VNIIFTRI’S tasks at the COOMET 786/RU/19 comparisons and approaches to their solution

A.E. Isaev, A.M. Polikarpov, B.I. Khatamtaev

FSUE “VNIIFTRI”, Mendeleevo, Moscow region, Russia,

Al’manac of Modern Metrology № 3 (27) 2021, pages 62–84

Annotation. Approaches to the construction of a hydrophone model, consisting of a “line of outpacing” and a minimum-phase part that including the effect of sound diffraction and the resonance properties of an active element, are proposed. This model makes it possible to use the Hilbert transform to obtain the phase response from the frequency response and the frequency response from the phase response, as well as to apply the methods of complex fractional-rational approximation to analytically representation the hydrophone sensitivity complex frequency response using data on its frequency response and/or minimum-phase response. Approbation of the proposed approaches at COOMET 786/RU/19 comparisons will allow not only testing the methods of their application, but will also provide additional ways to identify and assess sources of calibration uncertainty.

Key words: hydrophone phase calibration, minimum-phase frequency response, Hilbert transform, complex fractional-rational approximation.

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