A Novel Modulation Approach Based on Nonlinear Acoustic Signals for Underwater Communications

Abstract

Nonlinear acoustics is the catalyst of a new generation of applications that are being exploited in different fields. The parametric nonlinear effect, i.e. the appearance of extra harmonics in the spectrum besides the fundamental frequency is a particular feature in nonlinear acoustic and it can be used in the field of communications. In this sense, the study of modulation is an essential aspect that suits the needs of nonlinear acoustic communications. This paper presents a novel technique of nonlinear parametric modulation-induced harmonics. This type of modulation provides a narrow directivity using low transmission frequencies (2 to 50 kHz). Its feasibility and the parametric effect are demonstrated by analyzing a recorded 16-bit parametric signal and its spectrogram. Finally, detection performance is shown by applying cross-correlation to the received signal.