Publications by authors named "K Sabra"

Navigation of autonomous underwater vehicles requires accurate positioning information, notably during docking and homing operations. This letter demonstrates the feasibility of using a constellation of passive Acoustic Identification (AID) to enable accurate localization of a docking station by an of autonomous underwater vehicle. Scaled experiments are conducted using a pair of AID tags composed of multiple concentric hemispherical acrylic layers, each of which generates a unique backscattered acoustic signature when ensonified by a broadband ultrasonic transducer.

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This Letter investigates the influence of source motion on the performance of the ray-based blind deconvolution algorithm (RBD). RBD is used to estimate channel impulse responses and source signals from opportunistic sources such as shipping vessels but was derived under a stationary source assumption. A theoretical correction for Doppler from a simplified moving source model is used to quantify the biases in estimated arrival angles and travel times from RBD.

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Ocean acoustic tomography (OAT) methods aim at estimating variations of sound speed profiles (SSP) based on acoustic measurements between multiple source-receiver pairs (e.g., eigenray travel times).

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Autonomous underwater vehicle (AUV) operations are limited by currently achievable underwater localization and navigation solutions; hence, the development of low-cost and passive (i.e., operable without an active power supply) acoustic underwater markers (or tags) can provide accurate localization information to AUVs improving their situational awareness, especially when operating in small scales or confined missions.

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This work investigates how vertical resolution affects the prediction of ocean sound speed through a suite of regional simulations covering the DeSoto Canyon in the Gulf of Mexico. Simulations have identical horizontal resolution of 0.5 km, partially resolving submesoscale dynamics, and vertical resolution from 30 to 200 terrain-following layers.

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