Amplitude and phase calibration of hydrophones by heterodyne and time-gated time-delay spectrometry.

Two methods for the amplitude and phase calibration of hydrophones based on time-delay spectrometry are presented: a time-gating technique and heterodyne frequency conversion that allows the phase-locked (i.e., coherent detection) of hydrophone signals. Amplitude and phase of the hydrophone sensitivity are obtained in the frequency range 1-20 MHz. In addition, to show the broad-band capabilities of the methods, amplitude values are measured between 4 and 50 MHz.