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A Study on the Underwater Acoustic Communication with Direct Sequence Spread Spectrum

Spread spectrum techniques are used in communication systems to provide low probability of intercept and jamming, to overcome the channel where the transmitted signal is distorted by multipath propagation. In this paper, we consider spread spectrum modulation and demodulation techniques to overcome the inter symbol interference (ISI) by multipath propagation in underwater acoustic communication channels. We consider the quadrature phase shift keying (QPSK) direct sequence spread spectrum (DSSS). We confirm the performance of underwater acoustic communication by the simulation with underwater channel impulse response and experiment in underwater. As a result, the QPSK-DSSS technique presented low bit error rate (BER) than QPSK.