Target motion analysis using angular measurements and underwater sound pressure levels

This paper addresses the problem of target motion analysis using data acquired by sonars operating in passive mode. Most theoretical and applied studies rely solely on bearing information, and various filtering algorithms, especially particle filter methods, have demonstrated strong performance in this context. To improve upon existing approaches, bearing information is combined with received underwater sound pressure levels. This method requires no additional sensors compared to bearings-only trackings, as hydrophones—already used for beamforming—can also measure sound pressure levels. Additionally, underwater transmission losses can be estimated through simulations based on commonly available environmental data. The effectiveness of the proposed method is demonstrated using simulated data, showing improved performance—especially in scenarios without observer maneuvers. To increase realism, the impact of replacing bearing measurements with conical angle measurements is also investigated. These measurements account for both elevation and bearing angles, thereby providing a fairly comprehensive characterization of bottom-bounce paths commonly encountered under real-world conditions. This enables exploration of scenarios with different immersion levels for both target and observer. The results further emphasize the benefits of incorporating sound pressure levels measurements into the tracking process.