Alternative approach to passive sonar
An alternative approach to spatial processing for passive sonar is proposed and discussed. It isconsidered to offer better performance than conventional and high-resolution beamforming. Inparticular, the approach makes it possible to construct a broadband beamformer which outperformshigh-resolution techniques: it provides better resolution, is sidelobe-free, and allows the detection of rather weak sound sources. The approach is based on the analysis of the statistical properties of the different sound sources of interest and allows controlled extraction of the information of interest. It isalso possible with this approach to construct multibeam LOFAR plots which display more than onebeam simultaneously without loss of further information. Since the proposed approach abandons theestimation of the cross-spectral matrix, it has no greater requirement vis-a-vis the stationarity of the signals than the conventional approach has.
Zimmer, Walter M. X.