Feasibility of global-scale synthetic aperture communications

A recent paper [Higley et al., J. Acoust. Soc. Am. 118, 2365-2372 (2005)] investigated synthetic aperture communications in shallow water exploiting the relative motion between a source and a receiver. This letter presents a feasibility study of synthetic aperture communications at global distances using the 57 Hz acoustic data from the Heard Island Feasibility Test conducted in January 1991 [Baggeroer and Munk, Phys. Today 45, 22-30 (1992)]. Specifically, a reception at Ascension Island, about 9200 km from the source ship moving at about 3 kt near Heard Island, is analyzed by treating the 255-digit m-sequence tomography signal as a binary-phase shift-keying communication signal with an information rate of 11.4 bitss. The performance using a single receiver combining three consecutive receptions spaced 5.2 min ( approximately 470 m) apart indicates that synthetic aperture acoustic communications is feasible at global distances.