Experimental demonstration of phase-coherent underwater acoustic communications using a compact array

High-rate phase coherent acoustic communication systems generally require large arrays to obtain spatial diversity. Large arrays may not be suitable for small underwater platforms such as underwater unmanned vehicles (UUVs). In this paper, acoustic communication utilizing a compact array with closely spaced elements was demonstrated using the data collected during the August 2010 lake experiment. In addition, a bidirectional multichannel decision feedback equalizer (DFE) was developed to enhance the performance of communication systems. The recorded data from three communication ranges of 25 m, 920 m, and 1 300 m were processed to verify the system performance. The results showed an improvement in output symbol signal-to-noise ratio (OSNR) of approximately 3.4 dB, and 4.9 dB for bidirectional two-channel DFE and four-channel DFE over a single-channel DFE, respectively.