Acoustic Parametric Signal Generation for Underwater Communication

Abstract

This paper presents a study of different types of parametric signals with application to underwater acoustic communications. In all the signals, the carrier frequency is 200 kHz, which corresponds to the resonance frequency of the transducer under study and different modulations are presented and compared. In this sense, we study modulations with parametric sine sweeps (4 to 40 kHz) that represent binary codes (zeros and ones), getting closer to the application in acoustic communications. The different properties of the transmitting signals in terms of bit rate reconstruction, directivity, efficiency, and power needed are discussed as well.

Signal Processing for Parametric Acoustic Sources Applied to Underwater Communication

“…In Figure 10a, it is shown the variable propagation sound speed profile; in Figure 10b, the acoustic field with an omnidirectional source (directivity of ±90 • ); on the Figure 10c, the acoustic field with an directional source of ±10 • . These directivities correspond, referring to previous studies by the authors on the behaviour of the parametric sound field [10], those generated by an Airmar P19 transducer emitting a parametric sweep between 4 and 40 kHz by modulating a 200 kHz carrier.…”

“…In a search for new modulation techniques that allow both temporarily locating each of bits 1 and 0, as well as discriminating between them, sine-sweep modulation is applied by applying parametric sweeps Figure 8 . Given their robustness, these signals are being used recently as non-linear acoustic communication techniques [ 9 , 10 ]. Therefore, these signals will be analyzed by applying the 16-bit string to determine if the correlation detection is still appropriate for this type of signals.…”

“…Subsequently, it has become popular in the field of underwater acoustics as regards the processing of parametric array signals [ 2 , 3 , 4 ]. These parametric acoustic sources are gradually being used in detection sonars and communication sonars in shallow water [ 5 , 6 , 7 , 8 , 9 , 10 , 11 ].…”

Exploring the Parametric Effect in Nonlinear Acoustic Waves

“…However, when the intensity of the input signal is large, or in the case of materials with special properties, a series of new nonlinear effects appear, such as distortion of the acoustic wave shape due to the propagation velocity of the wave as a function of amplitude, generation of upper harmonics, generation of sum and difference frequencies of the emitted signals, among others. Knowledge of nonlinear effects is important for the development of new applications in high-intensity acoustics, since these effects are increasingly used in nondestructive characterization of materials [7], [8], [9], [10], medical acoustics [11], [12] and underwater acoustics [13], [14], [15], [16], [17], [18], [19], [20], [21], [22].…”

Positioning System and Acoustic Studies for the KM3NeT deep-sea neutrino telescope

“…This technique of being able to broadcast low frequencies in a directive (i.e. more directed) way has opened up the possibility of research into new underwater communications techniques [25,26,54,55]. For this second calibration step, two types of parametric signals are defined: sinusoidal and sweep.…”