Simulation of Passive and Multistatic Active Sonar Contacts

Fields of distributed passive and multistatic active sonar sensors provide a surveillance capability against quiet submarine threats in ASW scenarios. A significant challenge of heterogeneous, multi-sensor systems is the successful fusion of information from the various sensors to enable robust target detection, classification, localization, and tracking. Sensor fusion and tracking algorithms must be developed to accomplish this, yet suitable, real data-sets are often limited or unavailable. Simulated contact-level sonar data are essential to the process of design, development and testing of such algorithms. This paper describes a sonar modeling and contact simulation tool referred to as the Passive-Active Contact Simulator (PACsim). It models heterogeneous fields of mixed sonar sensors. The passive and active sonar equations are solved for any number of true and false targets along their trajectories as they move through the field. The user defines the scenario, the acoustic environment, and parameters for the expected measurement errors and signal fluctuations. The tool produces the following simulated active sonar contact measurement: signal excess, bearing, time of echo arrival, and Doppler. For passive sonar, simulated contact measurements are generated for: signal excess, frequency-line detection segments, and bearing, from which target states at the closestpoint-of-approach (CPA) can be hypothesized. Appropriate measurement errors are also simulated and incorporated into each active or passive detection. The outputs are suitable for input into multi-sensor fusion and tracking algorithms. This paper describes the PACsim modeling methodology, shows examples of simulated sonar contacts for an ASW scenario, and discusses system performance metrics.