Passive ranging in underwater acoustic environment subject to spatial coherence loss

• Published in: The Journal of the Acoustical Society of America Vol. 135; no. 4_Supplement; p. 2392
• Main Authors: Ge, Hongya, Kirsteins, Ivars P.
• Format: Journal Article
• Language: English
• Published: 01.04.2014
• ISSN: 0001-4966; 1520-8524
• DOI: 10.1121/1.4877913

In this work, a two-stage multi-rank solution for passive ranging is presented for acoustic sensing systems using multi-module towed hydrophone arrays operating in underwater environments subject to spatial coherence loss. The first stage of processing consists of adaptive beam-forming on the individual modular array level to improve the signal-to-noise ratio and at the same time to adaptively reduce the data dimensionality. The second stage of multi-rank filtering exploits the possible spatial coherence existing across the spatially distributed modular arrays to further improve the accuracy of passive ranging. The proposed solution reduces to either the well-known non-coherent solution under no spatial coherence, or the fully coherent solution under perfect spatial coherence. For large distributed arrays, the asymptotic approximation of the proposed solution has a simple beam-space interpretation. We conclude with a discussion of the estimator when the spatial coherence is unknown and its implications for the passive ranging system performance.