eigen-decomposition. Expressions for the ou
tput-signal to interference-plus-noise ratio are derived and used as a
measure to evaluate the performance of the beamformers. Simulation re
sults are also given to support the theory. (C) 1997 Elsevier Science
B.V.