RELIABLE ACOUSTIC LINK USING NON-COHERENT TURBO-CODED FSK

Abstract

The contents of this thesis explore the challenge of implementing a reliable, wireless, communication link in the highly variable environments of shallow underwater channels. The physical variability of the underwater acoustic channel is described with respect to signal attenuation, reflections, refraction, and temporal variations due to motion. These characteristics are implemented in a software model to represent a realistic ocean environment for in-lab algorithm design. The process for designing simple, non-coherent communication algorithms to achieve robust performances are discussed. Robustness is achieved through the implementation of turbo code. The results of the communication algorithms demonstrate successful communication for distances up to 10 km validated through sea trial, but yielded low-data rates (32 bps to 1.67 bps). Zero errors were received during the sea trial for the turbo coded algorithms. To confidently quantify the reliability of these algorithms, more symbols must be transmitted.