Acoustic quieting and high background noise have decreased the detection range of passive acoustics against threat submarines. Non-acoustic sensors can fill the gap and increase range, while maintaining covertness. ISL and its subcontractor USSI, will leverage extensive experience gained in designing, building and testing a two-sensor air-droppable A-size sonobuoy, into a successful multi-sensor sonobuoy (MSS) design that will improve air-ASW for tactical usage, intelligence, classification and tracking. In Phase 1, we will design a damped sonobuoy string that will minimize motion noise in acoustics, electric and magnetic field sensors. We will conduct tradeoff studies for extending the electric field aperture vs. reducing its SWAP, retaining directional capability and containing cost. We will integrate a scalar magnetic sensor into the MSS and minimize its noise via careful location and calibration/reduction algorithms. Adaptive algorithms that make use of colored clutter will be borrowed from radar processing to enhance the non-acoustic SNR, and we will create data fusion algorithms that effectively combine the three data types and optimize each sensors strengths. The increased detection ranges will benefit tactical scenarios, and the multiply sensed data types will improve classification, which will be a great benefit to the Navy in its ASW missions.
Benefit: The most immediate benefit from the multi-sensor sonobuoy (MSS) technology is that the AAI (Airborne ASW Intelligence) program will have a device which can detect and record signatures of submarines in not one but several different physical characteristics, including its sound level, its corrosion currents, and its ferromagnetic characteristics. The AAI program will also have a sonobuoy with extended detection range, by using extended aperture electric field sensors, combined with data fusion, in order to detect submarines at farther ranges than could be done with passive acoustics only. Further, by recording three different fields instead of one, the AAI program will have a more effective tool for classifying submarine threat targets. Once the technology is utilized and vetted by AAI, it will become available to be used by the Fleet for tactical operations in submarine detection, tracking and localization. The improved detection ranges will allow for more efficient operations, will better protect US naval assets, and will lower false alarms by verifying the target before deploying a weapon. Potential non-defense applications for the MSS technology are in marine oil exploration using controlled source electromagnetics (CSEM), and in mapping ocean currents for research and academic institutions.
Keywords: Air ASW, Air ASW, adaptive noise reduction, data fusion, magnetic and electric field sensors, colored clutter, intelligence data collection, Threat submarines, multi-sensor sonobuoys
