Narrowband Passive Sonar Tracking

Passive sonar sensors are the main source of information for a submerged submarine. Modern sonar systems like ISUS 90 offer a number of acoustic antennas and combined signal processing for broadband and narrowband detection and analysis of target noise. While broadband detection is often used to obtain an overview of the targets surrounding the own ship, narrowband processing enables the detection of target characteristic frequency lines, often produced by vibrations of the propulsion systems on surface ships which are radiated into the water. Narrowband processing is therefore essential for target analysis and classification. Frequency line information can be used to separate targets closely spaced in bearing, e.g. during target crossing situations, which can not be resolved by the broadband passive sonar information alone. In addition, target bearing histories containing frequency line information may be used in the Target Motion Analysis module to infer about target course, speed and range without an own-boat manoeuvre. Therefore, narrowband passive sonar tracking provides an additional valuable source of information and enhances the capabilities of a submarine sonar and combat system. In this paper we present multi-target tracking results for narrowband passive sonar based on a multi-hypothesis tracking approach. The tracking system is designed to automatically track all detectable frequency lines of multiple targets, while at the same time minimizing the number of false tracks.