The ambient noise energy motion in the near-surface layer in ocean wave-guide

Zoltowski

1997

IEEE J. Oceanic Eng.

130

Abstract-Aperture extension is achieved in this novel ESPRITbased two-dimensional angle estimation scheme using a uniform rectangular array of vector hydrophones spaced much farther apart than a half-wavelength. A vector hydrophone comprises two or three spatially co-located, orthogonally oriented identical velocity hydrophones (each of which measures one Cartesian component of the underwater acoustical particle velocity vector-field) plus an optional pressure hydrophone. Each incident source's directions-of-arrival are determined from the source's acoustical particle velocity components, which are extracted by decoupling the data covariance matrix's signal-subspace eigenvectors using the lower dimensional eigenvectors obtainable by ESPRIT. These direction-cosine estimates are unambiguous but have high variance; they are used as coarse references to disambiguate the cyclic phase ambiguities in ESPRIT's eigenvalues when the intervector-hydrophone spacing exceeds a halfwavelength. In one simulation scenario, the estimation standard deviation decreases with increasing intervector-hydrophone spacing up to 12 wavelengths, effecting a 97% reduction in the estimation standard deviation relative to the half-wavelength case. This proposed scheme and the attendant vector-hydrophone array outperform a uniform half-wavelength spaced pressurehydrophone array with the same aperture and slightly greater number of component hydrophones by an order of magnitude in estimation standard deviation. Other simulations demonstrate how this proposed method improves underwater acoustic communications link performance. The virtual array interpolation technique would allow this proposed algorithm to be used with irregular array geometries.

Section: B Summary Of Relevant Literaturementioning

confidence: 99%

Extended-aperture underwater acoustic multisource azimuth/elevation direction-finding using uniformly but sparsely spaced vector hydrophones

Zoltowski

1997

IEEE J. Oceanic Eng.

130

“…This diverse orientation is assumed to be known and time-invariant but needs to be neither orthogonal nor identical at the array's various grid points. This orientational flexibility contrasts with the more rigid orthogonal 1053-587X/99$10.00 © 1999 IEEE orientation requirements in direction finding algorithms [8], [11], [16], [18], [20]- [26], [30], [31], [34] that require the array's constituent velocity hydrophones to be grouped into "vector hydrophone" triads, each of which consisting of three orthogonally oriented and co-located velocity hydrophones. Instead, this present scheme allows any number of (one, two, or more 2 ) co-located and diversely oriented velocity hydrophones and/or a pressure hydrophone at each array grid point, and the number and orientations of velocity hydrophones may vary from grid position to grid position in some known manner.…”

Section: B Arbitrarily Oriented Velocity Hydrophonesmentioning

confidence: 98%

“…Instead, this present scheme allows any number of (one, two, or more 2 ) co-located and diversely oriented velocity hydrophones and/or a pressure hydrophone at each array grid point, and the number and orientations of velocity hydrophones may vary from grid position to grid position in some known manner. The "vector hydrophones" of D'Spain et al [8], [11], Shchurov et al [16], Nehorai and Paldi [18], Hawkes and Nehorai [20], [21], [26], [33], Wong and Zoltowski [22], [23], [25], [27], [30], [31], Hochwald and Nehorai [24], and Wong [34] thus represent a special case of the more general array configuration accommodated by the present algorithm.…”

Section: B Arbitrarily Oriented Velocity Hydrophonesmentioning

confidence: 99%

Root-MUSIC-based azimuth-elevation angle-of-arrival estimation with uniformly spaced but arbitrarily oriented velocity hydrophones

IEEE Trans. Signal Process.

Zoltowski

1999

144

This novel underwater acoustic azimuth-elevation source localization scheme realizes the eigenstructure-based polynomial rooting procedure for an L-shaped uniformly spaced array of diversely oriented and possibly spatially co-located velocity hydrophones and an optional pressure hydrophone. A velocity hydrophone measures a Cartesian component of the acoustic particle velocity vector of the incident wavefield. At each uniformly spaced array grid, one or more co-located and diversely oriented velocity hydrophones and/or a pressure hydrophone are placed, with the number and orientations of velocity hydrophones possibly varying from grid position to grid position in some known prearranged manner. The diverse orientation of the velocity hydrophones, however, disrupts the Vandermonde array manifold structure in each of the two uniform-linear-array legs of the L-shaped array. Nonetheless, ingenuous mathematical manipulations proposed in this paper restore the disrupted Vandermonde algebraic structure, thereby permitting once again the use of polynomial rooting to estimate the directions of arrival. A proposed pairing procedure matches each source's x x x-axis direction cosine estimate with its corresponding y y y-axis direction cosine estimate. Simulation results verify the efficacy of the proposed scheme.

“…The that maximizes the MVDR beamformer output's SINR equals (to within a multiplicative factor) [8] (13) Unlike , depends on the collected data, through . This maximizes the SINR to (14) where (15)…”

Section: B Mvdr Beamforming With a Vector Hydrophonementioning

confidence: 99%

Beam patterns of an underwater acoustic vector hydrophone located away from any reflecting boundary

Chu²

2002

IEEE J. Oceanic Eng.

A vector hydrophone is composed of two or three spatially collocated but orthogonally oriented velocity hydrophones plus an optional collocated pressure hydrophone. A vector hydrophone may form azimuth-elevation beams that are invariant with respect to the sources' frequencies, bandwidths and radial location (in near field as opposed to the far field). This paper characterizes the spatial matched filter beam patterns (a.k.a. fixed or conventional or maximum signal-to-noise ratio beam patterns) and the minimum variance distortionless response (MVDR) beam patterns associated with a single underwater acoustic vector hydrophone distant from any reflecting boundary.