| In shallow water, sea bottom reverberation which is mainly caused by sea bottom scattering, contributes most to sea reverberation. The scattering strength is important parameter of physics which describing the sea bottom scattering. Along with research on bistatic sonar and its application, It is necessary that research on sea bottom scattering strength with different incident and scattered azimuth angles, incident and scattered grazing angle, i.e. sea bottom three-dimensional. Method of measuring sea bottom three-dimensional scattering strength is thoroughly studied in this article.Beginning with the definition of sea bottom scattering strength, a model of calculating sea bottom three-dimensional scattering strength is introduced. According to this model, connections between sea bottom scattering strength and incident grazing angle, scattered grazing angle, bistatic angle and frequency are calculated. It is emphasis that extending and revising the method of measuring sea bottom scattering based on earlier work in this article study. the measuring method which be improved is thoroughly described, as well as the performance figures of every apparatus in the measuring system including the horizontal and vertical directivity of emission arrays, source level, directivity and sensitivity level of reception arrays and so on. Because T-type multiplicative arrays which can obtain space directivity are applied to collecting data and sea bottom scattering strength is calculated through output voltage of T-type multiplicative arrays, Formula of calculating sea bottom three-dimensional scattering strength is deduced based on definition of sea bottom scattering strength. lake bottom scattering strength is obtained by processing lake bottom scattering data with such formula. At last the experiment result and the result using the model of calculating sea bottom three-dimensional scattering strength are compared and analyzed. The result indicated that is matched quite well.
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