Adaptive Beamforming for Multistatic Active Sonar

Amron and its subcontractor BBN propose to show the feasibility of a broadband time-domain adaptive beamformer (ABF) to suppress uncorrelated narrowband sources and multipaths from correlated impulsive sources. The work is motivated by political developments which have emphasized warfare in littoral areas, where a key problem facing active sonar is scattering from topographic features. Active sonar receivers must use adaptive beamforming to suppress this interference. Unlike other AM, Amron's ABF suppresses both uncorrelated noise and broadband correlated interference from explosive sources without signal suppression. It improves echo to noise ratios without degrading echoes and simultaneously suppress false alarms from multipathed and other off-azimuth sources. The ABF was developed by and is available to Amron now at the Naval Research Laboratory. The proposed tasks are data collection, adapting the ABF to the multistatic active case, optimizing the ABF on a training data set, evaluating it on another data set, writing a final report, and optionally, developing a beam based ABF. In Phase II, we will implement and test a real-time optimized beam based ABF on dedicated Navy hardware. The ABF may find other applications in nuclear test monitoring and geophysical exploration