Ranging of a Moving Ship Using a Single Acoustic Receiver in Shallow Water

Passive acoustics is a versatile tool for maritime situational awareness, enabling applications such as source detection and localization, marine mammal tracking, and geoacoustic inversion. This study focuses on estimating the range between an acoustic receiver and a transiting ship in an acoustically range-independent shallow water environment. Here, acoustic propagation can be modeled by a set of normal modes that are determined by the shallow water waveguide and seabed characteristics. These modes are dispersive, with phase and group velocities varying with frequency, and their interference produces striation patterns that depend on range and frequency in single-hydrophone spectrograms. These patterns can often be characterized by the waveguide invariant, a single parameter describing the waveguide's properties. This paper presents a statistical waveguide invariant-based range estimation approach using a single hydrophone, leveraging broadband and tonal sounds from a transiting ship. Using data from the Seabed Characterization Experiment 2017 (SBCEX17), a large commercial ship's radiated acoustic signature within a 7 Hz bandwidth was processed to estimate its range up to 45 km with errors below three percent.