Comparison of underwater communication performances in two shallow-water sites with different sediment types located off the coast of Korea

Abstract

Shallow water waveguide characterized by multipath channel produces a significant delay spreading of transmitted signals, which is referred to as inter symbol interference (ISI). Since the ISI results in distortion of communication signals, many studies to reduce the effect of ISI have been conducted. For successful underwater communication, it is important to understand the correlation between the spatial and temporal properties of ISI and communication performance. Underwater acoustic communication experiments were conducted in two different seafloor environments with relatively fine-grained and coarse sediments. The experimental geometries were the same water depths of both sites were about 40 m andsource depths were about 32 m. Communication signals were measured by a four-channel receiving array, covering waters 5 to 35 m in depth. Sound speed profiles were measured by CTD casts and the surficial sediment samples were taken by a grab sampler. The received communication signals were demodulated using the time reversal, phase lock loop and decision feedback equalizer techniques. In this talk, the communication performances at two different sites are presented and compared with the channel impulse responses at two sites.