배열 불변량을 이용한 선박 위치 추적

Abstract

The array invariant (AI) proposed for robust source-range estimation with minimal knowledge of the environment in shallow water is based on the dispersion characteristics in ideal waveguides. This approach involves plane wave beamforming, utilizing coherent multiple arrivals separated in beam angle and travel time, referred to as “beam-time migration”. To resolve multipath arrivals in beam-time domain, AI requires either an impulsive source or Green’s function typically estimated from a known probe signal. For unknown source waveforms, it is possible to estimate the Green’s function using a ray-based blind deconvolution (RBD) which also utilizes simple conventional beamforming. Recently, the cascade of RBDand AI has been demonstrated for a towed source at 50-m depth broadcasting communication waveforms [J. Acoust. Soc. Am. 141, 3270-3273 (2017)]. Rather than the towed source, this study focuses on the feasibility of tracking a ship radiating random and anisotropic noise. The combination of RBD and AI is demonstrated to localize a ship of opportunity (200-900 Hz) along a track at ranges of 1.8-3.4 km and a 16-element, 56-m long vertical array in approximately 100-m deep shallow water.