VLF source localization with a freely drifting acoustic sensor array

The source localization and tracking capability of the freely drifting Swallow float volumetric array is demonstrated with the matched-field processing (MFP) technique using the 14-Hz CW data collected during a 1989 float experiment conducted in the northeast Pacific. Initial MFP of the experimental data revealed difficulties in estimating the source depth and range while the source azimuth estimate was quite successful. The main cause of the MFP performance degradation was incomplete knowledge of the environment. An environment adaptation technique using a global optimization algorithm was developed to alleviate the environmental mismatch problem, allowing the ocean-acoustic environment to be adapted to the acoustic data in a matched-field sense. Using the adapted environment, the 14-Hz source was successfully localized and tracked in azimuth and range within a region of interest using the MFP technique at a later time interval. Two types of environmental parameters were considered, i.e., sound speed and modal wave number. While both approaches yield similar results, the modal wave number adaptation implementation is more computationally efficient. >

[1]  John M. Ozard,et al.  Matched field processing in shallow water for range, depth, and bearing determination: Results of experiment and simulation , 1989 .

[2]  A. Pierce.  Extension of the Method of Normal Modes to Sound Propagation in an Almost‐Stratified Medium , 1965 .

[3]  Gerald L. D’Spain,et al.  Freely Drifting Swallow Float Array: May 1987 Trip Report , 1988 .

[4]  F. Middleton,et al.  An underwater acoustic sound velocity data model , 1980 .

[5]  C. D. Gelatt,et al.  Optimization by Simulated Annealing , 1983, Science.

[6]  R. B. Evans,et al.  A coupled mode solution for acoustic propagation in a waveguide with stepwise depth variations of a penetrable bottom , 1983 .

[7]  W. Kuperman,et al.  Matched field processing: source localization in correlated noise as an optimum parameter estimation problem , 1988 .

[8]  H. Bucker.  Use of calculated sound fields and matched‐field detection to locate sound sources in shallow water , 1976 .

[9]  Christopher Feuillade,et al.  Environmental mismatch in shallow‐water matched‐field processing: Geoacoustic parameter variability , 1989 .

[10]  E. R. Kanasewich,et al.  Time sequence analysis in geophysics , 1973 .

[11]  Donald Geman,et al.  Stochastic Relaxation, Gibbs Distributions, and the Bayesian Restoration of Images , 1984, IEEE Transactions on Pattern Analysis and Machine Intelligence.

[12]  Robert J. Urick,et al.  Principles of underwater sound , 1975 .

[13]  D.H. Johnson,et al.  The application of spectral estimation methods to bearing estimation problems , 1982, Proceedings of the IEEE.

[14]  H. Szu.  Fast simulated annealing , 1987 .

[15]  Donald F. Gingras,et al.  Methods for predicting the sensitivity of matched‐field processors to mismatch , 1989 .

[16]  W A Kuperman,et al.  Focalization: environmental focusing and source localization. , 1991, The Journal of the Acoustical Society of America.

[17]  John S. Perkins,et al.  An approximation to the three‐dimensional parabolic‐equation method for acoustic propagation , 1982 .

[18]  J. Capon.  High-resolution frequency-wavenumber spectrum analysis , 1969 .

[19]  George C. Chen,et al.  VLF Source Localization with a Freely Drifting Sensor Array , 1992 .

[20]  Christopher Feuillade,et al.  Shallow‐water matched‐field localization off Panama City, Florida , 1990 .

[21]  John M. Ozard,et al.  Matched‐field processing in a range‐dependent environment , 1990 .

[22]  William S. Hodgkiss,et al.  The simultaneous measurement of infrasonic acoustic particle velocity and acoustic pressure in the ocean by freely drifting Swallow floats , 1991 .

[23]  F. Harris.  On the use of windows for harmonic analysis with the discrete Fourier transform , 1978, Proceedings of the IEEE.

[24]  F. B. Jensen,et al.  Wave theory modelling: a convenient approach to CW and pulse propagation modelling in low-frequency acoustics , 1988 .

[25]  C. Allan Boyles.  Acoustic Waveguides: Applications to Oceanic Science , 1984 .

[27]  Rachel M. Hamson,et al.  Environmental and system effects on source localization in shallow water by the matched‐field processing of a vertical array , 1989 .

[28]  B. Carlson.  Covariance matrix estimation errors and diagonal loading in adaptive arrays , 1988 .

[29]  W. Kuperman,et al.  Environmentally tolerant beamforming for high‐resolution matched field processing: Deterministic mismatch , 1990 .

[30]  William S. Hodgkiss,et al.  Matched‐field processing of 200‐Hz continuous wave (cw) signals , 1991 .

[31]  Russ E. Davis,et al.  Predictability of Sea Surface Temperature and Sea Level Pressure Anomalies over the North Pacific Ocean , 1976 .

[32]  A. Tolstoy,et al.  Sensitivity of matched field processing to sound‐speed profile mismatch for vertical arrays in a deep water Pacific environment , 1988 .

[33]  R. L. Culver,et al.  Comparison of Kalman and least squares filters for locating autonomous very low frequency acoustic sensors , 1988 .

[34]  R. O. Schmidt,et al.  Multiple emitter location and signal Parameter estimation , 1986 .

[35]  Donald Roe Ross,et al.  Mechanics of underwater noise , 1976 .

[36]  J. Krolik.  Matched‐field minimum variance beamforming in a random ocean channel , 1992 .

[37]  Michael B. Porter,et al.  Simulations of Matched-Field Processing in a Deep-Water Pacific Environment , 1987 .

[38]  N. Metropolis,et al.  Equation of State Calculations by Fast Computing Machines , 1953, Resonance.

[39]  L. B. Palmer,et al.  The Range-Dependent Active System Performance Prediction Model (RASP) , 1992 .

[40]  Richard G. Fizell.  Application of high‐resolution processing to range and depth estimation using ambiguity function methods , 1984 .

[41]  William S. Hodgkiss,et al.  Matched field processing of deep-water ambient noise , 1990 .

[42]  K. Mackenzie.  Nine‐term equation for sound speed in the oceans , 1981 .

[43]  J. Lynch,et al.  Surface wave, internal wave, and source motion effects on matched field processing in a shallow water waveguide , 1989 .

[44]  A. Tolstoy,et al.  ACOUSTIC TOMOGRAPHY VIA MATCHED FIELD PROCESSING , 1991 .

[45]  W. Hodgkiss,et al.  Energetics of the deep ocean’s infrasonic sound field , 1991 .