Long-range underwater acoustic information transmission for combining FDM and MFSK

Aimed at the requirement of the long-range underwater acoustic information transmission with the low bit-error rate (BER), the method for combining the frequency division multiplexing (FDM) and the M-ary frequency shift keying (MFSK) is proposed. The transmitter end conducts MFSK modulation in each sub-channel, and transmits carrier frequencies belonged to different sub-channels in parallel. Firstly, the receiver end conducts the periodogram estimation in the frequency domain. Then it takes locations of spectral peaks as carrier frequencies, and conducts the demodulation according to the relationship between the carrier frequency and the transmitted information. Experimental results on the ocean indicate that information of 13.3 bit/s over the 30 km distance is successfully transmitted.