Optimal tone detection for optical fibre vector hydrophone

Abstract

An optimal tone detector based on the Neyman-Pearson criterion is proposed for the optical fibre vector hydrophone (OFVH). The detector takes account of the difference between noise levels on the acoustic pressure channel and the three particle acceleration channels of an OFVH. Explicit expressions for the impulse responses of pre-filters that are central to the proposed detector are given. Analyses show that the proposed detector is equivalent to the minimum variance distortionless response beamformer for the OFVH. In the case of identical noise on all particle acceleration channels, the signal-to-noise ratio (SNR) gain of the detector is 101g(1 + μ) dB (μ is the noise power ratio of OFVH channels at the tone frequency), whereas the SNR gain also depends on target direction and is bounded by 101g(1 + μ min ) and 101g(1 + μ max ) dB when noise on all particle acceleration channels are different. Results from both simulations and lake experiment data show that the proposed detector outperforms tone detectors that use (i) the acoustic pressure signal, (ii) the particle acceleration signals and (iii) equally the combination of acoustic pressure signal and particle acceleration signals.