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  • 1
    Online Resource
    Online Resource
    Acoustical Society of America (ASA) ; 2000
    In:  The Journal of the Acoustical Society of America Vol. 107, No. 2 ( 2000-02-01), p. 739-746
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 107, No. 2 ( 2000-02-01), p. 739-746
    Abstract: An approach for avoiding the problem of environmental uncertainty is tested using data from the TESPEX experiments. Acoustic data basing is an alternative to the difficult task of characterizing the environment by performing direct measurements and solving inverse problems. A source is towed throughout the region of interest to obtain a database of the acoustic field on an array of receivers. With this approach, there is no need to determine environmental parameters or solve the wave equation. Replica fields from an acoustic database are used to perform environmental source tracking [J. Acoust. Soc. Am. 94, 3335–3341 (1993)], which exploits environmental complexity and source motion.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2000
    detail.hit.zdb_id: 1461063-2
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  • 2
    Online Resource
    Online Resource
    Acoustical Society of America (ASA) ; 1994
    In:  The Journal of the Acoustical Society of America Vol. 96, No. 5_Supplement ( 1994-11-01), p. 3294-3295
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 96, No. 5_Supplement ( 1994-11-01), p. 3294-3295
    Abstract: Preliminary results will be presented for the second TTCP Environmental Signal Processing Exercise (TESPEX 2), which was conducted in June 1994 in shallow waters north of Darwin, Australia. There were two objectives: (1) demonstrate improvements in environmental source tracking [Collins et al., J. Acoust. Soc. Am. 94, 3335 (1993)] (a single-frequency, single-hydrophone synthetic-aperture tracking technique) by relying on a second, horizontally separated hydrophone, and (2) determine the horizontal resolution the environment provides to a vertical array through matched-field processing [Perkins and Kuperman, J. Acoust. Soc. Am. 87, 1553 (1990)] . The approach was to first characterize the region by towing a high-SNR source throughout the region and measure the replica fields using two vertical line arrays separated by several kilometers (one with 32 elements, the other 4 elements), and then to use this data to form the replicas needed to track the source as it traversed the region alone a variety of tracks. The measured replicas are supplemented by modeled replicas; the environment used in the modeling is determined by inverting the measured data. We present preliminary processing results relevant to both objectives, including environmental inversions and tracking with measured and modeled replicas. a)Present address: Scripps Institution of Oceanography, La Jolla, CA 92093.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 1994
    detail.hit.zdb_id: 1461063-2
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  • 3
    Online Resource
    Online Resource
    Acoustical Society of America (ASA) ; 1993
    In:  The Journal of the Acoustical Society of America Vol. 94, No. 3_Supplement ( 1993-09-01), p. 1844-1844
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 94, No. 3_Supplement ( 1993-09-01), p. 1844-1844
    Abstract: Preliminary results will be presented for TESPEX (Test of Environmental Signal Processing Experiment), which was performed in May 1993 off the east coast of New Zealand in a region of three-dimensional bathymetry variations. This complex environment was exploited to minimize ambiguity in environmental source tracking with a single receiver [Collins et al., J. Acoust. Soc. Am. 90, 2366 (1991)]. To overcome limited knowledge of environmental parameters, the acoustic field was measured by a fixed array of receivers while a ship towing a source swept over a sector. The receivers were linked to a recently developed satellite telemetry buoy that transmitted time series to a centralized computer facility for real time analysis. Expensive ship time was traded off for cheap computation time by interpolating the acoustic field using a WKB representation that permits a sparse sampling in azimuth. The main computational task for the data basing involves solving a nonlinear optimization problem for the WKB amplitude and phase functions, which vary slowly with range and azimuth. TESPEX data have been used to perform environmental source tracking using replicas constructed from the acoustic field data base. a)Present address: Scripps Institution of Oceanography, La Jolla, CA 92093.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 1993
    detail.hit.zdb_id: 1461063-2
    Location Call Number Limitation Availability
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  • 4
    Online Resource
    Online Resource
    Acoustical Society of America (ASA) ; 2018
    In:  The Journal of the Acoustical Society of America Vol. 144, No. 3_Supplement ( 2018-09-01), p. 1768-1768
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 144, No. 3_Supplement ( 2018-09-01), p. 1768-1768
    Abstract: Distinguishing objects of interest on the seafloor from clutter remains a key problem facing the automatic target recognition (ATR) community. Because scattering at high frequencies relates more to the geometry of the scatterer, traditional ATR on high frequency imaging sonars is known to suffer in areas of high clutter. Recently, there has been interest in low frequency (1–50 kHz) wideband imaging sonars, because the complex combination of external (geometric) and internal (elastic) scattering that occurs in this frequency range is thought to improve classification in areas of high clutter. This work investigates the classification problem of distinguishing unexploded ordnance (UXO) from clutter using image-based Convolutional Neural Networks on the TREX’13 dataset. This dataset consists of experimental and modelled acoustic backscatter for objects interrogated acoustically at 3–30 kHz across a range of aspects. The model data are used exclusively for training, and the experimental data are used exclusively for testing purposes. The generated feature-set is a combination of acoustic colour and perceptual features, which are derived from modelling how humans perceive timbre. Further in an effort to address the differing amplitude modulations between sets of model and experimental data and improve classified performance, several moving window normalizations will be investigated.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2018
    detail.hit.zdb_id: 1461063-2
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