Underwater Acoustic Network

Funder

Organizational Unit

Publications

Publication . Caiti, A.; Felisberto, P.; Husoy, T.; Jesus, S. M.; Karasalo, I.; Massimelli, R.; Reinen, Tor Arne; Silva, A.

Acoustic networks are for underwater what wifi is for terrestrial networks. The ocean is a nearly perfect media for acoustic waves in which regards long range propagation but poses a number of challenges in terms of available bandwidth, Doppler spread and channel fading. These limitations originate in the physical properties of the ocean, namely its anisotropy and boundary interaction which are particularly relevant in coastal waters where acoustic propagation becomes predominantly de- pendent on seafloor and sea surface properties. The acoustic communication channel is therefore multipath dominated and time and Doppler spread variable. The problem is aggravated when involving moving receivers as for instance when attempting to establish communication with or between moving autonomous underwater vehicles. The EU-funded project UAN - Underwater Acoustic Network aims at conceiving, developing and testing at sea an innovative and operational concept for integrating in a unique communication system submerged, surface and aerial sensors with the objective of protecting off-shore and coastline critical infrastructures. UAN went through various phases, including the development of hardware and software specific components, its testing independently and then in an integrated fashion, both in the lab and at sea. This paper reports on the project concept and vision as well as on the progress of its various development phases and the results obtained herein. At the time of writing, a final project sea trial is being planned and will take place two weeks before the conference so, although here we will concentrate on the progress obtained so far, the presentation at the conference may include additional results depending on the outcome of the sea trial.

2011Conference object

Open Access

Underwater Acoustic simulations with a time variable acoustic propagation model

Publication . Silva, A.; Rodríguez, O. C.; Zabel, F.; Huillery, J.; Jesus, S. M.

The Time Variable Acoustic Propagation Model (TV-APM) was developed to simulate underwater acoustic propagation in time-variable environments. Such environment variability induces a strong Doppler channel spread, which is an important factor to test and evaluate the performance of equalization algorithms. In current simulations, Doppler spread is usually included a posteriori in a stationary Acoustic Propagation Model (APM), and is designed for specific environmental parameters such as source-receiver range variability or surface motion. However, environmental variations affect Doppler spread in a complex manner, and an accurate TV-APM simulation for time varying channels, being performed at the same sampling rate as the transmitted signal, would require a large number of runs at high frequencies. A strategy in the current implementation of the TV-APM was developed to reduce the number of runs, while preserving the variable-channel Doppler spread. Simulations were done to draw a performance map for a given equalizer in a given environment and the results revealed that the TV-APM is a useful prediction tool of communication equalizers performance.

2010Conference object

Open Access

The TV-APM interface: a web service for collaborative modelling

Publication . Rodríguez, Orlando; Silva, António J.; Zabel, Friedrich; Jesus, S. M.

Current development of Internet access, together with available zero-cost Open Source applications (like, for instance, PHP, Python, etc.) can be integrated in order to minimize the constrains induced by the geographical separation of international centers, which collaborate in a given project. The advantage of such approach lies in the sharing of common analysis methods, without particular constrains to specific directions of analysis. The discussion presented in this paper describes the Time Variable Acoustic Propagation Model (TV-APM) web interface, which was created as a collaborative service of acoustic modeling for the participants of the PHITOM and UAN projects. This paper describes the general architecture of the interface, its current shortcomings and advantages, and presents a set of modeling results for short range acoustic propagation, which accounts for source–array and sea surface motion.

2010Conference object

Open Access

Acoustic emission and reception unit (AERU)

Publication . Saleiro, Mário

This document describes a data acquisition/data generation system, which consists of a portable waterproof case with all the integrated electronics. It features a high power battery, a precision DAQ board, a state-of-the-art GPS board and a complete computer system. Acquired data can be stored in the internal hard drive and download into another storage device or directly to another computer using the Ethernet connection. It is intended to be used with the Portable Acoustic Source Unit (PASU) for acoustic data transmission and with single or multiple hydrophones for acoustic data acquisition. The system also features a easy and ready-to-use graphical user interface that allows the user to use the system using the integrated LCD touch screen. A user manual is included as an installation, setup and maintenance guide for the system and its practical applications. The developed hardware and software is described in detail. Detailed schematics and designs can be found in the final section of this document, which can be used to further develop the system, perform maintenance, purchase spare parts or perform any type of modifications. A support equipment named OCU (Outdoor Communications Unit) is also described in this document. The OCU consists of a waterproof case that can be used to supply the AERU or the PASU and to add wireless connectivity to the AERU it can also provide a handy solution to charge the batteries of the AOB2 buoys in a wet deck environment. ACKNOWLEDGMENT:

2010Report

Open Access

UAN - Engineering Test: P2P Communications

Publication . Vilaipornsawai, U.; Silva, A.

This report describes the P2P communication setup and results from the engineering test conducted at Pianosa island, Italy during September 7-25, 2010.

2010Report

Open Access