A method for selecting a proper modulation technique for the parametric acoustic array

Farias, Felipe S.; Abdulla, Waleed H.

doi:10.1088/1742-6596/1075/1/012035

Cited by 6 publications

(2 citation statements)

References 7 publications

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“…Furthermore, the dual frequency PA needs to be produced as a special sound source to ensure that two high-frequency signals of strong output are collimated, while the broadband PA has the advantage of being a high-frequency sound source that can output a strong signal. Recently, studies have been conducted on a modulation technique of primary signal of broadband PA [ 29 , 30 , 31 ].…”

Section: Fundamental Principle Of the Parametric Arraymentioning

confidence: 99%

Comparative Experimental Investigation on Optimal Parametric Array Types

Jung

Song

Kim

et al. 2021

Sensors

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As a sound transmitting device that relies on the nonlinearity of a medium, a parametric array (PA) can generate high-directivity low-frequency signals using a small aperture transducer and high-frequency signals. Despite their relatively low source level, the PA is frequently used to measure the acoustic properties of materials in low-frequency regions owing to their high directivity in confined acoustic water tanks. Therefore, methods for improving the source level of secondary signals are of interest. Currently, there are two driving methods for PA: the dual-frequency PA and the broadband PA with amplitude modulation. In this study, we share the results of an elaborate and comparative experimental investigation of these two driving methods. Comparisons are made and discussed in terms of the intensity of the generated secondary signal and its characteristics in the frequency domain. Based on these factors, we confirmed that the broadband PA was more suitable as the sound source of the low-frequency characteristic measurement system of acoustic materials.

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Section: Fundamental Principle Of the Parametric Arraymentioning

confidence: 99%

Comparative Experimental Investigation on Optimal Parametric Array Types

Jung

Song

Kim

et al. 2021

Sensors

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show abstract

“…Various preprocessing techniques have been developed to reduce distortion using different modulations of the envelope E(t). Existing experimental measurements [8][9][10] are mostly based on the total harmonic distortion or at certain representative frequencies, which may not completely capture the non-linear response of the speakers. Here, we present an extensive comparison of the different amplitude modulation techniques under various modulation indices in terms of frequency response, harmonic distortion and intermodulation distortion.…”

Section: Introductionmentioning

confidence: 99%

Experimental Evaluation of Distortion in Amplitude Modulation Techniques for Parametric Loudspeakers

et al. 2020

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Parametric loudspeakers can generate a highly directional beam of sound, having applications in targeted audio delivery. Audible sound modulated into an ultrasonic carrier will get self-demodulated along the highly directive beam due to the non-linearity of air. This non-linear demodularization should be compensated to reduce audio distortion, different amplitude modulation techniques have been developed during the last years. However, some studies are only theoretical whereas others do not analyze the audio distortion in depth. Here, we present a detailed experimental evaluation of the frequency response, harmonic distortion and intermodulation distortion for various amplitude modulation techniques applied with different indices of modulation. We used a simple method to measure the audible signal that prevents the saturation of the microphones when the high levels of the ultrasonic carrier are present. This work could be useful for selecting predistortion techniques and indices of modulation for regular parametric arrays.whereand ω are the amplitude and the angular frequency of the carrier, and ( ) is the 4 This dependence implies that the self-demodulated wave ( ) is not linear to ( ) and that it will 5 suffer from high levels of distortion due to the generated harmonics and a strong low-pass 6 equalization. 7 Various preprocessing techniques have been developed to reduce distortion using different 8 modulations of the envelope ( ). Existing experimental measurements [8-10] are mostly based on 9 the total harmonic distortion or at certain representative frequencies, which may not completely 10 capture the non-linear response of the speakers. Here, we present an extensive comparison of the 11 different amplitude modulation techniques under various modulation indices in terms of frequency 12 response, harmonic distortion and intermodulation distortion. This study analyzes the 13 intermodulation distortion and the harmonics distortions of the different amplitude modulation 14 techniques for various modulation indices. Furthermore, the analysis is split by order. To avoid the 15 presence of spurious signal in the measurements, our method previously selects a dynamic 16 microphone with limited frequency response.

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Directivity Analysis of Ultrasonic Array in Directional Sound System

Zhao

Long

2021

Intelligent Robotics and Applications

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A method for selecting a proper modulation technique for the parametric acoustic array

Cited by 6 publications

References 7 publications

Comparative Experimental Investigation on Optimal Parametric Array Types

Comparative Experimental Investigation on Optimal Parametric Array Types

Experimental Evaluation of Distortion in Amplitude Modulation Techniques for Parametric Loudspeakers

Directivity Analysis of Ultrasonic Array in Directional Sound System

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