As an acoustic communications medium, water is characterized by frequency dependent attenuation, short range, very low bandwidth, scattering, and multi-path. It is generally difficult to acoustically communicate even terse messages underwater much less images. For the naval mine countermeasures mission, there is value in transmitting images, if possible. The contribution of this paper is a meth...

This paper presents a summary of results from several experiments using phase coherent underwater acoustic communications in shallow waters with weak to strong internal waves. Measurements of temporal coherence time of the underwater acoustic channels are presented and related to the equalizer performance.

In this paper, we proposed a novel receiver algorithm for coherent underwater acoustic communications. The proposed receiver is composed of three parts: (1) Doppler tracking and correction, (2) Time reversal channel estimation and combining, and (3) Joint iterative equalization and decoding (JIED). To reduce computational complexity and optimize the equalization algorithm, Time reversal (TR) ch...

This paper explores architecture, research challenges and potential applications for underwater sensor networks. Sensor networks have the promise of revolutionizing many areas of science, industry, and government with their ability to bring computation and sensing into the physical world. This report summarizes our research directions in underwater sensor networks. We highlight potential applic...

New forms of navigation aids for underwater vehicles are enabled through the use of acoustic communications. Both the content and form of the message may be used to estimate range, bearing, range rate, geo-location, and time. Accurate range estimates are available via a conventional 2-way method, but the transmitted signal also supports high precision bearing estimation and highly accurate rang...

In this paper, we develop a tractable mathematical model and an emulation framework for communicating information through water using acoustic signals. Water is considered one of the most complex media to due its vastness variety characteristics, which depend on scenario, type body (lakes, rivers, tanks, sea, etc.), geographical location being considered. Our proposed involves concept damped ha...