Underwater acoustic communication based on noise similar chaotic modulated signals

This paper presents a proposal for a new chaotic-based underwater acoustic modulation scheme. The proposed method is a differential chaotic shift keying modulation based on the Lorenz attractor. Unlike conventional techniques that use Chirp signals, synchronization is achieved using a chaotic signal. In the demodulator, a Doppler shift compensator is also implemented, capable of compensating shifts up to 10 m/s. This compensator is based on bank of Doppler shifts. In order to see the influence of underwater acoustic channel on the proposed acoustic signal, the simulations are performed. The channel was modeled by adding white Gaussian noise with a signal-to-noise ratio (SNR) ranging from -5 dB to 20 dB, multipath propagation with 7 received waves, and the Doppler effect with a speed of ±10 m/s.The experimental verification of the proposed waveform was conducted in an anechoic tank at the SEA Laboratory at the University of Newcastle, as well as during sea trials in Kumbor, Montenegro. The experiments tested the influence of high impulsive noise generated by crustaceans and the presence of high noise generated by vessels. Simulation results and experimental verification demonstrated that the proposed modulation technique is resistant to underwater noise, both Gaussian and impulsive, and is suitable for operation in complex channels with significant multipath fading and attenuation. Furthermore, it offers the advantage of being environmentally friendly.