Processing Techniques for Dynamic Sources

The Navy's most important current ASW problem is detecting quiet diesel-electric and air-independent propulsion (AIP) submarines in littoral regions where today's systems are ineffective due to interference from many loud moving surface ships. New adaptivealgorithms were developed by ORINCON during Phase I that are effective on simulated data for this nonstationary problem - rejecting multiple loud moving interferers while simultaneously improving signal matching for a quiet moving target. Our approachinvolved analysis and simulation of structured scenarios of increasing complexity to isolate specific effects and provide insight and understanding. Performance gains were quantified. The most surprising result was that two to three snapshots perinterferer are adequate to calculate adaptive weights and that post beamformer tracking is just as good as a further increase in the number of snapshots. During Phase II, the algorithms developed in Phase I will be demonstrated and tuned on Robust PassiveSonar (RPS) sea test data using a new real-time or near-real-time implementation. A subsequent Phase III transition of a real-time version of our algorithms to the Navy via the Advanced Process Build (APB) program for at-sea testing is planned. The newalgorithms will also be applicable to nonstationary interference problems in radar and wireless communication.