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The Measurement Backscatter Coefficient from a (从一个测量后向散射系数).pdf

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IEEE TRANSACTIONS O N ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL, VOL. 44, NO. 2, MARCH 1997 515 The Measurement of Backscatter Coefficient from a Broadband Pulse-Echo System: A New Formulation Xucai Chen, Dan Phillips, Karl Q. Schwarz, Jack G. Mottley, and Kevin J. Parker, Fellow, IEEE Abstract-A new formulation for obtaining the abso- echo measurements. This formulation uses simple func- lute backscatter coefficient from pulse-echo measurements tions with tractable approximations which are, in some is presented. Using this formulation, performing the diffrac- instances, simple constants. In Section 11,the sonar equa- tion correction and system calibration is straightforward. tions for a single scatterer as well as a distribution of scat- The diffraction correction function for the measurement of terers are derived. The diffraction correction function is backscatter coefficient and the acoustic coupling function for a pulse-echo system are defined. Details of these func- defined. The effect of the attenuation is includedl by using tions for two very useful cases are presented: a flat disk complex wave numbers and is elaborated in Appendix B. transducer and a spherically focused transducer. Approxi- System calibration is discussed, and the acoustic coupling mations of these functions are also provided. For a flat disk correction coefficient is defined. In Section 111,the diffrac- transducer, the final formulation appears as a modification to
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