Acoustics of the deepwater part of the Arctic Ocean and of Russia’s Arctic shelf

Litvak, A. G.

doi:10.1134/s1019331615030144

Cited by 6 publications

(1 citation statement)

References 8 publications

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“…Short range (less than ten kilometer) navigation efforts, on the other hand, can accurately rely on a nominal sound speed value and achieve minimal navigation error [9], [10], [16]. But this assumption breaks down in complex propagation environments such as the multipath incurred by the Beaufort Lens [17].…”

Section: Introductionmentioning

confidence: 99%

An Embedded Tactical Decision Aid Framework for Environmentally Adaptive Autonomous Underwater Vehicle Communication and Navigation

Bhatt

Howard

Schmidt

2022

IEEE J. Oceanic Eng.

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Section: Introductionmentioning

confidence: 99%

An Embedded Tactical Decision Aid Framework for Environmentally Adaptive Autonomous Underwater Vehicle Communication and Navigation

Bhatt

Howard

Schmidt

2022

IEEE J. Oceanic Eng.

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Transmission loss for the Beaufort Lens and the critica frequency for mode propagation during ICEX-18

Baggeroer

Collis

2022

The Journal of the Acoustical Society of America

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Complexities of acoustic propagation in ducts have long been known, e.g., shallow water environments and deep waters off Gibraltar. The “Beaufort Lens” (Lens) is a duct north of Alaska with nominal depths between 60 and 200 m and is reachable by oceanographic instruments and underwater unmanned vehicles and submarines. Propagation within the ducts is governed by waveguide physics. The frequencies must be high enough to support the modes within them such that there is a “critical frequency” (CF) where modes start to “detach” from surface loss mechanisms. Therefore, transmission losses (TLs) can abruptly decrease once a mode “fits” within a duct. This paper describes an experimental part of Ice Exercise 2018 supported by the U.S. Navy's Arctic Submarine Laboratory. The signals were transmitted from Camp Sargo north of Prudhoe Bay to the submarines SSN Hartford, SSN Connecticut, and HMS Trenchant. The data indicate low TLs near [Formula: see text] and an abrupt 10 dB decrease in TLs 244–280 Hz, both suggesting CFs. Modeling suggests CFs for modes 1 near [Formula: see text] and a higher CF when modes 3–6 “cascade” into the Lens starting near [Formula: see text]. There are also abrupt increases in TLs at other frequencies, which are explained by nulls in the product of the mode functions.

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Under-ice acoustic navigation using real-time model-aided range estimation

Bhatt

Víquez

Schmidt

2022

The Journal of the Acoustical Society of America

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The long baseline (LBL) underwater navigation paradigm relies on the conversion of travel times into pseudoranges to trilaterate position. For real-time autonomous underwater vehicle (AUV) operations, this conversion assumes an isovelocity sound speed. For re-navigation, computationally and/or labor-intensive acoustic modeling may be employed to reduce uncertainty. This work demonstrates a real-time ray-based prediction of the effective sound speed along a path from source to receiver. This method was implemented for an AUV-LBL system in the Beaufort Sea in an ice-covered and a double-ducted propagation environment. Given the lack of Global Navigation Satellite Systems (GNSS) data throughout the vehicle's mission, the pseudorange performance is first evaluated on acoustic transmissions between GNSS-linked beacons. The mean real-time absolute range error between beacons is roughly 11 m at distances up to 3 km. A consistent overestimation in the real-time method provides insights for improved eigenray filtering by the number of bounces. An operationally equivalent pipeline is used to reposition the LBL beacons and re-navigate the AUV, using modeled, historical, and locally observed sound speed profiles. The best re-navigation error is 1.84 ± 2.19 m root mean square. The improved performance suggests that this approach extends the single meter accuracy of the deployed GNSS units into the water column.

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Acoustics of the deepwater part of the Arctic Ocean and of Russia’s Arctic shelf

Cited by 6 publications

References 8 publications

An Embedded Tactical Decision Aid Framework for Environmentally Adaptive Autonomous Underwater Vehicle Communication and Navigation

An Embedded Tactical Decision Aid Framework for Environmentally Adaptive Autonomous Underwater Vehicle Communication and Navigation

Transmission loss for the Beaufort Lens and the critica frequency for mode propagation during ICEX-18

Under-ice acoustic navigation using real-time model-aided range estimation

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