Ray-tracing-based time-domain wideband fractional delay beamforming for underwater acoustic positioning

Haipeng Li,Qingdong Yuan,Xuebin Wang,Yingyuan Wu,V Goussev,J Yin

doi:10.1051/matecconf/201928305001

Abstract

Underwater acoustic positioning systems are essential for underwater vehicles positioning and navigation. In this paper, a time-domain wideband fractional delay beamforming (WFDB) technique is proposed to improve underwater localization capability of planar arrays. In our method, digital delay lines are combined with adaptive-finite-impulse-response filters to achieve high accuracy beamforming results and reduce the design burden of the WFDB systems. Further, the beamforming results are used in the ray-tracing method to eliminate curvature effect of sound rays caused by the inhomogeneity of water, and therefore improving the computation accuracy of target position. We further develop a hexagonal planar array of 30 elements to verify the WFDB method in an indoor experimental pool. The experimental results demonstrate that the proposed method could successfully mitigate the ray bending problem and accurately estimate the position of targets in low SNR condition.

Highlights

The sound wave is the most effective carrier for underwater information transmission [1,2]
When the steering angle is aligned with the incident angle of the signal, the signals are coherently summed while the noise are not which resulting in a higher signal-to-noise radio (SNR) at the output compared with the input SNR[10]
We propose a ray-tracing-based timedomain wideband fractional delay beamforming for Underwater acoustic positioning systems (UAPSs)

Summary

Introduction

The sound wave is the most effective carrier for underwater information transmission [1,2]. We apply the beamforming result as an initial grazing angle for raytracing to eliminate the curvature effect of the sound trajectory caused by the inhomogeneity of water, which is the main factor that influences the computation accuracy of target position. We propose a ray-tracing-based beamforming method, which combines CBF with raytracing to obtain the advantages of each method, for UAPSs. We first apply CBF, which combines digital delay line with adaptive FIR filter to get precise spatial direction-of-arrival (DOA). We apply the DOA as an initial grazing angle for ray-tracing to eliminate the curvature of the wave trajectory caused by the inhomogeneity of water, after that the position of target can be calculated with improved accuracy.

Ray-tracing-based beamforming

DOA estimation

Performance of the method in different SNR

Conclusions