Phase-shifted Sensitivity Calibration of Fiber Optic Vector Hydrophone Based on Heterodyne Method

In order to realize the calibration of fiber optic vector hydrophone with wide frequency band and large dynamic range, the research on the phase-shifted sensitivity calibration technology of fiber vector hydrophone based on heterodyne method has been carried out. The heterodyne-arctangent demodulation simulations were performed on signals with a large amplitude of 120 rad or a high frequency of 50 kHz respectively, which verified that the demodulation algorithm has the ability to demodulate signals with a wide frequency band or a large dynamic range. A phase-shifted sensitivity calibration system based on the heterodyne method was developed, and the standing wave tube comparison method was used to calibrate the phase-shifted sensitivity of fiber optic vector hydrophones in the frequency band of 20 Hz to 1.25 kHz. Below the resonant frequency of the fiber optic vector hydrophone, the maximum difference between the calibration result and the theoretical calculation result is 1.2 dB, and the measurement uncertainty of the calibration system is 1.5 dB (k = 2).