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海底沉积物作为海洋波导声传播的下边界普遍存在于大洋中,获知其特性对于准确的声传播和混响建模是十分必要的。为了能够快速而准确地测量沉积物中的声速和衰减系数,提出一种基于脉冲压缩技术的测量方法,对接收信号进行压缩来提取透射波,根据不同厚度样品的透射波来计算沉积物中的声速和衰减系数。该方法不仅可以克服实验过程中经常遇到的多途干扰,而且测量过程简单,可以同时获得测量频带内所有频点的声速和衰减系数,即实现了对声速和衰减系数的宽带测量。在实验室环境条件下,90~170 kHz的测量频带内,测得沙样品中的声速为1710~1713 m/s,衰减系数在56~70 dB/m之间。通过窄带和宽带测量结果的比较可以看出,声速的宽带测量结果与窄带测量结果吻合得较好,而衰减系数在频带后半部分存在较大的起伏。
The lower boundary of ocean floor sediment, which is the sound of ocean wave guide, is commonly found in the ocean. It is necessary to know its characteristics for accurate acoustic propagation and reverberation modeling. In order to measure the velocity of sound and attenuation in sediment quickly and accurately, a measurement method based on pulse compression technique is proposed. The transmitted signal is extracted by compressing the received signal. The transmitted waves of different thickness samples are used to calculate the Sound velocity and attenuation coefficient. The method can not only overcome the multipath interference often encountered in the experiment, but also has a simple measurement process. The sound velocity and the attenuation coefficient of all frequency points in the measurement band can be obtained at the same time, that is, the broadband measurement of the sound velocity and the attenuation coefficient is achieved. Under laboratory conditions, the sound velocity in sand samples was 1710-1713 m / s and the attenuation coefficient was between 56-70 dB / m in the 90-170 kHz measurement band. Through the comparison of narrowband and wideband measurement results, it can be seen that the broadband sounding velocity measurement is in good agreement with the narrowband measurement, while the attenuation coefficient has larger fluctuation in the latter half of the band.