Bearing estimation for optical fiber vector hydrophone with in-band resonance

The accelerometer-type optical fiber vector hydrophone (OFVH) shows resonance in its frequency response due to the mass-spring structure of the accelerometer. To avoid signal distortion, the usable frequency band of an OFVH is usually limited to far below the resonant frequency. Increasing the resonant frequency would extend the frequency band but at the expense of decreased hydrophone sensitivity. This paper points out that for bearing estimation, the out-of-band frequency components of the OFVH output are usable, which leads to efficient utilization of the OFVH signal and enhancement of target detection performance in some circumstances. A modification of the intensity-based algorithm, along with calibrations based on the simple oscillator model, are given for the bearing estimation in this paper. The analysis are confirmed by results of lake experiments using an acoustic source, a fixed pump and a small ship. (C) 2019 Elsevier Ltd. All rights reserved.