A SELF-RECIPROCITY CALIBRATION OF A RESONANT TRANSDUCER BY IMPEDANCE MEASUREMENTS UNDER HIGH HYDROSTATIC PRESSURE
1977 Volume 4 Issue Supplement Pages 78-86
Details
1977 Volume 4 Issue Supplement Pages 78-86
It was verified that a self-reciprocity calibration by impedance measurements employing a metal plate in a high hydraulic pressure tank as a sound wave reflector can provide easy calibration of a resonant transducer in the high frequency range under high hydrostatic pressure by measuring the transmitting and the receiving voltage responses of the high pressure transducer under hydrostatic pressure from atmospheric pressure to 630 kgf/cm2.
The measured value of the high pressure transducer response obtained by the self-reciprocity calibration corresponds to the measured value through the reciprocity calibration within 1 dB precision. Further, it is confirmed that the variation in characteristics that the frequency of the maximum transmitting and maximum receiving voltage responses measured by the self-reciprocity calibration increases by approximately 1.5 kHz under hydrostatic pressure of 630 kgf/cm2, which corresponds to variation in the resonant frequency and the anti-resonant frequency of the free field impedance loop.
