Tidal Effect in Small-Scale Sound Propagation Experiment

Self Cite

In this paper, an underwater acoustic (UWA) communication scheme for mobile platforms is proposed. The proposed scheme is based on the orthogonal signal division multiplexing (OSDM) scheme, which offers highly reliable UWA communication. However, OSDM is not suitable for mobile platforms as it is — it requires a receiver array and a large calculation cost for equalization. To establish a reliable link with small communication platforms, we design OSDM that can perform reliable communication without the need for an array and can reduce receiver complexity using the time-diversity technique (TD), and evaluate its performance in experiments. The experimental results suggest that OSDM-TD can simultaneously achieve power-efficient communications and receiver complexity reduction, and can realize small-scale communication platforms. In detail, OSDM-TD achieved almost the same communication quality as conventional OSDM, in exchange for an effective data rate. Moreover, the power efficiency of OSDM-TD was almost the same as that of conventional OSDM with two receiver array elements, although the calculation cost of OSDM-TD was far below that of conventional OSDM. As a result, it was found that OSDM-TD is suitable for UWA communication for mobile nodes whose capacity and computational resources are severely limited.

Section: Results Of Test-tank Experiments and Discussionmentioning

confidence: 99%

Underwater acoustic communication using orthogonal signal division multiplexing scheme with time diversity

Ebihara

Ogasawara

Mizutani

2016

Self Cite

“…When ultrasound reaches the seabed, scattering and absorption occur, whose profile depends on the roughness and type of material. Hence, the measurement of ultrasound propagation is useful for predicting underwater profiles, such as temperatures, currents, tidal effects, [449][450][451][452][453][454][455][456][457][458][459][460][461][462][463][464][465][466][467][468] and underwater structures. [469][470][471][472] Such measurement has been conducted over large regions of the ocean (e.g., on the order of 100 km).…”

Section: Biomedical Ultrasoundmentioning

confidence: 99%

“…Propagation [449][450][451][452][453][454][455][456][457][458][459][460][461][462][463][464][465][466][467][468] Noise [473][474][475][476][477][478][479] Seafloor=sediment [469][470][471][472] Transducers [529][530][531][532] Positioning=ranging 501,[523][524][525][526][527][528] Acoustic imaging Imaging systems [483][484][485][486] Lenses [487][488][489][490][491]...…”

Section: Underwater Measurementmentioning

confidence: 99%

Introduction of measurement techniques in ultrasonic electronics: Basic principles and recent trends

Mizutani¹,

Wakatsuki²,

Ebihara³

2016

Measurementthe act of measuring physical properties that we performhas the potential to contribute to the successful advancement of sciences and society. To open doors in physics and other sciences, various measurement methods and related applications have been developed, and ultrasound has remained a useful probe, power source, and interesting measurement object for the past two centuries. In this paper, we first summarize the basic principles of ultrasound from the viewpoint of measurement techniques for readers who just have started studying or are interested in the field of ultrasonic electronics. Moreover, we also introduce recent studiesultrasonic properties of materials, measurement techniques, piezoelectric devices, nonlinear acoustics, biomedical ultrasound, and ocean acousticsand their trends related to measurement techniques in ultrasonic electronics to provide some ideas for related applications.

“…Because of the interference of the surface and bottom reflections, the shape of the correlated signal varied according to the tidal level and water temperature. 25) In this paper, the authors show the results of a trial case of coastal environment monitoring, including temperature and current speed along the sound travel path with a set of reciprocal sound propagation data. This is a very fundamental trial case but it will suggest the optimal configuration of acoustical sensors for shallow-area monitoring.…”

Section: Introductionmentioning

confidence: 99%

Acoustical environment measurement at a very shallow port: Trial case in Hashirimizu Port

Ogasawara¹,

Mori²

2016

Self Cite

Recently, the needs for coastal environment measurement has been increasing for many purposes, such as fishing, weather forecasting, ocean noise measurement for power plants, and coastal security. Acoustical measurement is one of the solutions because it can cover a wide area with few sensors, and it is possible to monitor long term or in real time. In this study, a small-scale reciprocal sound travel experiment was carried out in Hashirimizu Port for coastal environment measurement, such as current speed and water temperature. Since the distance between the surface and the transducer becomes short according to the tidal effect, the direct signal is canceled by the surface-reflected signal under a specific condition. However, even under such a condition, mean water temperature could be estimated from the reciprocal travel time using bottom-reflected signals. The current along the travel path was a reasonable value. It is possible to obtain a special current speed with another reciprocal path, which is in a direction perpendicular to the current travel path.