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报道了一种含侧腔的机械抗混叠声低通滤波光纤水听器.基于电-声类比理论建立了该光纤水听器的低频集中参量模型,画出了声学等效电路图,利用电路分析方法给出了声压传递函数表达式,并对其声学特性进行了理论分析.研究表明,该光纤水听器具有三个共振频率,由于侧腔的引入使得传递函数出现了一个零点,从而加快了第二个共振频率之后的衰减速度,可以获得更好的高频整体衰减特性.在充水驻波罐中对自行设计并制作的含侧腔的声低通滤波光纤水听器进行了测试.在50—7000Hz频段上,该光纤水听器的声压灵敏度频响曲线与理论结果具有大致相同的变化形式,低频响应非常符合,声压灵敏度约为-140dB(0dB=1rad/μPa),受低频模型精度的限制,高频响应差异较大.这为解决光纤水听器的高频混叠问题提供了一条简单可行的技术途径.
A mechanically anti-aliasing acoustic low-pass filtered fiber hydrophone with side cavity is reported.The low-frequency lumped parameter model of the hydrophone is established based on the electro-acoustic analogy theory and the acoustic equivalent circuit diagram is drawn. The analytical method gives the expression of the sound pressure transfer function and analyzes its acoustic characteristics theoretically.The results show that the fiber hydrophone has three resonance frequencies and the transfer function appears a zero point due to the introduction of the side cavity, The decay rate after the second resonant frequency can achieve better overall attenuation characteristics of high frequency.The side cavity acoustic low pass filter fiber hydrophone designed and fabricated in water filled standing wave tank was tested In the 50-7000Hz band, the frequency response curve of the sound pressure sensitivity of this hydrophone shows roughly the same change as the theoretical result, and the low frequency response is in good agreement with the sound pressure sensitivity of -140dB (0dB = 1rad / μPa) Due to the limitation of the accuracy of the low-frequency model, the high-frequency response varies greatly, which provides a simple and feasible technical solution to the high-frequency aliasing problem of the fiber hydrophone.