Shallow-water channel sounding for high speed acoustic communication

Underwater acoustic communication at low and medium frequencies has been available for several years. The low frequency allows for long-range communication, but also limits the available bandwidth. To increase the available bandwidth and enhance the data-rate, higher frequency bands have to be exploited. This work focuses on channel sounding for acoustic digital communication in high-frequency (250kHz) horizontal shallow-water channels, targeting moving platforms. Results from two test locations in the Oslofjord, exemplifying two very different channels, both which a robust modern communication system must handle is presented. These are compared to soundings made for a medium frequency (25.6kHz) channel. The result includes channel impulse responses, scattering functions and power delay profiles. Doppler power spectrums are analyzed and quantized for different ranges, relevant for the design of a future high-speed underwater communication system.