Parametric Array Using Amplitude Modulated Pulse Trains: Experimental Evaluation of Beamforming and Single Sideband Modulation

Paper in proceeding, 2021

We present a parametric array system realized with a microcontroller and MOSFET drivers. Pulse train signals with fundamental frequency of 40 kHz are generated by the microcontroller. The pulse trains are amplitude modulated by exploiting the switching mechanism of the MOSFETs. The higher-order harmonics are attenuated by the band-pass characteristic of the ultrasonic transducers, emitting only the carrier frequency and the sideband components. The sound beam can be steered by applying phase shifts to the pulse signals, which can be implemented by relatively inexpensive hardware. A new single sideband modulation is also introduced, where the upper sidebands of two double sideband modulation signals are acoustically cancelled. The proposed approaches for beamforming and single sideband modulation are evaluated by anechoic measurements.