Incoherent coding techniques and performance characterization for multibeam sonar systems

Abstract

A sonar imaging technique which uses specially coded waveforms to project different sound signals in different directions was previously proposed. In this context, the problem of creating a set of frequency-hopped code words that have mutually small correlation properties has arisen. The authors report on their progress in designing these frequency-hopped signals for multibeam sonar imaging. The special case is considered in which medium spreading effects destroy the phase coherence of the imaging system. A design strategy is discussed which has allowed the design of a set of frequency-hopped code words that exhibit good performance bounds with respect to incoherent processing. The design strategy is a systematic constructions technique which can be used with any size Galois field GF(p) to generate p-1 codes of length p. Various theorems are presented and examples of the performance of the technique are illustrated for time-bandwidth products of interest in terms of sonar. >