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© Woods Hole Oceanographic Institution © University of Washington |
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| Last updated May 2010 |
Utilization of the pressure gradient along a sparse vertical line array to determine vertical arrival angle from partial reflections from a layered seabed
David R. Dall'Osto and Peter H Dahl
| Pressure signals measured by two four-element vertical line arrays, centered at depths 25 and 50 m, during an experiment off the New Jersey coast in summer 2006 (SW06, depth 80 m) are combined to determine the pressure gradient of the received signal. The pressure gradient is converted to an estimate of vertical particle velocity, which combined with an estimate of the mean-squared pressure, and the plane wave impedance establishes a non-dimensional quantity. This quantity is inverted to determine arrive angle estimates from separate multipath arrivals of the transmitted signals (1 kHz). A geoacoustic model for the seabed [Choi et al., J. Acoust. Soc. Am. 124 EL128-El134 (2008)] includes a prominent sub-bottom reflector at depth 20 m below water sediment interface, which produces an energetic arrival time separated from the bottom arrival. The arrival angle estimates are examined as the source moves out in range from 50 to 300 m, and results are compared to arrival angle estimates derived from PE simulations. The performance of this gradient-based estimator is evaluated for various types of noise sources and levels, utilizing both real and PE-simulated time series. [Work supported by ONR] |
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© Woods Hole Oceanographic Institution © University of Washington |
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| Last updated May 2010 |