Research And Design Of Acoustic Parametric Array Development Platform Based On PXIe And ELVIS ?~+

Acoustic parametric array is a new type of loudspeaker,which can emit audio signal to a specified direction.It is a research hotspot in recent years and has broad application prospects in the fields of broadcasting and communication.The acoustic parameter array loads the audio signal to the ultrasonic carrier through the amplitude modulation method and the modulated signal is emitted to the air by the ultrasonic transducer.Due to the nonlinear effect of air,the audio signal will be self-demodulated continuously and form a strong directional sound beam along the direction of signal propagation.The research of acoustic parameter array involves basic theories such as communication,signal processing,acoustics and technical fields such as DSP,electronics and electroacoustics,as well as nonlinear acoustics and nonlinear signal processing.Its research and development work is heavy,difficult.In view of this situation,this Thesis,based on the analysis and research of the basic theory and key technologies of acoustic parametric array,designs a development platform of acoustic parametric array based on the virtual instrument PXI Express(PXIe)and ELVIS II+of NI company.The main work contents are as follows:(1)On the basis of Berktay far-field solution,signal preprocessing,DSB modulation,RMS modulation,S SB modulation and other parametric array algorithms are described and analyzed.(2)The hardware platform for measuring and analyzing the sound field of acoustic parametric array is designed and built.It is composed of virtual instrument PXIe,NI PXIe-4499 acquisition card,broadband measurement microphone,sound calibrator,etc.It can collect sound signals from audio frequency to 100kHz and measure and analyze audio signals generated by ultrasonic carrier and parameter array at the same time.(3)The software for measuring and analyzing the sound field of acoustic parametric array is designed and programmed.The software is based on Lab VIEW language,including data acquisition,data processing,man-machine interface and other modules.The functions of audio and ultrasonic signal acquisition,sound pressure level calculation,waveform display,sound field drawing,data storage and signal playback are realized.(4)The hardware platform for generating sound field of acoustic parametric array is designed and built.It is composed of PC,virtual instrument suite NI ELVIS ?+,ultrasonic power amplifier,ultrasonic transducer array,etc.The modulated signal can be generated and emitted into the air by the ultrasonic power amplifier and the ultrasonic transducer array to form the sound beam.(5)The software for generating acoustic parametric array signals is designed and programmed.The software is based on LabVIEW language,including audio signal generation,signal preprocessing,signal modulation,modulation signal output,man-machine interface and other modules.The function of audio signal generation and modulation signal output module is solidified,and other modules can be modified according to different design schemes and algorithms.(6)The acoustic parametric array is experimentally studied by using the sound parametric array development platform Three kinds of signal modulation algorithms are measured and analyzed experimentally.The influence of modulation index on acoustic parameter array is analyzed by experiment.The directivity of single frequency expected signal demodulated by acoustic parametric array is analyzed by experiment.The development platform of acoustic parametric array designed in this thesis can flexibly realize signal preprocessing and modulation algorithm,generate sound source of parametric array,and collect self-demodulation signal for data processing and analysis,which provides favorable condition for the research of acoustic parametric array signal processing algorithm.