Normal-mode matching localization in shallow water: Environmental and system effects

Jesus, S. M.

doi:10.1121/1.401631

Cited by 23 publications

(8 citation statements)

References 6 publications

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“…The localization performance is strongly dependent of the matching accuracy between real and simulated acoustic fields. Study of the influence of environmental and system effects on the localization performance is presented in [11,22]. The dilation used to build masks in the f -k plane makes the method more robust against these errors.…”

Section: Depth Estimation Source Depth Estimation Is Basedmentioning

confidence: 99%

Underwater Broadband Source Localization Based on Modal Filtering and Features Extraction

Lopatka

Touzé

Nicolas

et al. 2010

EURASIP J. Adv. Signal Process.

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Passive source localization is a crucial issue in underwater acoustics. In this paper, we focus on shallow water environment (0 to 400 m) and broadband Ultra-Low Frequency acoustic sources (1 to 100 Hz). In this configuration and at a long range, the acoustic propagation can be described by normal mode theory. The propagating signal breaks up into a series of depth-dependent modes. These modes carry information about the source position. Mode excitation factors and mode phases analysis allow, respectively, localization in depth and distance. We propose two different approaches to achieve the localization: multidimensional approach (using a horizontal array of hydrophones) based on frequency-wavenumber transform (F-K method) and monodimensional approach (using a single hydrophone) based on adapted spectral representation (FT a method). For both approaches, we propose first complete tools for modal filtering, and then depth and distance estimators. We show that adding mode sign and source spectrum informations improves considerably the localization performance in depth. The reference acoustic field needed for depth localization is simulated with the new realistic propagation modelMoctesuma. The feasibility of both approaches, F-K and FT a , are validated on data simulated in shallow water for different configurations. The performance of localization, in depth and distance, is very satisfactory.

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Section: Depth Estimation Source Depth Estimation Is Basedmentioning

confidence: 99%

Underwater Broadband Source Localization Based on Modal Filtering and Features Extraction

Lopatka

Touzé

Nicolas

et al. 2010

EURASIP J. Adv. Signal Process.

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“…Hence, a large body of work has been devoted to studying the sensitivity of MFP localization to mismatch errors since the mid-1980's. These have included examinations of mismatch in sound-speed profile, 1,5-13 water depth, 9,[13][14][15] bottom properties, [5][6]9,10,13,15,16 array parameters ͑array tilt or placement, or element locations͒, 8,11,15,16 and errors introduced by sea surface roughness [17][18][19] and internal waves. 18,20,21 A high sensitivity to mismatch, however, does not render the source localization problem hopeless, for this sensitivity enables one to invert for mismatched parameters by performing searches over these parameters until an optimal response is obtained.…”

Section: Introductionmentioning

confidence: 99%

Matched-field replica model optimization and bottom property inversion in shallow water

Baxley

Booth

Hodgkiss

2000

The Journal of the Acoustical Society of America

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Matched-field replica models based on an inaccurate knowledge of geoacoustic parameters such as bottom attenuation, shear, and interfacial sound-speed discontinuities, can predict an incorrect number of propagating modes for a shallow-water channel. The resulting degradation in the matched-field ambiguity surface can be substantially reduced by obtaining optimal replica models via modal-sum-limit optimization or bottom-property inversion. The use of these techniques for multi-tone (70, 95, 145, and 195 Hz) source-tow data recorded near San Diego during the first Shallow-Water Evaluation Cell Experiment (SWellEX-1) significantly increased matched-field correlation levels and improved source localization relative to results obtained with a previous nonoptimized model. The predicted number of propagating modes was also reduced substantially. The inversion for bottom properties (attenuation, interfacial sound-speed discontinuities, no shear) provided sediment attenuation estimates which agree well with Hamilton's models and were an order-of-magnitude greater than that used in the nonoptimized model, which accounts for the reduction in the number of modes. A simulated modal decomposition using the inverted optimal replica model verifies the number of modes predicted by the modal-sum-limit optimization.

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“…Mismatch also occurs when there is uncertainty in the measurement geometry, such as receiver array position. 4,5 In classical MFP the environment and measurement geometry are assumed known and the inversion search space includes only parameters relating to the source location.…”

Section: Introductionmentioning

confidence: 99%

Source localization in a time-varying ocean waveguide

Soares

Siderius

Jesus

2002

The Journal of the Acoustical Society of America

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One of the most stringent impairments in matched-field processing is the impact of missing or erroneous environmental information on the final source location estimate. This problem is known in the literature as model mismatch and is strongly frequency dependent. Another unavoidable factor that contributes to model mismatch is the natural time and spatial variability of the ocean waveguide. As a consequence, most of the experimental results obtained to date focus on short source-receiver ranges (usually <5 km), stationary sources, reduced time windows and frequencies generally below 600 Hz. This paper shows that MFP source localization can be made robust to time-space environmental mismatch if the parameters responsible for the mismatch are clearly identified, properly modeled and (time-)adaptively estimated by a focalization procedure prior to MFP source localization. The data acquired during the ADVENT'99 sea trial at 2, 5, and 10 km source-receiver ranges and in two frequency bands, below and above 600 Hz, provided an excellent opportunity to test the proposed techniques. The results indicate that an adequate parametrization of the waveguide is effective up to 10 km range in both frequency bands achieving a precise localization during the whole recording of the 5 km track, and most of the 10 km track. It is shown that the increasing MFP dependence on erroneous environmental information in the higher frequency and at longer ranges can only be accounted for by including a time dependent modeling of the water column sound speed profile.

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Normal-mode matching localization in shallow water: Environmental and system effects

Cited by 23 publications

References 6 publications

Underwater Broadband Source Localization Based on Modal Filtering and Features Extraction

Underwater Broadband Source Localization Based on Modal Filtering and Features Extraction

Matched-field replica model optimization and bottom property inversion in shallow water

Source localization in a time-varying ocean waveguide

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