SBIR-STTR Award

This research is directed toward the Navy's current ASW problem, 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 algorithms will be developed that are effective for this nonstationary problem, rejecting multiple loud moving interferers while simultaneously improving signal matching for a quiet moving target. In addition, we will develop absolute bounds on the performance that can be achieved by any algorithm. The approach involves analysis and simulation of structured scenarios of increasing complexity to isolate specific effects and provide insight and understanding. This work builds on ORINCON's extensive experience with adaptive beamforming and leading role in recent efforts that address the nonstationary problem. It takes advantage of an existing simulation capability to permit rapid progress with limited resources. Algorithms developed in Phase I will be demonstrated on sea test data recording using a real-time implementation in Phase II. A subsequent transition to the Navy via the Advanced Process Build (APB) program is planned. The new algorithms will also be applicable to nonstationary problems in radar and wireless communication. This research will provide new adaptive algorithms that are effective in nonstationary environments. Simulation scenarios will be developed along with performance bounds that can be used as benchmarks for other algorithms. Results will be applicable to nonstationary problems in bistatic radar and wireless communications, as well as for passive sonar.

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 adaptive algorithms 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 approach involved 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 per interferer 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 Passive Sonar (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 new algorithms will also be applicable to nonstationary interference problems in radar and wireless communication.

Keywords:
Adaptive Beamforming, Nonstationary, Performance Bounds, Motion Compensation, Broadband, Simulation, Passive Sonar