DIN EN IEC 62127-2:2025-11

This part of the IEC 62127 series of standards specifies: - absolute hydrophone calibration methods; - relative (comparative) 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 document. This document is applicable to - hydrophones used for measurements made in water and in the ultrasonic frequency range up to 100 MHz; - hydrophones employing piezoelectric sensor elements, designed to measure the pulsed wave and continuous wave ultrasonic fields generated by ultrasonic equipment; - hydrophones with or without a hydrophone pre-amplifier. Although some physiotherapeutic medical applications derive from medical ultrasound that operates in the frequency range of 40 kHz to 100 kHz, the primary frequency range for diagnostic imaging remains above 2 MHz. Recently it has been determined that even in the latter case the hydrophone response can influence measurements of key acoustic parameters at significantly lower frequencies. Calibration procedures for underwater acoustic hydrophones, applicable in the frequency range from 200 Hz to 1 MHz, are available in IEC 60565-1, and for frequencies from 0,01 Hz to several kHz in IEC 60565-2. Some hydrophones may have non-circular active elements that result from slight deviations from a circular structure; or conversely, the active elements may actually be square. The clauses of this standard remain valid although in these cases special attention should be paid to the directional characteristics and the effective radii of the active element with respect to various axes of rotation. The standard differs from DIN EN 62127-2:2018-02 as follows: a) the upper frequency limit of 40 MHz has been removed; b) hydrophone sensitivity definitions have been changed to recognize sensitivities as complex-valued quantities; c) directional response measurement and effective size determination procedures have been updated in 12.5.1 to align with recent changes in IEC 62127-3; d) Annex F has been amended to comprise a calibration technique for high-frequency complex-valued calibration; e) the reciprocity method description in Annex K has been extended to also comprise focusing transducers. This standard applies to: hydrophones used for measurements made in water and in the ultrasonic frequency range up to 100 MHz; - hydrophones employing piezoelectric sensor elements, designed to measure the pulsed wave and continuous wave ultrasonic fields generated by ultrasonic equipment; - hydrophones with or without a hydrophone pre-amplifier.