The four common ultrasonic methods for measuring Q value in the laboratory, rise time, pulse echo, spectral ration and waveform inversion techniques are reviewed.
回顾了实验室中超声波测量Q值的四种常用方法：上升时间法、回声法、频谱振比法和波形反演法。
The frequency response of the transducers is measured experimentally using laser ultrasound and a pulse echo reflecting method. The spectral analysis results are compared and analyzed.
由激光超声方法和自发自收脉冲反射法实验测定了所制作的换能器的频率响应，并比较了频谱分析结果。
Maximum entropy spectral estimation and LMS adaptive algorithm were proposed to extract the reflection echo signal of laser ranging system.
提出了最大熵谱估计和LMS自适应算法提取激光测距系统的反射回波信号。
Simluation results show that the maximum entropy spectral estimation and LMS adaptive algorithm can extract echo signal of laser ranging system effectively from background noises.
仿真分析表明，最大熵谱估计和LMS自适应算法相结合可以有效地从背景噪声中提取有用的激光反射回波信号。
Based on synthesizing advantages of the pulse echo and spectral ration techniques, a new method, the equivalent acoustic impedance technique is proposed.
在综合了回声法和频谱振幅比法优点的基础上，提出等效声阻抗法。
Based on synthesizing advantages of the pulse echo and spectral ration techniques, a new method, the equivalent acoustic impedance technique is proposed.
在综合了回声法和频谱振幅比法优点的基础上，提出等效声阻抗法。
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