Long-range acoustic communication in deep water using a towed array.

In September 2010 a long-range acoustic communication (LRAC10) experiment was carried out in deep water off the Southern California Coast. The experiment involved two mobile components: (1) a source towed slowly at a speed of 2-3 knots at ∼75-m depth and (2) a horizontal line array towed at 3.5 knots at a depth of ∼200 m. Phase-coherent communication sequences were transmitted in the frequency band of 200-300 Hz at various ranges (100-700 km). Initial analysis of the LRAC10 data demonstrates that an information rate of 50 bits/s can be achieved over ∼550-km range using quadrature-phase shift-keying (QPSK) modulation and error-correction coding combined with beamforming.