Sonobuoy Improvements for Multistatic Active Sonar - Phase II

Transmission loss is a crucial input to the sonar equation for predicting the ability of an active sonar system to detect and track a target. The proposed technical effort centers on developing physics-based models to interpret and predict transmission loss (TL) variability caused by hydrodynamic tilt associated with the SSQ-125 projector array and a hardware solution to measure and mitigate tilt effects.   The concept under development proposes the addition of motion and temperature sensors to the AN/SSQ-125 source sonobuoy. These sensors will provide a direct measure of array tilt, facilitate some insight into buoy drift, and provide much greater spatial and temporal estimates of the sound velocity field over the operation area (OPAREA). Monte Carlo simulations are used to assess the extent to which these measurements and interventions can improve the accuracy and reliability of detection processing, with an objective of a 25% improvement. The result is a performance simulation, hardware solution, and integrated algorithms that consume modeled and in situ oceanographic information, estimate the likelihood of occurrence of various physical phenomena that lead to SSQ-125 array tilt, mitigate the effects, and produce a 25% or greater improvement in MAC detection capability.   Metron and APL-UW developed a basic, wind-only hydrodynamic performance model of SSQ-125 array motion. Metron also created a software simulation capability that they have named Multistatic Active Coherent Environmental Tactical Estimator (MAChETE). MAChETE incorporates the hydrodynamic model into a physics-based simulation to demonstrate the viability of the proposed hardware solution and supporting algorithms.  MAChETE will support mission planning for a MAC system that can opportunistically exploit SSQ-125 array tilt and SSQ-125 buoys that can adjust projector ping elevation.   In exploring this effort, Metron has also developed additional software approaches and solutions that increase MAC detection capability over traditional planning and employment methods that can be employed with or without Metron's proposed hardware implementation. The preliminary findings in our MAChETE simulations indicate that Metron's algorithms can achieve up to a 24% improvement in detection capability mid-mission and an 8-10% improvement in overall detection capability via mission planning software alone.  MAChETE has also demonstrated that the Adaptive Intelligent Transmission (AIT) hardware delay logic can produce an 8% improvement in MAC system performance in some multi-path scenarios.  Additionally, Metron's hardware and simulation approach indicates a more accurate CPD calculation than the current NAVAIR model is possible and likely required in conditions where ocean currents and hydrodynamic effects are prevalent. This capability will allow mission planners and operators to better gauge MAC system performance and realize an appreciable increase in detection capability.