IEC 62092 pdf download.Utrasonics – Hydrophones – Characteristics and calibration in the frequency range from 15 MHz to 40 MHz
This International Standard is applicable to • hydrophones employing piezoelectric sensor elements, designed to measure the pulsed and continuous-wave ultrasonic fields generated by ultrasonic equipment; • hydrophones used for measurements made in water and in the frequency range between 1 5 MHz and 40 MHz; • hydrophones with or without an integral amplifier; • hydrophones with a circular piezoelectrically active element. This International Standard specifies • relevant hydrophone characteristics; • methods of determining directional response and hydrophone sensitivity based on relative or comparative measurements; and describes • absolute hydrophone calibration methods. Recommendations and references to accepted literature are made for the various relative and absolute calibration methods in the frequency range covered by this International Standard.
For the purposes of this International Standard, the following definitions apply. 3.1 acoustic centre the point on or near a transducer from which the spherically divergent sound waves emitted by the transducer, and observable at remote points, appear to diverge [definition 3.3 of IEC 60866] 3.2 beam-alignment axis used for alignment purposes only, beam-alignment axis is a straight line joining two points of spatial-peak temporal-peak acoustic pressure on two hemispherical surfaces whose centres are at the approximate geometrical centre of an ultrasonic transducer or ultrasonic transducer element group. One hemisphere has a radius of curvature of approximately πλ g A , where g A is the geometrical area of the ultrasonic transducer or ultrasonic transducer element group and λ is the wavelength of the ultrasound corresponding to the nominal frequency. The second hemisphere has a radius of curvature either πλ g 2 A , or πλ 3 g A , whichever is the more appropriate. For the purposes of alignment, this line may be projected to the face of the ultrasonic transducer or ultrasonic transducer element group. For most practical applications, two plane surfaces perpendicular to the direction of propagation of the ultrasound are used. In cases where a unique peak is not located on a hemispherical surface, another hemispherical surface is chosen with a different radius of curvature yielding a unique peak [definition 3.5 of IEC 61 1 02] 3.3 directional response directional response of a hydrophone description, generally presented graphically, of the response of a hydrophone, as a function of direction of propagation of the incident plane sound wave, in a specified plane through the acoustic centre and at a specified frequency [definition 3.1 2 of IEC 60866] 3.4 effective radius effective radius of a hydrophone active element radius of a stiff disc receiver hydrophone which has a predicted directional response function with an angular width equal to the observed angular width. The angular width is determined at a specified level below the peak of the directional response function. For the specified levels of 3 dB and 6 dB, the radii are denoted by 3 a and 6 a respectively [definitions 3.4 of IEC 61 1 01 and 3.1 3 of IEC 61 1 02] Symbols: a , 3 a , 6 a Unit: metre, m 3.5 electric load impedance electric input impedance (consisting of a real and an imaginary part) to which the hydrophone unit output cable is connected or is to be connected3.6 end-of-cable loaded sensitivity end-of-cable loaded sensitivity of a hydrophone ratio of the instantaneous voltage at the end of any integral cable or connector of a hydrophone, when connected to a specified electrical input impedance, to the instantaneous acoustic pressure in the undisturbed free field of a plane wave in the position of the acoustic centre of the hydrophone if the hydrophone were removed [definitions 3.5 of IEC 61 1 01 and 3.1 4 of IEC 61 1 02, modified] Symbol: L M Unit: volt per pascal, V/Pa 3.7 end-of-cable open-circuit sensitivity end-of-cable open-circuit sensitivity of a hydrophone ratio of the instantaneous open-circuit voltage at the end of any integral cable or connector of a hydrophone to the instantaneous acoustic pressure in the undisturbed free field of a plane wave in the position of the acoustic centre of the hydrophone if the hydrophone were removed [definition 3.1 5 of IEC 61 1 02, modified] Symbol: c M Unit: volt per pascal, V/Pa