VNIIFTRI reference base in the field of underwater acoustic measurements: metrological characteristics, functional capabilities, innovations and prospects for improving standards

The updated VNIIFTRI’s underwater acoustic reference base is described. The article provides information about a special multifunctional metrological water tank, an underwater acoustic excess pressure tank, metrological characteristics of reference facilities of state primary standard of units of sound pressure and oscillating velocity in the water media GET 55-2017, state primary standard of the unit of ultrasound power in water GET 169-2019, state primary standard of the unit of sound velocity in liquid media GET 201-2012. A model of a hydrophone as an operational link and a minimum-phase four-terminal network is proposed, the concept of energy sensitivity in frequency bands is introduced, a method for determining the effective size of a hydrophone and obtaining its minimum-phase frequency response of sensitivity is proposed, implemented in GET 55-2017. A method for representing the complex frequency response of sensitivity by a formula is proposed, and requirements for the functionality of a digital metrology platform are formulated. GET 169-2019 is supplemented with two facilities for reproducing units of intensity and pressure of ultrasound in water, which will make it possible to find a comprehensive solution to the problem of metrological support for ultrasound medical and other equipment manufactured and used in Russia. GET 201-2012 is supplemented with a facility for reproducing and transmitting the unit of sound velocity in water using the time-of-flight pulse method with a variable base. The change in the base length is measured using the optical interference method, and the time delay is measured using characteristic points of pulse signals. Prospects for improving primary standards are discussed. Attention is drawn to the problems that have arisen in the participation of the Russia in international comparisons and possible ways to solve them.