Network Computing for Distributed Underwater Acoustic Sensors

Abstract : Our main investigations are about underwater communications using acoustic waves. Electromagnetic and optical waves do not work well underwater due to the nature of the medium, especially in the case of seawater. Acoustic waves are used for underwater communication due to the relatively low attenuation (i.e., signal reduction) of sound in water, specially in thermally stable, deep water settings. With the current acoustic modem technology, underwater communications concentrate in the 5 to 80 kilo Hertz range. For instance, EvoLogics modems may operate, according to the model, from 7 to 78 kiloHertz. All Teledyne Benthos modems operate in three bands: 9-14, 16-21 or 22-27 kilo Hertz. More particularly, we focus on software emulation of underwater acoustic wave propagation and software modulation and demodulation of underwater acoustic digital data signals in presence of mobility, with integration with other protocol layers. For underwater operation, mobility is relevant because there are underwater vehicles and environmental conditions cause displacements of sensors.