Determination of a reflecting surface by Hilbert transform method

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概要

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• A new method for measuring a delay time is proposed. If an observed signal is regarded as an output signal of a minimum phase system with delay, its delay time can be estimated by use of the Hilbert transform relationship between the log magnitude and phase of the transfer function of the minimum phase system. Discussions are mainly focused on practical cases where the observed signal is band limited. A procedure for extrapolating the frequency characteristics of the signal is also presented to minimize the estimation error due to the bandwidth limitaion. The method is applied to measure the boundary location of acoustic materials whose reflection characteristics are minimum phase. The estimation error less than +-0. 7mm in distance is achieved when the test signal of 5 kHz bandwidth is used. As an example, the location of the reflecting surface of a gravel layer is estimated. Using this result, the acoustic impedance of gravel is computed.

• 社団法人日本音響学会の論文

著者

• Miki Yasushi

  Faculty Of Engineering Takushoku University

関連論文

• Acoustical properties of porous materials : Generalizations of empirical models
• Determination of a reflecting surface by Hilbert transform method
• Acoustical Properties of porous materials : Modifications of Delany-Bazley models

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