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Communication Dans Un Congrès Année : 2020

Digital-Analog conversion in acoustic domain using a Digital Parametric Array

Résumé

A Digital Acoustic Projector (DAP) is a hybrid sound system combining the physical principles of both digital loudspeaker and parametric array to directly convert a digital electrical signal to an analog acoustic one. This DAP is composed of a set of ultrasonic transducers driven by a n-bit digital electric audio signal. Each bit of the digital signal drives a group of ultrasonic transducers: When the value of the bit is equal to zero, the associated group of ultrasonic transducers does not emit any signal. When the value of the bit is equal to 1, it emits a high frequency sinusoidal acoustic signal the frequency of which is denoted fc. Thus, the total signal emitted by the DAP is an ultrasonic carrier signal the amplitude of which is modulated by the sampled and quantized audio signal. Consequently, the frequency content of the low-frequency modulating signal is shifted to a higher frequency band centered around the carrier frequency fc. The amplitude of the emitted sound beam is sufficiently high to cause a distortion of the waveform during its propagation. This distortion is responsible for the generation of sound the frequency content of which corresponds to the frequency differences between the sideband components and the carrier frequency. Such a process, also called self-demodulation, is the basis for the operation of parametric arrays. It is used for DAP to demodulate the amplitude modulated radiated soundwave. Thus, the sampled and quantized audio signal is demodulated and audible signal is restored. This presentation will focus on both development and experimental characterization of such a DAP, and solutions for sound quality improvements will be explored.
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Dates et versions

hal-03231879 , version 1 (26-05-2021)

Identifiants

Citer

Pierrick Lotton, Gautier Gillot, Philippe Béquin, Libor Husnik, Antonin Novak. Digital-Analog conversion in acoustic domain using a Digital Parametric Array. Forum Acusticum, Dec 2020, Lyon, France. pp.2543-2543, ⟨10.48465/fa.2020.0735⟩. ⟨hal-03231879⟩
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