Acoustic telemetry - An overview

Baggeroer, A. B.

doi:10.1109/joe.1984.1145629

Cited by 144 publications

(59 citation statements)

References 21 publications

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“…The ocean imposes severe limitations on acoustic communication, including low available bandwidth and long propagation delays [1,5,108], which lead to frequent data corruption and high latencies. encode its data using spreading or block codes with varying levels of redundancy.…”

Section: Small Multi-hop Relay Linksmentioning

confidence: 99%

Progressively communicating rich telemetry from autonomous underwater vehicles via relays

Murphy¹

2012

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As analysis of imagery and environmental data plays a greater role in mission construction and execution, there is an increasing need for autonomous marine vehicles to transmit this data to the surface. Without access to the data acquired by a vehicle, surface operators cannot fully understand the state of the mission. Communicating imagery and high-resolution sensor readings to surface observers remains a significant challenge -as a result, current telemetry from free-roaming autonomous marine vehicles remains limited to 'heartbeat' status messages, with minimal scientific data available until after recovery. Increasing the challenge, longdistance communication may require relaying data across multiple acoustic hops between vehicles, yet fixed infrastructure is not always appropriate or possible.In this thesis I present an analysis of the unique considerations facing telemetry systems for free-roaming Autonomous Underwater Vehicles (AUVs) used in exploration. These considerations include high-cost vehicle nodes with persistent storage and significant computation capabilities, combined with human surface operators monitoring each node. I then propose mechanisms for interactive, progressive communication of data across multiple acoustic hops. These mechanisms include wavelet-based embedded coding methods, and a novel image compression scheme based on texture classification and synthesis. The specific characteristics of underwater communication channels, including high latency, intermittent communication, the lack of instantaneous end-to-end connectivity, and a broadcast medium, inform these proposals. Human feedback is incorporated by allowing operators to identify segments of data that warrant higher quality refinement, ensuring efficient use of limited throughput. I then analyze the performance of these mechanisms relative to current practices.Finally, I present CAPTURE, a telemetry architecture that builds on this analysis. CAPTURE draws on advances in compression and delay tolerant networking to enable progressive transmission of scientific data, including imagery, across mul-3 tiple acoustic hops. In concert with a physical layer, CAPTURE provides an endto-end networking solution for communicating science data from autonomous marine vehicles. Automatically selected imagery, sonar, and time-series sensor data are progressively transmitted across multiple hops to surface operators. Human operators can request arbitrarily high-quality refinement of any resource, up to an error-free reconstruction. The components of this system are then demonstrated through three field trials in diverse environments on SeaBED, OceanServer and Bluefin AUVs, each in different software architectures.

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Section: Small Multi-hop Relay Linksmentioning

confidence: 99%

Progressively communicating rich telemetry from autonomous underwater vehicles via relays

Murphy¹

2012

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“…A complicated communication channel with multi-path and temporal variability is frequently characterized by two parameters: the time-spread τ and the Doppler-spread B or their reciprocals: the fading bandwidth W and the coherence time T [1]. Uncompensated time-spread limits the coherent processing bandwidth W to a value 1/ τ.…”

Section: Acoustic Communicationsmentioning

confidence: 99%

Navy Applications of High-Frequency Acoustics

Cox¹

2004

AIP Conference Proceedings

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Abstract. Although the emphasis in underwater acoustics for the last few decades has been in low-frequency acoustics, motivated by long range detection of submarines, there has been a continuing use of high-frequency acoustics in traditional specialized applications such as bottom mapping, mine hunting, torpedo homing and under ice navigation. The attractive characteristics of high-frequency sonar, high spatial resolution, wide bandwidth, small size and relatively low cost must be balanced against the severe range limitation imposed by attenuation that increases approximately as frequency-squared. Many commercial applications of acoustics are ideally served by high-frequency active systems. The small size and low cost, coupled with the revolution in small powerful signal processing hardware has led to the consideration of more sophisticated systems. Driven by commercial applications, there are currently available several commercial-off-the-shelf products including acoustic modems for underwater communication, multi-beam fathometers, side scan sonars for bottom mapping, and even synthetic aperture side scan sonar. Much of the work in high frequency sonar today continues to be focused on specialized applications in which the application is emphasized over the underlying acoustics. Today's vision for the Navy of the future involves Autonomous Undersea Vehicles (AUVs) and off-board ASW sensors. High-frequency acoustics will play a central role in the fulfillment of this vision as a means of communication and as a sensor. The acoustic communication problems for moving AUVs and deep sensors are discussed. Explicit relationships are derived between the communication theoretic description of channel parameters in terms of time and Doppler spreads and ocean acoustic parameters, group velocities, phase velocities and horizontal wavenumbers. Finally the application of synthetic aperture sonar to the mine hunting problems is described.

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“…The analog systems that were developed were essentially sophisticated loudspeakers that had no capabilty for mitigating the distortion introduced by the underwater acoustic channeL. Paralleling the developments applied to severely fading radio frequency atmospheric channels, the next generation of systems employed frequency-shift-keyed (FSK) modulation of digitally encoded data (2,18). The use of digital techniques enabled the use of explicit error-correction algorithms to increase reliabilty of transmissions and permitted some level of compensation for the distortion introduced by the channeL.…”

Section: Prior Workmentioning

confidence: 99%

A channel subspace post-filtering approach to adaptive equalization

Nadakuditi¹

2002

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Acoustic telemetry - An overview

Cited by 144 publications

References 21 publications

Progressively communicating rich telemetry from autonomous underwater vehicles via relays

Progressively communicating rich telemetry from autonomous underwater vehicles via relays

Navy Applications of High-Frequency Acoustics

A channel subspace post-filtering approach to adaptive equalization

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