Contact Localization and Motion Analysis in the Ocean Environment: A Perspective

Abstract

UNCLASSIFIED 15«. DECLASSIFICATION / DOWNGRADING SCHEDULE ie. DISTRIBUTION STATEMENT lof IhU ReponI 17. DISTRIBUTION STATEMENT lof the abttract enumd in Block 20, if differttU from Reponi Approved for public release; distribution unlimited. 19. SUPPLEMENTARY NOTES 19. KEY WORDS fContmua on rewne iide if neemsMry and idmntify by block number/ Contact Location and Motion Analysis 20. ABSTRACT {Continue on mvene aide if neceaaary and identify by block numbert This document provides an overview of Contact Localization and Motion Analysis (CLMA) in the ocean environment. Such well-studied cases as passive bearings-only contact motion analysis, multipath ranging, and localization/tracking via arrays are used to illustrate the concept. The performance of current CLMA systems is shown to depend on the type and characteristics of the basic measurements developed by their time delay estimators, the acoustic channels linking contact and observer, and the DD, 'r"147 3 20. Abstract (Cont'd) type and description of relative motion between contact and observer. General classes of CLMA schemes are presented. Complexity is shown to depend on the linearity/nonlinearity of their solution equations, the degree to which a contact is observable at each sample time, and the relative motion or degree of stationarity between contact and observer. Contributions to total system gain, biasing issues, and candidate solutions are discussed. Comprehensive references are provided.

Time-varying spatial spectrum estimation with a maneuverable towed array

“…This is the type of disambiguation referred to in Gerstoft et al 2 and is the basis of TMA. 3 It is also made evident, when looking at Fig. 6(a), of the time when the vehicle made its 90 turns (at the 30 and 300 second marks).…”

“…This method is analogous to performing target motion analysis (TMA) by using the contact's estimated stabilized bearing as the observable parameter. 3 However, TMA methods for exploiting changing array heading are typically performed post-detection and they are not designed to mitigate backlobe interference which can mask low signal-to-noise ratio (SNR) targets of interest. Furthermore, these methods neglect to address the potential for improving bearing resolution near endfire that comes as the array deforms during a maneuver.…”

Time Delay Estimation in Room Acoustic Environments: An Overview

“…where α nm is the attenuation factor from the unknown source to the nth sensor via the mth path, t is the propagation time from the source to sensor 0 via direct path, τ nm is the relative delay between sensor n and sensor 0 for path m with τ 01 = 0, M is the number of different paths, and w n [k] is stationary Gaussian noise and assumed to be uncorrelated with both the source signal and the noise signals observed at other sensors. This model is widely adopted in the oceanic propagation environments as illustrated in Figure 1, where each sensor receives not only the direct path signal, but reflections from both the sea surface and the sea bottom as well [33,34]. The primary interest of the TDE problem for this model is to measure τ n1 , n = 1, .…”