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Detection of underwater buried objects requires low-frequency wave as the detecting source and high-resolution imaging. Taken these into account, this paper proposes a method to process the linear frequency modulated signal (LFM) based on parametric array theory. The distortion of the LFM demodulated by the parametric array and corresponding matched filter are studied by numerical method. The numerical...
Coupled extensional and flexural vibrations of an ultrasonic piezoelectric transducer are studied in the paper. The ultrasonic piezoelectric transducer is made of piezoelectric polymer PVDF films and modeled as a corrugated cylindrical shell with a finite width in the ridge direction, which consists of multiple pieces of circular cylindrical surfaces smoothly connected along their ridges. The classical...
The acoustic boundary element method is applied to solve the Helmholtz boundary integral equation for the sound field problem in the exterior region. Basing on the acoustic boundary element method, the SYSNOISE software is used to numerically calculate the far field sound pressure in the exterior region of piezoelectric micromachined ultrasound transducer array. On the other hand, according to given...
This paper presents a novel piezoelectric micromachine ultrasound transducer (pMUT), consisted Pb(Zr,Ti)O3 (PZT) film on silicon membrane. The proposed micro-transducer is applied in an audio beam loudspeaker for mobile communication devices. At present, most of the portable productspsila energy supply are provided by battery, so the power consumption of the pMUT has been attracted more attention...
According to the Hilbert transform properties, the self-demodulated signalpsilas distortion of the single side band (SSB) method for parametric loudspeaker is analyzed theoretically by employing the orthogonal envelope detection method. It is proved that there is no distortion in the self-demodulated signal of the single side band method when a single-frequency signal is inputted, but the distortion...
The paper describes a method to estimate the power consumption of miniature audio directional transducer using KZK equation according to a larger transducer with the same structure and the same material. A theoretical analysis of sound propagation and sound power for concave-convex cylindrical transducers is presented, which are made by PVDF film of 28 mum with two-sided silver ink of 10 mum at each...
Aimed at solving the harmonic distortion problem of the DSB (Double Side Band) method which is employed in audio directional loudspeaker, an improved amplitude modulation (AM) method is investigated. According to the parametric acoustic array principle and self-demodulation theory, the theoretical self-demodulation model of the improved AM method is established, and a conclusion that the variational...
Audio beam system is a revolutionary way of projecting audio signal in a highly directional manner to listener. This paper focuses on the power management of audio beam system. A specific loudspeaker, which is fabricated by polyvinylidene fluoride (PVDF), is proposed according to the theory of corrugated structure for PVDF film. Based on the test and analysis results, a unique digital amplifier, Class...
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