Acoustic communication in deep water exploiting multiple beams with a horizontal array

A recent experiment showed that coherent long-range acoustic communication (200-300 Hz) is feasible in deep water over a ∼550-km range between a source and a horizontal towed array (∼100 m aperture). The low input signal-to-noise ratio (SNR) (e.g., -10 dB) at an element level required conventional beamforming to enhance the SNR of the communication signals for subsequent channel equalization and decoding. This paper demonstrates that with a larger aperture (∼200 m), multiple adjacent beams can be exploited to further improve the communication performance, achieving an almost error-free data rate of 100 bits/s for QPSK modulation at ∼550 km range.