Modems for underwater acoustic communications (acomms) have become nearly as much of a commodity technology as underwater releases or transponder systems. Modems today are at a similar stage as were mobile phones perhaps 15 years ago -- basic ...

A Marine Test Field (MTF) in the Sizihwan coastal area near Kaohsiung, Taiwan has been developed since the summer of 2006. It represents an effort on a long-term investment for the study of underwater acoustics in a very-shallow-water and/or harbor ...

Advancement in acoustic modem technology has gradually brought underwater network into real life. Despite high cost of sea testing, there have been initial realization effort, such as Sea-Web, Aqua-Net, SUNSET, etc. As the main developers of Aqua-Net, ...

We describe the newest design and development of the Sapienza University Networking framework for underwater Simulation Emulation and real-life Testing (SUNSET), a powerful toolkit for implementation and testing of novel protocol solutions for ...

The single-carrier block transmission (SCBT) method has been considered for bandwidth efficiency in underwater acoustic (UWA) communication recently. The cyclic prefix (CP) in the SCBT method should be longer than the multipath spread, but a long CP ...

The performance of underwater acoustic communications is linked to the capability of a communication system to cope with a large variety of underwater acoustic channel dynamics, which are dependent on the environmental and seasonal acoustic propagation ...

With increasing concern for the oceanic environmental problems caused by artificial pollution or natural disasters, there is a rapidly increasing requirement for dense and low cost monitoring of oceanographic parameters such as CO₂, nutrition, O₂, etc. ...

With more and more marine missions such as oceanic environment monitoring, oceanographic investigation, and underwater engineering construction, there is an increasing interest for the R&D of the frequency hopped UWA modem due to its robustness to inter-...

The sensitivity of an underwater acoustic sensor is the most important characteristic to measure in a calibration experiment. In this paper, a theoretical sensitivity formulation for the second-order quantities of underwater acoustic dyadic sensors ...

We have designed and developed a new acoustic system for monitoring rip currents. The system consists of one dual-frequency acoustic fishfinder, two broad-band acoustic transducers, a set of sound reflectors and a data acquisition network. The ...

Due to the long preamble problem in underwater acoustic networks (UANs), traditional sender initiated handshaking MAC protocols are facing high overhead of control messages. To mitigate this problem, we propose a traffic estimation based receiver ...

Multipath arrivals in many underwater acoustic channels are often cross-correlated and as a result, the path cross-correlation matrix shows a smaller rank than the number of multipath delay taps. Channel tracking error, measured in terms of the signal ...

Underwater communication network simulators play a very important role in underwater network research due to the cost of field experiments. Several simulators have been proposed for tackling this problem in past years, such as Aqua, UAN, DESERT and ...

Recent underwater sensor network research has focused on developing physical, medium access control, and network layer protocols to enable high data rate, energy-efficient and reliable acoustic communications. However, it is now essential to design and ...

Due to the differences of scattering areas and directions, the sound scattering influences imposed by a cylindrical baffle on a vector sensor are different when the sensor is installed at different locations. Using the BEM method, the directivities of ...

This work shows some results of synchronization and channel estimation in simple underwater acoustic communication systems using On-off keying and binary phase-shift keying.

In this paper, we discuss the performance of different network protocols for RACUN, a European Defence Agency project with the objective of demonstrating ad hoc underwater networks for multiple purposes related to security. The RACUN network is designed ...

Orthogonal frequency division multiplexing (OFDM) techniques are attractive for underwater acoustic (UWA) communications due to their robustness against large multipath spread. However, OFDM systems in UWA channels suffer from intercarrier interference (...

There is increasing interest in ocean transect sampling missions to do environmental (pollution, coral reef, seismic, ocean current, etc.) monitoring, oceanography parameter gathering (CO2, temperature, current, etc.), oceanographic investigation, and ...

The main problems for a frogman in the shallow water are bubbles in the breath mask, environmental noise and low channel capacity. This paper studies the speech signal of a contact conduction transmitter that can avoid interference. A mixed excitation ...