Using broadband, ship-radiated noise in shallow water environments to perform physics-based localization

Unintentionally radiated noise from surface ships is often seen as a problem for many areas of underwater acoustics, as it tends to raise the ambient noise floor and upsets various forms of marine life. This paper will discuss techniques for using this broadband noise to aid in localization of these sources. The paper will cover methods born of normal modes theory, including waveguide invariant approaches, which utilize striation patterns seen in time-frequency representations of received signals. These striations are the result of modal interference in the shallow water waveguide and their character depends on acoustical propagation parameters. Techniques for range dependent and independent analysis using horizontal line arrays will be discussed, as well as their effectiveness in several simulated and real scenarios.