Direct sequence spread spectrum based modem for under water acoustic communication and channel measurements

An underwater acoustic communication system based on direct-sequence spread-spectrum signaling is presented. The method is intended for use in multiple-access underwater communication networks. In this paper, the transmitter and receiver designs are proposed, discussed, and demonstrated using real data. At the receiver, a RAKE filter is employed. The same signaling scheme is also used to obtain an adaptive estimate of the time-varying channel coefficients. The channel estimator performance is demonstrated using simulations and experimental data.