暂态信号形成的参量阵声场特性

Parametric Array’sAcoustic Characteristics Generated by Transient Signal

摘要:

暂态参量阵技术容易获得低频宽带信号,是诸多声呐系统广泛使用的信号模式。在众多描述非线性声波 传播的理论模型中,KZK方程能够准确地描述有限振幅声波传播的衍射、吸收及非线性效应,是描述参量阵非线性 声场最为精确的方程之一。文章从KZK方程的时域求解出发,对常见暂态信号自解调形成的参量阵进行分析。 理论研究表明,暂态信号参量阵的声场特性主要与信号包络的载波、上升沿有直接关系。高斯包络脉冲的上升沿 越陡峭,相同轴向位置的低频分量幅值越大,相同峰值功率前提下的能量转换效率越高；当被调制载波的中心频率 一致时,正线性调频信号调制得到的参量阵声压幅值要略高于负线性调频信号。文章可为暂态信号参量阵的辐射 波形选择提供初步的理论指导。

Abstract:

Transient parametric array technology was easy to obtain the low-frequency broadband signal, so it was widely used in many sonar system. In many theoretical model for describing nonlinear propagation of the sound waves, KZK equa? tion can accurately describe the diffraction, absorption and nonlinear effect of the finite amplitude wave. Based on the time domain solution of the KZK equation, in this paper, the parametric array that generated by the common transient signals was analyzed. The theoretical study showed that the acoustic field characteristic of the transient signal parametric array was mainly related to the carrier wave and the rising edge of the signal envelope. The steeper of Gaussian envelope pulse rising edge, the larger of the low-frequency components amplitude at the same axial position, the higher of the energy con version efficiency that with the same peak power. When the center frequency of the modulated carrier was consistent, the sound pressure amplitude of the transient parametric array obtained by the positive linear frequency modulation (LFM) was slightly higher than negative LFM signal. This paper could provide a theoretical guide for the selection of the radiation waveform of the transient signal parameter array.